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linux-next/virt/kvm/ioapic.c
Paolo Bonzini 0f6c0a740b KVM: x86: always exit on EOIs for interrupts listed in the IOAPIC redir table
Currently, the EOI exit bitmap (used for APICv) does not include
interrupts that are masked.  However, this can cause a bug that manifests
as an interrupt storm inside the guest.  Alex Williamson reported the
bug and is the one who really debugged this; I only wrote the patch. :)

The scenario involves a multi-function PCI device with OHCI and EHCI
USB functions and an audio function, all assigned to the guest, where
both USB functions use legacy INTx interrupts.

As soon as the guest boots, interrupts for these devices turn into an
interrupt storm in the guest; the host does not see the interrupt storm.
Basically the EOI path does not work, and the guest continues to see the
interrupt over and over, even after it attempts to mask it at the APIC.
The bug is only visible with older kernels (RHEL6.5, based on 2.6.32
with not many changes in the area of APIC/IOAPIC handling).

Alex then tried forcing bit 59 (corresponding to the USB functions' IRQ)
on in the eoi_exit_bitmap and TMR, and things then work.  What happens
is that VFIO asserts IRQ11, then KVM recomputes the EOI exit bitmap.
It does not have set bit 59 because the RTE was masked, so the IOAPIC
never sees the EOI and the interrupt continues to fire in the guest.

My guess was that the guest is masking the interrupt in the redirection
table in the interrupt routine, i.e. while the interrupt is set in a
LAPIC's ISR, The simplest fix is to ignore the masking state, we would
rather have an unnecessary exit rather than a missed IRQ ACK and anyway
IOAPIC interrupts are not as performance-sensitive as for example MSIs.
Alex tested this patch and it fixed his bug.

[Thanks to Alex for his precise description of the problem
 and initial debugging effort.  A lot of the text above is
 based on emails exchanged with him.]

Reported-by: Alex Williamson <alex.williamson@redhat.com>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-07-30 20:22:30 +02:00

646 lines
16 KiB
C

/*
* Copyright (C) 2001 MandrakeSoft S.A.
* Copyright 2010 Red Hat, Inc. and/or its affiliates.
*
* MandrakeSoft S.A.
* 43, rue d'Aboukir
* 75002 Paris - France
* http://www.linux-mandrake.com/
* http://www.mandrakesoft.com/
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Yunhong Jiang <yunhong.jiang@intel.com>
* Yaozu (Eddie) Dong <eddie.dong@intel.com>
* Based on Xen 3.1 code.
*/
#include <linux/kvm_host.h>
#include <linux/kvm.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/smp.h>
#include <linux/hrtimer.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/current.h>
#include <trace/events/kvm.h>
#include "ioapic.h"
#include "lapic.h"
#include "irq.h"
#if 0
#define ioapic_debug(fmt,arg...) printk(KERN_WARNING fmt,##arg)
#else
#define ioapic_debug(fmt, arg...)
#endif
static int ioapic_service(struct kvm_ioapic *vioapic, int irq,
bool line_status);
static unsigned long ioapic_read_indirect(struct kvm_ioapic *ioapic,
unsigned long addr,
unsigned long length)
{
unsigned long result = 0;
switch (ioapic->ioregsel) {
case IOAPIC_REG_VERSION:
result = ((((IOAPIC_NUM_PINS - 1) & 0xff) << 16)
| (IOAPIC_VERSION_ID & 0xff));
break;
case IOAPIC_REG_APIC_ID:
case IOAPIC_REG_ARB_ID:
result = ((ioapic->id & 0xf) << 24);
break;
default:
{
u32 redir_index = (ioapic->ioregsel - 0x10) >> 1;
u64 redir_content;
if (redir_index < IOAPIC_NUM_PINS)
redir_content =
ioapic->redirtbl[redir_index].bits;
else
redir_content = ~0ULL;
result = (ioapic->ioregsel & 0x1) ?
