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lguest: the host code

Browse Source 
This is the code for the "lg.ko" module, which allows lguest guests to
be launched.

[akpm@linux-foundation.org: update for futex-new-private-futexes]
[akpm@linux-foundation.org: build fix]
[jmorris@namei.org: lguest: use hrtimers]
[akpm@linux-foundation.org: x86_64 build fix]
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Rusty Russell 2007-07-19 01:49:23 -07:00 committed by Linus Torvalds
parent 07ad157f6e
commit d7e28ffe6c
17 changed files with 2703 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/i386/kernel/tsc.c
View File

@ -27,6 +27,7 @@ static int tsc_enabled;
* an extra value to store the TSC freq
*/
unsigned int tsc_khz;
EXPORT_SYMBOL_GPL(tsc_khz);
int tsc_disable;
@ -58,10 +59,11 @@ __setup("notsc", tsc_setup);
*/
static int tsc_unstable;
static inline int check_tsc_unstable(void)
int check_tsc_unstable(void)
{
return tsc_unstable;
}
EXPORT_SYMBOL_GPL(check_tsc_unstable);
/* Accellerators for sched_clock()
* convert from cycles(64bits) => nanoseconds (64bits)

2
arch/x86_64/kernel/tsc.c
View File

@ -44,7 +44,7 @@ unsigned long long sched_clock(void)
static int tsc_unstable;
static inline int check_tsc_unstable(void)
inline int check_tsc_unstable(void)
{
return tsc_unstable;
}

462
drivers/lguest/core.c Normal file
View File

@ -0,0 +1,462 @@
/* World's simplest hypervisor, to test paravirt_ops and show
* unbelievers that virtualization is the future. Plus, it's fun! */
#include <linux/module.h>
#include <linux/stringify.h>
#include <linux/stddef.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/cpu.h>
#include <linux/freezer.h>
#include <asm/paravirt.h>
#include <asm/desc.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/poll.h>
#include <asm/highmem.h>
#include <asm/asm-offsets.h>
#include <asm/i387.h>
#include "lg.h"
/* Found in switcher.S */
extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];
extern unsigned long default_idt_entries[];
/* Every guest maps the core switcher code. */
#define SHARED_SWITCHER_PAGES \
DIV_ROUND_UP(end_switcher_text - start_switcher_text, PAGE_SIZE)
/* Pages for switcher itself, then two pages per cpu */
#define TOTAL_SWITCHER_PAGES (SHARED_SWITCHER_PAGES + 2 * NR_CPUS)
/* We map at -4M for ease of mapping into the guest (one PTE page). */
#define SWITCHER_ADDR 0xFFC00000
static struct vm_struct *switcher_vma;
static struct page **switcher_page;
static int cpu_had_pge;
static struct {
unsigned long offset;
unsigned short segment;
} lguest_entry;
/* This One Big lock protects all inter-guest data structures. */
DEFINE_MUTEX(lguest_lock);
static DEFINE_PER_CPU(struct lguest *, last_guest);
/* FIXME: Make dynamic. */
#define MAX_LGUEST_GUESTS 16
struct lguest lguests[MAX_LGUEST_GUESTS];
/* Offset from where switcher.S was compiled to where we've copied it */
static unsigned long switcher_offset(void)
{
return SWITCHER_ADDR - (unsigned long)start_switcher_text;
}
/* This cpu's struct lguest_pages. */
static struct lguest_pages *lguest_pages(unsigned int cpu)
{
return &(((struct lguest_pages *)
(SWITCHER_ADDR + SHARED_SWITCHER_PAGES*PAGE_SIZE))[cpu]);
}
static __init int map_switcher(void)
{
int i, err;
struct page **pagep;
switcher_page = kmalloc(sizeof(switcher_page[0])*TOTAL_SWITCHER_PAGES,
GFP_KERNEL);
if (!switcher_page) {
err = -ENOMEM;
goto out;
}
for (i = 0; i < TOTAL_SWITCHER_PAGES; i++) {
unsigned long addr = get_zeroed_page(GFP_KERNEL);
if (!addr) {
err = -ENOMEM;
goto free_some_pages;
}
switcher_page[i] = virt_to_page(addr);
}
switcher_vma = __get_vm_area(TOTAL_SWITCHER_PAGES * PAGE_SIZE,
VM_ALLOC, SWITCHER_ADDR, VMALLOC_END);
if (!switcher_vma) {
err = -ENOMEM;
printk("lguest: could not map switcher pages high\n");
goto free_pages;
}
pagep = switcher_page;
err = map_vm_area(switcher_vma, PAGE_KERNEL, &pagep);
if (err) {
printk("lguest: map_vm_area failed: %i\n", err);
goto free_vma;
}
memcpy(switcher_vma->addr, start_switcher_text,
end_switcher_text - start_switcher_text);
/* Fix up IDT entries to point into copied text. */
for (i = 0; i < IDT_ENTRIES; i++)
default_idt_entries[i] += switcher_offset();
for_each_possible_cpu(i) {
struct lguest_pages *pages = lguest_pages(i);
struct lguest_ro_state *state = &pages->state;
/* These fields are static: rest done in copy_in_guest_info */
state->host_gdt_desc.size = GDT_SIZE-1;
state->host_gdt_desc.address = (long)get_cpu_gdt_table(i);
store_idt(&state->host_idt_desc);
state->guest_idt_desc.size = sizeof(state->guest_idt)-1;
state->guest_idt_desc.address = (long)&state->guest_idt;
state->guest_gdt_desc.size = sizeof(state->guest_gdt)-1;
state->guest_gdt_desc.address = (long)&state->guest_gdt;
state->guest_tss.esp0 = (long)(&pages->regs + 1);
state->guest_tss.ss0 = LGUEST_DS;
/* No I/O for you! */
state->guest_tss.io_bitmap_base = sizeof(state->guest_tss);
setup_default_gdt_entries(state);
setup_default_idt_entries(state, default_idt_entries);
/* Setup LGUEST segments on all cpus */
get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
}
/* Initialize entry point into switcher. */
lguest_entry.offset = (long)switch_to_guest + switcher_offset();
lguest_entry.segment = LGUEST_CS;
printk(KERN_INFO "lguest: mapped switcher at %p\n",
switcher_vma->addr);
return 0;
free_vma:
vunmap(switcher_vma->addr);
free_pages:
i = TOTAL_SWITCHER_PAGES;
free_some_pages:
for (--i; i >= 0; i--)
__free_pages(switcher_page[i], 0);
kfree(switcher_page);
out:
return err;
}
static void unmap_switcher(void)
{
unsigned int i;
vunmap(switcher_vma->addr);
for (i = 0; i < TOTAL_SWITCHER_PAGES; i++)
__free_pages(switcher_page[i], 0);
}
/* IN/OUT insns: enough to get us past boot-time probing. */
static int emulate_insn(struct lguest *lg)
{
u8 insn;
unsigned int insnlen = 0, in = 0, shift = 0;
unsigned long physaddr = guest_pa(lg, lg->regs->eip);
/* This only works for addresses in linear mapping... */
if (lg->regs->eip < lg->page_offset)
return 0;
lgread(lg, &insn, physaddr, 1);
/* Operand size prefix means it's actually for ax. */
if (insn == 0x66) {
shift = 16;
insnlen = 1;
lgread(lg, &insn, physaddr + insnlen, 1);
}
switch (insn & 0xFE) {
case 0xE4: /* in <next byte>,%al */
insnlen += 2;
in = 1;
break;
case 0xEC: /* in (%dx),%al */
insnlen += 1;
in = 1;
break;
case 0xE6: /* out %al,<next byte> */
insnlen += 2;
break;
case 0xEE: /* out %al,(%dx) */
insnlen += 1;
break;
default:
return 0;
}
if (in) {
/* Lower bit tells is whether it's a 16 or 32 bit access */
if (insn & 0x1)
lg->regs->eax = 0xFFFFFFFF;
else
lg->regs->eax |= (0xFFFF << shift);
}
lg->regs->eip += insnlen;
return 1;
}
int lguest_address_ok(const struct lguest *lg,
unsigned long addr, unsigned long len)
{
return (addr+len) / PAGE_SIZE < lg->pfn_limit && (addr+len >= addr);
}
/* Just like get_user, but don't let guest access lguest binary. */
u32 lgread_u32(struct lguest *lg, unsigned long addr)
{
u32 val = 0;
/* Don't let them access lguest binary */
if (!lguest_address_ok(lg, addr, sizeof(val))
|| get_user(val, (u32 __user *)addr) != 0)
kill_guest(lg, "bad read address %#lx", addr);
return val;
}
void lgwrite_u32(struct lguest *lg, unsigned long addr, u32 val)
{
if (!lguest_address_ok(lg, addr, sizeof(val))
|| put_user(val, (u32 __user *)addr) != 0)
kill_guest(lg, "bad write address %#lx", addr);
}
void lgread(struct lguest *lg, void *b, unsigned long addr, unsigned bytes)
{
if (!lguest_address_ok(lg, addr, bytes)
|| copy_from_user(b, (void __user *)addr, bytes) != 0) {
/* copy_from_user should do this, but as we rely on it... */
memset(b, 0, bytes);
kill_guest(lg, "bad read address %#lx len %u", addr, bytes);
}
}
void lgwrite(struct lguest *lg, unsigned long addr, const void *b,
unsigned bytes)
{
if (!lguest_address_ok(lg, addr, bytes)
|| copy_to_user((void __user *)addr, b, bytes) != 0)
kill_guest(lg, "bad write address %#lx len %u", addr, bytes);
}
static void set_ts(void)
{
u32 cr0;
cr0 = read_cr0();
if (!(cr0 & 8))
write_cr0(cr0|8);
}
static void copy_in_guest_info(struct lguest *lg, struct lguest_pages *pages)
{
if (__get_cpu_var(last_guest) != lg || lg->last_pages != pages) {
__get_cpu_var(last_guest) = lg;
lg->last_pages = pages;
lg->changed = CHANGED_ALL;
}
/* These are pretty cheap, so we do them unconditionally. */
pages->state.host_cr3 = __pa(current->mm->pgd);
map_switcher_in_guest(lg, pages);
pages->state.guest_tss.esp1 = lg->esp1;
pages->state.guest_tss.ss1 = lg->ss1;
/* Copy direct trap entries. */
if (lg->changed & CHANGED_IDT)
copy_traps(lg, pages->state.guest_idt, default_idt_entries);
/* Copy all GDT entries but the TSS. */
if (lg->changed & CHANGED_GDT)
copy_gdt(lg, pages->state.guest_gdt);
/* If only the TLS entries have changed, copy them. */
else if (lg->changed & CHANGED_GDT_TLS)
copy_gdt_tls(lg, pages->state.guest_gdt);
lg->changed = 0;
}
static void run_guest_once(struct lguest *lg, struct lguest_pages *pages)
{
unsigned int clobber;
copy_in_guest_info(lg, pages);
/* Put eflags on stack, lcall does rest: suitable for iret return. */
asm volatile("pushf; lcall *lguest_entry"
: "=a"(clobber), "=b"(clobber)
: "0"(pages), "1"(__pa(lg->pgdirs[lg->pgdidx].pgdir))
: "memory", "%edx", "%ecx", "%edi", "%esi");
}
int run_guest(struct lguest *lg, unsigned long __user *user)
{
while (!lg->dead) {
unsigned int cr2 = 0; /* Damn gcc */
/* Hypercalls first: we might have been out to userspace */
do_hypercalls(lg);
if (lg->dma_is_pending) {
if (put_user(lg->pending_dma, user) ||
put_user(lg->pending_key, user+1))
return -EFAULT;
return sizeof(unsigned long)*2;
}
if (signal_pending(current))
return -ERESTARTSYS;
/* If Waker set break_out, return to Launcher. */
if (lg->break_out)
return -EAGAIN;
maybe_do_interrupt(lg);
try_to_freeze();
if (lg->dead)
break;
if (lg->halted) {
set_current_state(TASK_INTERRUPTIBLE);
schedule();
continue;
}
local_irq_disable();
/* Even if *we* don't want FPU trap, guest might... */
if (lg->ts)
set_ts();
/* Don't let Guest do SYSENTER: we can't handle it. */
if (boot_cpu_has(X86_FEATURE_SEP))
wrmsr(MSR_IA32_SYSENTER_CS, 0, 0);
run_guest_once(lg, lguest_pages(raw_smp_processor_id()));
/* Save cr2 now if we page-faulted. */
if (lg->regs->trapnum == 14)
cr2 = read_cr2();
else if (lg->regs->trapnum == 7)
math_state_restore();
if (boot_cpu_has(X86_FEATURE_SEP))
wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
local_irq_enable();
switch (lg->regs->trapnum) {
case 13: /* We've intercepted a GPF. */
if (lg->regs->errcode == 0) {
if (emulate_insn(lg))
continue;
}
break;
case 14: /* We've intercepted a page fault. */
if (demand_page(lg, cr2, lg->regs->errcode))
continue;
/* If lguest_data is NULL, this won't hurt. */
if (put_user(cr2, &lg->lguest_data->cr2))
kill_guest(lg, "Writing cr2");
break;
case 7: /* We've intercepted a Device Not Available fault. */
/* If they don't want to know, just absorb it. */
if (!lg->ts)
continue;
break;
case 32 ... 255: /* Real interrupt, fall thru */
cond_resched();
case LGUEST_TRAP_ENTRY: /* Handled at top of loop */
continue;
}
if (deliver_trap(lg, lg->regs->trapnum))
continue;
kill_guest(lg, "unhandled trap %li at %#lx (%#lx)",
lg->regs->trapnum, lg->regs->eip,
lg->regs->trapnum == 14 ? cr2 : lg->regs->errcode);
}
return -ENOENT;
}
int find_free_guest(void)
{
unsigned int i;
for (i = 0; i < MAX_LGUEST_GUESTS; i++)
if (!lguests[i].tsk)
return i;
return -1;
}
static void adjust_pge(void *on)
{
if (on)
write_cr4(read_cr4() | X86_CR4_PGE);
else
write_cr4(read_cr4() & ~X86_CR4_PGE);
}
static int __init init(void)
{
int err;
if (paravirt_enabled()) {
printk("lguest is afraid of %s\n", paravirt_ops.name);
return -EPERM;
}
err = map_switcher();
if (err)
return err;
err = init_pagetables(switcher_page, SHARED_SWITCHER_PAGES);
if (err) {
unmap_switcher();
return err;
}
lguest_io_init();
err = lguest_device_init();
if (err) {
free_pagetables();
unmap_switcher();
return err;
}
lock_cpu_hotplug();
if (cpu_has_pge) { /* We have a broader idea of "global". */
cpu_had_pge = 1;
on_each_cpu(adjust_pge, (void *)0, 0, 1);
clear_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
}
unlock_cpu_hotplug();
return 0;
}
static void __exit fini(void)
{
lguest_device_remove();
free_pagetables();
unmap_switcher();
lock_cpu_hotplug();
if (cpu_had_pge) {
set_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
on_each_cpu(adjust_pge, (void *)1, 0, 1);
}
unlock_cpu_hotplug();
}
module_init(init);
module_exit(fini);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");

