lkml.org 
[lkml]   [2020]   [Feb]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH 46/61] KVM: x86: Remove the unnecessary loop on CPUID 0x7 sub-leafs
Date
Sean Christopherson <sean.j.christopherson@intel.com> writes:

> Explicitly handle CPUID 0x7 sub-leaf 1. The kernel is currently aware
> of exactly one feature in CPUID 0x7.1, which means there is room for
> another 127 features before CPUID 0x7.2 will see the light of day, i.e.
> the looping is likely to be dead code for years to come.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> arch/x86/kvm/cpuid.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 7362e5238799..47f61f4497fb 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -533,11 +533,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
> if (boot_cpu_has(X86_FEATURE_AMD_SSBD))
> cpuid_entry_set(entry, X86_FEATURE_SPEC_CTRL_SSBD);
>
> - for (i = 1, max_idx = entry->eax; i <= max_idx; i++) {
> - if (WARN_ON_ONCE(i > 1))
> - break;
> -
> - entry = do_host_cpuid(array, function, i);
> + /* KVM only supports 0x7.0 and 0x7.1, capped above via min(). */
> + if (entry->eax == 1) {
> + entry = do_host_cpuid(array, function, 1);
> if (!entry)
> goto out;

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>

--
Vitaly

\
 
 \ /
  Last update: 2020-02-24 23:26    [W:0.757 / U:3.788 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site