[PATCH 4/4] arm/arm64: KVM: Keep elrsr/aisr in sync with software model
From: Marc Zyngier <hidden>
Date: 2015-02-28 13:37:57
Also in:
kvm, kvmarm, lkml
On Wed, 25 Feb 2015 15:36:22 +0000 Alex Benn?e [off-list ref] wrote:
From: Christoffer Dall <redacted> There is an interesting bug in the vgic code, which manifests itself when the KVM run loop has a signal pending or needs a vmid generation rollover after having disabled interrupts but before actually switching to the guest. In this case, we flush the vgic as usual, but we sync back the vgic state and exit to userspace before entering the guest. The consequence is that we will be syncing the list registers back to the software model using the GICH_ELRSR and GICH_EISR from the last execution of the guest, potentially overwriting a list register containing an interrupt. This showed up during migration testing where we would capture a state where the VM has masked the arch timer but there were no interrupts, resulting in a hung test. Cc: Marc Zyngier <redacted> Reported-by: Alex Bennee <redacted> Signed-off-by: Christoffer Dall <redacted> Signed-off-by: Alex Benn?e <redacted>
Looks OK to me. Acked-by: Marc Zyngier <redacted>
quoted hunk ↗ jump to hunk
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h index 7042251..e2a676e 100644 --- a/include/kvm/arm_vgic.h +++ b/include/kvm/arm_vgic.h@@ -114,6 +114,7 @@ struct vgic_ops { void (*sync_lr_elrsr)(struct kvm_vcpu *, int, structvgic_lr); u64 (*get_elrsr)(const struct kvm_vcpu *vcpu); u64 (*get_eisr)(const struct kvm_vcpu *vcpu); + void (*clear_eisr)(struct kvm_vcpu *vcpu); u32 (*get_interrupt_status)(const struct kvm_vcpu *vcpu); void (*enable_underflow)(struct kvm_vcpu *vcpu); void (*disable_underflow)(struct kvm_vcpu *vcpu);diff --git a/virt/kvm/arm/vgic-v2.c b/virt/kvm/arm/vgic-v2.c index a0a7b5d..f9b9c7c 100644 --- a/virt/kvm/arm/vgic-v2.c +++ b/virt/kvm/arm/vgic-v2.c@@ -72,6 +72,8 @@ static void vgic_v2_sync_lr_elrsr(struct kvm_vcpu*vcpu, int lr, { if (!(lr_desc.state & LR_STATE_MASK)) vcpu->arch.vgic_cpu.vgic_v2.vgic_elrsr |= (1ULL << lr); + else + vcpu->arch.vgic_cpu.vgic_v2.vgic_elrsr &= ~(1ULL << lr); } static u64 vgic_v2_get_elrsr(const struct kvm_vcpu *vcpu)@@ -84,6 +86,11 @@ static u64 vgic_v2_get_eisr(const struct kvm_vcpu*vcpu) return vcpu->arch.vgic_cpu.vgic_v2.vgic_eisr; } +static void vgic_v2_clear_eisr(struct kvm_vcpu *vcpu) +{ + vcpu->arch.vgic_cpu.vgic_v2.vgic_eisr = 0; +} + static u32 vgic_v2_get_interrupt_status(const struct kvm_vcpu *vcpu) { u32 misr = vcpu->arch.vgic_cpu.vgic_v2.vgic_misr;@@ -148,6 +155,7 @@ static const struct vgic_ops vgic_v2_ops = { .sync_lr_elrsr = vgic_v2_sync_lr_elrsr, .get_elrsr = vgic_v2_get_elrsr, .get_eisr = vgic_v2_get_eisr, + .clear_eisr = vgic_v2_clear_eisr, .get_interrupt_status = vgic_v2_get_interrupt_status, .enable_underflow = vgic_v2_enable_underflow, .disable_underflow = vgic_v2_disable_underflow,diff --git a/virt/kvm/arm/vgic-v3.c b/virt/kvm/arm/vgic-v3.c index 3a62d8a..dff0602 100644 --- a/virt/kvm/arm/vgic-v3.c +++ b/virt/kvm/arm/vgic-v3.c@@ -104,6 +104,8 @@ static void vgic_v3_sync_lr_elrsr(struct kvm_vcpu*vcpu, int lr, { if (!(lr_desc.state & LR_STATE_MASK)) vcpu->arch.vgic_cpu.vgic_v3.vgic_elrsr |= (1U << lr); + else + vcpu->arch.vgic_cpu.vgic_v3.vgic_elrsr &= ~(1U << lr); } static u64 vgic_v3_get_elrsr(const struct kvm_vcpu *vcpu)@@ -116,6 +118,11 @@ static u64 vgic_v3_get_eisr(const structkvm_vcpu *vcpu) return vcpu->arch.vgic_cpu.vgic_v3.vgic_eisr; } +static void vgic_v3_clear_eisr(struct kvm_vcpu *vcpu) +{ + vcpu->arch.vgic_cpu.vgic_v3.vgic_eisr = 0; +} + static u32 vgic_v3_get_interrupt_status(const struct kvm_vcpu *vcpu) { u32 misr = vcpu->arch.vgic_cpu.vgic_v3.vgic_misr;@@ -192,6 +199,7 @@ static const struct vgic_ops vgic_v3_ops = { .sync_lr_elrsr = vgic_v3_sync_lr_elrsr, .get_elrsr = vgic_v3_get_elrsr, .get_eisr = vgic_v3_get_eisr, + .clear_eisr = vgic_v3_clear_eisr, .get_interrupt_status = vgic_v3_get_interrupt_status, .enable_underflow = vgic_v3_enable_underflow, .disable_underflow = vgic_v3_disable_underflow,diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c index 3b4ded2..3690c1e 100644 --- a/virt/kvm/arm/vgic.c +++ b/virt/kvm/arm/vgic.c@@ -980,6 +980,11 @@ static inline u64 vgic_get_eisr(struct kvm_vcpu*vcpu) return vgic_ops->get_eisr(vcpu); } +static inline void vgic_clear_eisr(struct kvm_vcpu *vcpu) +{ + vgic_ops->clear_eisr(vcpu); +} + static inline u32 vgic_get_interrupt_status(struct kvm_vcpu *vcpu) { return vgic_ops->get_interrupt_status(vcpu);@@ -1019,6 +1024,7 @@ static void vgic_retire_lr(int lr_nr, int irq,struct kvm_vcpu *vcpu) vgic_set_lr(vcpu, lr_nr, vlr); clear_bit(lr_nr, vgic_cpu->lr_used); vgic_cpu->vgic_irq_lr_map[irq] = LR_EMPTY; + vgic_sync_lr_elrsr(vcpu, lr_nr, vlr); } /*@@ -1063,6 +1069,7 @@ static void vgic_queue_irq_to_lr(structkvm_vcpu *vcpu, int irq, vlr.state |= LR_EOI_INT; vgic_set_lr(vcpu, lr_nr, vlr); + vgic_sync_lr_elrsr(vcpu, lr_nr, vlr); } /*@@ -1258,6 +1265,14 @@ static bool vgic_process_maintenance(structkvm_vcpu *vcpu) if (status & INT_STATUS_UNDERFLOW) vgic_disable_underflow(vcpu); + /* + * In the next iterations of the vcpu loop, if we sync the vgic state + * after flushing it, but before entering the guest (this happens for + * pending signals and vmid rollovers), then make sure we don't pick + * up any old maintenance interrupts here. + */ + vgic_clear_eisr(vcpu); + return level_pending; }
-- Jazz is not dead. It just smells funny.