Re: [PATCH v4 2/8] KVM: nVMX: Keep KVM updates to PERF_GLOBAL_CTRL ctrl bits across MSR write

[Paolo Bonzini <pbonzini@xxxxxxxxxx>]

On 3/1/22 07:03, Oliver Upton wrote:
> +
> +	/*
> +	 * KVM supports a 1-setting of the "load IA32_PERF_GLOBAL_CTRL"
> +	 * VM-{Entry,Exit} controls if the vPMU supports IA32_PERF_GLOBAL_CTRL.
> +	 */
> +	if (kvm_pmu_version(vcpu) >= 2) {
> +		vmx->nested.msrs.entry_ctls_high |= VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL;
> +		vmx->nested.msrs.exit_ctls_high |= VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL;
> +	} else {
> +		vmx->nested.msrs.entry_ctls_high &= ~VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL;
> +		vmx->nested.msrs.exit_ctls_high &= ~VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL;
> +	}

This one I understand, following what's done with MPX, but I cannot make 
sense of the commit message just like in the case of patch 1.

Paolo