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authorMarcelo Tosatti <mtosatti@redhat.com>2008-06-05 00:08:11 -0300
committerAvi Kivity <avi@qumranet.com>2008-06-06 21:32:39 +0300
commitff4b9df877b30b8a371d706d3552999dee450738 (patch)
treef2195b2d4305643b59b78be266e98215a31bdcf4
parent8d2d73b9a5c35f2c6abf427afba7888cfc4cc65d (diff)
downloadlinux-ff4b9df877b30b8a371d706d3552999dee450738.tar.gz
KVM: IOAPIC: only set remote_irr if interrupt was injected
There's a bug in the IOAPIC code for level-triggered interrupts. Its relatively easy to trigger by sharing (virtio-blk + usbtablet was the testcase, initially reported by Gerd von Egidy). The "remote_irr" variable is used to indicate accepted but not yet acked interrupts. Its cleared from the EOI handler. Problem is that the EOI handler clears remote_irr unconditionally, even if it reinjected another pending interrupt. In that case, kvm_ioapic_set_irq() proceeds to ioapic_service() which sets remote_irr even if it failed to inject (since the IRR was high due to EOI reinjection). Since the TMR bit has been cleared by the first EOI, the second one fails to clear remote_irr. End result is interrupt line dead. Fix it by setting remote_irr only if a new pending interrupt has been generated (and the TMR bit for vector in question set). Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
-rw-r--r--virt/kvm/ioapic.c21
1 files changed, 11 insertions, 10 deletions
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index 4232fd75dd2..98778cb69c6 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -45,7 +45,7 @@
#else
#define ioapic_debug(fmt, arg...)
#endif
-static void ioapic_deliver(struct kvm_ioapic *vioapic, int irq);
+static int ioapic_deliver(struct kvm_ioapic *vioapic, int irq);
static unsigned long ioapic_read_indirect(struct kvm_ioapic *ioapic,
unsigned long addr,
@@ -89,8 +89,8 @@ static void ioapic_service(struct kvm_ioapic *ioapic, unsigned int idx)
pent = &ioapic->redirtbl[idx];
if (!pent->fields.mask) {
- ioapic_deliver(ioapic, idx);
- if (pent->fields.trig_mode == IOAPIC_LEVEL_TRIG)
+ int injected = ioapic_deliver(ioapic, idx);
+ if (injected && pent->fields.trig_mode == IOAPIC_LEVEL_TRIG)
pent->fields.remote_irr = 1;
}
if (!pent->fields.trig_mode)
@@ -133,7 +133,7 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
}
}
-static void ioapic_inj_irq(struct kvm_ioapic *ioapic,
+static int ioapic_inj_irq(struct kvm_ioapic *ioapic,
struct kvm_vcpu *vcpu,
u8 vector, u8 trig_mode, u8 delivery_mode)
{
@@ -143,7 +143,7 @@ static void ioapic_inj_irq(struct kvm_ioapic *ioapic,
ASSERT((delivery_mode == IOAPIC_FIXED) ||
(delivery_mode == IOAPIC_LOWEST_PRIORITY));
- kvm_apic_set_irq(vcpu, vector, trig_mode);
+ return kvm_apic_set_irq(vcpu, vector, trig_mode);
}
static u32 ioapic_get_delivery_bitmask(struct kvm_ioapic *ioapic, u8 dest,
@@ -186,7 +186,7 @@ static u32 ioapic_get_delivery_bitmask(struct kvm_ioapic *ioapic, u8 dest,
return mask;
}
-static void ioapic_deliver(struct kvm_ioapic *ioapic, int irq)
+static int ioapic_deliver(struct kvm_ioapic *ioapic, int irq)
{
u8 dest = ioapic->redirtbl[irq].fields.dest_id;
u8 dest_mode = ioapic->redirtbl[irq].fields.dest_mode;
@@ -195,7 +195,7 @@ static void ioapic_deliver(struct kvm_ioapic *ioapic, int irq)
u8 trig_mode = ioapic->redirtbl[irq].fields.trig_mode;
u32 deliver_bitmask;
struct kvm_vcpu *vcpu;
- int vcpu_id;
+ int vcpu_id, r = 0;
ioapic_debug("dest=%x dest_mode=%x delivery_mode=%x "
"vector=%x trig_mode=%x\n",
@@ -204,7 +204,7 @@ static void ioapic_deliver(struct kvm_ioapic *ioapic, int irq)
deliver_bitmask = ioapic_get_delivery_bitmask(ioapic, dest, dest_mode);
if (!deliver_bitmask) {
ioapic_debug("no target on destination\n");
- return;
+ return 0;
}
switch (delivery_mode) {
@@ -216,7 +216,7 @@ static void ioapic_deliver(struct kvm_ioapic *ioapic, int irq)
vcpu = ioapic->kvm->vcpus[0];
#endif
if (vcpu != NULL)
- ioapic_inj_irq(ioapic, vcpu, vector,
+ r = ioapic_inj_irq(ioapic, vcpu, vector,
trig_mode, delivery_mode);
else
ioapic_debug("null lowest prio vcpu: "
@@ -234,7 +234,7 @@ static void ioapic_deliver(struct kvm_ioapic *ioapic, int irq)
deliver_bitmask &= ~(1 << vcpu_id);
vcpu = ioapic->kvm->vcpus[vcpu_id];
if (vcpu) {
- ioapic_inj_irq(ioapic, vcpu, vector,
+ r = ioapic_inj_irq(ioapic, vcpu, vector,
trig_mode, delivery_mode);
}
}
@@ -246,6 +246,7 @@ static void ioapic_deliver(struct kvm_ioapic *ioapic, int irq)
delivery_mode);
break;
}
+ return r;
}
void kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level)