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x86/xen: remove 32-bit Xen PV guest support

Browse Source 
Xen is requiring 64-bit machines today and since Xen 4.14 it can be
built without 32-bit PV guest support. There is no need to carry the
burden of 32-bit PV guest support in the kernel any longer, as new
guests can be either HVM or PVH, or they can use a 64 bit kernel.

Remove the 32-bit Xen PV support from the kernel.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Juergen Gross 2020-06-29 10:35:39 +02:00
parent d7b461caa6
commit a13f2ef168
18 changed files with 50 additions and 840 deletions
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109
arch/x86/entry/entry_32.S
View File

@ -449,8 +449,6 @@
.macro SWITCH_TO_KERNEL_STACK
ALTERNATIVE "", "jmp .Lend_\@", X86_FEATURE_XENPV
BUG_IF_WRONG_CR3
SWITCH_TO_KERNEL_CR3 scratch_reg=%eax
@ -599,8 +597,6 @@
*/
.macro SWITCH_TO_ENTRY_STACK
ALTERNATIVE "", "jmp .Lend_\@", X86_FEATURE_XENPV
/* Bytes to copy */
movl $PTREGS_SIZE, %ecx
@ -872,17 +868,6 @@ SYM_ENTRY(__begin_SYSENTER_singlestep_region, SYM_L_GLOBAL, SYM_A_NONE)
* will ignore all of the single-step traps generated in this range.
*/
#ifdef CONFIG_XEN_PV
/*
* Xen doesn't set %esp to be precisely what the normal SYSENTER
* entry point expects, so fix it up before using the normal path.
*/
SYM_CODE_START(xen_sysenter_target)
addl $5*4, %esp /* remove xen-provided frame */
jmp .Lsysenter_past_esp
SYM_CODE_END(xen_sysenter_target)
#endif
/*
* 32-bit SYSENTER entry.
*
@ -965,9 +950,8 @@ SYM_FUNC_START(entry_SYSENTER_32)
movl %esp, %eax
call do_SYSENTER_32
/* XEN PV guests always use IRET path */
ALTERNATIVE "testl %eax, %eax; jz .Lsyscall_32_done", \
"jmp .Lsyscall_32_done", X86_FEATURE_XENPV
testl %eax, %eax
jz .Lsyscall_32_done
STACKLEAK_ERASE
@ -1165,95 +1149,6 @@ SYM_FUNC_END(entry_INT80_32)
#endif
.endm
#ifdef CONFIG_PARAVIRT
SYM_CODE_START(native_iret)
iret
_ASM_EXTABLE(native_iret, asm_iret_error)
SYM_CODE_END(native_iret)
#endif
#ifdef CONFIG_XEN_PV
/*
* See comment in entry_64.S for further explanation
*
* Note: This is not an actual IDT entry point. It's a XEN specific entry
* point and therefore named to match the 64-bit trampoline counterpart.
*/
SYM_FUNC_START(xen_asm_exc_xen_hypervisor_callback)
/*
* Check to see if we got the event in the critical
* region in xen_iret_direct, after we've reenabled
* events and checked for pending events. This simulates
* iret instruction's behaviour where it delivers a
* pending interrupt when enabling interrupts:
*/
cmpl $xen_iret_start_crit, (%esp)
jb 1f
cmpl $xen_iret_end_crit, (%esp)
jae 1f
call xen_iret_crit_fixup
1:
pushl $-1 /* orig_ax = -1 => not a system call */
SAVE_ALL
ENCODE_FRAME_POINTER
mov %esp, %eax
call xen_pv_evtchn_do_upcall
jmp handle_exception_return
SYM_FUNC_END(xen_asm_exc_xen_hypervisor_callback)
/*
* Hypervisor uses this for application faults while it executes.
* We get here for two reasons:
* 1. Fault while reloading DS, ES, FS or GS
* 2. Fault while executing IRET
* Category 1 we fix up by reattempting the load, and zeroing the segment
* register if the load fails.
* Category 2 we fix up by jumping to do_iret_error. We cannot use the
* normal Linux return path in this case because if we use the IRET hypercall
* to pop the stack frame we end up in an infinite loop of failsafe callbacks.
* We distinguish between categories by maintaining a status value in EAX.
*/
SYM_FUNC_START(xen_failsafe_callback)
pushl %eax
movl $1, %eax
1: mov 4(%esp), %ds
2: mov 8(%esp), %es
3: mov 12(%esp), %fs
4: mov 16(%esp), %gs
/* EAX == 0 => Category 1 (Bad segment)
EAX != 0 => Category 2 (Bad IRET) */
testl %eax, %eax
popl %eax
lea 16(%esp), %esp
jz 5f
jmp asm_iret_error
5: pushl $-1 /* orig_ax = -1 => not a system call */
SAVE_ALL
ENCODE_FRAME_POINTER
jmp handle_exception_return
.section .fixup, "ax"
6: xorl %eax, %eax
movl %eax, 4(%esp)
jmp 1b
7: xorl %eax, %eax
movl %eax, 8(%esp)
jmp 2b
8: xorl %eax, %eax
movl %eax, 12(%esp)
jmp 3b
9: xorl %eax, %eax
movl %eax, 16(%esp)
jmp 4b
.previous
_ASM_EXTABLE(1b, 6b)
_ASM_EXTABLE(2b, 7b)
_ASM_EXTABLE(3b, 8b)
_ASM_EXTABLE(4b, 9b)
SYM_FUNC_END(xen_failsafe_callback)
#endif /* CONFIG_XEN_PV */
SYM_CODE_START_LOCAL_NOALIGN(handle_exception)
/* the function address is in %gs's slot on the stack */
SAVE_ALL switch_stacks=1 skip_gs=1 unwind_espfix=1

30
arch/x86/entry/vdso/vdso32/note.S
View File

@ -16,33 +16,3 @@ ELFNOTE_START(Linux, 0, "a")
ELFNOTE_END
BUILD_SALT
#ifdef CONFIG_XEN
/*
* Add a special note telling glibc's dynamic linker a fake hardware
* flavor that it will use to choose the search path for libraries in the
* same way it uses real hardware capabilities like "mmx".
* We supply "nosegneg" as the fake capability, to indicate that we
* do not like negative offsets in instructions using segment overrides,
* since we implement those inefficiently. This makes it possible to
* install libraries optimized to avoid those access patterns in someplace
* like /lib/i686/tls/nosegneg. Note that an /etc/ld.so.conf.d/file
* corresponding to the bits here is needed to make ldconfig work right.
* It should contain:
* hwcap 1 nosegneg
* to match the mapping of bit to name that we give here.
*
* At runtime, the fake hardware feature will be considered to be present
* if its bit is set in the mask word. So, we start with the mask 0, and
* at boot time we set VDSO_NOTE_NONEGSEG_BIT if running under Xen.
*/
#include "../../xen/vdso.h" /* Defines VDSO_NOTE_NONEGSEG_BIT. */
ELFNOTE_START(GNU, 2, "a")
.long 1 /* ncaps */
VDSO32_NOTE_MASK: /* Symbol used by arch/x86/xen/setup.c */
.long 0 /* mask */
.byte VDSO_NOTE_NONEGSEG_BIT; .asciz "nosegneg" /* bit, name */
ELFNOTE_END
#endif