(redir_content >> 32) & 0xffffffff :
redir_content & 0xffffffff;
break;
}
}
return result;
}
static void rtc_irq_eoi_tracking_reset(struct kvm_ioapic *ioapic)
{
ioapic->rtc_status.pending_eoi = 0;
bitmap_zero(ioapic->rtc_status.dest_map, KVM_MAX_VCPUS);
}
static void kvm_rtc_eoi_tracking_restore_all(struct kvm_ioapic *ioapic);
static void rtc_status_pending_eoi_check_valid(struct kvm_ioapic *ioapic)
{
if (WARN_ON(ioapic->rtc_status.pending_eoi < 0))
kvm_rtc_eoi_tracking_restore_all(ioapic);
}
static void __rtc_irq_eoi_tracking_restore_one(struct kvm_vcpu *vcpu)
{
bool new_val, old_val;
struct kvm_ioapic *ioapic = vcpu->kvm->arch.vioapic;
union kvm_ioapic_redirect_entry *e;
e = &ioapic->redirtbl[RTC_GSI];
if (!kvm_apic_match_dest(vcpu, NULL, 0, e->fields.dest_id,
e->fields.dest_mode))
return;
new_val = kvm_apic_pending_eoi(vcpu, e->fields.vector);
old_val = test_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map);
if (new_val == old_val)
return;
if (new_val) {
__set_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map);
ioapic->rtc_status.pending_eoi++;
} else {
__clear_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map);
ioapic->rtc_status.pending_eoi--;
rtc_status_pending_eoi_check_valid(ioapic);
}
}
void kvm_rtc_eoi_tracking_restore_one(struct kvm_vcpu *vcpu)
{
struct kvm_ioapic *ioapic = vcpu->kvm->arch.vioapic;
spin_lock(&ioapic->lock);
__rtc_irq_eoi_tracking_restore_one(vcpu);
spin_unlock(&ioapic->lock);
}
static void kvm_rtc_eoi_tracking_restore_all(struct kvm_ioapic *ioapic)
{
struct kvm_vcpu *vcpu;
int i;
if (RTC_GSI >= IOAPIC_NUM_PINS)
return;
rtc_irq_eoi_tracking_reset(ioapic);
kvm_for_each_vcpu(i, vcpu, ioapic->kvm)
__rtc_irq_eoi_tracking_restore_one(vcpu);
}
static void rtc_irq_eoi(struct kvm_ioapic *ioapic, struct kvm_vcpu *vcpu)
{
if (test_and_clear_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map)) {
--ioapic->rtc_status.pending_eoi;
rtc_status_pending_eoi_check_valid(ioapic);
}
}
static bool rtc_irq_check_coalesced(struct kvm_ioapic *ioapic)
{
if (ioapic->rtc_status.pending_eoi > 0)
return true; /* coalesced */
return false;
}
static int ioapic_set_irq(struct kvm_ioapic *ioapic, unsigned int irq,
int irq_level, bool line_status)
{
union kvm_ioapic_redirect_entry entry;
u32 mask = 1 << irq;
u32 old_irr;
int edge, ret;
entry = ioapic->redirtbl[irq];
edge = (entry.fields.trig_mode == IOAPIC_EDGE_TRIG);
if (!irq_level) {
ioapic->irr &= ~mask;
ret = 1;
goto out;
}
/*
* Return 0 for coalesced interrupts; for edge-triggered interrupts,
* this only happens if a previous edge has not been delivered due
* do masking. For level interrupts, the remote_irr field tells
* us if the interrupt is waiting for an EOI.
*
* RTC is special: it is edge-triggered, but userspace likes to know
* if it has been already ack-ed via EOI because coalesced RTC
* interrupts lead to time drift in Windows guests. So we track
* EOI manually for the RTC interrupt.