192
drivers/lguest/hypercalls.c Normal file
View File

@ -0,0 +1,192 @@
/* Actual hypercalls, which allow guests to actually do something.
Copyright (C) 2006 Rusty Russell IBM Corporation
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <linux/uaccess.h>
#include <linux/syscalls.h>
#include <linux/mm.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <irq_vectors.h>
#include "lg.h"
static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
{
switch (regs->eax) {
case LHCALL_FLUSH_ASYNC:
break;
case LHCALL_LGUEST_INIT:
kill_guest(lg, "already have lguest_data");
break;
case LHCALL_CRASH: {
char msg[128];
lgread(lg, msg, regs->edx, sizeof(msg));
msg[sizeof(msg)-1] = '\0';
kill_guest(lg, "CRASH: %s", msg);
break;
}
case LHCALL_FLUSH_TLB:
if (regs->edx)
guest_pagetable_clear_all(lg);
else
guest_pagetable_flush_user(lg);
break;
case LHCALL_GET_WALLCLOCK: {
struct timespec ts;
ktime_get_real_ts(&ts);
regs->eax = ts.tv_sec;
break;
}
case LHCALL_BIND_DMA:
regs->eax = bind_dma(lg, regs->edx, regs->ebx,
regs->ecx >> 8, regs->ecx & 0xFF);
break;
case LHCALL_SEND_DMA:
send_dma(lg, regs->edx, regs->ebx);
break;
case LHCALL_LOAD_GDT:
load_guest_gdt(lg, regs->edx, regs->ebx);
break;
case LHCALL_LOAD_IDT_ENTRY:
load_guest_idt_entry(lg, regs->edx, regs->ebx, regs->ecx);
break;
case LHCALL_NEW_PGTABLE:
guest_new_pagetable(lg, regs->edx);
break;
case LHCALL_SET_STACK:
guest_set_stack(lg, regs->edx, regs->ebx, regs->ecx);
break;
case LHCALL_SET_PTE:
guest_set_pte(lg, regs->edx, regs->ebx, mkgpte(regs->ecx));
break;
case LHCALL_SET_PMD:
guest_set_pmd(lg, regs->edx, regs->ebx);
break;
case LHCALL_LOAD_TLS:
guest_load_tls(lg, regs->edx);
break;
case LHCALL_SET_CLOCKEVENT:
guest_set_clockevent(lg, regs->edx);
break;
case LHCALL_TS:
lg->ts = regs->edx;
break;
case LHCALL_HALT:
lg->halted = 1;
break;
default:
kill_guest(lg, "Bad hypercall %li\n", regs->eax);
}
}
/* We always do queued calls before actual hypercall. */
static void do_async_hcalls(struct lguest *lg)
{
unsigned int i;
u8 st[LHCALL_RING_SIZE];
if (copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st)))
return;
for (i = 0; i < ARRAY_SIZE(st); i++) {
struct lguest_regs regs;
unsigned int n = lg->next_hcall;
if (st[n] == 0xFF)
break;
if (++lg->next_hcall == LHCALL_RING_SIZE)
lg->next_hcall = 0;
if (get_user(regs.eax, &lg->lguest_data->hcalls[n].eax)
|| get_user(regs.edx, &lg->lguest_data->hcalls[n].edx)
|| get_user(regs.ecx, &lg->lguest_data->hcalls[n].ecx)
|| get_user(regs.ebx, &lg->lguest_data->hcalls[n].ebx)) {
kill_guest(lg, "Fetching async hypercalls");
break;
}
do_hcall(lg, &regs);
if (put_user(0xFF, &lg->lguest_data->hcall_status[n])) {
kill_guest(lg, "Writing result for async hypercall");
break;
}
if (lg->dma_is_pending)
break;
}
}
static void initialize(struct lguest *lg)
{
u32 tsc_speed;
if (lg->regs->eax != LHCALL_LGUEST_INIT) {
kill_guest(lg, "hypercall %li before LGUEST_INIT",
lg->regs->eax);
return;
}
/* We only tell the guest to use the TSC if it's reliable. */
if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && !check_tsc_unstable())
tsc_speed = tsc_khz;
else
tsc_speed = 0;
lg->lguest_data = (struct lguest_data __user *)lg->regs->edx;
/* We check here so we can simply copy_to_user/from_user */
if (!lguest_address_ok(lg, lg->regs->edx, sizeof(*lg->lguest_data))) {
kill_guest(lg, "bad guest page %p", lg->lguest_data);
return;
}
if (get_user(lg->noirq_start, &lg->lguest_data->noirq_start)
|| get_user(lg->noirq_end, &lg->lguest_data->noirq_end)
/* We reserve the top pgd entry. */
|| put_user(4U*1024*1024, &lg->lguest_data->reserve_mem)
|| put_user(tsc_speed, &lg->lguest_data->tsc_khz)
|| put_user(lg->guestid, &lg->lguest_data->guestid))
kill_guest(lg, "bad guest page %p", lg->lguest_data);
/* This is the one case where the above accesses might have
* been the first write to a Guest page. This may have caused
* a copy-on-write fault, but the Guest might be referring to
* the old (read-only) page. */
guest_pagetable_clear_all(lg);
}
/* Even if we go out to userspace and come back, we don't want to do
* the hypercall again. */
static void clear_hcall(struct lguest *lg)
{
lg->regs->trapnum = 255;
}
void do_hypercalls(struct lguest *lg)
{
if (unlikely(!lg->lguest_data)) {
if (lg->regs->trapnum == LGUEST_TRAP_ENTRY) {
initialize(lg);
clear_hcall(lg);
}
return;
}
do_async_hcalls(lg);
if (!lg->dma_is_pending && lg->regs->trapnum == LGUEST_TRAP_ENTRY) {
do_hcall(lg, lg->regs);
clear_hcall(lg);
}
}

