KVM: x86: DR7.GD should be cleared upon any #DB exception (6bdf0662) · Commits · 戴 / test

Intel SDM 17.2.4 (Debug Control Register (DR7)) says: "The processor clears the GD flag upon entering to the debug exception handler." This sentence may be misunderstood as if it happens only on #DB due to debug-register protection, but it happens regardless to the cause of the #DB. Fix the behavior to match both real hardware and Bochs. Signed-off-by:

Nadav Amit <namit@cs.technion.ac.il> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx.c

+0 −2

Original line number	Diff line number	Diff line
		@@ -5185,9 +5185,7 @@ static int handle_dr(struct kvm_vcpu *vcpu)
		vcpu->run->exit_reason = KVM_EXIT_DEBUG;
		return 0;
		} else {
		vcpu->arch.dr7 &= ~DR7_GD;
		vcpu->arch.dr6 \|= DR6_BD \| DR6_RTM;
		vmcs_writel(GUEST_DR7, vcpu->arch.dr7);
		kvm_queue_exception(vcpu, DB_VECTOR);
		return 1;
		}

arch/x86/kvm/x86.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -5965,6 +5965,12 @@ static int inject_pending_event(struct kvm_vcpu *vcpu, bool req_int_win)
		__kvm_set_rflags(vcpu, kvm_get_rflags(vcpu) \|
		X86_EFLAGS_RF);

		if (vcpu->arch.exception.nr == DB_VECTOR &&
		(vcpu->arch.dr7 & DR7_GD)) {
		vcpu->arch.dr7 &= ~DR7_GD;
		kvm_update_dr7(vcpu);
		}

		kvm_x86_ops->queue_exception(vcpu, vcpu->arch.exception.nr,
		vcpu->arch.exception.has_error_code,
		vcpu->arch.exception.error_code,

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