Re: [Xen-devel] [PATCH v2 1/3] x86emul: honor guest CR4.OSFXSR and CR4.OSXSAVE

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 04/10/16 16:10, Jan Beulich wrote:
> @@ -767,9 +770,23 @@ static int _get_fpu(
>          unsigned long cr0;
>  
>          fail_if(!ops->read_cr);
> +        if ( type >= X86EMUL_FPU_xmm )
> +        {
> +            unsigned long cr4;
> +
> +            rc = ops->read_cr(4, &cr4, ctxt);
> +            if ( rc != X86EMUL_OKAY )
> +                return rc;
> +            generate_exception_if(!(cr4 & ((type == X86EMUL_FPU_xmm)
> +                                           ? CR4_OSFXSR : CR4_OSXSAVE)),
> +                                  EXC_UD, -1);
> +        }
> +
>          rc = ops->read_cr(0, &cr0, ctxt);
>          if ( rc != X86EMUL_OKAY )
>              return rc;
> +        if ( type >= X86EMUL_FPU_ymm )

I would be tempted to add here

/* Should not be reachable if VEX decoding is working correctly. */

Otherwise, Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

> +            ASSERT((cr0 & CR0_PE) && !(ctxt->regs->eflags & EFLG_VM));
>          if ( cr0 & CR0_EM )
>          {
>              generate_exception_if(type == X86EMUL_FPU_fpu, EXC_NM, -1);
>
>
>


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