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Commit 6bdf0662 authored by Nadav Amit's avatar Nadav Amit Committed by Paolo Bonzini
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KVM: x86: DR7.GD should be cleared upon any #DB exception 



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: default avatarNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 394457a9

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,