Re: [PATCH 1/2] x86: Conditionalise PV-only fallback branches on CONFIG_PV

["Teddy Astie" <teddy.astie@xxxxxxxxxx>]

Le 12/11/2025 à 16:25, Alejandro Vallejo a écrit :
> A couple of branches rely on PV being the "else" branch, making it
> be compiled even when PV support is not itself compiled-in.
>
> Add a explicit conditional on CONFIG_PV in those cases to remove the
> code in !CONFIG_PV builds.
>
> Not a functional change.
>
> Signed-off-by: Alejandro Vallejo <alejandro.garciavallejo@xxxxxxx>
> ---
>   xen/arch/x86/cpuid.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/xen/arch/x86/cpuid.c b/xen/arch/x86/cpuid.c
> index b63a82dd38..2e24c84708 100644
> --- a/xen/arch/x86/cpuid.c
> +++ b/xen/arch/x86/cpuid.c
> @@ -297,7 +297,7 @@ void guest_cpuid(const struct vcpu *v, uint32_t leaf,
>               if ( v->arch.hvm.guest_cr[4] & X86_CR4_OSXSAVE )
>                   res->c |= cpufeat_mask(X86_FEATURE_OSXSAVE);
>           }
> -        else /* PV domain */
> +        else if ( IS_ENABLED(CONFIG_PV) )
>           {
>               regs = guest_cpu_user_regs();
>
> @@ -509,7 +509,7 @@ void guest_cpuid(const struct vcpu *v, uint32_t leaf,
>               if ( !hap_enabled(d) && !hvm_pae_enabled(v) )
>                   res->d &= ~cpufeat_mask(X86_FEATURE_PSE36);
>           }
> -        else /* PV domain */
> +        else if ( IS_ENABLED(CONFIG_PV) )
>           {
>               /*
>                * MTRR used to unconditionally leak into PV guests.  They 
> cannot

I don't like having IS_ENABLED(CONFIG_PV) here, but I don't think of a
better solution as using e.g is_pv_domain isn't really better as it
would make us evaluate d->options twice.

That said,
Reviewed-by: Teddy Astie <teddy.astie@xxxxxxxxxx>

Teddy


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Teddy Astie | Vates XCP-ng Developer

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