Re: [PATCH 2/7] KVM: nVMX: Load GUEST_IA32_PERF_GLOBAL_CTRL MSR on vmentry

[Sean Christopherson <sean.j.christopherson@intel.com>]

On Wed, Aug 28, 2019 at 04:41:29PM -0700, Oliver Upton wrote:
> If the "load IA32_PERF_GLOBAL_CTRL" bit on the VM-entry control is
> set, the IA32_PERF_GLOBAL_CTRL MSR is loaded from GUEST_IA32_PERF_GLOBAL_CTRL
> on VM-entry. Adding condition to prepare_vmcs02 to set
> MSR_CORE_PERF_GLOBAL_CTRL if the "load IA32_PERF_GLOBAL_CTRL" bit is set.
> 
> Suggested-by: Jim Mattson <jmattson@google.com>
> Signed-off-by: Oliver Upton <oupton@google.com>
> ---
>  arch/x86/kvm/vmx/nested.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index b0ca34bf4d21..9ba90b38d74b 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -2281,6 +2281,7 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
>  {
>  	struct vcpu_vmx *vmx = to_vmx(vcpu);
>  	struct hv_enlightened_vmcs *hv_evmcs = vmx->nested.hv_evmcs;
> +	struct msr_data msr_info;
>  	bool load_guest_pdptrs_vmcs12 = false;
>  
>  	if (vmx->nested.dirty_vmcs12 || hv_evmcs) {
> @@ -2404,6 +2405,16 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
>  	if (!enable_ept)
>  		vcpu->arch.walk_mmu->inject_page_fault = vmx_inject_page_fault_nested;
>  
> +	if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL) {
> +		msr_info.host_initiated = false;
> +		msr_info.index = MSR_CORE_PERF_GLOBAL_CTRL;
> +		msr_info.data = vmcs12->guest_ia32_perf_global_ctrl;
> +		if (kvm_set_msr(vcpu, &msr_info))
> +			pr_debug_ratelimited(
> +				"%s cannot write MSR (0x%x, 0x%llx)\n",
> +				__func__, msr_info.index, msr_info.data);

Blech, I was going to say you should add a helper to consolidate this code
for patches 1/7 and 2/7, but there are something like 10 different places
in KVM that have similar blobs.  I'll put together a patch or three to
add helpers, no need to address a wider problem with this series.

> +	}
> +
>  	kvm_rsp_write(vcpu, vmcs12->guest_rsp);
>  	kvm_rip_write(vcpu, vmcs12->guest_rip);
>  	return 0;
> -- 
> 2.23.0.187.g17f5b7556c-goog
>