2
arch/x86/include/asm/proto.h
View File

@ -25,7 +25,7 @@ void entry_SYSENTER_compat(void);
void __end_entry_SYSENTER_compat(void);
void entry_SYSCALL_compat(void);
void entry_INT80_compat(void);
#if defined(CONFIG_X86_64) && defined(CONFIG_XEN_PV)
#ifdef CONFIG_XEN_PV
void xen_entry_INT80_compat(void);
#endif
#endif

2
arch/x86/include/asm/segment.h
View File

@ -301,7 +301,7 @@ static inline void vdso_read_cpunode(unsigned *cpu, unsigned *node)
extern const char early_idt_handler_array[NUM_EXCEPTION_VECTORS][EARLY_IDT_HANDLER_SIZE];
extern void early_ignore_irq(void);
#if defined(CONFIG_X86_64) && defined(CONFIG_XEN_PV)
#ifdef CONFIG_XEN_PV
extern const char xen_early_idt_handler_array[NUM_EXCEPTION_VECTORS][XEN_EARLY_IDT_HANDLER_SIZE];
#endif

31
arch/x86/kernel/head_32.S
View File

@ -134,38 +134,7 @@ SYM_CODE_START(startup_32)
movl %eax,pa(initial_page_table+0xffc)
#endif
#ifdef CONFIG_PARAVIRT
/* This is can only trip for a broken bootloader... */
cmpw $0x207, pa(boot_params + BP_version)
jb .Ldefault_entry
/* Paravirt-compatible boot parameters. Look to see what architecture
we're booting under. */
movl pa(boot_params + BP_hardware_subarch), %eax
cmpl $num_subarch_entries, %eax
jae .Lbad_subarch
movl pa(subarch_entries)(,%eax,4), %eax
subl $__PAGE_OFFSET, %eax
jmp *%eax
.Lbad_subarch:
SYM_INNER_LABEL_ALIGN(xen_entry, SYM_L_WEAK)
/* Unknown implementation; there's really
nothing we can do at this point. */
ud2a
__INITDATA
subarch_entries:
.long .Ldefault_entry /* normal x86/PC */
.long xen_entry /* Xen hypervisor */
.long .Ldefault_entry /* Moorestown MID */
num_subarch_entries = (. - subarch_entries) / 4
.previous
#else
jmp .Ldefault_entry
#endif /* CONFIG_PARAVIRT */
SYM_CODE_END(startup_32)
#ifdef CONFIG_HOTPLUG_CPU

3
arch/x86/xen/Kconfig
View File

@ -19,6 +19,7 @@ config XEN_PV
bool "Xen PV guest support"
default y
depends on XEN
depends on X86_64
select PARAVIRT_XXL
select XEN_HAVE_PVMMU
select XEN_HAVE_VPMU
@ -50,7 +51,7 @@ config XEN_PVHVM_SMP
config XEN_512GB
bool "Limit Xen pv-domain memory to 512GB"
depends on XEN_PV && X86_64
depends on XEN_PV
default y
help
Limit paravirtualized user domains to 512GB of RAM.

17
arch/x86/xen/apic.c
View File

@ -58,10 +58,6 @@ static u32 xen_apic_read(u32 reg)
if (reg == APIC_LVR)
return 0x14;
#ifdef CONFIG_X86_32
if (reg == APIC_LDR)
return SET_APIC_LOGICAL_ID(1UL << smp_processor_id());
#endif
if (reg != APIC_ID)
return 0;
@ -127,14 +123,6 @@ static int xen_phys_pkg_id(int initial_apic_id, int index_msb)
return initial_apic_id >> index_msb;
}
#ifdef CONFIG_X86_32
static int xen_x86_32_early_logical_apicid(int cpu)
{
/* Match with APIC_LDR read. Otherwise setup_local_APIC complains. */
return 1 << cpu;
}
#endif
static void xen_noop(void)
{
}
@ -197,11 +185,6 @@ static struct apic xen_pv_apic = {
.icr_write = xen_apic_icr_write,
.wait_icr_idle = xen_noop,
.safe_wait_icr_idle = xen_safe_apic_wait_icr_idle,
#ifdef CONFIG_X86_32
/* generic_processor_info and setup_local_APIC. */
.x86_32_early_logical_apicid = xen_x86_32_early_logical_apicid,
#endif
};
static void __init xen_apic_check(void)