268
drivers/lguest/interrupts_and_traps.c Normal file
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@ -0,0 +1,268 @@
#include <linux/uaccess.h>
#include "lg.h"
static unsigned long idt_address(u32 lo, u32 hi)
{
return (lo & 0x0000FFFF) | (hi & 0xFFFF0000);
}
static int idt_type(u32 lo, u32 hi)
{
return (hi >> 8) & 0xF;
}
static int idt_present(u32 lo, u32 hi)
{
return (hi & 0x8000);
}
static void push_guest_stack(struct lguest *lg, unsigned long *gstack, u32 val)
{
*gstack -= 4;
lgwrite_u32(lg, *gstack, val);
}
static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err)
{
unsigned long gstack;
u32 eflags, ss, irq_enable;
/* If they want a ring change, we use new stack and push old ss/esp */
if ((lg->regs->ss&0x3) != GUEST_PL) {
gstack = guest_pa(lg, lg->esp1);
ss = lg->ss1;
push_guest_stack(lg, &gstack, lg->regs->ss);
push_guest_stack(lg, &gstack, lg->regs->esp);
} else {
gstack = guest_pa(lg, lg->regs->esp);
ss = lg->regs->ss;
}
/* We use IF bit in eflags to indicate whether irqs were disabled
(it's always 0, since irqs are enabled when guest is running). */
eflags = lg->regs->eflags;
if (get_user(irq_enable, &lg->lguest_data->irq_enabled))
irq_enable = 0;
eflags |= (irq_enable & X86_EFLAGS_IF);
push_guest_stack(lg, &gstack, eflags);
push_guest_stack(lg, &gstack, lg->regs->cs);
push_guest_stack(lg, &gstack, lg->regs->eip);
if (has_err)
push_guest_stack(lg, &gstack, lg->regs->errcode);
/* Change the real stack so switcher returns to trap handler */
lg->regs->ss = ss;
lg->regs->esp = gstack + lg->page_offset;
lg->regs->cs = (__KERNEL_CS|GUEST_PL);
lg->regs->eip = idt_address(lo, hi);
/* Disable interrupts for an interrupt gate. */
if (idt_type(lo, hi) == 0xE)
if (put_user(0, &lg->lguest_data->irq_enabled))
kill_guest(lg, "Disabling interrupts");
}
void maybe_do_interrupt(struct lguest *lg)
{
unsigned int irq;
DECLARE_BITMAP(blk, LGUEST_IRQS);
struct desc_struct *idt;
if (!lg->lguest_data)
return;
/* Mask out any interrupts they have blocked. */
if (copy_from_user(&blk, lg->lguest_data->blocked_interrupts,
sizeof(blk)))
return;
bitmap_andnot(blk, lg->irqs_pending, blk, LGUEST_IRQS);
irq = find_first_bit(blk, LGUEST_IRQS);
if (irq >= LGUEST_IRQS)
return;
if (lg->regs->eip >= lg->noirq_start && lg->regs->eip < lg->noirq_end)
return;
/* If they're halted, we re-enable interrupts. */
if (lg->halted) {
/* Re-enable interrupts. */
if (put_user(X86_EFLAGS_IF, &lg->lguest_data->irq_enabled))
kill_guest(lg, "Re-enabling interrupts");
lg->halted = 0;
} else {
/* Maybe they have interrupts disabled? */
u32 irq_enabled;
if (get_user(irq_enabled, &lg->lguest_data->irq_enabled))
irq_enabled = 0;
if (!irq_enabled)
return;
}
idt = &lg->idt[FIRST_EXTERNAL_VECTOR+irq];
if (idt_present(idt->a, idt->b)) {
clear_bit(irq, lg->irqs_pending);
set_guest_interrupt(lg, idt->a, idt->b, 0);
}
}
static int has_err(unsigned int trap)
{
return (trap == 8 || (trap >= 10 && trap <= 14) || trap == 17);
}
int deliver_trap(struct lguest *lg, unsigned int num)
{
u32 lo = lg->idt[num].a, hi = lg->idt[num].b;
if (!idt_present(lo, hi))
return 0;
set_guest_interrupt(lg, lo, hi, has_err(num));
return 1;
}
static int direct_trap(const struct lguest *lg,
const struct desc_struct *trap,
unsigned int num)
{
/* Hardware interrupts don't go to guest (except syscall). */
if (num >= FIRST_EXTERNAL_VECTOR && num != SYSCALL_VECTOR)
return 0;
/* We intercept page fault (demand shadow paging & cr2 saving)
protection fault (in/out emulation) and device not
available (TS handling), and hypercall */
if (num == 14 || num == 13 || num == 7 || num == LGUEST_TRAP_ENTRY)
return 0;
/* Interrupt gates (0xE) or not present (0x0) can't go direct. */
return idt_type(trap->a, trap->b) == 0xF;
}
void pin_stack_pages(struct lguest *lg)
{
unsigned int i;
for (i = 0; i < lg->stack_pages; i++)
pin_page(lg, lg->esp1 - i * PAGE_SIZE);
}
void guest_set_stack(struct lguest *lg, u32 seg, u32 esp, unsigned int pages)
{
/* You cannot have a stack segment with priv level 0. */
if ((seg & 0x3) != GUEST_PL)
kill_guest(lg, "bad stack segment %i", seg);
if (pages > 2)
kill_guest(lg, "bad stack pages %u", pages);
lg->ss1 = seg;
lg->esp1 = esp;
lg->stack_pages = pages;
pin_stack_pages(lg);
}
/* Set up trap in IDT. */
static void set_trap(struct lguest *lg, struct desc_struct *trap,
unsigned int num, u32 lo, u32 hi)
{
u8 type = idt_type(lo, hi);
if (!idt_present(lo, hi)) {
trap->a = trap->b = 0;
return;
}
if (type != 0xE && type != 0xF)
kill_guest(lg, "bad IDT type %i", type);
trap->a = ((__KERNEL_CS|GUEST_PL)<<16) | (lo&0x0000FFFF);
trap->b = (hi&0xFFFFEF00);
}
void load_guest_idt_entry(struct lguest *lg, unsigned int num, u32 lo, u32 hi)
{
/* Guest never handles: NMI, doublefault, hypercall, spurious irq. */
if (num == 2 || num == 8 || num == 15 || num == LGUEST_TRAP_ENTRY)
return;
lg->changed |= CHANGED_IDT;
if (num < ARRAY_SIZE(lg->idt))
set_trap(lg, &lg->idt[num], num, lo, hi);
else if (num == SYSCALL_VECTOR)
set_trap(lg, &lg->syscall_idt, num, lo, hi);
}
static void default_idt_entry(struct desc_struct *idt,
int trap,
const unsigned long handler)
{
u32 flags = 0x8e00;
/* They can't "int" into any of them except hypercall. */
if (trap == LGUEST_TRAP_ENTRY)
flags |= (GUEST_PL << 13);
idt->a = (LGUEST_CS<<16) | (handler&0x0000FFFF);
idt->b = (handler&0xFFFF0000) | flags;
}
void setup_default_idt_entries(struct lguest_ro_state *state,
const unsigned long *def)
{
unsigned int i;
for (i = 0; i < ARRAY_SIZE(state->guest_idt); i++)
default_idt_entry(&state->guest_idt[i], i, def[i]);
}
void copy_traps(const struct lguest *lg, struct desc_struct *idt,
const unsigned long *def)
{
unsigned int i;
/* All hardware interrupts are same whatever the guest: only the
* traps might be different. */
for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++) {
if (direct_trap(lg, &lg->idt[i], i))
idt[i] = lg->idt[i];
else
default_idt_entry(&idt[i], i, def[i]);
}
i = SYSCALL_VECTOR;
if (direct_trap(lg, &lg->syscall_idt, i))
idt[i] = lg->syscall_idt;
else
default_idt_entry(&idt[i], i, def[i]);
}
void guest_set_clockevent(struct lguest *lg, unsigned long delta)
{
ktime_t expires;
if (unlikely(delta == 0)) {
/* Clock event device is shutting down. */
hrtimer_cancel(&lg->hrt);
return;
}
expires = ktime_add_ns(ktime_get_real(), delta);
hrtimer_start(&lg->hrt, expires, HRTIMER_MODE_ABS);
}
static enum hrtimer_restart clockdev_fn(struct hrtimer *timer)
{
struct lguest *lg = container_of(timer, struct lguest, hrt);
set_bit(0, lg->irqs_pending);
if (lg->halted)
wake_up_process(lg->tsk);
return HRTIMER_NORESTART;
}
void init_clockdev(struct lguest *lg)
{
hrtimer_init(&lg->hrt, CLOCK_REALTIME, HRTIMER_MODE_ABS);
lg->hrt.function = clockdev_fn;
}

399
drivers/lguest/io.c Normal file
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/* Simple I/O model for guests, based on shared memory.
* Copyright (C) 2006 Rusty Russell IBM Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <linux/types.h>
#include <linux/futex.h>
#include <linux/jhash.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/uaccess.h>
#include "lg.h"
static struct list_head dma_hash[61];
void lguest_io_init(void)
{
unsigned int i;
for (i = 0; i < ARRAY_SIZE(dma_hash); i++)
INIT_LIST_HEAD(&dma_hash[i]);
}
/* FIXME: allow multi-page lengths. */
static int check_dma_list(struct lguest *lg, const struct lguest_dma *dma)
{
unsigned int i;
for (i = 0; i < LGUEST_MAX_DMA_SECTIONS; i++) {
if (!dma->len[i])
return 1;
if (!lguest_address_ok(lg, dma->addr[i], dma->len[i]))
goto kill;
if (dma->len[i] > PAGE_SIZE)
goto kill;
/* We could do over a page, but is it worth it? */
if ((dma->addr[i] % PAGE_SIZE) + dma->len[i] > PAGE_SIZE)
goto kill;
}
return 1;
kill:
kill_guest(lg, "bad DMA entry: %u@%#lx", dma->len[i], dma->addr[i]);
return 0;
}
static unsigned int hash(const union futex_key *key)
{
return jhash2((u32*)&key->both.word,
(sizeof(key->both.word)+sizeof(key->both.ptr))/4,
key->both.offset)
% ARRAY_SIZE(dma_hash);
}
static inline int key_eq(const union futex_key *a, const union futex_key *b)
{
return (a->both.word == b->both.word
&& a->both.ptr == b->both.ptr
&& a->both.offset == b->both.offset);
}
/* Must hold read lock on dmainfo owner's current->mm->mmap_sem */
static void unlink_dma(struct lguest_dma_info *dmainfo)
{
BUG_ON(!mutex_is_locked(&lguest_lock));
dmainfo->interrupt = 0;
list_del(&dmainfo->list);
drop_futex_key_refs(&dmainfo->key);
}
static int unbind_dma(struct lguest *lg,
const union futex_key *key,
unsigned long dmas)
{
int i, ret = 0;
for (i = 0; i < LGUEST_MAX_DMA; i++) {
if (key_eq(key, &lg->dma[i].key) && dmas == lg->dma[i].dmas) {
unlink_dma(&lg->dma[i]);
ret = 1;
break;
}
}
return ret;
}
int bind_dma(struct lguest *lg,
unsigned long ukey, unsigned long dmas, u16 numdmas, u8 interrupt)
{
unsigned int i;
int ret = 0;
union futex_key key;
struct rw_semaphore *fshared = &current->mm->mmap_sem;
if (interrupt >= LGUEST_IRQS)
return 0;
mutex_lock(&lguest_lock);
down_read(fshared);
if (get_futex_key((u32 __user *)ukey, fshared, &key) != 0) {
kill_guest(lg, "bad dma key %#lx", ukey);
goto unlock;
}
get_futex_key_refs(&key);
if (interrupt == 0)
ret = unbind_dma(lg, &key, dmas);
else {
for (i = 0; i < LGUEST_MAX_DMA; i++) {
if (lg->dma[i].interrupt)
continue;
lg->dma[i].dmas = dmas;
lg->dma[i].num_dmas = numdmas;
lg->dma[i].next_dma = 0;
lg->dma[i].key = key;
lg->dma[i].guestid = lg->guestid;
lg->dma[i].interrupt = interrupt;
list_add(&lg->dma[i].list, &dma_hash[hash(&key)]);
ret = 1;
goto unlock;
}
}
drop_futex_key_refs(&key);
unlock:
up_read(fshared);
mutex_unlock(&lguest_lock);
return ret;
}
/* lgread from another guest */
static int lgread_other(struct lguest *lg,
void *buf, u32 addr, unsigned bytes)
{
if (!lguest_address_ok(lg, addr, bytes)
|| access_process_vm(lg->tsk, addr, buf, bytes, 0) != bytes) {
memset(buf, 0, bytes);
kill_guest(lg, "bad address in registered DMA struct");
return 0;
}
return 1;
}
/* lgwrite to another guest */
static int lgwrite_other(struct lguest *lg, u32 addr,
const void *buf, unsigned bytes)
{
if (!lguest_address_ok(lg, addr, bytes)
|| (access_process_vm(lg->tsk, addr, (void *)buf, bytes, 1)
!= bytes)) {
kill_guest(lg, "bad address writing to registered DMA");
return 0;
}
return 1;
}
static u32 copy_data(struct lguest *srclg,
const struct lguest_dma *src,
const struct lguest_dma *dst,
struct page *pages[])
{
unsigned int totlen, si, di, srcoff, dstoff;
void *maddr = NULL;
totlen = 0;
si = di = 0;
srcoff = dstoff = 0;
while (si < LGUEST_MAX_DMA_SECTIONS && src->len[si]
&& di < LGUEST_MAX_DMA_SECTIONS && dst->len[di]) {
u32 len = min(src->len[si] - srcoff, dst->len[di] - dstoff);
if (!maddr)
maddr = kmap(pages[di]);
/* FIXME: This is not completely portable, since
archs do different things for copy_to_user_page. */
if (copy_from_user(maddr + (dst->addr[di] + dstoff)%PAGE_SIZE,
(void *__user)src->addr[si], len) != 0) {
kill_guest(srclg, "bad address in sending DMA");
totlen = 0;
break;
}
totlen += len;
srcoff += len;
dstoff += len;
if (srcoff == src->len[si]) {
si++;
srcoff = 0;
}
if (dstoff == dst->len[di]) {
kunmap(pages[di]);
maddr = NULL;
di++;
dstoff = 0;
}
}
if (maddr)
kunmap(pages[di]);
return totlen;
}
/* Src is us, ie. current. */
static u32 do_dma(struct lguest *srclg, const struct lguest_dma *src,
struct lguest *dstlg, const struct lguest_dma *dst)
{
int i;
u32 ret;
struct page *pages[LGUEST_MAX_DMA_SECTIONS];
if (!check_dma_list(dstlg, dst) || !check_dma_list(srclg, src))
return 0;
/* First get the destination pages */
for (i = 0; i < LGUEST_MAX_DMA_SECTIONS; i++) {
if (dst->len[i] == 0)
break;
if (get_user_pages(dstlg->tsk, dstlg->mm,
dst->addr[i], 1, 1, 1, pages+i, NULL)
!= 1) {
kill_guest(dstlg, "Error mapping DMA pages");
ret = 0;
goto drop_pages;
}
}
/* Now copy until we run out of src or dst. */
ret = copy_data(srclg, src, dst, pages);
drop_pages:
while (--i >= 0)
put_page(pages[i]);
return ret;
}
static int dma_transfer(struct lguest *srclg,
unsigned long udma,
struct lguest_dma_info *dst)
{
struct lguest_dma dst_dma, src_dma;
struct lguest *dstlg;
u32 i, dma = 0;
dstlg = &lguests[dst->guestid];
/* Get our dma list. */
lgread(srclg, &src_dma, udma, sizeof(src_dma));
/* We can't deadlock against them dmaing to us, because this
* is all under the lguest_lock. */
down_read(&dstlg->mm->mmap_sem);
for (i = 0; i < dst->num_dmas; i++) {
dma = (dst->next_dma + i) % dst->num_dmas;
if (!lgread_other(dstlg, &dst_dma,
dst->dmas + dma * sizeof(struct lguest_dma),
sizeof(dst_dma))) {
goto fail;
}
if (!dst_dma.used_len)
break;
}
if (i != dst->num_dmas) {
unsigned long used_lenp;
unsigned int ret;
ret = do_dma(srclg, &src_dma, dstlg, &dst_dma);
/* Put used length in src. */
lgwrite_u32(srclg,
udma+offsetof(struct lguest_dma, used_len), ret);
if (ret == 0 && src_dma.len[0] != 0)
goto fail;
/* Make sure destination sees contents before length. */
wmb();
used_lenp = dst->dmas
+ dma * sizeof(struct lguest_dma)
+ offsetof(struct lguest_dma, used_len);
lgwrite_other(dstlg, used_lenp, &ret, sizeof(ret));
dst->next_dma++;
}
up_read(&dstlg->mm->mmap_sem);
/* Do this last so dst doesn't simply sleep on lock. */
set_bit(dst->interrupt, dstlg->irqs_pending);
wake_up_process(dstlg->tsk);
return i == dst->num_dmas;
fail:
up_read(&dstlg->mm->mmap_sem);
return 0;
}
void send_dma(struct lguest *lg, unsigned long ukey, unsigned long udma)
{
union futex_key key;
int empty = 0;
struct rw_semaphore *fshared = &current->mm->mmap_sem;
again:
mutex_lock(&lguest_lock);
down_read(fshared);
if (get_futex_key((u32 __user *)ukey, fshared, &key) != 0) {
kill_guest(lg, "bad sending DMA key");
goto unlock;
}
/* Shared mapping? Look for other guests... */
if (key.shared.offset & 1) {
struct lguest_dma_info *i;
list_for_each_entry(i, &dma_hash[hash(&key)], list) {
if (i->guestid == lg->guestid)
continue;
if (!key_eq(&key, &i->key))
continue;
empty += dma_transfer(lg, udma, i);
break;
}
if (empty == 1) {
/* Give any recipients one chance to restock. */
up_read(&current->mm->mmap_sem);
mutex_unlock(&lguest_lock);
empty++;
goto again;
}
} else {
/* Private mapping: tell our userspace. */
lg->dma_is_pending = 1;
lg->pending_dma = udma;
lg->pending_key = ukey;
}
unlock:
up_read(fshared);
mutex_unlock(&lguest_lock);
}
void release_all_dma(struct lguest *lg)
{
unsigned int i;
BUG_ON(!mutex_is_locked(&lguest_lock));
down_read(&lg->mm->mmap_sem);
for (i = 0; i < LGUEST_MAX_DMA; i++) {
if (lg->dma[i].interrupt)
unlink_dma(&lg->dma[i]);
}
up_read(&lg->mm->mmap_sem);
}
/* Userspace wants a dma buffer from this guest. */
unsigned long get_dma_buffer(struct lguest *lg,
unsigned long ukey, unsigned long *interrupt)
{
unsigned long ret = 0;
union futex_key key;
struct lguest_dma_info *i;
struct rw_semaphore *fshared = &current->mm->mmap_sem;
mutex_lock(&lguest_lock);
down_read(fshared);
if (get_futex_key((u32 __user *)ukey, fshared, &key) != 0) {
kill_guest(lg, "bad registered DMA buffer");
goto unlock;
}
list_for_each_entry(i, &dma_hash[hash(&key)], list) {
if (key_eq(&key, &i->key) && i->guestid == lg->guestid) {
unsigned int j;
for (j = 0; j < i->num_dmas; j++) {
struct lguest_dma dma;
ret = i->dmas + j * sizeof(struct lguest_dma);
lgread(lg, &dma, ret, sizeof(dma));
if (dma.used_len == 0)
break;
}
*interrupt = i->interrupt;
break;
}
}
unlock:
up_read(fshared);
mutex_unlock(&lguest_lock);
return ret;
}