*/
if (irq == RTC_GSI && line_status &&
rtc_irq_check_coalesced(ioapic)) {
ret = 0;
goto out;
}
old_irr = ioapic->irr;
ioapic->irr |= mask;
if ((edge && old_irr == ioapic->irr) ||
(!edge && entry.fields.remote_irr)) {
ret = 0;
goto out;
}
ret = ioapic_service(ioapic, irq, line_status);
out:
trace_kvm_ioapic_set_irq(entry.bits, irq, ret == 0);
return ret;
}
static void kvm_ioapic_inject_all(struct kvm_ioapic *ioapic, unsigned long irr)
{
u32 idx;
rtc_irq_eoi_tracking_reset(ioapic);
for_each_set_bit(idx, &irr, IOAPIC_NUM_PINS)
ioapic_set_irq(ioapic, idx, 1, true);
kvm_rtc_eoi_tracking_restore_all(ioapic);
}
static void update_handled_vectors(struct kvm_ioapic *ioapic)
{
DECLARE_BITMAP(handled_vectors, 256);
int i;
memset(handled_vectors, 0, sizeof(handled_vectors));
for (i = 0; i < IOAPIC_NUM_PINS; ++i)
__set_bit(ioapic->redirtbl[i].fields.vector, handled_vectors);
memcpy(ioapic->handled_vectors, handled_vectors,
sizeof(handled_vectors));
smp_wmb();
}
void kvm_ioapic_scan_entry(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap,
u32 *tmr)
{
struct kvm_ioapic *ioapic = vcpu->kvm->arch.vioapic;
union kvm_ioapic_redirect_entry *e;
int index;
spin_lock(&ioapic->lock);
for (index = 0; index < IOAPIC_NUM_PINS; index++) {
e = &ioapic->redirtbl[index];
if (e->fields.trig_mode == IOAPIC_LEVEL_TRIG ||
kvm_irq_has_notifier(ioapic->kvm, KVM_IRQCHIP_IOAPIC, index) ||
index == RTC_GSI) {
if (kvm_apic_match_dest(vcpu, NULL, 0,
e->fields.dest_id, e->fields.dest_mode)) {
__set_bit(e->fields.vector,
(unsigned long *)eoi_exit_bitmap);
if (e->fields.trig_mode == IOAPIC_LEVEL_TRIG)
__set_bit(e->fields.vector,
(unsigned long *)tmr);
}
}
}
spin_unlock(&ioapic->lock);
}
#ifdef CONFIG_X86
void kvm_vcpu_request_scan_ioapic(struct kvm *kvm)
{
struct kvm_ioapic *ioapic = kvm->arch.vioapic;
if (!ioapic)
return;
kvm_make_scan_ioapic_request(kvm);
}
#else
void kvm_vcpu_request_scan_ioapic(struct kvm *kvm)
{
return;
}
#endif
static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
{
unsigned index;
bool mask_before, mask_after;
union kvm_ioapic_redirect_entry *e;
switch (ioapic->ioregsel) {
case IOAPIC_REG_VERSION:
/* Writes are ignored. */
break;
case IOAPIC_REG_APIC_ID:
ioapic->id = (val >> 24) & 0xf;
break;
case IOAPIC_REG_ARB_ID:
break;
default:
index = (ioapic->ioregsel - 0x10) >> 1;
ioapic_debug("change redir index %x val %x\n", index, val);
if (index >= IOAPIC_NUM_PINS)
return;
e = &ioapic->redirtbl[index];
mask_before = e->fields.mask;
if (ioapic->ioregsel & 1) {
e->bits &= 0xffffffff;
e->bits |= (u64) val << 32;
} else {
e->bits &= ~0xffffffffULL;
e->bits |= (u32) val;
e->fields.remote_irr = 0;
}
update_handled_vectors(ioapic);
mask_after = e->fields.mask;
if (mask_before != mask_after)
kvm_fire_mask_notifiers(ioapic->kvm, KVM_IRQCHIP_IOAPIC, index, mask_after);
if (e->fields.trig_mode == IOAPIC_LEVEL_TRIG
&& ioapic->irr & (1 << index))
ioapic_service(ioapic, index, false);
kvm_vcpu_request_scan_ioapic(ioapic->kvm);
break;
}
}
static int ioapic_service(struct kvm_ioapic *ioapic, int irq, bool line_status)
{
union kvm_ioapic_redirect_entry *entry = &ioapic->redirtbl[irq];
struct kvm_lapic_irq irqe;
int ret;
if (entry->fields.mask)
return -1;
ioapic_debug("dest=%x dest_mode=%x delivery_mode=%x "
"vector=%x trig_mode=%x\n",
entry->fields.dest_id, entry->fields.dest_mode,
entry->fields.delivery_mode, entry->fields.vector,
entry->fields.trig_mode);
irqe.dest_id = entry->fields.dest_id;
irqe.vector = entry->fields.vector;
irqe.dest_mode = entry->fields.dest_mode;
irqe.trig_mode = entry->fields.trig_mode;
irqe.delivery_mode = entry->fields.delivery_mode << 8;
irqe.level = 1;
irqe.shorthand = 0;
if (irqe.trig_mode == IOAPIC_EDGE_TRIG)
ioapic->irr &= ~(1 << irq);
if (irq == RTC_GSI && line_status) {
/*
* pending_eoi cannot ever become negative (see
* rtc_status_pending_eoi_check_valid) and the caller
* ensures that it is only called if it is >= zero, namely
* if rtc_irq_check_coalesced returns false).
