KVM: emulator: emulate XLAT

This is used by SGABIOS, KVM breaks with emulate_invalid_guest_state=1.
It is just a MOV in disguise, with a funny source address.

Reported-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: stable@vger.kernel.org # 3.9
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 55322a7c113d..a06a550c2db8 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -60,6 +60,7 @@
 #define OpGS              25ull  /* GS */
 #define OpMem8            26ull  /* 8-bit zero extended memory operand */
 #define OpImm64           27ull  /* Sign extended 16/32/64-bit immediate */
+#define OpXLat            28ull  /* memory at BX/EBX/RBX + zero-extended AL */
 
 #define OpBits             5  /* Width of operand field */
 #define OpMask             ((1ull << OpBits) - 1)
@@ -99,6 +100,7 @@
 #define SrcImmUByte (OpImmUByte << SrcShift)
 #define SrcImmU     (OpImmU << SrcShift)
 #define SrcSI       (OpSI << SrcShift)
+#define SrcXLat     (OpXLat << SrcShift)
 #define SrcImmFAddr (OpImmFAddr << SrcShift)
 #define SrcMemFAddr (OpMemFAddr << SrcShift)
 #define SrcAcc      (OpAcc << SrcShift)
@@ -3959,7 +3961,8 @@ static const struct opcode opcode_table[256] = {
         G(Src2One | ByteOp, group2), G(Src2One, group2),
         G(Src2CL | ByteOp, group2), G(Src2CL, group2),
         I(DstAcc | SrcImmUByte | No64, em_aam),
-        I(DstAcc | SrcImmUByte | No64, em_aad), N, N,
+        I(DstAcc | SrcImmUByte | No64, em_aad), N,
+        I(DstAcc | SrcXLat | ByteOp, em_mov),
         /* 0xD8 - 0xDF */
         N, E(0, &escape_d9), N, E(0, &escape_db), N, E(0, &escape_dd), N, N,
         /* 0xE0 - 0xE7 */
@@ -4221,6 +4224,16 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op,
                 op->val = 0;
                 op->count = 1;
                 break;
+        case OpXLat:
+                op->type = OP_MEM;
+                op->bytes = (ctxt->d & ByteOp) ? 1 : ctxt->op_bytes;
+                op->addr.mem.ea =
+                        register_address(ctxt,
+                                reg_read(ctxt, VCPU_REGS_RBX) +
+                                (reg_read(ctxt, VCPU_REGS_RAX) & 0xff));
+                op->addr.mem.seg = seg_override(ctxt);
+                op->val = 0;
+                break;
         case OpImmFAddr:
                 op->type = OP_IMM;
                 op->addr.mem.ea = ctxt->_eip;