Re: [PATCH 11/12] x86/cpu: Migrate vendor checks to use cpu_vendor()

[Jan Beulich <jbeulich@xxxxxxxx>]

On 06.02.2026 17:15, Alejandro Vallejo wrote:
> --- a/xen/arch/x86/cpu/intel_cacheinfo.c
> +++ b/xen/arch/x86/cpu/intel_cacheinfo.c
> @@ -168,9 +168,8 @@ void init_intel_cacheinfo(struct cpuinfo_x86 *c)
>        * Don't use cpuid2 if cpuid4 is supported. For P4, we use cpuid2 for
>        * trace cache
>        */
> -     if ((num_cache_leaves == 0 || c->x86 == 15) && c->cpuid_level > 1 &&
> -         c->x86_vendor != X86_VENDOR_SHANGHAI)
> -     {
> +     if (((num_cache_leaves == 0 || c->x86 == 15) && c->cpuid_level > 1) &&
> +         (!(cpu_vendor() & X86_VENDOR_SHANGHAI))) {

Nit: Again, no need for the extra parentheses (here: around the !()). Nor do
I see a need to alter the first line at all.

> --- a/xen/arch/x86/cpu/mtrr/generic.c
> +++ b/xen/arch/x86/cpu/mtrr/generic.c
> @@ -218,9 +218,8 @@ static void __init print_mtrr_state(const char *level)
>                       printk("%s  %u disabled\n", level, i);
>       }
>  
> -     if ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
> -          boot_cpu_data.x86 >= 0xf) ||
> -          boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
> +     if (((cpu_vendor() & X86_VENDOR_AMD) && boot_cpu_data.x86 >= 0xf) ||
> +         (cpu_vendor() & X86_VENDOR_HYGON)) {

Perhaps easier as

        if ((cpu_vendor() & (X86_VENDOR_AMD | X86_VENDOR_HYGON)) &&
            boot_cpu_data.x86 >= 0xf) {

, seeing that there's no Hygon hardware lower than Fam18?

> --- a/xen/arch/x86/cpu/vpmu.c
> +++ b/xen/arch/x86/cpu/vpmu.c
> @@ -398,7 +398,6 @@ int vpmu_load(struct vcpu *v, bool from_guest)
>  static int vpmu_arch_initialise(struct vcpu *v)
>  {
>      struct vpmu_struct *vpmu = vcpu_vpmu(v);
> -    uint8_t vendor = current_cpu_data.x86_vendor;
>      int ret;
>  
>      BUILD_BUG_ON(sizeof(struct xen_pmu_intel_ctxt) > XENPMU_CTXT_PAD_SZ);
> @@ -418,7 +417,7 @@ static int vpmu_arch_initialise(struct vcpu *v)
>          if ( vpmu_mode != XENPMU_MODE_OFF )
>          {
>              printk(XENLOG_G_WARNING "VPMU: Unknown CPU vendor %d. "
> -                   "Disabling VPMU\n", vendor);
> +                   "Disabling VPMU\n", cpu_vendor());

Why would you want to make the log message less useful?

Jan