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Commit 71c4dfaf authored by Joerg Roedel's avatar Joerg Roedel Committed by Avi Kivity
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KVM: detect if VCPU triple faults 



In the current inject_page_fault path KVM only checks if there is another PF
pending and injects a DF then. But it has to check for a pending DF too to
detect a shutdown condition in the VCPU.  If this is not detected the VCPU goes
to a PF -> DF -> PF loop when it should triple fault. This patch detects this
condition and handles it with an KVM_SHUTDOWN exit to userspace.

Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 3e4bb3ac

arch/x86/kvm/x86.c

+15 −5
Original line number Original line Diff line number Diff line
@@ -155,11 +155,16 @@ void kvm_inject_page_fault(struct kvm_vcpu *vcpu, unsigned long addr, 
			   u32 error_code)

			   u32 error_code)

{

{

	++vcpu->stat.pf_guest;

	++vcpu->stat.pf_guest;

	if (vcpu->arch.exception.pending && vcpu->arch.exception.nr == PF_VECTOR) {

	if (vcpu->arch.exception.pending) {

		if (vcpu->arch.exception.nr == PF_VECTOR) {

			printk(KERN_DEBUG "kvm: inject_page_fault:"

			printk(KERN_DEBUG "kvm: inject_page_fault:"

					" double fault 0x%lx\n", addr);

					" double fault 0x%lx\n", addr);

			vcpu->arch.exception.nr = DF_VECTOR;

			vcpu->arch.exception.nr = DF_VECTOR;

			vcpu->arch.exception.error_code = 0;

			vcpu->arch.exception.error_code = 0;

		} else if (vcpu->arch.exception.nr == DF_VECTOR) {

			/* triple fault -> shutdown */

			set_bit(KVM_REQ_TRIPLE_FAULT, &vcpu->requests);

		}

		return;

		return;

	}

	}

	vcpu->arch.cr2 = addr;

	vcpu->arch.cr2 = addr;
@@ -2676,6 +2681,11 @@ static int __vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 
			r = 0;

			r = 0;

			goto out;

			goto out;

		}

		}

		if (test_and_clear_bit(KVM_REQ_TRIPLE_FAULT, &vcpu->requests)) {

			kvm_run->exit_reason = KVM_EXIT_SHUTDOWN;

			r = 0;

			goto out;

		}

	}

	}





	kvm_inject_pending_timer_irqs(vcpu);

	kvm_inject_pending_timer_irqs(vcpu);

include/linux/kvm_host.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -38,6 +38,7 @@ 
#define KVM_REQ_MIGRATE_TIMER      1

#define KVM_REQ_MIGRATE_TIMER      1

#define KVM_REQ_REPORT_TPR_ACCESS  2

#define KVM_REQ_REPORT_TPR_ACCESS  2

#define KVM_REQ_MMU_RELOAD         3

#define KVM_REQ_MMU_RELOAD         3

#define KVM_REQ_TRIPLE_FAULT       4





struct kvm_vcpu;

struct kvm_vcpu;

extern struct kmem_cache *kvm_vcpu_cache;

extern struct kmem_cache *kvm_vcpu_cache;