Re: [PATCH 2/4] x86/xstate: Rework XSAVE/XRSTOR given a newer toolchain baseline

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 30/12/2025 1:54 pm, Andrew Cooper wrote:
> diff --git a/xen/arch/x86/xstate.c b/xen/arch/x86/xstate.c
> index 384f78bd5281..4215a83efefb 100644
> --- a/xen/arch/x86/xstate.c
> +++ b/xen/arch/x86/xstate.c
> @@ -310,21 +310,21 @@ void xsave(struct vcpu *v, uint64_t mask)
>      uint32_t hmask = mask >> 32;
>      uint32_t lmask = mask;
>      unsigned int fip_width = v->domain->arch.x87_fip_width;
> -#define XSAVE(pfx) \
> -        if ( v->arch.xcr0_accum & XSTATE_XSAVES_ONLY ) \
> -            asm volatile ( ".byte " pfx "0x0f,0xc7,0x2f\n" /* xsaves */ \
> -                           : "=m" (*ptr) \
> -                           : "a" (lmask), "d" (hmask), "D" (ptr) ); \
> -        else \
> -            alternative_io(".byte " pfx "0x0f,0xae,0x27\n", /* xsave */ \
> -                           ".byte " pfx "0x0f,0xae,0x37\n", /* xsaveopt */ \
> -                           X86_FEATURE_XSAVEOPT, \
> -                           "=m" (*ptr), \
> -                           "a" (lmask), "d" (hmask), "D" (ptr))
> +
> +#define XSAVE(pfx)                                                      \
> +    if ( v->arch.xcr0_accum & XSTATE_XSAVES_ONLY )                      \
> +        asm volatile ( "xsaves %0"                                      \
> +                       : "=m" (*ptr)                                    \
> +                       : "a" (lmask), "d" (hmask) );                    \
> +    else                                                                \
> +        alternative_io("xsave %0",                                      \
> +                       "xsaveopt %0", X86_FEATURE_XSAVEOPT,             \
> +                       "=m" (*ptr),                                     \
> +                       "a" (lmask), "d" (hmask))

This loses the pfx.  I've fixed up locally and double checked the
disassembly.

~Andrew