261
drivers/lguest/lg.h Normal file
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#ifndef _LGUEST_H
#define _LGUEST_H
#include <asm/desc.h>
#define GDT_ENTRY_LGUEST_CS 10
#define GDT_ENTRY_LGUEST_DS 11
#define LGUEST_CS (GDT_ENTRY_LGUEST_CS * 8)
#define LGUEST_DS (GDT_ENTRY_LGUEST_DS * 8)
#ifndef __ASSEMBLY__
#include <linux/types.h>
#include <linux/init.h>
#include <linux/stringify.h>
#include <linux/binfmts.h>
#include <linux/futex.h>
#include <linux/lguest.h>
#include <linux/lguest_launcher.h>
#include <linux/wait.h>
#include <linux/err.h>
#include <asm/semaphore.h>
#include "irq_vectors.h"
#define GUEST_PL 1
struct lguest_regs
{
/* Manually saved part. */
unsigned long ebx, ecx, edx;
unsigned long esi, edi, ebp;
unsigned long gs;
unsigned long eax;
unsigned long fs, ds, es;
unsigned long trapnum, errcode;
/* Trap pushed part */
unsigned long eip;
unsigned long cs;
unsigned long eflags;
unsigned long esp;
unsigned long ss;
};
void free_pagetables(void);
int init_pagetables(struct page **switcher_page, unsigned int pages);
/* Full 4G segment descriptors, suitable for CS and DS. */
#define FULL_EXEC_SEGMENT ((struct desc_struct){0x0000ffff, 0x00cf9b00})
#define FULL_SEGMENT ((struct desc_struct){0x0000ffff, 0x00cf9300})
struct lguest_dma_info
{
struct list_head list;
union futex_key key;
unsigned long dmas;
u16 next_dma;
u16 num_dmas;
u16 guestid;
u8 interrupt; /* 0 when not registered */
};
/* We have separate types for the guest's ptes & pgds and the shadow ptes &
* pgds. Since this host might use three-level pagetables and the guest and
* shadow pagetables don't, we can't use the normal pte_t/pgd_t. */
typedef union {
struct { unsigned flags:12, pfn:20; };
struct { unsigned long val; } raw;
} spgd_t;
typedef union {
struct { unsigned flags:12, pfn:20; };
struct { unsigned long val; } raw;
} spte_t;
typedef union {
struct { unsigned flags:12, pfn:20; };
struct { unsigned long val; } raw;
} gpgd_t;
typedef union {
struct { unsigned flags:12, pfn:20; };
struct { unsigned long val; } raw;
} gpte_t;
#define mkgpte(_val) ((gpte_t){.raw.val = _val})
#define mkgpgd(_val) ((gpgd_t){.raw.val = _val})
struct pgdir
{
unsigned long cr3;
spgd_t *pgdir;
};
/* This is a guest-specific page (mapped ro) into the guest. */
struct lguest_ro_state
{
/* Host information we need to restore when we switch back. */
u32 host_cr3;
struct Xgt_desc_struct host_idt_desc;
struct Xgt_desc_struct host_gdt_desc;
u32 host_sp;
/* Fields which are used when guest is running. */
struct Xgt_desc_struct guest_idt_desc;
struct Xgt_desc_struct guest_gdt_desc;
struct i386_hw_tss guest_tss;
struct desc_struct guest_idt[IDT_ENTRIES];
struct desc_struct guest_gdt[GDT_ENTRIES];
};
/* We have two pages shared with guests, per cpu. */
struct lguest_pages
{
/* This is the stack page mapped rw in guest */
char spare[PAGE_SIZE - sizeof(struct lguest_regs)];
struct lguest_regs regs;
/* This is the host state & guest descriptor page, ro in guest */
struct lguest_ro_state state;
} __attribute__((aligned(PAGE_SIZE)));
#define CHANGED_IDT 1
#define CHANGED_GDT 2
#define CHANGED_GDT_TLS 4 /* Actually a subset of CHANGED_GDT */
#define CHANGED_ALL 3
/* The private info the thread maintains about the guest. */
struct lguest
{
/* At end of a page shared mapped over lguest_pages in guest. */
unsigned long regs_page;
struct lguest_regs *regs;
struct lguest_data __user *lguest_data;
struct task_struct *tsk;
struct mm_struct *mm; /* == tsk->mm, but that becomes NULL on exit */
u16 guestid;
u32 pfn_limit;
u32 page_offset;
u32 cr2;
int halted;
int ts;
u32 next_hcall;
u32 esp1;
u8 ss1;
/* Do we need to stop what we're doing and return to userspace? */
int break_out;
wait_queue_head_t break_wq;
/* Bitmap of what has changed: see CHANGED_* above. */
int changed;
struct lguest_pages *last_pages;
/* We keep a small number of these. */
u32 pgdidx;
struct pgdir pgdirs[4];
/* Cached wakeup: we hold a reference to this task. */
struct task_struct *wake;
unsigned long noirq_start, noirq_end;
int dma_is_pending;
unsigned long pending_dma; /* struct lguest_dma */
unsigned long pending_key; /* address they're sending to */
unsigned int stack_pages;
u32 tsc_khz;
struct lguest_dma_info dma[LGUEST_MAX_DMA];
/* Dead? */
const char *dead;
/* The GDT entries copied into lguest_ro_state when running. */
struct desc_struct gdt[GDT_ENTRIES];
/* The IDT entries: some copied into lguest_ro_state when running. */
struct desc_struct idt[FIRST_EXTERNAL_VECTOR+LGUEST_IRQS];
struct desc_struct syscall_idt;
/* Virtual clock device */
struct hrtimer hrt;
/* Pending virtual interrupts */
DECLARE_BITMAP(irqs_pending, LGUEST_IRQS);
};
extern struct lguest lguests[];
extern struct mutex lguest_lock;
/* core.c: */
u32 lgread_u32(struct lguest *lg, unsigned long addr);
void lgwrite_u32(struct lguest *lg, unsigned long addr, u32 val);
void lgread(struct lguest *lg, void *buf, unsigned long addr, unsigned len);
void lgwrite(struct lguest *lg, unsigned long, const void *buf, unsigned len);
int find_free_guest(void);
int lguest_address_ok(const struct lguest *lg,
unsigned long addr, unsigned long len);
int run_guest(struct lguest *lg, unsigned long __user *user);
/* interrupts_and_traps.c: */
void maybe_do_interrupt(struct lguest *lg);
int deliver_trap(struct lguest *lg, unsigned int num);
void load_guest_idt_entry(struct lguest *lg, unsigned int i, u32 low, u32 hi);
void guest_set_stack(struct lguest *lg, u32 seg, u32 esp, unsigned int pages);
void pin_stack_pages(struct lguest *lg);
void setup_default_idt_entries(struct lguest_ro_state *state,
const unsigned long *def);
void copy_traps(const struct lguest *lg, struct desc_struct *idt,
const unsigned long *def);
void guest_set_clockevent(struct lguest *lg, unsigned long delta);
void init_clockdev(struct lguest *lg);
/* segments.c: */
void setup_default_gdt_entries(struct lguest_ro_state *state);
void setup_guest_gdt(struct lguest *lg);
void load_guest_gdt(struct lguest *lg, unsigned long table, u32 num);
void guest_load_tls(struct lguest *lg, unsigned long tls_array);
void copy_gdt(const struct lguest *lg, struct desc_struct *gdt);
void copy_gdt_tls(const struct lguest *lg, struct desc_struct *gdt);
/* page_tables.c: */
int init_guest_pagetable(struct lguest *lg, unsigned long pgtable);
void free_guest_pagetable(struct lguest *lg);
void guest_new_pagetable(struct lguest *lg, unsigned long pgtable);
void guest_set_pmd(struct lguest *lg, unsigned long cr3, u32 i);
void guest_pagetable_clear_all(struct lguest *lg);
void guest_pagetable_flush_user(struct lguest *lg);
void guest_set_pte(struct lguest *lg, unsigned long cr3,
unsigned long vaddr, gpte_t val);
void map_switcher_in_guest(struct lguest *lg, struct lguest_pages *pages);
int demand_page(struct lguest *info, unsigned long cr2, int errcode);
void pin_page(struct lguest *lg, unsigned long vaddr);
/* lguest_user.c: */
int lguest_device_init(void);
void lguest_device_remove(void);
/* io.c: */
void lguest_io_init(void);
int bind_dma(struct lguest *lg,
unsigned long key, unsigned long udma, u16 numdmas, u8 interrupt);
void send_dma(struct lguest *info, unsigned long key, unsigned long udma);
void release_all_dma(struct lguest *lg);
unsigned long get_dma_buffer(struct lguest *lg, unsigned long key,
unsigned long *interrupt);
/* hypercalls.c: */
void do_hypercalls(struct lguest *lg);
#define kill_guest(lg, fmt...) \
do { \
if (!(lg)->dead) { \
(lg)->dead = kasprintf(GFP_ATOMIC, fmt); \
if (!(lg)->dead) \
(lg)->dead = ERR_PTR(-ENOMEM); \
} \
} while(0)
static inline unsigned long guest_pa(struct lguest *lg, unsigned long vaddr)
{
return vaddr - lg->page_offset;
}
#endif /* __ASSEMBLY__ */
#endif /* _LGUEST_H */

