Re: [PATCH 3/5] x86/kvm: Convert some slow-path static_cpu_has() callers to boot_cpu_has()

Paolo Bonzini
2019-03-31T14:20:28Z

On 30/03/19 12:20, Borislav Petkov wrote:
> @@ -2252,7 +2252,7 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)
> rdmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);
>
> - if (static_cpu_has(X86_FEATURE_TSCRATEMSR)) {
> + if (boot_cpu_has(X86_FEATURE_TSCRATEMSR)) {
> u64 tsc_ratio = vcpu->arch.tsc_scaling_ratio;
> if (tsc_ratio != __this_cpu_read(current_tsc_ratio)) {
> __this_cpu_write(current_tsc_ratio, tsc_ratio);
> @@ -2260,7 +2260,7 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> }
> }
> /* This assumes that the kernel never uses MSR_TSC_AUX */
> - if (static_cpu_has(X86_FEATURE_RDTSCP))
> + if (boot_cpu_has(X86_FEATURE_RDTSCP))
> wrmsrl(MSR_TSC_AUX, svm->tsc_aux);
>
> if (sd->current_vmcb != svm->vmcb) {
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index c73375e01ab8..0cb0d26564ca 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6423,7 +6423,7 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu)
> if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
> vmx_set_interrupt_shadow(vcpu, 0);
>
> - if (static_cpu_has(X86_FEATURE_PKU) &&
> + if (boot_cpu_has(X86_FEATURE_PKU) &&
> kvm_read_cr4_bits(vcpu, X86_CR4_PKE) &&
> vcpu->arch.pkru != vmx->host_pkru)
> __write_pkru(vcpu->arch.pkru);
> @@ -6512,7 +6512,7 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu)
> * back on host, so it is safe to read guest PKRU from current
> * XSAVE.
> */
> - if (static_cpu_has(X86_FEATURE_PKU) &&
> + if (boot_cpu_has(X86_FEATURE_PKU) &&
> kvm_read_cr4_bits(vcpu, X86_CR4_PKE)) {
> vcpu->arch.pkru = __read_pkru();

These are not slow path.

Paolo