KVM: SVM: Fix reading of DR6

In contrast to VMX, SVM dose not automatically transfer DR6 into the
VCPU's arch.dr6. So if we face a DR6 read, we must consult a new vendor
hook to obtain the current value. And as SVM now picks the DR6 state
from its VMCB, we also need a set callback in order to write updates of
DR6 back.

Fixes a regression of 020df0794f.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 7661eb171936..79b360e4fed1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5149,6 +5149,15 @@ static int handle_dr(struct kvm_vcpu *vcpu)
         return 1;
 }
 
+static u64 vmx_get_dr6(struct kvm_vcpu *vcpu)
+{
+        return vcpu->arch.dr6;
+}
+
+static void vmx_set_dr6(struct kvm_vcpu *vcpu, unsigned long val)
+{
+}
+
 static void vmx_set_dr7(struct kvm_vcpu *vcpu, unsigned long val)
 {
         vmcs_writel(GUEST_DR7, val);
@@ -8556,6 +8565,8 @@ static struct kvm_x86_ops vmx_x86_ops = {
         .set_idt = vmx_set_idt,
         .get_gdt = vmx_get_gdt,
         .set_gdt = vmx_set_gdt,
+        .get_dr6 = vmx_get_dr6,
+        .set_dr6 = vmx_set_dr6,
         .set_dr7 = vmx_set_dr7,
         .cache_reg = vmx_cache_reg,
         .get_rflags = vmx_get_rflags,