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authorMichael S. Tsirkin <mst@redhat.com>2012-07-19 13:45:20 +0300
committerMarcelo Tosatti <mtosatti@redhat.com>2012-07-20 16:12:00 -0300
commit1a577b72475d161b6677c05abe57301362023bb2 (patch)
treed8a9910f0016ada479c5a88c1a330b5e1cbc7ef1 /virt
parentd63d3e6217c49b81d74141b7920bbe5950532432 (diff)
downloadlinux-1a577b72475d161b6677c05abe57301362023bb2.tar.gz
KVM: fix race with level interrupts
When more than 1 source id is in use for the same GSI, we have the following race related to handling irq_states race: CPU 0 clears bit 0. CPU 0 read irq_state as 0. CPU 1 sets level to 1. CPU 1 calls kvm_ioapic_set_irq(1). CPU 0 calls kvm_ioapic_set_irq(0). Now ioapic thinks the level is 0 but irq_state is not 0. Fix by performing all irq_states bitmap handling under pic/ioapic lock. This also removes the need for atomics with irq_states handling. Reported-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/ioapic.c19
-rw-r--r--virt/kvm/ioapic.h4
-rw-r--r--virt/kvm/irq_comm.c31
3 files changed, 23 insertions, 31 deletions
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index 26fd54dc459..ef61d529a6c 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -191,7 +191,8 @@ static int ioapic_deliver(struct kvm_ioapic *ioapic, int irq)
return kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe);
}
-int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level)
+int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int irq_source_id,
+ int level)
{
u32 old_irr;
u32 mask = 1 << irq;
@@ -201,9 +202,11 @@ int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level)
spin_lock(&ioapic->lock);
old_irr = ioapic->irr;
if (irq >= 0 && irq < IOAPIC_NUM_PINS) {
+ int irq_level = __kvm_irq_line_state(&ioapic->irq_states[irq],
+ irq_source_id, level);
entry = ioapic->redirtbl[irq];
- level ^= entry.fields.polarity;
- if (!level)
+ irq_level ^= entry.fields.polarity;
+ if (!irq_level)
ioapic->irr &= ~mask;
else {
int edge = (entry.fields.trig_mode == IOAPIC_EDGE_TRIG);
@@ -221,6 +224,16 @@ int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level)
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_ioapic *ioapic, int vector,
int trigger_mode)
{
diff --git a/virt/kvm/ioapic.h b/virt/kvm/ioapic.h
index 32872a09b63..a30abfe6ed1 100644
--- a/virt/kvm/ioapic.h
+++ b/virt/kvm/ioapic.h
@@ -74,7 +74,9 @@ void kvm_ioapic_update_eoi(struct kvm *kvm, int vector, int trigger_mode);
bool kvm_ioapic_handles_vector(struct kvm *kvm, int vector);
int kvm_ioapic_init(struct kvm *kvm);
void kvm_ioapic_destroy(struct kvm *kvm);
-int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level);
+int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int irq_source_id,
+ int level);
+void kvm_ioapic_clear_all(struct kvm_ioapic *ioapic, int irq_source_id);
void kvm_ioapic_reset(struct kvm_ioapic *ioapic);
int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
struct kvm_lapic_irq *irq);
diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index a6a0365475e..cc59c68da03 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -33,26 +33,12 @@
#include "ioapic.h"
-static inline int kvm_irq_line_state(unsigned long *irq_state,
- int irq_source_id, int level)
-{
- /* Logical OR for level trig interrupt */
- if (level)
- set_bit(irq_source_id, irq_state);
- else
- clear_bit(irq_source_id, irq_state);
-
- return !!(*irq_state);
-}
-
static int kvm_set_pic_irq(struct kvm_kernel_irq_routing_entry *e,
struct kvm *kvm, int irq_source_id, int level)
{
#ifdef CONFIG_X86
struct kvm_pic *pic = pic_irqchip(kvm);
- level = kvm_irq_line_state(&pic->irq_states[e->irqchip.pin],
- irq_source_id, level);
- return kvm_pic_set_irq(pic, e->irqchip.pin, level);
+ return kvm_pic_set_irq(pic, e->irqchip.pin, irq_source_id, level);
#else
return -1;
#endif
@@ -62,10 +48,7 @@ static int kvm_set_ioapic_irq(struct kvm_kernel_irq_routing_entry *e,
struct kvm *kvm, int irq_source_id, int level)
{
struct kvm_ioapic *ioapic = kvm->arch.vioapic;
- level = kvm_irq_line_state(&ioapic->irq_states[e->irqchip.pin],
- irq_source_id, level);
-
- return kvm_ioapic_set_irq(ioapic, e->irqchip.pin, level);
+ return kvm_ioapic_set_irq(ioapic, e->irqchip.pin, irq_source_id, level);
}
inline static bool kvm_is_dm_lowest_prio(struct kvm_lapic_irq *irq)
@@ -249,8 +232,6 @@ unlock:
void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id)
{
- int i;
-
ASSERT(irq_source_id != KVM_USERSPACE_IRQ_SOURCE_ID);
mutex_lock(&kvm->irq_lock);
@@ -263,14 +244,10 @@ void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id)
if (!irqchip_in_kernel(kvm))
goto unlock;
- for (i = 0; i < KVM_IOAPIC_NUM_PINS; i++) {
- clear_bit(irq_source_id, &kvm->arch.vioapic->irq_states[i]);
- if (i >= 16)
- continue;
+ kvm_ioapic_clear_all(kvm->arch.vioapic, irq_source_id);
#ifdef CONFIG_X86
- clear_bit(irq_source_id, &pic_irqchip(kvm)->irq_states[i]);
+ kvm_pic_clear_all(pic_irqchip(kvm), irq_source_id);
#endif
- }
unlock:
mutex_unlock(&kvm->irq_lock);
}