From ff4b9df877b30b8a371d706d3552999dee450738 Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Thu, 5 Jun 2008 00:08:11 -0300 Subject: 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 Signed-off-by: Avi Kivity --- virt/kvm/ioapic.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) (limited to 'virt/kvm/ioapic.c') diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c index 4232fd75dd20..98778cb69c6e 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) -- cgit v1.2.2 From 4fa6b9c5dc4134bdeac341d731a87783cc11ca10 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Tue, 17 Jun 2008 15:36:36 -0700 Subject: KVM: ioapic: fix lost interrupt when changing a device's irq The ioapic acknowledge path translates interrupt vectors to irqs. It currently uses a first match algorithm, stopping when it finds the first redirection table entry containing the vector. That fails however if the guest changes the irq to a different line, leaving the old redirection table entry in place (though masked). Result is interrupts not making it to the guest. Fix by always scanning the entire redirection table. Signed-off-by: Avi Kivity --- virt/kvm/ioapic.c | 31 +++++++++++-------------------- 1 file changed, 11 insertions(+), 20 deletions(-) (limited to 'virt/kvm/ioapic.c') diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c index 98778cb69c6e..1dcf9f3d1107 100644 --- a/virt/kvm/ioapic.c +++ b/virt/kvm/ioapic.c @@ -269,28 +269,9 @@ void kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level) } } -static int get_eoi_gsi(struct kvm_ioapic *ioapic, int vector) +static void __kvm_ioapic_update_eoi(struct kvm_ioapic *ioapic, int gsi) { - int i; - - for (i = 0; i < IOAPIC_NUM_PINS; i++) - if (ioapic->redirtbl[i].fields.vector == vector) - return i; - return -1; -} - -void kvm_ioapic_update_eoi(struct kvm *kvm, int vector) -{ - struct kvm_ioapic *ioapic = kvm->arch.vioapic; union ioapic_redir_entry *ent; - int gsi; - - gsi = get_eoi_gsi(ioapic, vector); - if (gsi == -1) { - printk(KERN_WARNING "Can't find redir item for %d EOI\n", - vector); - return; - } ent = &ioapic->redirtbl[gsi]; ASSERT(ent->fields.trig_mode == IOAPIC_LEVEL_TRIG); @@ -300,6 +281,16 @@ void kvm_ioapic_update_eoi(struct kvm *kvm, int vector) ioapic_deliver(ioapic, gsi); } +void kvm_ioapic_update_eoi(struct kvm *kvm, int vector) +{ + struct kvm_ioapic *ioapic = kvm->arch.vioapic; + int i; + + for (i = 0; i < IOAPIC_NUM_PINS; i++) + if (ioapic->redirtbl[i].fields.vector == vector) + __kvm_ioapic_update_eoi(ioapic, i); +} + static int ioapic_in_range(struct kvm_io_device *this, gpa_t addr) { struct kvm_ioapic *ioapic = (struct kvm_ioapic *)this->private; -- cgit v1.2.2