64
arch/x86/xen/enlighten_pv.c
View File

@ -119,14 +119,6 @@ static void __init xen_banner(void)
printk(KERN_INFO "Xen version: %d.%d%s%s\n",
version >> 16, version & 0xffff, extra.extraversion,
xen_feature(XENFEAT_mmu_pt_update_preserve_ad) ? " (preserve-AD)" : "");
#ifdef CONFIG_X86_32
pr_warn("WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! WARNING!\n"
"Support for running as 32-bit PV-guest under Xen will soon be removed\n"
"from the Linux kernel!\n"
"Please use either a 64-bit kernel or switch to HVM or PVH mode!\n"
"WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! WARNING!\n");
#endif
}
static void __init xen_pv_init_platform(void)
@ -538,30 +530,12 @@ static void load_TLS_descriptor(struct thread_struct *t,
static void xen_load_tls(struct thread_struct *t, unsigned int cpu)
{
/*
* XXX sleazy hack: If we're being called in a lazy-cpu zone
* and lazy gs handling is enabled, it means we're in a
* context switch, and %gs has just been saved. This means we
* can zero it out to prevent faults on exit from the
* hypervisor if the next process has no %gs. Either way, it
* has been saved, and the new value will get loaded properly.
* This will go away as soon as Xen has been modified to not
* save/restore %gs for normal hypercalls.
*
* On x86_64, this hack is not used for %gs, because gs points
* to KERNEL_GS_BASE (and uses it for PDA references), so we
* must not zero %gs on x86_64
*
* For x86_64, we need to zero %fs, otherwise we may get an
* In lazy mode we need to zero %fs, otherwise we may get an
* exception between the new %fs descriptor being loaded and
* %fs being effectively cleared at __switch_to().
*/
if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_CPU) {
#ifdef CONFIG_X86_32
lazy_load_gs(0);
#else
if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_CPU)
loadsegment(fs, 0);
#endif
}
xen_mc_batch();
@ -572,13 +546,11 @@ static void xen_load_tls(struct thread_struct *t, unsigned int cpu)
xen_mc_issue(PARAVIRT_LAZY_CPU);
}
#ifdef CONFIG_X86_64
static void xen_load_gs_index(unsigned int idx)
{
if (HYPERVISOR_set_segment_base(SEGBASE_GS_USER_SEL, idx))
BUG();
}
#endif
static void xen_write_ldt_entry(struct desc_struct *dt, int entrynum,
const void *ptr)
@ -597,7 +569,6 @@ static void xen_write_ldt_entry(struct desc_struct *dt, int entrynum,
preempt_enable();
}
#ifdef CONFIG_X86_64
void noist_exc_debug(struct pt_regs *regs);
DEFINE_IDTENTRY_RAW(xenpv_exc_nmi)
@ -697,7 +668,6 @@ static bool __ref get_trap_addr(void **addr, unsigned int ist)
return true;
}
#endif
static int cvt_gate_to_trap(int vector, const gate_desc *val,
struct trap_info *info)
@ -710,10 +680,8 @@ static int cvt_gate_to_trap(int vector, const gate_desc *val,
info->vector = vector;
addr = gate_offset(val);
#ifdef CONFIG_X86_64
if (!get_trap_addr((void **)&addr, val->bits.ist))
return 0;
#endif /* CONFIG_X86_64 */
info->address = addr;
info->cs = gate_segment(val);
@ -958,15 +926,12 @@ static u64 xen_read_msr_safe(unsigned int msr, int *err)
static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)
{
int ret;
#ifdef CONFIG_X86_64
unsigned int which;
u64 base;
#endif
ret = 0;
switch (msr) {
#ifdef CONFIG_X86_64
case MSR_FS_BASE: which = SEGBASE_FS; goto set;
case MSR_KERNEL_GS_BASE: which = SEGBASE_GS_USER; goto set;
case MSR_GS_BASE: which = SEGBASE_GS_KERNEL; goto set;
@ -976,7 +941,6 @@ static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)
if (HYPERVISOR_set_segment_base(which, base) != 0)
ret = -EIO;
break;
#endif
case MSR_STAR:
case MSR_CSTAR:
@ -1058,9 +1022,7 @@ void __init xen_setup_vcpu_info_placement(void)
static const struct pv_info xen_info __initconst = {
.shared_kernel_pmd = 0,
#ifdef CONFIG_X86_64
.extra_user_64bit_cs = FLAT_USER_CS64,
#endif
.name = "Xen",
};
@ -1086,18 +1048,14 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = {
.read_pmc = xen_read_pmc,
.iret = xen_iret,
#ifdef CONFIG_X86_64
.usergs_sysret64 = xen_sysret64,
#endif
.load_tr_desc = paravirt_nop,
.set_ldt = xen_set_ldt,
.load_gdt = xen_load_gdt,
.load_idt = xen_load_idt,
.load_tls = xen_load_tls,
#ifdef CONFIG_X86_64
.load_gs_index = xen_load_gs_index,
#endif
.alloc_ldt = xen_alloc_ldt,
.free_ldt = xen_free_ldt,
@ -1364,15 +1322,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
/* keep using Xen gdt for now; no urgent need to change it */
#ifdef CONFIG_X86_32
pv_info.kernel_rpl = 1;
if (xen_feature(XENFEAT_supervisor_mode_kernel))
pv_info.kernel_rpl = 0;
#else
pv_info.kernel_rpl = 0;
#endif
/* set the limit of our address space */
xen_reserve_top();
/*
* We used to do this in xen_arch_setup, but that is too late
@ -1384,12 +1334,6 @@ asmlinkage __visible void __init xen_start_kernel(void)
if (rc != 0)
xen_raw_printk("physdev_op failed %d\n", rc);
#ifdef CONFIG_X86_32
/* set up basic CPUID stuff */
cpu_detect(&new_cpu_data);
set_cpu_cap(&new_cpu_data, X86_FEATURE_FPU);
new_cpu_data.x86_capability[CPUID_1_EDX] = cpuid_edx(1);
#endif
if (xen_start_info->mod_start) {
if (xen_start_info->flags & SIF_MOD_START_PFN)
@ -1458,12 +1402,8 @@ asmlinkage __visible void __init xen_start_kernel(void)
xen_efi_init(&boot_params);
/* Start the world */
#ifdef CONFIG_X86_32
i386_start_kernel();
#else
cr4_init_shadow(); /* 32b kernel does this in i386_start_kernel() */
x86_64_start_reservations((char *)__pa_symbol(&boot_params));
#endif
}
static int xen_cpu_up_prepare_pv(unsigned int cpu)