127
drivers/lguest/lguest.c
View File

@ -25,6 +25,8 @@
#include <linux/screen_info.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/lguest.h>
#include <linux/lguest_launcher.h>
#include <linux/lguest_bus.h>
@ -37,6 +39,7 @@
#include <asm/e820.h>
#include <asm/mce.h>
#include <asm/io.h>
//#include <asm/sched-clock.h>
/* Declarations for definitions in lguest_guest.S */
extern char lguest_noirq_start[], lguest_noirq_end[];
@ -54,7 +57,6 @@ struct lguest_data lguest_data = {
.blocked_interrupts = { 1 }, /* Block timer interrupts */
};
struct lguest_device_desc *lguest_devices;
static __initdata const struct lguest_boot_info *boot = __va(0);
static enum paravirt_lazy_mode lazy_mode;
static void lguest_lazy_mode(enum paravirt_lazy_mode mode)
@ -210,7 +212,7 @@ static void lguest_cpuid(unsigned int *eax, unsigned int *ebx,
case 1: /* Basic feature request. */
/* We only allow kernel to see SSE3, CMPXCHG16B and SSSE3 */
*ecx &= 0x00002201;
/* Similarly: SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, FPU. */
/* SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, FPU. */
*edx &= 0x07808101;
/* Host wants to know when we flush kernel pages: set PGE. */
*edx |= 0x00002000;
@ -346,24 +348,104 @@ static unsigned long lguest_get_wallclock(void)
return hcall(LHCALL_GET_WALLCLOCK, 0, 0, 0);
}
static void lguest_time_irq(unsigned int irq, struct irq_desc *desc)
static cycle_t lguest_clock_read(void)
{
do_timer(hcall(LHCALL_TIMER_READ, 0, 0, 0));
update_process_times(user_mode_vm(get_irq_regs()));
if (lguest_data.tsc_khz)
return native_read_tsc();
else
return jiffies;
}
/* This is what we tell the kernel is our clocksource. */
static struct clocksource lguest_clock = {
.name = "lguest",
.rating = 400,
.read = lguest_clock_read,
};
/* We also need a "struct clock_event_device": Linux asks us to set it to go
* off some time in the future. Actually, James Morris figured all this out, I
* just applied the patch. */
static int lguest_clockevent_set_next_event(unsigned long delta,
struct clock_event_device *evt)
{
if (delta < LG_CLOCK_MIN_DELTA) {
if (printk_ratelimit())
printk(KERN_DEBUG "%s: small delta %lu ns\n",
__FUNCTION__, delta);
return -ETIME;
}
hcall(LHCALL_SET_CLOCKEVENT, delta, 0, 0);
return 0;
}
static void lguest_clockevent_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
switch (mode) {
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_SHUTDOWN:
/* A 0 argument shuts the clock down. */
hcall(LHCALL_SET_CLOCKEVENT, 0, 0, 0);
break;
case CLOCK_EVT_MODE_ONESHOT:
/* This is what we expect. */
break;
case CLOCK_EVT_MODE_PERIODIC:
BUG();
}
}
/* This describes our primitive timer chip. */
static struct clock_event_device lguest_clockevent = {
.name = "lguest",
.features = CLOCK_EVT_FEAT_ONESHOT,
.set_next_event = lguest_clockevent_set_next_event,
.set_mode = lguest_clockevent_set_mode,
.rating = INT_MAX,
.mult = 1,
.shift = 0,
.min_delta_ns = LG_CLOCK_MIN_DELTA,
.max_delta_ns = LG_CLOCK_MAX_DELTA,
};
/* This is the Guest timer interrupt handler (hardware interrupt 0). We just
* call the clockevent infrastructure and it does whatever needs doing. */
static void lguest_time_irq(unsigned int irq, struct irq_desc *desc)
{
unsigned long flags;
/* Don't interrupt us while this is running. */
local_irq_save(flags);
lguest_clockevent.event_handler(&lguest_clockevent);
local_irq_restore(flags);
}
static u64 sched_clock_base;
static void lguest_time_init(void)
{
set_irq_handler(0, lguest_time_irq);
hcall(LHCALL_TIMER_READ, 0, 0, 0);
sched_clock_base = jiffies_64;
enable_lguest_irq(0);
}
static unsigned long long lguest_sched_clock(void)
{
return (jiffies_64 - sched_clock_base) * (1000000000 / HZ);
/* We use the TSC if the Host tells us we can, otherwise a dumb
* jiffies-based clock. */
if (lguest_data.tsc_khz) {
lguest_clock.shift = 22;
lguest_clock.mult = clocksource_khz2mult(lguest_data.tsc_khz,
lguest_clock.shift);
lguest_clock.mask = CLOCKSOURCE_MASK(64);
lguest_clock.flags = CLOCK_SOURCE_IS_CONTINUOUS;
} else {
/* To understand this, start at kernel/time/jiffies.c... */
lguest_clock.shift = 8;
lguest_clock.mult = (((u64)NSEC_PER_SEC<<8)/ACTHZ) << 8;
lguest_clock.mask = CLOCKSOURCE_MASK(32);
}
clocksource_register(&lguest_clock);
/* We can't set cpumask in the initializer: damn C limitations! */
lguest_clockevent.cpumask = cpumask_of_cpu(0);
clockevents_register_device(&lguest_clockevent);
enable_lguest_irq(0);
}
static void lguest_load_esp0(struct tss_struct *tss,
@ -418,8 +500,7 @@ static __init char *lguest_memory_setup(void)
/* We do this here because lockcheck barfs if before start_kernel */
atomic_notifier_chain_register(&panic_notifier_list, &paniced);
e820.nr_map = 0;
add_memory_region(0, PFN_PHYS(boot->max_pfn), E820_RAM);
add_memory_region(E820_MAP->addr, E820_MAP->size, E820_MAP->type);
return "LGUEST";
}
@ -450,8 +531,13 @@ static unsigned lguest_patch(u8 type, u16 clobber, void *insns, unsigned len)
return insn_len;
}
__init void lguest_init(void)
__init void lguest_init(void *boot)
{
/* Copy boot parameters first. */
memcpy(&boot_params, boot, PARAM_SIZE);
memcpy(boot_command_line, __va(boot_params.hdr.cmd_line_ptr),
COMMAND_LINE_SIZE);
paravirt_ops.name = "lguest";
paravirt_ops.paravirt_enabled = 1;
paravirt_ops.kernel_rpl = 1;
@ -498,10 +584,8 @@ __init void lguest_init(void)
paravirt_ops.time_init = lguest_time_init;
paravirt_ops.set_lazy_mode = lguest_lazy_mode;
paravirt_ops.wbinvd = lguest_wbinvd;
paravirt_ops.sched_clock = lguest_sched_clock;
hcall(LHCALL_LGUEST_INIT, __pa(&lguest_data), 0, 0);
strncpy(boot_command_line, boot->cmdline, COMMAND_LINE_SIZE);
/* We use top of mem for initial pagetables. */
init_pg_tables_end = __pa(pg0);
@ -532,13 +616,6 @@ __init void lguest_init(void)
add_preferred_console("hvc", 0, NULL);
if (boot->initrd_size) {
/* We stash this at top of memory. */
INITRD_START = boot->max_pfn*PAGE_SIZE - boot->initrd_size;
INITRD_SIZE = boot->initrd_size;
LOADER_TYPE = 0xFF;
}
pm_power_off = lguest_power_off;
start_kernel();
}

5
drivers/lguest/lguest_asm.S
View File

@ -10,7 +10,8 @@
* This is where we begin: we have a magic signature which the launcher looks
* for. The plan is that the Linux boot protocol will be extended with a
* "platform type" field which will guide us here from the normal entry point,
* but for the moment this suffices.
* but for the moment this suffices. We pass the virtual address of the boot
* info to lguest_init().
*
* We put it in .init.text will be discarded after boot.
*/
@ -18,6 +19,8 @@
.ascii "GenuineLguest"
/* Set up initial stack. */
movl $(init_thread_union+THREAD_SIZE),%esp
movl %esi, %eax
addl $__PAGE_OFFSET, %eax
jmp lguest_init
/* The templates for inline patching. */

