linux-kernel - Re: [PATCH v3 1/4] KVM: nVMX: Setup VMX MSRs on loading CPU during nested_vmx_hardware

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Message-ID: <dd83c23b-80f9-42e6-a1f8-fb2f45384dbf@intel.com>
Date: Fri, 9 Jan 2026 19:24:33 +0800
From: Xiaoyao Li <xiaoyao.li@...el.com>
To: Sean Christopherson <seanjc@...gle.com>,
 Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
 Chao Gao <chao.gao@...el.com>, Xin Li <xin@...or.com>,
 Yosry Ahmed <yosry.ahmed@...ux.dev>
Subject: Re: [PATCH v3 1/4] KVM: nVMX: Setup VMX MSRs on loading CPU during
 nested_vmx_hardware_setup()

On 1/9/2026 12:15 PM, Sean Christopherson wrote:
> Move the call to nested_vmx_setup_ctls_msrs() from vmx_hardware_setup() to
> nested_vmx_hardware_setup() so that the nested code can deal with ordering
> dependencies without having to straddle vmx_hardware_setup() and
> nested_vmx_hardware_setup().  Specifically, an upcoming change will
> sanitize the vmcs12 fields based on hardware support, and that code needs
> to run _before_ the MSRs are configured, because the lovely vmcs_enum MSR
> depends on the max support vmcs12 field.
> 
> No functional change intended.
> 
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>

Reviewed-by: Xiaoyao Li <xiaoyao.li@...el.com>

> ---
>   arch/x86/kvm/vmx/nested.c | 2 ++
>   arch/x86/kvm/vmx/vmx.c    | 2 --
>   2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 6137e5307d0f..61113ead3d7b 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -7407,6 +7407,8 @@ __init int nested_vmx_hardware_setup(int (*exit_handlers[])(struct kvm_vcpu *))
>   {
>   	int i;
>   
> +	nested_vmx_setup_ctls_msrs(&vmcs_config, vmx_capability.ept);
> +
>   	if (!cpu_has_vmx_shadow_vmcs())
>   		enable_shadow_vmcs = 0;
>   	if (enable_shadow_vmcs) {
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 6b96f7aea20b..5bb67566e43a 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -8670,8 +8670,6 @@ __init int vmx_hardware_setup(void)
>   	 * can hide/show features based on kvm_cpu_cap_has().
>   	 */
>   	if (nested) {
> -		nested_vmx_setup_ctls_msrs(&vmcs_config, vmx_capability.ept);
> -
>   		r = nested_vmx_hardware_setup(kvm_vmx_exit_handlers);
>   		if (r)
>   			return r;