KVM: x86 emulator: fix smsw and lmsw with a memory operand

lmsw and smsw were implemented only with a register operand.  Extend them
to support a memory operand as well.  Fixes Windows running some display
compatibility test on AMD hosts.

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

diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
index 8e1b32f..46ef78f 100644 (file)
--- a/arch/x86/kvm/x86_emulate.c
+++ b/arch/x86/kvm/x86_emulate.c
@@ -275,12 +275,15 @@ static u16 group_table[] = {
        SrcMem | ModRM, 0, SrcMem | ModRM | Stack, 0,
        [Group7*8] =
        0, 0, ModRM | SrcMem, ModRM | SrcMem,
-       SrcNone | ModRM | DstMem, 0, SrcMem | ModRM, SrcMem | ModRM | ByteOp,
+       SrcNone | ModRM | DstMem | Mov, 0,
+       SrcMem16 | ModRM | Mov, SrcMem | ModRM | ByteOp,
 };
 
 static u16 group2_table[] = {
        [Group7*8] =
-       SrcNone | ModRM, 0, 0, 0, SrcNone | ModRM | DstMem, 0, SrcMem | ModRM, 0,
+       SrcNone | ModRM, 0, 0, 0,
+       SrcNone | ModRM | DstMem | Mov, 0,
+       SrcMem16 | ModRM | Mov, 0,
 };
 
 /* EFLAGS bit definitions. */
@@ -1722,6 +1725,8 @@ twobyte_insn:
                                goto done;
 
                        kvm_emulate_hypercall(ctxt->vcpu);
+                       /* Disable writeback. */
+                       c->dst.type = OP_NONE;
                        break;
                case 2: /* lgdt */
                        rc = read_descriptor(ctxt, ops, c->src.ptr,
@@ -1729,6 +1734,8 @@ twobyte_insn:
                        if (rc)
                                goto done;
                        realmode_lgdt(ctxt->vcpu, size, address);
+                       /* Disable writeback. */
+                       c->dst.type = OP_NONE;
                        break;
                case 3: /* lidt/vmmcall */
                        if (c->modrm_mod == 3 && c->modrm_rm == 1) {
@@ -1744,27 +1751,25 @@ twobyte_insn:
                                        goto done;
                                realmode_lidt(ctxt->vcpu, size, address);
                        }
+                       /* Disable writeback. */
+                       c->dst.type = OP_NONE;
                        break;
                case 4: /* smsw */
-                       if (c->modrm_mod != 3)
-                               goto cannot_emulate;
-                       *(u16 *)&c->regs[c->modrm_rm]
-                               = realmode_get_cr(ctxt->vcpu, 0);
+                       c->dst.bytes = 2;
+                       c->dst.val = realmode_get_cr(ctxt->vcpu, 0);
                        break;
                case 6: /* lmsw */
-                       if (c->modrm_mod != 3)
-                               goto cannot_emulate;
-                       realmode_lmsw(ctxt->vcpu, (u16)c->modrm_val,
-                                                 &ctxt->eflags);
+                       realmode_lmsw(ctxt->vcpu, (u16)c->src.val,
+                                     &ctxt->eflags);
                        break;
                case 7: /* invlpg*/
                        emulate_invlpg(ctxt->vcpu, memop);
+                       /* Disable writeback. */
+                       c->dst.type = OP_NONE;
                        break;
                default:
                        goto cannot_emulate;
                }
-               /* Disable writeback. */
-               c->dst.type = OP_NONE;
                break;
        case 0x06:
                emulate_clts(ctxt->vcpu);