356
arch/x86/xen/mmu_pv.c
View File

@ -86,19 +86,8 @@
#include "mmu.h"
#include "debugfs.h"
#ifdef CONFIG_X86_32
/*
* Identity map, in addition to plain kernel map. This needs to be
* large enough to allocate page table pages to allocate the rest.
* Each page can map 2MB.
*/
#define LEVEL1_IDENT_ENTRIES (PTRS_PER_PTE * 4)
static RESERVE_BRK_ARRAY(pte_t, level1_ident_pgt, LEVEL1_IDENT_ENTRIES);
#endif
#ifdef CONFIG_X86_64
/* l3 pud for userspace vsyscall mapping */
static pud_t level3_user_vsyscall[PTRS_PER_PUD] __page_aligned_bss;
#endif /* CONFIG_X86_64 */
/*
* Protects atomic reservation decrease/increase against concurrent increases.
@ -280,10 +269,7 @@ static inline void __xen_set_pte(pte_t *ptep, pte_t pteval)
if (!xen_batched_set_pte(ptep, pteval)) {
/*
* Could call native_set_pte() here and trap and
* emulate the PTE write but with 32-bit guests this
* needs two traps (one for each of the two 32-bit
* words in the PTE) so do one hypercall directly
* instead.
* emulate the PTE write, but a hypercall is much cheaper.
*/
struct mmu_update u;
@ -439,26 +425,6 @@ static void xen_set_pud(pud_t *ptr, pud_t val)
xen_set_pud_hyper(ptr, val);
}
#ifdef CONFIG_X86_PAE
static void xen_set_pte_atomic(pte_t *ptep, pte_t pte)
{
trace_xen_mmu_set_pte_atomic(ptep, pte);
__xen_set_pte(ptep, pte);
}
static void xen_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
trace_xen_mmu_pte_clear(mm, addr, ptep);
__xen_set_pte(ptep, native_make_pte(0));
}
static void xen_pmd_clear(pmd_t *pmdp)
{
trace_xen_mmu_pmd_clear(pmdp);
set_pmd(pmdp, __pmd(0));
}
#endif /* CONFIG_X86_PAE */
__visible pmd_t xen_make_pmd(pmdval_t pmd)
{
pmd = pte_pfn_to_mfn(pmd);
@ -466,7 +432,6 @@ __visible pmd_t xen_make_pmd(pmdval_t pmd)
}
PV_CALLEE_SAVE_REGS_THUNK(xen_make_pmd);
#ifdef CONFIG_X86_64
__visible pudval_t xen_pud_val(pud_t pud)
{
return pte_mfn_to_pfn(pud.pud);
@ -571,7 +536,6 @@ __visible p4d_t xen_make_p4d(p4dval_t p4d)
}
PV_CALLEE_SAVE_REGS_THUNK(xen_make_p4d);
#endif /* CONFIG_PGTABLE_LEVELS >= 5 */
#endif /* CONFIG_X86_64 */
static int xen_pmd_walk(struct mm_struct *mm, pmd_t *pmd,
int (*func)(struct mm_struct *mm, struct page *, enum pt_level),
@ -636,11 +600,8 @@ static int xen_p4d_walk(struct mm_struct *mm, p4d_t *p4d,
* will be STACK_TOP_MAX, but at boot we need to pin up to
* FIXADDR_TOP.
*
* For 32-bit the important bit is that we don't pin beyond there,
* because then we start getting into Xen's ptes.
*
* For 64-bit, we must skip the Xen hole in the middle of the address
* space, just after the big x86-64 virtual hole.
* We must skip the Xen hole in the middle of the address space, just after
* the big x86-64 virtual hole.
*/
static int __xen_pgd_walk(struct mm_struct *mm, pgd_t *pgd,
int (*func)(struct mm_struct *mm, struct page *,
@ -654,14 +615,12 @@ static int __xen_pgd_walk(struct mm_struct *mm, pgd_t *pgd,
limit--;
BUG_ON(limit >= FIXADDR_TOP);
#ifdef CONFIG_X86_64
/*
* 64-bit has a great big hole in the middle of the address
* space, which contains the Xen mappings.
*/
hole_low = pgd_index(GUARD_HOLE_BASE_ADDR);
hole_high = pgd_index(GUARD_HOLE_END_ADDR);
#endif
nr = pgd_index(limit) + 1;
for (i = 0; i < nr; i++) {
@ -787,6 +746,8 @@ static int xen_pin_page(struct mm_struct *mm, struct page *page,
read-only, and can be pinned. */
static void __xen_pgd_pin(struct mm_struct *mm, pgd_t *pgd)
{
pgd_t *user_pgd = xen_get_user_pgd(pgd);
trace_xen_mmu_pgd_pin(mm, pgd);
xen_mc_batch();
@ -800,26 +761,14 @@ static void __xen_pgd_pin(struct mm_struct *mm, pgd_t *pgd)
xen_mc_batch();
}
#ifdef CONFIG_X86_64
{
pgd_t *user_pgd = xen_get_user_pgd(pgd);
xen_do_pin(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa(pgd)));
xen_do_pin(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa(pgd)));
if (user_pgd) {
xen_pin_page(mm, virt_to_page(user_pgd), PT_PGD);
xen_do_pin(MMUEXT_PIN_L4_TABLE,
PFN_DOWN(__pa(user_pgd)));
}
if (user_pgd) {
xen_pin_page(mm, virt_to_page(user_pgd), PT_PGD);
xen_do_pin(MMUEXT_PIN_L4_TABLE,
PFN_DOWN(__pa(user_pgd)));
}
#else /* CONFIG_X86_32 */
#ifdef CONFIG_X86_PAE
/* Need to make sure unshared kernel PMD is pinnable */
xen_pin_page(mm, pgd_page(pgd[pgd_index(TASK_SIZE)]),
PT_PMD);
#endif
xen_do_pin(MMUEXT_PIN_L3_TABLE, PFN_DOWN(__pa(pgd)));
#endif /* CONFIG_X86_64 */
xen_mc_issue(0);
}
@ -870,9 +819,7 @@ static int __init xen_mark_pinned(struct mm_struct *mm, struct page *page,
static void __init xen_after_bootmem(void)
{
static_branch_enable(&xen_struct_pages_ready);
#ifdef CONFIG_X86_64
SetPagePinned(virt_to_page(level3_user_vsyscall));
#endif
xen_pgd_walk(&init_mm, xen_mark_pinned, FIXADDR_TOP);
}
@ -919,29 +866,19 @@ static int xen_unpin_page(struct mm_struct *mm, struct page *page,
/* Release a pagetables pages back as normal RW */
static void __xen_pgd_unpin(struct mm_struct *mm, pgd_t *pgd)
{
pgd_t *user_pgd = xen_get_user_pgd(pgd);
trace_xen_mmu_pgd_unpin(mm, pgd);
xen_mc_batch();
xen_do_pin(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
#ifdef CONFIG_X86_64
{
pgd_t *user_pgd = xen_get_user_pgd(pgd);
if (user_pgd) {
xen_do_pin(MMUEXT_UNPIN_TABLE,
PFN_DOWN(__pa(user_pgd)));
xen_unpin_page(mm, virt_to_page(user_pgd), PT_PGD);
}
if (user_pgd) {
xen_do_pin(MMUEXT_UNPIN_TABLE,
PFN_DOWN(__pa(user_pgd)));
xen_unpin_page(mm, virt_to_page(user_pgd), PT_PGD);
}
#endif
#ifdef CONFIG_X86_PAE
/* Need to make sure unshared kernel PMD is unpinned */
xen_unpin_page(mm, pgd_page(pgd[pgd_index(TASK_SIZE)]),
PT_PMD);
#endif
__xen_pgd_walk(mm, pgd, xen_unpin_page, USER_LIMIT);
@ -1089,7 +1026,6 @@ static void __init pin_pagetable_pfn(unsigned cmd, unsigned long pfn)
BUG();
