From 6bdf06625d240361e92254143a123ab432e337f8 Mon Sep 17 00:00:00 2001 From: Nadav Amit Date: Tue, 30 Sep 2014 20:49:14 +0300 Subject: [PATCH] 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: Nadav Amit Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 2 -- arch/x86/kvm/x86.c | 6 ++++++ 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 2627ffa..63e7cf1 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -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; } diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 0033df32..1ab7361 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -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, -- 2.7.4