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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 /arch/x86
parentd63d3e6217c49b81d74141b7920bbe5950532432 (diff)
downloadlinaro-lsk-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 'arch/x86')
-rw-r--r--arch/x86/include/asm/kvm_host.h15
-rw-r--r--arch/x86/kvm/i8259.c17
2 files changed, 28 insertions, 4 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index a3e9409e90b..2c75b400e40 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -816,7 +816,20 @@ int kvm_read_guest_page_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
void kvm_propagate_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault);
bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl);
-int kvm_pic_set_irq(void *opaque, int irq, int level);
+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);
+}
+
+int kvm_pic_set_irq(struct kvm_pic *pic, int irq, int irq_source_id, int level);
+void kvm_pic_clear_all(struct kvm_pic *pic, int irq_source_id);
void kvm_inject_nmi(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index 81cf4fa4a2b..1df8fb9e1d5 100644
--- a/arch/x86/kvm/i8259.c
+++ b/arch/x86/kvm/i8259.c
@@ -188,14 +188,15 @@ void kvm_pic_update_irq(struct kvm_pic *s)
pic_unlock(s);
}
-int kvm_pic_set_irq(void *opaque, int irq, int level)
+int kvm_pic_set_irq(struct kvm_pic *s, int irq, int irq_source_id, int level)
{
- struct kvm_pic *s = opaque;
int ret = -1;
pic_lock(s);
if (irq >= 0 && irq < PIC_NUM_PINS) {
- ret = pic_set_irq1(&s->pics[irq >> 3], irq & 7, level);
+ int irq_level = __kvm_irq_line_state(&s->irq_states[irq],
+ irq_source_id, level);
+ ret = pic_set_irq1(&s->pics[irq >> 3], irq & 7, irq_level);
pic_update_irq(s);
trace_kvm_pic_set_irq(irq >> 3, irq & 7, s->pics[irq >> 3].elcr,
s->pics[irq >> 3].imr, ret == 0);
@@ -205,6 +206,16 @@ int kvm_pic_set_irq(void *opaque, int irq, int level)
return ret;
}
+void kvm_pic_clear_all(struct kvm_pic *s, int irq_source_id)
+{
+ int i;
+
+ pic_lock(s);
+ for (i = 0; i < PIC_NUM_PINS; i++)
+ __clear_bit(irq_source_id, &s->irq_states[i]);
+ pic_unlock(s);
+}
+
/*
* acknowledge interrupt 'irq'
*/