*/
BUG_ON(ioapic->rtc_status.pending_eoi != 0);
ret = kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe,
ioapic->rtc_status.dest_map);
ioapic->rtc_status.pending_eoi = (ret < 0 ? 0 : ret);
} else
ret = kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe, NULL);
if (ret && irqe.trig_mode == IOAPIC_LEVEL_TRIG)
entry->fields.remote_irr = 1;
return ret;
}
int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int irq_source_id,
int level, bool line_status)
{
int ret, irq_level;
BUG_ON(irq < 0 || irq >= IOAPIC_NUM_PINS);
spin_lock(&ioapic->lock);
irq_level = __kvm_irq_line_state(&ioapic->irq_states[irq],
irq_source_id, level);
ret = ioapic_set_irq(ioapic, irq, irq_level, line_status);
spin_unlock(&ioapic->lock);
return ret;
}
void kvm_ioapic_clear_all(struct kvm_ioapic *ioapic, int irq_source_id)
{
int i;
spin_lock(&ioapic->lock);
for (i = 0; i < KVM_IOAPIC_NUM_PINS; i++)
__clear_bit(irq_source_id, &ioapic->irq_states[i]);
spin_unlock(&ioapic->lock);
}
static void __kvm_ioapic_update_eoi(struct kvm_vcpu *vcpu,
struct kvm_ioapic *ioapic, int vector, int trigger_mode)
{
int i;
for (i = 0; i < IOAPIC_NUM_PINS; i++) {
union kvm_ioapic_redirect_entry *ent = &ioapic->redirtbl[i];
if (ent->fields.vector != vector)
continue;
if (i == RTC_GSI)
rtc_irq_eoi(ioapic, vcpu);
/*
* We are dropping lock while calling ack notifiers because ack
* notifier callbacks for assigned devices call into IOAPIC
* recursively. Since remote_irr is cleared only after call
* to notifiers if the same vector will be delivered while lock
* is dropped it will be put into irr and will be delivered
* after ack notifier returns.
*/
spin_unlock(&ioapic->lock);
kvm_notify_acked_irq(ioapic->kvm, KVM_IRQCHIP_IOAPIC, i);
spin_lock(&ioapic->lock);
if (trigger_mode != IOAPIC_LEVEL_TRIG)
continue;
ASSERT(ent->fields.trig_mode == IOAPIC_LEVEL_TRIG);
ent->fields.remote_irr = 0;
if (ioapic->irr & (1 << i))
ioapic_service(ioapic, i, false);
}
}
bool kvm_ioapic_handles_vector(struct kvm *kvm, int vector)
{
struct kvm_ioapic *ioapic = kvm->arch.vioapic;
smp_rmb();
return test_bit(vector, ioapic->handled_vectors);
}
void kvm_ioapic_update_eoi(struct kvm_vcpu *vcpu, int vector, int trigger_mode)
{
struct kvm_ioapic *ioapic = vcpu->kvm->arch.vioapic;
spin_lock(&ioapic->lock);
__kvm_ioapic_update_eoi(vcpu, ioapic, vector, trigger_mode);
spin_unlock(&ioapic->lock);
}
static inline struct kvm_ioapic *to_ioapic(struct kvm_io_device *dev)
{
return container_of(dev, struct kvm_ioapic, dev);
}
static inline int ioapic_in_range(struct kvm_ioapic *ioapic, gpa_t addr)
{
return ((addr >= ioapic->base_address &&
(addr < ioapic->base_address + IOAPIC_MEM_LENGTH)));
}
static int ioapic_mmio_read(struct kvm_io_device *this, gpa_t addr, int len,
void *val)
{
struct kvm_ioapic *ioapic = to_ioapic(this);
u32 result;
if (!ioapic_in_range(ioapic, addr))
return -EOPNOTSUPP;
ioapic_debug("addr %lx\n", (unsigned long)addr);
ASSERT(!(addr & 0xf)); /* check alignment */
addr &= 0xff;
spin_lock(&ioapic->lock);
switch (addr) {
case IOAPIC_REG_SELECT:
result = ioapic->ioregsel;
break;
case IOAPIC_REG_WINDOW:
