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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 <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Jan Kiszka 2014-01-04 18:47:17 +01:00 committed by Paolo Bonzini
parent 73aaf249ee
commit 8246bf52c7
1 changed files with 2 additions and 1 deletions
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3
arch/x86/kvm/vmx.c
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@ -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;
}