From 8246bf52c75aa9b9b336a84f31ed2248754d0f71 Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Sat, 4 Jan 2014 18:47:17 +0100 Subject: [PATCH] KVM: VMX: Fix DR6 update on #DB exception According to the SDM, only bits 0-3 of DR6 "may" be cleared by "certain" debug exception. So do update them on #DB exception in KVM, but leave the rest alone, only setting BD and BS in addition to already set bits in DR6. This also aligns us with kvm_vcpu_check_singlestep. Signed-off-by: Jan Kiszka Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 79b360e4fed1..c8eb27ff1a2d 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -4869,7 +4869,8 @@ static int handle_exception(struct kvm_vcpu *vcpu) dr6 = vmcs_readl(EXIT_QUALIFICATION); if (!(vcpu->guest_debug & (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))) { - vcpu->arch.dr6 = dr6 | DR6_FIXED_1; + vcpu->arch.dr6 &= ~15; + vcpu->arch.dr6 |= dr6; kvm_queue_exception(vcpu, DB_VECTOR); return 1; } -- 2.39.2