}
#ifdef CONFIG_X86_64
static void __init xen_cleanhighmap(unsigned long vaddr,
unsigned long vaddr_end)
{
@ -1273,17 +1209,15 @@ static void __init xen_pagetable_cleanhighmap(void)
xen_cleanhighmap(addr, roundup(addr + size, PMD_SIZE * 2));
xen_start_info->pt_base = (unsigned long)__va(__pa(xen_start_info->pt_base));
}
#endif
static void __init xen_pagetable_p2m_setup(void)
{
xen_vmalloc_p2m_tree();
#ifdef CONFIG_X86_64
xen_pagetable_p2m_free();
xen_pagetable_cleanhighmap();
#endif
/* And revector! Bye bye old array */
xen_start_info->mfn_list = (unsigned long)xen_p2m_addr;
}
@ -1420,6 +1354,8 @@ static void __xen_write_cr3(bool kernel, unsigned long cr3)
}
static void xen_write_cr3(unsigned long cr3)
{
pgd_t *user_pgd = xen_get_user_pgd(__va(cr3));
BUG_ON(preemptible());
xen_mc_batch(); /* disables interrupts */
@ -1430,20 +1366,14 @@ static void xen_write_cr3(unsigned long cr3)
__xen_write_cr3(true, cr3);
#ifdef CONFIG_X86_64
{
pgd_t *user_pgd = xen_get_user_pgd(__va(cr3));
if (user_pgd)
__xen_write_cr3(false, __pa(user_pgd));
else
__xen_write_cr3(false, 0);
}
#endif
if (user_pgd)
__xen_write_cr3(false, __pa(user_pgd));
else
__xen_write_cr3(false, 0);
xen_mc_issue(PARAVIRT_LAZY_CPU); /* interrupts restored */
}
#ifdef CONFIG_X86_64
/*
* At the start of the day - when Xen launches a guest, it has already
* built pagetables for the guest. We diligently look over them
@ -1478,49 +1408,39 @@ static void __init xen_write_cr3_init(unsigned long cr3)
xen_mc_issue(PARAVIRT_LAZY_CPU); /* interrupts restored */
}
#endif
static int xen_pgd_alloc(struct mm_struct *mm)
{
pgd_t *pgd = mm->pgd;
int ret = 0;
struct page *page = virt_to_page(pgd);
pgd_t *user_pgd;
int ret = -ENOMEM;
BUG_ON(PagePinned(virt_to_page(pgd)));
BUG_ON(page->private != 0);
#ifdef CONFIG_X86_64
{
struct page *page = virt_to_page(pgd);
pgd_t *user_pgd;
user_pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
page->private = (unsigned long)user_pgd;
BUG_ON(page->private != 0);
ret = -ENOMEM;
user_pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
page->private = (unsigned long)user_pgd;
if (user_pgd != NULL) {
if (user_pgd != NULL) {
#ifdef CONFIG_X86_VSYSCALL_EMULATION
user_pgd[pgd_index(VSYSCALL_ADDR)] =
__pgd(__pa(level3_user_vsyscall) | _PAGE_TABLE);
user_pgd[pgd_index(VSYSCALL_ADDR)] =
__pgd(__pa(level3_user_vsyscall) | _PAGE_TABLE);
#endif
ret = 0;
}
BUG_ON(PagePinned(virt_to_page(xen_get_user_pgd(pgd))));
ret = 0;
}
#endif
BUG_ON(PagePinned(virt_to_page(xen_get_user_pgd(pgd))));
return ret;
}
static void xen_pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
#ifdef CONFIG_X86_64
pgd_t *user_pgd = xen_get_user_pgd(pgd);
if (user_pgd)
free_page((unsigned long)user_pgd);
#endif
}
/*
@ -1539,7 +1459,6 @@ static void xen_pgd_free(struct mm_struct *mm, pgd_t *pgd)
*/
__visible pte_t xen_make_pte_init(pteval_t pte)
{
#ifdef CONFIG_X86_64
unsigned long pfn;
/*
@ -1553,7 +1472,7 @@ __visible pte_t xen_make_pte_init(pteval_t pte)
pfn >= xen_start_info->first_p2m_pfn &&
pfn < xen_start_info->first_p2m_pfn + xen_start_info->nr_p2m_frames)
pte &= ~_PAGE_RW;
#endif
pte = pte_pfn_to_mfn(pte);
return native_make_pte(pte);
}
@ -1561,13 +1480,6 @@ PV_CALLEE_SAVE_REGS_THUNK(xen_make_pte_init);
static void __init xen_set_pte_init(pte_t *ptep, pte_t pte)
{
#ifdef CONFIG_X86_32
/* If there's an existing pte, then don't allow _PAGE_RW to be set */
if (pte_mfn(pte) != INVALID_P2M_ENTRY
&& pte_val_ma(*ptep) & _PAGE_PRESENT)
pte = __pte_ma(((pte_val_ma(*ptep) & _PAGE_RW) | ~_PAGE_RW) &
pte_val_ma(pte));
#endif
__xen_set_pte(ptep, pte);
}
@ -1702,7 +1614,6 @@ static void xen_release_pmd(unsigned long pfn)
xen_release_ptpage(pfn, PT_PMD);
}
#ifdef CONFIG_X86_64
static void xen_alloc_pud(struct mm_struct *mm, unsigned long pfn)
{
xen_alloc_ptpage(mm, pfn, PT_PUD);
@ -1712,20 +1623,6 @@ static void xen_release_pud(unsigned long pfn)
{
xen_release_ptpage(pfn, PT_PUD);
}
#endif
void __init xen_reserve_top(void)
{
#ifdef CONFIG_X86_32
unsigned long top = HYPERVISOR_VIRT_START;
struct xen_platform_parameters pp;
if (HYPERVISOR_xen_version(XENVER_platform_parameters, &pp) == 0)
top = pp.virt_start;
reserve_top_address(-top);
#endif /* CONFIG_X86_32 */
}
/*
* Like __va(), but returns address in the kernel mapping (which is
@ -1733,11 +1630,7 @@ void __init xen_reserve_top(void)
*/
static void * __init __ka(phys_addr_t paddr)
{
#ifdef CONFIG_X86_64
return (void *)(paddr + __START_KERNEL_map);
#else
return __va(paddr);
#endif
}
/* Convert a machine address to physical address */
@ -1771,56 +1664,7 @@ static void __init set_page_prot(void *addr, pgprot_t prot)
{
return set_page_prot_flags(addr, prot, UVMF_NONE);
}
#ifdef CONFIG_X86_32
static void __init xen_map_identity_early(pmd_t *pmd, unsigned long max_pfn)
{
unsigned pmdidx, pteidx;
unsigned ident_pte;
unsigned long pfn;
level1_ident_pgt = extend_brk(sizeof(pte_t) * LEVEL1_IDENT_ENTRIES,
PAGE_SIZE);
ident_pte = 0;
pfn = 0;
for (pmdidx = 0; pmdidx < PTRS_PER_PMD && pfn < max_pfn; pmdidx++) {
pte_t *pte_page;
/* Reuse or allocate a page of ptes */
if (pmd_present(pmd[pmdidx]))
pte_page = m2v(pmd[pmdidx].pmd);
else {
/* Check for free pte pages */
if (ident_pte == LEVEL1_IDENT_ENTRIES)
break;
pte_page = &level1_ident_pgt[ident_pte];
ident_pte += PTRS_PER_PTE;
pmd[pmdidx] = __pmd(__pa(pte_page) | _PAGE_TABLE);
}
/* Install mappings */
for (pteidx = 0; pteidx < PTRS_PER_PTE; pteidx++, pfn++) {
pte_t pte;
if (pfn > max_pfn_mapped)
max_pfn_mapped = pfn;
if (!pte_none(pte_page[pteidx]))
continue;
pte = pfn_pte(pfn, PAGE_KERNEL_EXEC);
pte_page[pteidx] = pte;
}
}
