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| author | Nadav Amit <namit@cs.technion.ac.il> | 2014-07-15 17:37:46 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2014-07-21 17:17:52 +0200 |
| commit | 6f43ed01e87c8a8dbd8c826eaf0f714c1342c039 (patch) | |
| tree | 96064816637d154889b1b4bea5e6c5dd6062c9bf /arch/x86/kvm/vmx.c | |
| parent | 9a2a05b9ed618b1bb6d4cbec0c2e1f80d6636609 (diff) | |
| download | lwn-6f43ed01e87c8a8dbd8c826eaf0f714c1342c039.tar.gz lwn-6f43ed01e87c8a8dbd8c826eaf0f714c1342c039.zip | |
KVM: x86: DR6/7.RTM cannot be written
Haswell and newer Intel CPUs have support for RTM, and in that case DR6.RTM is
not fixed to 1 and DR7.RTM is not fixed to zero. That is not the case in the
current KVM implementation. This bug is apparent only if the MOV-DR instruction
is emulated or the host also debugs the guest.
This patch is a partial fix which enables DR6.RTM and DR7.RTM to be cleared and
set respectively. It also sets DR6.RTM upon every debug exception. Obviously,
it is not a complete fix, as debugging of RTM is still unsupported.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/vmx.c')
| -rw-r--r-- | arch/x86/kvm/vmx.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 3300f4f2da48..fd24f68378a7 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -4892,7 +4892,7 @@ static int handle_exception(struct kvm_vcpu *vcpu) if (!(vcpu->guest_debug & (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))) { vcpu->arch.dr6 &= ~15; - vcpu->arch.dr6 |= dr6; + vcpu->arch.dr6 |= dr6 | DR6_RTM; if (!(dr6 & ~DR6_RESERVED)) /* icebp */ skip_emulated_instruction(vcpu); @@ -5151,7 +5151,7 @@ static int handle_dr(struct kvm_vcpu *vcpu) return 0; } else { vcpu->arch.dr7 &= ~DR7_GD; - vcpu->arch.dr6 |= DR6_BD; + vcpu->arch.dr6 |= DR6_BD | DR6_RTM; vmcs_writel(GUEST_DR7, vcpu->arch.dr7); kvm_queue_exception(vcpu, DB_VECTOR); return 1; |