236
drivers/lguest/lguest_user.c Normal file
View File

@ -0,0 +1,236 @@
/* Userspace control of the guest, via /dev/lguest. */
#include <linux/uaccess.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include "lg.h"
static void setup_regs(struct lguest_regs *regs, unsigned long start)
{
/* Write out stack in format lguest expects, so we can switch to it. */
regs->ds = regs->es = regs->ss = __KERNEL_DS|GUEST_PL;
regs->cs = __KERNEL_CS|GUEST_PL;
regs->eflags = 0x202; /* Interrupts enabled. */
regs->eip = start;
/* esi points to our boot information (physical address 0) */
}
/* + addr */
static long user_get_dma(struct lguest *lg, const u32 __user *input)
{
unsigned long key, udma, irq;
if (get_user(key, input) != 0)
return -EFAULT;
udma = get_dma_buffer(lg, key, &irq);
if (!udma)
return -ENOENT;
/* We put irq number in udma->used_len. */
lgwrite_u32(lg, udma + offsetof(struct lguest_dma, used_len), irq);
return udma;
}
/* To force the Guest to stop running and return to the Launcher, the
* Waker sets writes LHREQ_BREAK and the value "1" to /dev/lguest. The
* Launcher then writes LHREQ_BREAK and "0" to release the Waker. */
static int break_guest_out(struct lguest *lg, const u32 __user *input)
{
unsigned long on;
/* Fetch whether they're turning break on or off.. */
if (get_user(on, input) != 0)
return -EFAULT;
if (on) {
lg->break_out = 1;
/* Pop it out (may be running on different CPU) */
wake_up_process(lg->tsk);
/* Wait for them to reset it */
return wait_event_interruptible(lg->break_wq, !lg->break_out);
} else {
lg->break_out = 0;
wake_up(&lg->break_wq);
return 0;
}
}
/* + irq */
static int user_send_irq(struct lguest *lg, const u32 __user *input)
{
u32 irq;
if (get_user(irq, input) != 0)
return -EFAULT;
if (irq >= LGUEST_IRQS)
return -EINVAL;
set_bit(irq, lg->irqs_pending);
return 0;
}
static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
{
struct lguest *lg = file->private_data;
if (!lg)
return -EINVAL;
/* If you're not the task which owns the guest, go away. */
if (current != lg->tsk)
return -EPERM;
if (lg->dead) {
size_t len;
if (IS_ERR(lg->dead))
return PTR_ERR(lg->dead);
len = min(size, strlen(lg->dead)+1);
if (copy_to_user(user, lg->dead, len) != 0)
return -EFAULT;
return len;
}
if (lg->dma_is_pending)
lg->dma_is_pending = 0;
return run_guest(lg, (unsigned long __user *)user);
}
/* Take: pfnlimit, pgdir, start, pageoffset. */
static int initialize(struct file *file, const u32 __user *input)
{
struct lguest *lg;
int err, i;
u32 args[4];
/* We grab the Big Lguest lock, which protects the global array
* "lguests" and multiple simultaneous initializations. */
mutex_lock(&lguest_lock);
if (file->private_data) {
err = -EBUSY;
goto unlock;
}
if (copy_from_user(args, input, sizeof(args)) != 0) {
err = -EFAULT;
goto unlock;
}
i = find_free_guest();
if (i < 0) {
err = -ENOSPC;
goto unlock;
}
lg = &lguests[i];
lg->guestid = i;
lg->pfn_limit = args[0];
lg->page_offset = args[3];
lg->regs_page = get_zeroed_page(GFP_KERNEL);
if (!lg->regs_page) {
err = -ENOMEM;
goto release_guest;
}
lg->regs = (void *)lg->regs_page + PAGE_SIZE - sizeof(*lg->regs);
err = init_guest_pagetable(lg, args[1]);
if (err)
goto free_regs;
setup_regs(lg->regs, args[2]);
setup_guest_gdt(lg);
init_clockdev(lg);
lg->tsk = current;
lg->mm = get_task_mm(lg->tsk);
init_waitqueue_head(&lg->break_wq);
lg->last_pages = NULL;
file->private_data = lg;
mutex_unlock(&lguest_lock);
return sizeof(args);
free_regs:
free_page(lg->regs_page);
release_guest:
memset(lg, 0, sizeof(*lg));
unlock:
mutex_unlock(&lguest_lock);
return err;
}
static ssize_t write(struct file *file, const char __user *input,
size_t size, loff_t *off)
{
struct lguest *lg = file->private_data;
u32 req;
if (get_user(req, input) != 0)
return -EFAULT;
input += sizeof(req);
if (req != LHREQ_INITIALIZE && !lg)
return -EINVAL;
if (lg && lg->dead)
return -ENOENT;
/* If you're not the task which owns the Guest, you can only break */
if (lg && current != lg->tsk && req != LHREQ_BREAK)
return -EPERM;
switch (req) {
case LHREQ_INITIALIZE:
return initialize(file, (const u32 __user *)input);
case LHREQ_GETDMA:
return user_get_dma(lg, (const u32 __user *)input);
case LHREQ_IRQ:
return user_send_irq(lg, (const u32 __user *)input);
case LHREQ_BREAK:
return break_guest_out(lg, (const u32 __user *)input);
default:
return -EINVAL;
}
}
static int close(struct inode *inode, struct file *file)
{
struct lguest *lg = file->private_data;
if (!lg)
return 0;
mutex_lock(&lguest_lock);
/* Cancels the hrtimer set via LHCALL_SET_CLOCKEVENT. */
hrtimer_cancel(&lg->hrt);
release_all_dma(lg);
free_guest_pagetable(lg);
mmput(lg->mm);
if (!IS_ERR(lg->dead))
kfree(lg->dead);
free_page(lg->regs_page);
memset(lg, 0, sizeof(*lg));
mutex_unlock(&lguest_lock);
return 0;
}
static struct file_operations lguest_fops = {
.owner = THIS_MODULE,
.release = close,
.write = write,
.read = read,
};
static struct miscdevice lguest_dev = {
.minor = MISC_DYNAMIC_MINOR,
.name = "lguest",
.fops = &lguest_fops,
};
int __init lguest_device_init(void)
{
return misc_register(&lguest_dev);
}
void __exit lguest_device_remove(void)
{
misc_deregister(&lguest_dev);
}