for (pteidx = 0; pteidx < ident_pte; pteidx += PTRS_PER_PTE)
set_page_prot(&level1_ident_pgt[pteidx], PAGE_KERNEL_RO);
set_page_prot(pmd, PAGE_KERNEL_RO);
}
#endif
void __init xen_setup_machphys_mapping(void)
{
struct xen_machphys_mapping mapping;
@ -1831,13 +1675,8 @@ void __init xen_setup_machphys_mapping(void)
} else {
machine_to_phys_nr = MACH2PHYS_NR_ENTRIES;
}
#ifdef CONFIG_X86_32
WARN_ON((machine_to_phys_mapping + (machine_to_phys_nr - 1))
< machine_to_phys_mapping);
#endif
}
#ifdef CONFIG_X86_64
static void __init convert_pfn_mfn(void *v)
{
pte_t *pte = v;
@ -2168,105 +2007,6 @@ void __init xen_relocate_p2m(void)
xen_start_info->nr_p2m_frames = n_frames;
}
#else /* !CONFIG_X86_64 */
static RESERVE_BRK_ARRAY(pmd_t, initial_kernel_pmd, PTRS_PER_PMD);
static RESERVE_BRK_ARRAY(pmd_t, swapper_kernel_pmd, PTRS_PER_PMD);
RESERVE_BRK(fixup_kernel_pmd, PAGE_SIZE);
RESERVE_BRK(fixup_kernel_pte, PAGE_SIZE);
static void __init xen_write_cr3_init(unsigned long cr3)
{
unsigned long pfn = PFN_DOWN(__pa(swapper_pg_dir));
BUG_ON(read_cr3_pa() != __pa(initial_page_table));
BUG_ON(cr3 != __pa(swapper_pg_dir));
/*
* We are switching to swapper_pg_dir for the first time (from
* initial_page_table) and therefore need to mark that page
* read-only and then pin it.
*
* Xen disallows sharing of kernel PMDs for PAE
* guests. Therefore we must copy the kernel PMD from
* initial_page_table into a new kernel PMD to be used in
* swapper_pg_dir.
*/
swapper_kernel_pmd =
extend_brk(sizeof(pmd_t) * PTRS_PER_PMD, PAGE_SIZE);
copy_page(swapper_kernel_pmd, initial_kernel_pmd);
swapper_pg_dir[KERNEL_PGD_BOUNDARY] =
__pgd(__pa(swapper_kernel_pmd) | _PAGE_PRESENT);
set_page_prot(swapper_kernel_pmd, PAGE_KERNEL_RO);
set_page_prot(swapper_pg_dir, PAGE_KERNEL_RO);
xen_write_cr3(cr3);
pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE, pfn);
pin_pagetable_pfn(MMUEXT_UNPIN_TABLE,
PFN_DOWN(__pa(initial_page_table)));
set_page_prot(initial_page_table, PAGE_KERNEL);
set_page_prot(initial_kernel_pmd, PAGE_KERNEL);
pv_ops.mmu.write_cr3 = &xen_write_cr3;
}
/*
* For 32 bit domains xen_start_info->pt_base is the pgd address which might be
* not the first page table in the page table pool.
* Iterate through the initial page tables to find the real page table base.
*/
static phys_addr_t __init xen_find_pt_base(pmd_t *pmd)
{
phys_addr_t pt_base, paddr;
unsigned pmdidx;
pt_base = min(__pa(xen_start_info->pt_base), __pa(pmd));
for (pmdidx = 0; pmdidx < PTRS_PER_PMD; pmdidx++)
if (pmd_present(pmd[pmdidx]) && !pmd_large(pmd[pmdidx])) {
paddr = m2p(pmd[pmdidx].pmd);
pt_base = min(pt_base, paddr);
}
return pt_base;
}
void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
{
pmd_t *kernel_pmd;
kernel_pmd = m2v(pgd[KERNEL_PGD_BOUNDARY].pgd);
xen_pt_base = xen_find_pt_base(kernel_pmd);
xen_pt_size = xen_start_info->nr_pt_frames * PAGE_SIZE;
initial_kernel_pmd =
extend_brk(sizeof(pmd_t) * PTRS_PER_PMD, PAGE_SIZE);
max_pfn_mapped = PFN_DOWN(xen_pt_base + xen_pt_size + 512 * 1024);
copy_page(initial_kernel_pmd, kernel_pmd);
xen_map_identity_early(initial_kernel_pmd, max_pfn);
copy_page(initial_page_table, pgd);
initial_page_table[KERNEL_PGD_BOUNDARY] =
__pgd(__pa(initial_kernel_pmd) | _PAGE_PRESENT);
set_page_prot(initial_kernel_pmd, PAGE_KERNEL_RO);
set_page_prot(initial_page_table, PAGE_KERNEL_RO);
set_page_prot(empty_zero_page, PAGE_KERNEL_RO);
pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE,
PFN_DOWN(__pa(initial_page_table)));
xen_write_cr3(__pa(initial_page_table));
memblock_reserve(xen_pt_base, xen_pt_size);
}
#endif /* CONFIG_X86_64 */
void __init xen_reserve_special_pages(void)
{
phys_addr_t paddr;
@ -2300,12 +2040,7 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot)
switch (idx) {
case FIX_BTMAP_END ... FIX_BTMAP_BEGIN:
#ifdef CONFIG_X86_32
case FIX_WP_TEST:
# ifdef CONFIG_HIGHMEM
case FIX_KMAP_BEGIN ... FIX_KMAP_END:
# endif
#elif defined(CONFIG_X86_VSYSCALL_EMULATION)
#ifdef CONFIG_X86_VSYSCALL_EMULATION
case VSYSCALL_PAGE:
#endif
/* All local page mappings */
@ -2357,9 +2092,7 @@ static void __init xen_post_allocator_init(void)
pv_ops.mmu.set_pte = xen_set_pte;
pv_ops.mmu.set_pmd = xen_set_pmd;
pv_ops.mmu.set_pud = xen_set_pud;
#ifdef CONFIG_X86_64
pv_ops.mmu.set_p4d = xen_set_p4d;
#endif
/* This will work as long as patching hasn't happened yet
(which it hasn't) */
@ -2367,15 +2100,11 @@ static void __init xen_post_allocator_init(void)
pv_ops.mmu.alloc_pmd = xen_alloc_pmd;
pv_ops.mmu.release_pte = xen_release_pte;
pv_ops.mmu.release_pmd = xen_release_pmd;
#ifdef CONFIG_X86_64
pv_ops.mmu.alloc_pud = xen_alloc_pud;
pv_ops.mmu.release_pud = xen_release_pud;
#endif
pv_ops.mmu.make_pte = PV_CALLEE_SAVE(xen_make_pte);
#ifdef CONFIG_X86_64
pv_ops.mmu.write_cr3 = &xen_write_cr3;
#endif
}
static void xen_leave_lazy_mmu(void)
@ -2420,17 +2149,11 @@ static const struct pv_mmu_ops xen_mmu_ops __initconst = {
.make_pte = PV_CALLEE_SAVE(xen_make_pte_init),
.make_pgd = PV_CALLEE_SAVE(xen_make_pgd),
#ifdef CONFIG_X86_PAE
.set_pte_atomic = xen_set_pte_atomic,
.pte_clear = xen_pte_clear,
.pmd_clear = xen_pmd_clear,
#endif /* CONFIG_X86_PAE */
.set_pud = xen_set_pud_hyper,
.make_pmd = PV_CALLEE_SAVE(xen_make_pmd),
.pmd_val = PV_CALLEE_SAVE(xen_pmd_val),
#ifdef CONFIG_X86_64
.pud_val = PV_CALLEE_SAVE(xen_pud_val),
.make_pud = PV_CALLEE_SAVE(xen_make_pud),
.set_p4d = xen_set_p4d_hyper,
@ -2442,7 +2165,6 @@ static const struct pv_mmu_ops xen_mmu_ops __initconst = {
.p4d_val = PV_CALLEE_SAVE(xen_p4d_val),
.make_p4d = PV_CALLEE_SAVE(xen_make_p4d),
#endif
#endif /* CONFIG_X86_64 */
.activate_mm = xen_activate_mm,
.dup_mmap = xen_dup_mmap,

