Re: [PATCH 1/2] kvm/x86/vmx: enable X86_FEATURE_WAITPKG in KVM capabilities

Sean Christopherson
2020-05-27T01:20:41Z

On Sat, May 23, 2020 at 07:14:54PM +0300, Maxim Levitsky wrote:
> Even though we might not allow the guest to use
> WAITPKG's new instructions, we should tell KVM
> that the feature is supported by the host CPU.
>
> Note that vmx_waitpkg_supported checks that WAITPKG
> _can_ be set in secondary execution controls as specified
> by VMX capability MSR, rather that we actually enable it for a guest.

These line wraps are quite weird and inconsistent.

>
> Fixes: e69e72faa3a0 KVM: x86: Add support for user wait instructions

Checkpatch doesn't complain, but the preferred Fixes format is

Fixes: e69e72faa3a07 ("KVM: x86: Add support for user wait instructions")

e.g.

git show -s --pretty='tformat:%h ("%s")'

For the code itself:

Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>

> Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> ---
> arch/x86/kvm/vmx/vmx.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 55712dd86bafa..fca493d4517c5 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -7298,6 +7298,9 @@ static __init void vmx_set_cpu_caps(void)
> /* CPUID 0x80000001 */
> if (!cpu_has_vmx_rdtscp())
> kvm_cpu_cap_clear(X86_FEATURE_RDTSCP);
> +
> + if (vmx_waitpkg_supported())
> + kvm_cpu_cap_check_and_set(X86_FEATURE_WAITPKG);
> }
>
> static void vmx_request_immediate_exit(struct kvm_vcpu *vcpu)
> --
> 2.26.2
>