Re: [PATCH v3 04/22] x86/fsgsbase: Update fs/gs helpers to use wrmsrns()

[Jan Beulich <jbeulich@suse.com>]

On 04.10.2025 00:53, Andrew Cooper wrote:
> ... and rdmsr() while here.
> 
> Most of these accesses are in fastpaths and do not need serialising behaviour,
> but the write side is serialising on all Intel hardware as well as older AMD
> hardware.
> 
> No functional change.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

Acked-by: Jan Beulich <jbeulich@suse.com>
in the interest of not blocking the tidying over ...

> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -2737,8 +2737,8 @@ static uint64_t cf_check vmx_get_reg(struct vcpu *v, unsigned int reg)
>      case MSR_SHADOW_GS_BASE:
>          if ( v != curr )
>              return v->arch.hvm.vmx.shadow_gs;
> -        rdmsrl(MSR_SHADOW_GS_BASE, val);
> -        return val;
> +        else
> +            return rdmsr(MSR_SHADOW_GS_BASE);

... the addition of useless (and confusing, and possibly being Misra violations)
"else" here and elsewhere. If you were to drop them, feel free to "upgrade" to
R-b.

Jan