6
arch/x86/xen/p2m.c
View File

@ -379,12 +379,8 @@ static void __init xen_rebuild_p2m_list(unsigned long *p2m)
if (type == P2M_TYPE_PFN || i < chunk) {
/* Use initial p2m page contents. */
#ifdef CONFIG_X86_64
mfns = alloc_p2m_page();
copy_page(mfns, xen_p2m_addr + pfn);
#else
mfns = xen_p2m_addr + pfn;
#endif
ptep = populate_extra_pte((unsigned long)(p2m + pfn));
set_pte(ptep,
pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL));
@ -467,7 +463,7 @@ EXPORT_SYMBOL_GPL(get_phys_to_machine);
* Allocate new pmd(s). It is checked whether the old pmd is still in place.
* If not, nothing is changed. This is okay as the only reason for allocating
* a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual
* pmd. In case of PAE/x86-32 there are multiple pmds to allocate!
* pmd.
*/
static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg)
{

36
arch/x86/xen/setup.c
View File

@ -32,7 +32,6 @@
#include <xen/features.h>
#include <xen/hvc-console.h>
#include "xen-ops.h"
#include "vdso.h"
#include "mmu.h"
#define GB(x) ((uint64_t)(x) * 1024 * 1024 * 1024)
@ -545,13 +544,10 @@ static unsigned long __init xen_get_pages_limit(void)
{
unsigned long limit;
#ifdef CONFIG_X86_32
limit = GB(64) / PAGE_SIZE;
#else
limit = MAXMEM / PAGE_SIZE;
if (!xen_initial_domain() && xen_512gb_limit)
limit = GB(512) / PAGE_SIZE;
#endif
return limit;
}
@ -722,17 +718,8 @@ static void __init xen_reserve_xen_mfnlist(void)
if (!xen_is_e820_reserved(start, size))
return;
#ifdef CONFIG_X86_32
/*
* Relocating the p2m on 32 bit system to an arbitrary virtual address
* is not supported, so just give up.
*/
xen_raw_console_write("Xen hypervisor allocated p2m list conflicts with E820 map\n");
BUG();
#else
xen_relocate_p2m();
memblock_free(start, size);
#endif
}
/**
@ -921,20 +908,6 @@ char * __init xen_memory_setup(void)
return "Xen";
}
/*
* Set the bit indicating "nosegneg" library variants should be used.
* We only need to bother in pure 32-bit mode; compat 32-bit processes
* can have un-truncated segments, so wrapping around is allowed.
*/
static void __init fiddle_vdso(void)
{
#ifdef CONFIG_X86_32
u32 *mask = vdso_image_32.data +
vdso_image_32.sym_VDSO32_NOTE_MASK;
*mask |= 1 << VDSO_NOTE_NONEGSEG_BIT;
#endif
}
static int register_callback(unsigned type, const void *func)
{
struct callback_register callback = {
@ -951,11 +924,7 @@ void xen_enable_sysenter(void)
int ret;
unsigned sysenter_feature;
#ifdef CONFIG_X86_32
sysenter_feature = X86_FEATURE_SEP;
#else
sysenter_feature = X86_FEATURE_SYSENTER32;
#endif
if (!boot_cpu_has(sysenter_feature))
return;
@ -967,7 +936,6 @@ void xen_enable_sysenter(void)
void xen_enable_syscall(void)
{
#ifdef CONFIG_X86_64
int ret;
ret = register_callback(CALLBACKTYPE_syscall, xen_syscall_target);
@ -983,7 +951,6 @@ void xen_enable_syscall(void)
if (ret != 0)
setup_clear_cpu_cap(X86_FEATURE_SYSCALL32);
}
#endif /* CONFIG_X86_64 */
}
static void __init xen_pvmmu_arch_setup(void)
@ -1024,7 +991,6 @@ void __init xen_arch_setup(void)
disable_cpuidle();
disable_cpufreq();
WARN_ON(xen_set_default_idle());
fiddle_vdso();
#ifdef CONFIG_NUMA
numa_off = 1;
#endif

18
arch/x86/xen/smp_pv.c
View File

@ -212,15 +212,6 @@ static void __init xen_pv_smp_prepare_boot_cpu(void)
* sure the old memory can be recycled. */
make_lowmem_page_readwrite(xen_initial_gdt);
#ifdef CONFIG_X86_32
/*
* Xen starts us with XEN_FLAT_RING1_DS, but linux code
* expects __USER_DS
*/
loadsegment(ds, __USER_DS);
loadsegment(es, __USER_DS);
#endif
xen_filter_cpu_maps();
xen_setup_vcpu_info_placement();
@ -301,10 +292,6 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
gdt = get_cpu_gdt_rw(cpu);
#ifdef CONFIG_X86_32
ctxt->user_regs.fs = __KERNEL_PERCPU;
ctxt->user_regs.gs = __KERNEL_STACK_CANARY;
#endif
memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
/*
@ -342,12 +329,7 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
ctxt->kernel_ss = __KERNEL_DS;
ctxt->kernel_sp = task_top_of_stack(idle);
#ifdef CONFIG_X86_32
ctxt->event_callback_cs = __KERNEL_CS;
ctxt->failsafe_callback_cs = __KERNEL_CS;
#else
ctxt->gs_base_kernel = per_cpu_offset(cpu);
#endif
ctxt->event_callback_eip =
(unsigned long)xen_asm_exc_xen_hypervisor_callback;
ctxt->failsafe_callback_eip =

6
arch/x86/xen/vdso.h
View File

@ -1,6 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0 */
/* Bit used for the pseudo-hwcap for non-negative segments. We use
bit 1 to avoid bugs in some versions of glibc when bit 0 is
used; the choice is otherwise arbitrary. */
#define VDSO_NOTE_NONEGSEG_BIT 1

14
arch/x86/xen/xen-asm.S
View File

@ -76,11 +76,7 @@ SYM_FUNC_END(xen_save_fl_direct)
*/
SYM_FUNC_START(xen_restore_fl_direct)
FRAME_BEGIN
#ifdef CONFIG_X86_64
testw $X86_EFLAGS_IF, %di
#else
testb $X86_EFLAGS_IF>>8, %ah
#endif
setz PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
/*
* Preempt here doesn't matter because that will deal with any
@ -104,15 +100,6 @@ SYM_FUNC_END(xen_restore_fl_direct)
*/
SYM_FUNC_START(check_events)
FRAME_BEGIN
#ifdef CONFIG_X86_32
push %eax
push %ecx
push %edx
call xen_force_evtchn_callback
pop %edx
pop %ecx
pop %eax
#else
push %rax
push %rcx
push %rdx
@ -132,7 +119,6 @@ SYM_FUNC_START(check_events)
pop %rdx
pop %rcx
pop %rax
#endif
FRAME_END
ret
SYM_FUNC_END(check_events)

