Re: [Xen-devel] [PATCH v3 12/18] x86emul: add tables for 0f38 and 0f3a extension space

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 15/02/17 11:14, Jan Beulich wrote:
> @@ -2207,12 +2231,12 @@ x86_decode_twobyte(
>          switch ( modrm_reg & 7 )
>          {
>          case 2: /* {,v}ldmxcsr */
> -            state->desc = DstImplicit | SrcMem | ModRM | Mov;
> +            state->desc = DstImplicit | SrcMem | Mov;
>              op_bytes = 4;
>              break;
>  
>          case 3: /* {,v}stmxcsr */
> -            state->desc = DstMem | SrcImplicit | ModRM | Mov;
> +            state->desc = DstMem | SrcImplicit | Mov;
>              op_bytes = 4;
>              break;
>          }

Shouldn't this be folded into patch 7?

> @@ -2571,6 +2595,25 @@ x86_decode(
>                  }
>                  break;
>              }
> +            break;
> +
> +        case vex_0f38:
> +            d = ext0f38_table[b].to_memory ? DstMem | SrcReg
> +                                           : DstReg | SrcMem;
> +            if ( ext0f38_table[b].two_op )
> +                d |= TwoOp;
> +            if ( ext0f38_table[b].vsib )
> +                d |= vSIB;

What prevents vSIB becoming set for a non-vex encoded 0f38 instruction?

> +            state->simd_size = ext0f38_table[b].simd_size;
> +            break;
> +
> +        case vex_0f3a:
> +            /*
> +             * Cannot update d here yet, as the immediate operand still
> +             * needs fetching.
> +             */
> +        default:
> +            break;
>          }
>  
>          if ( modrm_mod == 3 )
> @@ -7382,7 +7438,7 @@ x86_insn_modrm(const struct x86_emulate_
>  {
>      check_state(state);
>  
> -    if ( !(state->desc & ModRM) )
> +    if ( state->modrm_mod > 3 )

Speaking of, there is still a bug with some existing x86_insn_modrm()
callsites.

Consider this a ping on the "Re: [Xen-devel] [PATCH] x86/svm: Adjust
ModRM Mode check in is_invlpg()" thread.

~Andrew

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