KVM: SVM: Clean up and enhance mov dr emulation

Enhance mov dr instruction emulation used by SVM so that it properly
handles dr4/5: alias to dr6/7 if cr4.de is cleared. Otherwise return
EMULATE_FAIL which will let our only possible caller in that scenario,
ud_interception, re-inject UD.

We do not need to inject faults, SVM does this for us (exceptions take
precedence over instruction interceptions). For the same reason, the
value overflow checks can be removed.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 2 insertions, 3 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index a1f0b5dd7d75..d73ed48587e4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -506,9 +506,8 @@ struct kvm_x86_ops {
         void (*set_idt)(struct kvm_vcpu *vcpu, struct descriptor_table *dt);
         void (*get_gdt)(struct kvm_vcpu *vcpu, struct descriptor_table *dt);
         void (*set_gdt)(struct kvm_vcpu *vcpu, struct descriptor_table *dt);
-        unsigned long (*get_dr)(struct kvm_vcpu *vcpu, int dr);
-        void (*set_dr)(struct kvm_vcpu *vcpu, int dr, unsigned long value,
-                       int *exception);
+        int (*get_dr)(struct kvm_vcpu *vcpu, int dr, unsigned long *dest);
+        int (*set_dr)(struct kvm_vcpu *vcpu, int dr, unsigned long value);
         void (*cache_reg)(struct kvm_vcpu *vcpu, enum kvm_reg reg);
         unsigned long (*get_rflags)(struct kvm_vcpu *vcpu);
         void (*set_rflags)(struct kvm_vcpu *vcpu, unsigned long rflags);