185
arch/x86/xen/xen-asm_32.S
View File

@ -1,185 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Asm versions of Xen pv-ops, suitable for direct use.
*
* We only bother with direct forms (ie, vcpu in pda) of the
* operations here; the indirect forms are better handled in C.
*/
#include <asm/thread_info.h>
#include <asm/processor-flags.h>
#include <asm/segment.h>
#include <asm/asm.h>
#include <xen/interface/xen.h>
#include <linux/linkage.h>
/* Pseudo-flag used for virtual NMI, which we don't implement yet */
#define XEN_EFLAGS_NMI 0x80000000
/*
* This is run where a normal iret would be run, with the same stack setup:
* 8: eflags
* 4: cs
* esp-> 0: eip
*
* This attempts to make sure that any pending events are dealt with
* on return to usermode, but there is a small window in which an
* event can happen just before entering usermode. If the nested
* interrupt ends up setting one of the TIF_WORK_MASK pending work
* flags, they will not be tested again before returning to
* usermode. This means that a process can end up with pending work,
* which will be unprocessed until the process enters and leaves the
* kernel again, which could be an unbounded amount of time. This
* means that a pending signal or reschedule event could be
* indefinitely delayed.
*
* The fix is to notice a nested interrupt in the critical window, and
* if one occurs, then fold the nested interrupt into the current
* interrupt stack frame, and re-process it iteratively rather than
* recursively. This means that it will exit via the normal path, and
* all pending work will be dealt with appropriately.
*
* Because the nested interrupt handler needs to deal with the current
* stack state in whatever form its in, we keep things simple by only
* using a single register which is pushed/popped on the stack.
*/
.macro POP_FS
1:
popw %fs
.pushsection .fixup, "ax"
2: movw $0, (%esp)
jmp 1b
.popsection
_ASM_EXTABLE(1b,2b)
.endm
SYM_CODE_START(xen_iret)
/* test eflags for special cases */
testl $(X86_EFLAGS_VM | XEN_EFLAGS_NMI), 8(%esp)
jnz hyper_iret
push %eax
ESP_OFFSET=4 # bytes pushed onto stack
/* Store vcpu_info pointer for easy access */
#ifdef CONFIG_SMP
pushw %fs
movl $(__KERNEL_PERCPU), %eax
movl %eax, %fs
movl %fs:xen_vcpu, %eax
POP_FS
#else
movl %ss:xen_vcpu, %eax
#endif
/* check IF state we're restoring */
testb $X86_EFLAGS_IF>>8, 8+1+ESP_OFFSET(%esp)
/*
* Maybe enable events. Once this happens we could get a
* recursive event, so the critical region starts immediately
* afterwards. However, if that happens we don't end up
* resuming the code, so we don't have to be worried about
* being preempted to another CPU.
*/
setz %ss:XEN_vcpu_info_mask(%eax)
xen_iret_start_crit:
/* check for unmasked and pending */
cmpw $0x0001, %ss:XEN_vcpu_info_pending(%eax)
/*
* If there's something pending, mask events again so we can
* jump back into exc_xen_hypervisor_callback. Otherwise do not
* touch XEN_vcpu_info_mask.
*/
jne 1f
movb $1, %ss:XEN_vcpu_info_mask(%eax)
1: popl %eax
/*
* From this point on the registers are restored and the stack
* updated, so we don't need to worry about it if we're
* preempted
*/
iret_restore_end:
/*
* Jump to hypervisor_callback after fixing up the stack.
* Events are masked, so jumping out of the critical region is
* OK.
*/
je xen_asm_exc_xen_hypervisor_callback
1: iret
xen_iret_end_crit:
_ASM_EXTABLE(1b, asm_iret_error)
hyper_iret:
/* put this out of line since its very rarely used */
jmp hypercall_page + __HYPERVISOR_iret * 32
SYM_CODE_END(xen_iret)
.globl xen_iret_start_crit, xen_iret_end_crit
/*
* This is called by xen_asm_exc_xen_hypervisor_callback in entry_32.S when it sees
* that the EIP at the time of interrupt was between
* xen_iret_start_crit and xen_iret_end_crit.
*
* The stack format at this point is:
* ----------------
* ss : (ss/esp may be present if we came from usermode)
* esp :
* eflags } outer exception info
* cs }
* eip }
* ----------------
* eax : outer eax if it hasn't been restored
* ----------------
* eflags }
* cs } nested exception info
* eip }
* return address : (into xen_asm_exc_xen_hypervisor_callback)
*
* In order to deliver the nested exception properly, we need to discard the
* nested exception frame such that when we handle the exception, we do it
* in the context of the outer exception rather than starting a new one.
*
* The only caveat is that if the outer eax hasn't been restored yet (i.e.
* it's still on stack), we need to restore its value here.
*/
.pushsection .noinstr.text, "ax"
SYM_CODE_START(xen_iret_crit_fixup)
/*
* Paranoia: Make sure we're really coming from kernel space.
* One could imagine a case where userspace jumps into the
* critical range address, but just before the CPU delivers a
* PF, it decides to deliver an interrupt instead. Unlikely?
* Definitely. Easy to avoid? Yes.
*/
testb $2, 2*4(%esp) /* nested CS */
jnz 2f
/*
* If eip is before iret_restore_end then stack
* hasn't been restored yet.
*/
cmpl $iret_restore_end, 1*4(%esp)
jae 1f
movl 4*4(%esp), %eax /* load outer EAX */
ret $4*4 /* discard nested EIP, CS, and EFLAGS as
* well as the just restored EAX */
1:
ret $3*4 /* discard nested EIP, CS, and EFLAGS */
2:
ret
SYM_CODE_END(xen_iret_crit_fixup)
.popsection

6
arch/x86/xen/xen-head.S
View File

@ -35,13 +35,8 @@ SYM_CODE_START(startup_xen)
rep __ASM_SIZE(stos)
mov %_ASM_SI, xen_start_info
#ifdef CONFIG_X86_64
mov initial_stack(%rip), %rsp
#else
mov initial_stack, %esp
#endif
#ifdef CONFIG_X86_64
/* Set up %gs.
*
* The base of %gs always points to fixed_percpu_data. If the
@ -53,7 +48,6 @@ SYM_CODE_START(startup_xen)
movq $INIT_PER_CPU_VAR(fixed_percpu_data),%rax
cdq
wrmsr
#endif
call xen_start_kernel
SYM_CODE_END(startup_xen)

1
arch/x86/xen/xen-ops.h
View File

@ -33,7 +33,6 @@ void xen_setup_mfn_list_list(void);
void xen_build_mfn_list_list(void);
void xen_setup_machphys_mapping(void);
void xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn);
void xen_reserve_top(void);
void __init xen_reserve_special_pages(void);
void __init xen_pt_check_e820(void);

4
drivers/xen/Kconfig
View File

@ -52,9 +52,7 @@ config XEN_BALLOON_MEMORY_HOTPLUG
config XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
int "Hotplugged memory limit (in GiB) for a PV guest"
default 512 if X86_64
default 4 if X86_32
range 0 64 if X86_32
default 512
depends on XEN_HAVE_PVMMU
depends on XEN_BALLOON_MEMORY_HOTPLUG
help