411
drivers/lguest/page_tables.c Normal file
View File

@ -0,0 +1,411 @@
/* Shadow page table operations.
* Copyright (C) Rusty Russell IBM Corporation 2006.
* GPL v2 and any later version */
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/random.h>
#include <linux/percpu.h>
#include <asm/tlbflush.h>
#include "lg.h"
#define PTES_PER_PAGE_SHIFT 10
#define PTES_PER_PAGE (1 << PTES_PER_PAGE_SHIFT)
#define SWITCHER_PGD_INDEX (PTES_PER_PAGE - 1)
static DEFINE_PER_CPU(spte_t *, switcher_pte_pages);
#define switcher_pte_page(cpu) per_cpu(switcher_pte_pages, cpu)
static unsigned vaddr_to_pgd_index(unsigned long vaddr)
{
return vaddr >> (PAGE_SHIFT + PTES_PER_PAGE_SHIFT);
}
/* These access the shadow versions (ie. the ones used by the CPU). */
static spgd_t *spgd_addr(struct lguest *lg, u32 i, unsigned long vaddr)
{
unsigned int index = vaddr_to_pgd_index(vaddr);
if (index >= SWITCHER_PGD_INDEX) {
kill_guest(lg, "attempt to access switcher pages");
index = 0;
}
return &lg->pgdirs[i].pgdir[index];
}
static spte_t *spte_addr(struct lguest *lg, spgd_t spgd, unsigned long vaddr)
{
spte_t *page = __va(spgd.pfn << PAGE_SHIFT);
BUG_ON(!(spgd.flags & _PAGE_PRESENT));
return &page[(vaddr >> PAGE_SHIFT) % PTES_PER_PAGE];
}
/* These access the guest versions. */
static unsigned long gpgd_addr(struct lguest *lg, unsigned long vaddr)
{
unsigned int index = vaddr >> (PAGE_SHIFT + PTES_PER_PAGE_SHIFT);
return lg->pgdirs[lg->pgdidx].cr3 + index * sizeof(gpgd_t);
}
static unsigned long gpte_addr(struct lguest *lg,
gpgd_t gpgd, unsigned long vaddr)
{
unsigned long gpage = gpgd.pfn << PAGE_SHIFT;
BUG_ON(!(gpgd.flags & _PAGE_PRESENT));
return gpage + ((vaddr>>PAGE_SHIFT) % PTES_PER_PAGE) * sizeof(gpte_t);
}
/* Do a virtual -> physical mapping on a user page. */
static unsigned long get_pfn(unsigned long virtpfn, int write)
{
struct page *page;
unsigned long ret = -1UL;
down_read(&current->mm->mmap_sem);
if (get_user_pages(current, current->mm, virtpfn << PAGE_SHIFT,
1, write, 1, &page, NULL) == 1)
ret = page_to_pfn(page);
up_read(&current->mm->mmap_sem);
return ret;
}
static spte_t gpte_to_spte(struct lguest *lg, gpte_t gpte, int write)
{
spte_t spte;
unsigned long pfn;
/* We ignore the global flag. */
spte.flags = (gpte.flags & ~_PAGE_GLOBAL);
pfn = get_pfn(gpte.pfn, write);
if (pfn == -1UL) {
kill_guest(lg, "failed to get page %u", gpte.pfn);
/* Must not put_page() bogus page on cleanup. */
spte.flags = 0;
}
spte.pfn = pfn;
return spte;
}
static void release_pte(spte_t pte)
{
if (pte.flags & _PAGE_PRESENT)
put_page(pfn_to_page(pte.pfn));
}
static void check_gpte(struct lguest *lg, gpte_t gpte)
{
if ((gpte.flags & (_PAGE_PWT|_PAGE_PSE)) || gpte.pfn >= lg->pfn_limit)
kill_guest(lg, "bad page table entry");
}
static void check_gpgd(struct lguest *lg, gpgd_t gpgd)
{
if ((gpgd.flags & ~_PAGE_TABLE) || gpgd.pfn >= lg->pfn_limit)
kill_guest(lg, "bad page directory entry");
}
/* FIXME: We hold reference to pages, which prevents them from being
swapped. It'd be nice to have a callback when Linux wants to swap out. */
/* We fault pages in, which allows us to update accessed/dirty bits.
* Return true if we got page. */
int demand_page(struct lguest *lg, unsigned long vaddr, int errcode)
{
gpgd_t gpgd;
spgd_t *spgd;
unsigned long gpte_ptr;
gpte_t gpte;
spte_t *spte;
gpgd = mkgpgd(lgread_u32(lg, gpgd_addr(lg, vaddr)));
if (!(gpgd.flags & _PAGE_PRESENT))
return 0;
spgd = spgd_addr(lg, lg->pgdidx, vaddr);
if (!(spgd->flags & _PAGE_PRESENT)) {
/* Get a page of PTEs for them. */
unsigned long ptepage = get_zeroed_page(GFP_KERNEL);
/* FIXME: Steal from self in this case? */
if (!ptepage) {
kill_guest(lg, "out of memory allocating pte page");
return 0;
}
check_gpgd(lg, gpgd);
spgd->raw.val = (__pa(ptepage) | gpgd.flags);
}
gpte_ptr = gpte_addr(lg, gpgd, vaddr);
gpte = mkgpte(lgread_u32(lg, gpte_ptr));
/* No page? */
if (!(gpte.flags & _PAGE_PRESENT))
return 0;
/* Write to read-only page? */
if ((errcode & 2) && !(gpte.flags & _PAGE_RW))
return 0;
/* User access to a non-user page? */
if ((errcode & 4) && !(gpte.flags & _PAGE_USER))
return 0;
check_gpte(lg, gpte);
gpte.flags |= _PAGE_ACCESSED;
if (errcode & 2)
gpte.flags |= _PAGE_DIRTY;
/* We're done with the old pte. */
spte = spte_addr(lg, *spgd, vaddr);
release_pte(*spte);
/* We don't make it writable if this isn't a write: later
* write will fault so we can set dirty bit in guest. */
if (gpte.flags & _PAGE_DIRTY)
*spte = gpte_to_spte(lg, gpte, 1);
else {
gpte_t ro_gpte = gpte;
ro_gpte.flags &= ~_PAGE_RW;
*spte = gpte_to_spte(lg, ro_gpte, 0);
}
/* Now we update dirty/accessed on guest. */
lgwrite_u32(lg, gpte_ptr, gpte.raw.val);
return 1;
}
/* This is much faster than the full demand_page logic. */
static int page_writable(struct lguest *lg, unsigned long vaddr)
{
spgd_t *spgd;
unsigned long flags;
spgd = spgd_addr(lg, lg->pgdidx, vaddr);
if (!(spgd->flags & _PAGE_PRESENT))
return 0;
flags = spte_addr(lg, *spgd, vaddr)->flags;
return (flags & (_PAGE_PRESENT|_PAGE_RW)) == (_PAGE_PRESENT|_PAGE_RW);
}
void pin_page(struct lguest *lg, unsigned long vaddr)
{
if (!page_writable(lg, vaddr) && !demand_page(lg, vaddr, 2))
kill_guest(lg, "bad stack page %#lx", vaddr);
}
static void release_pgd(struct lguest *lg, spgd_t *spgd)
{
if (spgd->flags & _PAGE_PRESENT) {
unsigned int i;
spte_t *ptepage = __va(spgd->pfn << PAGE_SHIFT);
for (i = 0; i < PTES_PER_PAGE; i++)
release_pte(ptepage[i]);
free_page((long)ptepage);
spgd->raw.val = 0;
}
}
static void flush_user_mappings(struct lguest *lg, int idx)
{
unsigned int i;
for (i = 0; i < vaddr_to_pgd_index(lg->page_offset); i++)
release_pgd(lg, lg->pgdirs[idx].pgdir + i);
}
void guest_pagetable_flush_user(struct lguest *lg)
{
flush_user_mappings(lg, lg->pgdidx);
}
static unsigned int find_pgdir(struct lguest *lg, unsigned long pgtable)
{
unsigned int i;
for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
if (lg->pgdirs[i].cr3 == pgtable)
break;
return i;
}
static unsigned int new_pgdir(struct lguest *lg,
unsigned long cr3,
int *blank_pgdir)
{
unsigned int next;
next = random32() % ARRAY_SIZE(lg->pgdirs);
if (!lg->pgdirs[next].pgdir) {
lg->pgdirs[next].pgdir = (spgd_t *)get_zeroed_page(GFP_KERNEL);
if (!lg->pgdirs[next].pgdir)
next = lg->pgdidx;
else
/* There are no mappings: you'll need to re-pin */
*blank_pgdir = 1;
}
lg->pgdirs[next].cr3 = cr3;
/* Release all the non-kernel mappings. */
flush_user_mappings(lg, next);
return next;
}
void guest_new_pagetable(struct lguest *lg, unsigned long pgtable)
{
int newpgdir, repin = 0;
newpgdir = find_pgdir(lg, pgtable);
if (newpgdir == ARRAY_SIZE(lg->pgdirs))
newpgdir = new_pgdir(lg, pgtable, &repin);
lg->pgdidx = newpgdir;
if (repin)
pin_stack_pages(lg);
}
static void release_all_pagetables(struct lguest *lg)
{
unsigned int i, j;
for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
if (lg->pgdirs[i].pgdir)
for (j = 0; j < SWITCHER_PGD_INDEX; j++)
release_pgd(lg, lg->pgdirs[i].pgdir + j);
}
void guest_pagetable_clear_all(struct lguest *lg)
{
release_all_pagetables(lg);
pin_stack_pages(lg);
}
static void do_set_pte(struct lguest *lg, int idx,
unsigned long vaddr, gpte_t gpte)
{
spgd_t *spgd = spgd_addr(lg, idx, vaddr);
if (spgd->flags & _PAGE_PRESENT) {
spte_t *spte = spte_addr(lg, *spgd, vaddr);
release_pte(*spte);
if (gpte.flags & (_PAGE_DIRTY | _PAGE_ACCESSED)) {
check_gpte(lg, gpte);
*spte = gpte_to_spte(lg, gpte, gpte.flags&_PAGE_DIRTY);
} else
spte->raw.val = 0;
}
}
void guest_set_pte(struct lguest *lg,
unsigned long cr3, unsigned long vaddr, gpte_t gpte)
{
/* Kernel mappings must be changed on all top levels. */
if (vaddr >= lg->page_offset) {
unsigned int i;
for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
if (lg->pgdirs[i].pgdir)
do_set_pte(lg, i, vaddr, gpte);
} else {
int pgdir = find_pgdir(lg, cr3);
if (pgdir != ARRAY_SIZE(lg->pgdirs))
do_set_pte(lg, pgdir, vaddr, gpte);
}
}
void guest_set_pmd(struct lguest *lg, unsigned long cr3, u32 idx)
{
int pgdir;
if (idx >= SWITCHER_PGD_INDEX)
return;
pgdir = find_pgdir(lg, cr3);
if (pgdir < ARRAY_SIZE(lg->pgdirs))
release_pgd(lg, lg->pgdirs[pgdir].pgdir + idx);
}
int init_guest_pagetable(struct lguest *lg, unsigned long pgtable)
{
/* We assume this in flush_user_mappings, so check now */
if (vaddr_to_pgd_index(lg->page_offset) >= SWITCHER_PGD_INDEX)
return -EINVAL;
lg->pgdidx = 0;
lg->pgdirs[lg->pgdidx].cr3 = pgtable;
lg->pgdirs[lg->pgdidx].pgdir = (spgd_t*)get_zeroed_page(GFP_KERNEL);
if (!lg->pgdirs[lg->pgdidx].pgdir)
return -ENOMEM;
return 0;
}
void free_guest_pagetable(struct lguest *lg)
{
unsigned int i;
release_all_pagetables(lg);
for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
free_page((long)lg->pgdirs[i].pgdir);
}
/* Caller must be preempt-safe */
void map_switcher_in_guest(struct lguest *lg, struct lguest_pages *pages)
{
spte_t *switcher_pte_page = __get_cpu_var(switcher_pte_pages);
spgd_t switcher_pgd;
spte_t regs_pte;
/* Since switcher less that 4MB, we simply mug top pte page. */
switcher_pgd.pfn = __pa(switcher_pte_page) >> PAGE_SHIFT;
switcher_pgd.flags = _PAGE_KERNEL;
lg->pgdirs[lg->pgdidx].pgdir[SWITCHER_PGD_INDEX] = switcher_pgd;
/* Map our regs page over stack page. */
regs_pte.pfn = __pa(lg->regs_page) >> PAGE_SHIFT;
regs_pte.flags = _PAGE_KERNEL;
switcher_pte_page[(unsigned long)pages/PAGE_SIZE%PTES_PER_PAGE]
= regs_pte;
}
static void free_switcher_pte_pages(void)
{
unsigned int i;
for_each_possible_cpu(i)
free_page((long)switcher_pte_page(i));
}
static __init void populate_switcher_pte_page(unsigned int cpu,
struct page *switcher_page[],
unsigned int pages)
{
unsigned int i;
spte_t *pte = switcher_pte_page(cpu);
for (i = 0; i < pages; i++) {
pte[i].pfn = page_to_pfn(switcher_page[i]);
pte[i].flags = _PAGE_PRESENT|_PAGE_ACCESSED;
}
/* We only map this CPU's pages, so guest can't see others. */
i = pages + cpu*2;
/* First page (regs) is rw, second (state) is ro. */
pte[i].pfn = page_to_pfn(switcher_page[i]);
pte[i].flags = _PAGE_PRESENT|_PAGE_ACCESSED|_PAGE_RW;
pte[i+1].pfn = page_to_pfn(switcher_page[i+1]);
pte[i+1].flags = _PAGE_PRESENT|_PAGE_ACCESSED;
}
__init int init_pagetables(struct page **switcher_page, unsigned int pages)
{
unsigned int i;
for_each_possible_cpu(i) {
switcher_pte_page(i) = (spte_t *)get_zeroed_page(GFP_KERNEL);
if (!switcher_pte_page(i)) {
free_switcher_pte_pages();
return -ENOMEM;
}
populate_switcher_pte_page(i, switcher_page, pages);
}
return 0;
}
void free_pagetables(void)
{
free_switcher_pte_pages();
}

125
drivers/lguest/segments.c Normal file
View File

@ -0,0 +1,125 @@
#include "lg.h"
static int desc_ok(const struct desc_struct *gdt)
{
/* MBZ=0, P=1, DT=1 */
return ((gdt->b & 0x00209000) == 0x00009000);
}
static int segment_present(const struct desc_struct *gdt)
{
return gdt->b & 0x8000;
}
static int ignored_gdt(unsigned int num)
{
return (num == GDT_ENTRY_TSS
|| num == GDT_ENTRY_LGUEST_CS
|| num == GDT_ENTRY_LGUEST_DS
|| num == GDT_ENTRY_DOUBLEFAULT_TSS);
}
/* We don't allow removal of CS, DS or SS; it doesn't make sense. */
static void check_segment_use(struct lguest *lg, unsigned int desc)
{
if (lg->regs->gs / 8 == desc)
lg->regs->gs = 0;
if (lg->regs->fs / 8 == desc)
lg->regs->fs = 0;
if (lg->regs->es / 8 == desc)
lg->regs->es = 0;
if (lg->regs->ds / 8 == desc
|| lg->regs->cs / 8 == desc
|| lg->regs->ss / 8 == desc)
kill_guest(lg, "Removed live GDT entry %u", desc);
}
static void fixup_gdt_table(struct lguest *lg, unsigned start, unsigned end)
{
unsigned int i;
for (i = start; i < end; i++) {
/* We never copy these ones to real gdt */
if (ignored_gdt(i))
continue;
/* We could fault in switch_to_guest if they are using
* a removed segment. */
if (!segment_present(&lg->gdt[i])) {
check_segment_use(lg, i);
continue;
}
if (!desc_ok(&lg->gdt[i]))
kill_guest(lg, "Bad GDT descriptor %i", i);
/* DPL 0 presumably means "for use by guest". */
if ((lg->gdt[i].b & 0x00006000) == 0)
lg->gdt[i].b |= (GUEST_PL << 13);
/* Set accessed bit, since gdt isn't writable. */
lg->gdt[i].b |= 0x00000100;
}
}
void setup_default_gdt_entries(struct lguest_ro_state *state)
{
struct desc_struct *gdt = state->guest_gdt;
unsigned long tss = (unsigned long)&state->guest_tss;
/* Hypervisor segments. */
gdt[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
gdt[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
/* This is the one which we *cannot* copy from guest, since tss
is depended on this lguest_ro_state, ie. this cpu. */
gdt[GDT_ENTRY_TSS].a = 0x00000067 | (tss << 16);
gdt[GDT_ENTRY_TSS].b = 0x00008900 | (tss & 0xFF000000)
| ((tss >> 16) & 0x000000FF);
}
void setup_guest_gdt(struct lguest *lg)
{
lg->gdt[GDT_ENTRY_KERNEL_CS] = FULL_EXEC_SEGMENT;
lg->gdt[GDT_ENTRY_KERNEL_DS] = FULL_SEGMENT;
lg->gdt[GDT_ENTRY_KERNEL_CS].b |= (GUEST_PL << 13);
lg->gdt[GDT_ENTRY_KERNEL_DS].b |= (GUEST_PL << 13);
}
/* This is a fast version for the common case where only the three TLS entries
* have changed. */
void copy_gdt_tls(const struct lguest *lg, struct desc_struct *gdt)
{
unsigned int i;
for (i = GDT_ENTRY_TLS_MIN; i <= GDT_ENTRY_TLS_MAX; i++)
gdt[i] = lg->gdt[i];
}
void copy_gdt(const struct lguest *lg, struct desc_struct *gdt)
{
unsigned int i;
for (i = 0; i < GDT_ENTRIES; i++)
if (!ignored_gdt(i))
gdt[i] = lg->gdt[i];
}
void load_guest_gdt(struct lguest *lg, unsigned long table, u32 num)
{
if (num > ARRAY_SIZE(lg->gdt))
kill_guest(lg, "too many gdt entries %i", num);
lgread(lg, lg->gdt, table, num * sizeof(lg->gdt[0]));
fixup_gdt_table(lg, 0, ARRAY_SIZE(lg->gdt));
lg->changed |= CHANGED_GDT;
}
void guest_load_tls(struct lguest *lg, unsigned long gtls)
{
struct desc_struct *tls = &lg->gdt[GDT_ENTRY_TLS_MIN];
lgread(lg, tls, gtls, sizeof(*tls)*GDT_ENTRY_TLS_ENTRIES);
fixup_gdt_table(lg, GDT_ENTRY_TLS_MIN, GDT_ENTRY_TLS_MAX+1);
lg->changed |= CHANGED_GDT_TLS;
}

