Re: [Xen-devel] [PATCH 4/6] x86emul: reduce FPU handling code size

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 06/12/16 14:13, Jan Beulich wrote:
> @@ -3670,6 +3652,7 @@ x86_emulate(
>  
>      case 0xd8: /* FPU 0xd8 */
>          host_and_vcpu_must_have(fpu);
> +        get_fpu(X86EMUL_FPU_fpu, &fic);
>          switch ( modrm )
>          {
>          case 0xc0 ... 0xc7: /* fadd %stN,%st */
> @@ -3715,10 +3698,12 @@ x86_emulate(
>                  break;
>              }
>          }
> +        put_fpu(&fic);
>          break;

This repositioning does mean that we might skip the put_fpu() call,
although we still retain the catch-all _put_fpu().

I think this is still safe as we only skip this put_fpu() in cases where
we didn't emulate an instruction, and there isn't the risk of missing a
pending FPU exception.

~Andrew

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