KVM: emulator: emulate XLAT

commit 7fa57952d70f5737513d8319395e471d107e4e0d upstream.

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>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 82df6aad8a7de567f68f07b4e0c31b65b8a0db5f..56c10f128d94d07951dba65b3e329625e7f1f710 100644 (file)
--- 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)
@@ -3949,7 +3951,8 @@ 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 */
@@ -4211,6 +4214,16 @@ 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;