159
drivers/lguest/switcher.S Normal file
View File

@ -0,0 +1,159 @@
/* This code sits at 0xFFC00000 to do the low-level guest<->host switch.
There is are two pages above us for this CPU (struct lguest_pages).
The second page (struct lguest_ro_state) becomes read-only after the
context switch. The first page (the stack for traps) remains writable,
but while we're in here, the guest cannot be running.
*/
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include "lg.h"
.text
ENTRY(start_switcher_text)
/* %eax points to lguest pages for this CPU. %ebx contains cr3 value.
All normal registers can be clobbered! */
ENTRY(switch_to_guest)
/* Save host segments on host stack. */
pushl %es
pushl %ds
pushl %gs
pushl %fs
/* With CONFIG_FRAME_POINTER, gcc doesn't let us clobber this! */
pushl %ebp
/* Save host stack. */
movl %esp, LGUEST_PAGES_host_sp(%eax)
/* Switch to guest stack: if we get NMI we expect to be there. */
movl %eax, %edx
addl $LGUEST_PAGES_regs, %edx
movl %edx, %esp
/* Switch to guest's GDT, IDT. */
lgdt LGUEST_PAGES_guest_gdt_desc(%eax)
lidt LGUEST_PAGES_guest_idt_desc(%eax)
/* Switch to guest's TSS while GDT still writable. */
movl $(GDT_ENTRY_TSS*8), %edx
ltr %dx
/* Set host's TSS GDT entry to available (clear byte 5 bit 2). */
movl (LGUEST_PAGES_host_gdt_desc+2)(%eax), %edx
andb $0xFD, (GDT_ENTRY_TSS*8 + 5)(%edx)
/* Switch to guest page tables: lguest_pages->state now read-only. */
movl %ebx, %cr3
/* Restore guest regs */
popl %ebx
popl %ecx
popl %edx
popl %esi
popl %edi
popl %ebp
popl %gs
popl %eax
popl %fs
popl %ds
popl %es
/* Skip error code and trap number */
addl $8, %esp
iret
#define SWITCH_TO_HOST \
/* Save guest state */ \
pushl %es; \
pushl %ds; \
pushl %fs; \
pushl %eax; \
pushl %gs; \
pushl %ebp; \
pushl %edi; \
pushl %esi; \
pushl %edx; \
pushl %ecx; \
pushl %ebx; \
/* Load lguest ds segment for convenience. */ \
movl $(LGUEST_DS), %eax; \
movl %eax, %ds; \
/* Figure out where we are, based on stack (at top of regs). */ \
movl %esp, %eax; \
subl $LGUEST_PAGES_regs, %eax; \
/* Put trap number in %ebx before we switch cr3 and lose it. */ \
movl LGUEST_PAGES_regs_trapnum(%eax), %ebx; \
/* Switch to host page tables (host GDT, IDT and stack are in host \
mem, so need this first) */ \
movl LGUEST_PAGES_host_cr3(%eax), %edx; \
movl %edx, %cr3; \
/* Set guest's TSS to available (clear byte 5 bit 2). */ \
andb $0xFD, (LGUEST_PAGES_guest_gdt+GDT_ENTRY_TSS*8+5)(%eax); \
/* Switch to host's GDT & IDT. */ \
lgdt LGUEST_PAGES_host_gdt_desc(%eax); \
lidt LGUEST_PAGES_host_idt_desc(%eax); \
/* Switch to host's stack. */ \
movl LGUEST_PAGES_host_sp(%eax), %esp; \
/* Switch to host's TSS */ \
movl $(GDT_ENTRY_TSS*8), %edx; \
ltr %dx; \
popl %ebp; \
popl %fs; \
popl %gs; \
popl %ds; \
popl %es
/* Return to run_guest_once. */
return_to_host:
SWITCH_TO_HOST
iret
deliver_to_host:
SWITCH_TO_HOST
/* Decode IDT and jump to hosts' irq handler. When that does iret, it
* will return to run_guest_once. This is a feature. */
movl (LGUEST_PAGES_host_idt_desc+2)(%eax), %edx
leal (%edx,%ebx,8), %eax
movzwl (%eax),%edx
movl 4(%eax), %eax
xorw %ax, %ax
orl %eax, %edx
jmp *%edx
/* Real hardware interrupts are delivered straight to the host. Others
cause us to return to run_guest_once so it can decide what to do. Note
that some of these are overridden by the guest to deliver directly, and
never enter here (see load_guest_idt_entry). */
.macro IRQ_STUB N TARGET
.data; .long 1f; .text; 1:
/* Make an error number for most traps, which don't have one. */
.if (\N <> 8) && (\N < 10 || \N > 14) && (\N <> 17)
pushl $0
.endif
pushl $\N
jmp \TARGET
ALIGN
.endm
.macro IRQ_STUBS FIRST LAST TARGET
irq=\FIRST
.rept \LAST-\FIRST+1
IRQ_STUB irq \TARGET
irq=irq+1
.endr
.endm
/* We intercept every interrupt, because we may need to switch back to
* host. Unfortunately we can't tell them apart except by entry
* point, so we need 256 entry points.
*/
.data
.global default_idt_entries
default_idt_entries:
.text
IRQ_STUBS 0 1 return_to_host /* First two traps */
IRQ_STUB 2 handle_nmi /* NMI */
IRQ_STUBS 3 31 return_to_host /* Rest of traps */
IRQ_STUBS 32 127 deliver_to_host /* Real interrupts */
IRQ_STUB 128 return_to_host /* System call (overridden) */
IRQ_STUBS 129 255 deliver_to_host /* Other real interrupts */
/* We ignore NMI and return. */
handle_nmi:
addl $8, %esp
iret
ENTRY(end_switcher_text)

1
include/asm-i386/tsc.h
View File

@ -63,6 +63,7 @@ extern void tsc_init(void);
extern void mark_tsc_unstable(char *reason);
extern int unsynchronized_tsc(void);
extern void init_tsc_clocksource(void);
int check_tsc_unstable(void);
/*
* Boot-time check whether the TSCs are synchronized across

12
include/linux/lguest.h
View File

@ -3,11 +3,6 @@
#ifndef _ASM_LGUEST_H
#define _ASM_LGUEST_H
/* These are randomly chosen numbers which indicate we're an lguest at boot */
#define LGUEST_MAGIC_EBP 0x4C687970
#define LGUEST_MAGIC_EDI 0x652D4D65
#define LGUEST_MAGIC_ESI 0xFFFFFFFF
#ifndef __ASSEMBLY__
#include <asm/irq.h>
@ -20,7 +15,7 @@
#define LHCALL_LOAD_IDT_ENTRY 6
#define LHCALL_SET_STACK 7
#define LHCALL_TS 8
#define LHCALL_TIMER_READ 9
#define LHCALL_SET_CLOCKEVENT 9
#define LHCALL_HALT 10
#define LHCALL_GET_WALLCLOCK 11
#define LHCALL_BIND_DMA 12
@ -29,6 +24,9 @@
#define LHCALL_SET_PMD 15
#define LHCALL_LOAD_TLS 16
#define LG_CLOCK_MIN_DELTA 100UL
#define LG_CLOCK_MAX_DELTA ULONG_MAX
#define LGUEST_TRAP_ENTRY 0x1F
static inline unsigned long
@ -75,6 +73,8 @@ struct lguest_data
unsigned long reserve_mem;
/* ID of this guest (used by network driver to set ethernet address) */
u16 guestid;
/* KHz for the TSC clock. */
u32 tsc_khz;
/* Fields initialized by the guest at boot: */
/* Instruction range to suppress interrupts even if enabled */

73
include/linux/lguest_launcher.h Normal file
View File

@ -0,0 +1,73 @@
#ifndef _ASM_LGUEST_USER
#define _ASM_LGUEST_USER
/* Everything the "lguest" userspace program needs to know. */
/* They can register up to 32 arrays of lguest_dma. */
#define LGUEST_MAX_DMA 32
/* At most we can dma 16 lguest_dma in one op. */
#define LGUEST_MAX_DMA_SECTIONS 16
/* How many devices? Assume each one wants up to two dma arrays per device. */
#define LGUEST_MAX_DEVICES (LGUEST_MAX_DMA/2)
struct lguest_dma
{
/* 0 if free to be used, filled by hypervisor. */
u32 used_len;
unsigned long addr[LGUEST_MAX_DMA_SECTIONS];
u16 len[LGUEST_MAX_DMA_SECTIONS];
};
struct lguest_block_page
{
/* 0 is a read, 1 is a write. */
int type;
u32 sector; /* Offset in device = sector * 512. */
u32 bytes; /* Length expected to be read/written in bytes */
/* 0 = pending, 1 = done, 2 = done, error */
int result;
u32 num_sectors; /* Disk length = num_sectors * 512 */
};
/* There is a shared page of these. */
struct lguest_net
{
/* Simply the mac address (with multicast bit meaning promisc). */
unsigned char mac[6];
};
/* Where the Host expects the Guest to SEND_DMA console output to. */
#define LGUEST_CONSOLE_DMA_KEY 0
/* We have a page of these descriptors in the lguest_device page. */
struct lguest_device_desc {
u16 type;
#define LGUEST_DEVICE_T_CONSOLE 1
#define LGUEST_DEVICE_T_NET 2
#define LGUEST_DEVICE_T_BLOCK 3
u16 features;
#define LGUEST_NET_F_NOCSUM 0x4000 /* Don't bother checksumming */
#define LGUEST_DEVICE_F_RANDOMNESS 0x8000 /* IRQ is fairly random */
u16 status;
/* 256 and above are device specific. */
#define LGUEST_DEVICE_S_ACKNOWLEDGE 1 /* We have seen device. */
#define LGUEST_DEVICE_S_DRIVER 2 /* We have found a driver */
#define LGUEST_DEVICE_S_DRIVER_OK 4 /* Driver says OK! */
#define LGUEST_DEVICE_S_REMOVED 8 /* Device has gone away. */
#define LGUEST_DEVICE_S_REMOVED_ACK 16 /* Driver has been told. */
#define LGUEST_DEVICE_S_FAILED 128 /* Something actually failed */
u16 num_pages;
u32 pfn;
};
/* Write command first word is a request. */
enum lguest_req
{
LHREQ_INITIALIZE, /* + pfnlimit, pgdir, start, pageoffset */
LHREQ_GETDMA, /* + addr (returns &lguest_dma, irq in ->used_len) */
LHREQ_IRQ, /* + irq */
LHREQ_BREAK, /* + on/off flag (on blocks until someone does off) */
};
#endif /* _ASM_LGUEST_USER */

1
kernel/fork.c
View File

@ -127,7 +127,6 @@ void __put_task_struct(struct task_struct *tsk)
if (!profile_handoff_task(tsk))
free_task(tsk);
}
EXPORT_SYMBOL_GPL(__put_task_struct);
void __init fork_init(unsigned long mempages)
{