KVM: Fix vmload and friends misinterpreted as lidt

The AMD SVM instruction family all overload the 0f 01 /3 opcode, further
multiplexing on the three r/m bits.  But the code decided that anything that
isn't a vmmcall must be an lidt (which shares the 0f 01 /3 opcode, for the
case that mod = 3).

Fix by aborting emulation if this isn't a vmmcall.

Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 10 insertions, 5 deletions

diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
index d174db7a3370..54fb09889a80 100644
--- a/arch/x86/kvm/x86_emulate.c
+++ b/arch/x86/kvm/x86_emulate.c
@@ -1908,11 +1908,16 @@ twobyte_insn:
                         c->dst.type = OP_NONE;
                         break;
                 case 3: /* lidt/vmmcall */
-                        if (c->modrm_mod == 3 && c->modrm_rm == 1) {
-                                rc = kvm_fix_hypercall(ctxt->vcpu);
-                                if (rc)
-                                        goto done;
-                                kvm_emulate_hypercall(ctxt->vcpu);
+                        if (c->modrm_mod == 3) {
+                                switch (c->modrm_rm) {
+                                case 1:
+                                        rc = kvm_fix_hypercall(ctxt->vcpu);
+                                        if (rc)
+                                                goto done;
+                                        break;
+                                default:
+                                        goto cannot_emulate;
+                                }
                         } else {
                                 rc = read_descriptor(ctxt, ops, c->src.ptr,
                                                      &size, &address,