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KVM: x86: DR7.GD should be cleared upon any #DB exception

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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>
This commit is contained in:
Nadav Amit 2014-09-30 20:49:14 +03:00 committed by Paolo Bonzini
parent 394457a928
commit 6bdf06625d
2 changed files with 6 additions and 2 deletions
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2
arch/x86/kvm/vmx.c
View File

@ -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;
}

6
arch/x86/kvm/x86.c
View File

@ -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,