result = ioapic_read_indirect(ioapic, addr, len);
break;
default:
result = 0;
break;
}
spin_unlock(&ioapic->lock);
switch (len) {
case 8:
*(u64 *) val = result;
break;
case 1:
case 2:
case 4:
memcpy(val, (char *)&result, len);
break;
default:
printk(KERN_WARNING "ioapic: wrong length %d\n", len);
}
return 0;
}
static int ioapic_mmio_write(struct kvm_io_device *this, gpa_t addr, int len,
const void *val)
{
struct kvm_ioapic *ioapic = to_ioapic(this);
u32 data;
if (!ioapic_in_range(ioapic, addr))
return -EOPNOTSUPP;
ioapic_debug("ioapic_mmio_write addr=%p len=%d val=%p\n",
(void*)addr, len, val);
ASSERT(!(addr & 0xf)); /* check alignment */
switch (len) {
case 8:
case 4:
data = *(u32 *) val;
break;
case 2:
data = *(u16 *) val;
break;
case 1:
data = *(u8 *) val;
break;
default:
printk(KERN_WARNING "ioapic: Unsupported size %d\n", len);
return 0;
}
addr &= 0xff;
spin_lock(&ioapic->lock);
switch (addr) {
case IOAPIC_REG_SELECT:
ioapic->ioregsel = data & 0xFF; /* 8-bit register */
break;
case IOAPIC_REG_WINDOW:
ioapic_write_indirect(ioapic, data);
break;
#ifdef CONFIG_IA64
case IOAPIC_REG_EOI:
__kvm_ioapic_update_eoi(NULL, ioapic, data, IOAPIC_LEVEL_TRIG);
break;
#endif
default:
break;
}
spin_unlock(&ioapic->lock);
return 0;
}
static void kvm_ioapic_reset(struct kvm_ioapic *ioapic)
{
int i;
for (i = 0; i < IOAPIC_NUM_PINS; i++)
ioapic->redirtbl[i].fields.mask = 1;
ioapic->base_address = IOAPIC_DEFAULT_BASE_ADDRESS;
ioapic->ioregsel = 0;
ioapic->irr = 0;
ioapic->id = 0;
rtc_irq_eoi_tracking_reset(ioapic);
update_handled_vectors(ioapic);
}
static const struct kvm_io_device_ops ioapic_mmio_ops = {
.read = ioapic_mmio_read,
.write = ioapic_mmio_write,
};
int kvm_ioapic_init(struct kvm *kvm)
{
struct kvm_ioapic *ioapic;
int ret;
ioapic = kzalloc(sizeof(struct kvm_ioapic), GFP_KERNEL);
if (!ioapic)
return -ENOMEM;
spin_lock_init(&ioapic->lock);
kvm->arch.vioapic = ioapic;
kvm_ioapic_reset(ioapic);
kvm_iodevice_init(&ioapic->dev, &ioapic_mmio_ops);
ioapic->kvm = kvm;
mutex_lock(&kvm->slots_lock);
ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, ioapic->base_address,
IOAPIC_MEM_LENGTH, &ioapic->dev);
mutex_unlock(&kvm->slots_lock);
if (ret < 0) {
kvm->arch.vioapic = NULL;
kfree(ioapic);
}
return ret;
}
void kvm_ioapic_destroy(struct kvm *kvm)
{
struct kvm_ioapic *ioapic = kvm->arch.vioapic;
if (ioapic) {
kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS, &ioapic->dev);
kvm->arch.vioapic = NULL;
kfree(ioapic);
}
}
int kvm_get_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
{
struct kvm_ioapic *ioapic = ioapic_irqchip(kvm);
if (!ioapic)
return -EINVAL;
spin_lock(&ioapic->lock);
memcpy(state, ioapic, sizeof(struct kvm_ioapic_state));
spin_unlock(&ioapic->lock);
return 0;
}
int kvm_set_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
{
struct kvm_ioapic *ioapic = ioapic_irqchip(kvm);
if (!ioapic)
return -EINVAL;
spin_lock(&ioapic->lock);
memcpy(ioapic, state, sizeof(struct kvm_ioapic_state));
ioapic->irr = 0;
update_handled_vectors(ioapic);
kvm_vcpu_request_scan_ioapic(kvm);
kvm_ioapic_inject_all(ioapic, state->irr);
spin_unlock(&ioapic->lock);
return 0;
}