linux-kernel - Re: [PATCH 2/3] x86/mmio: Rename cpu_buf_vm_clear to cpu_buf_vm_clear_mmio

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Message-ID: <aQKuy34wmCWvXcMS@google.com>
Date: Wed, 29 Oct 2025 17:18:19 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>, 
	Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...nel.org>, 
	Ingo Molnar <mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org, 
	kvm@...r.kernel.org, Tao Zhang <tao1.zhang@...el.com>, 
	Jim Mattson <jmattson@...gle.com>, Brendan Jackman <jackmanb@...gle.com>
Subject: Re: [PATCH 2/3] x86/mmio: Rename cpu_buf_vm_clear to cpu_buf_vm_clear_mmio_only

On Wed, Oct 29, 2025, Pawan Gupta wrote:
> cpu_buf_vm_clear static key is only used by the MMIO Stale Data mitigation.
> Rename it to avoid mixing it up with X86_FEATURE_CLEAR_CPU_BUF_VM.
> 
> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
> ---

...

> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index f87c216d976d7d344c924aa4cc18fe1bf8f9b731..451be757b3d1b2fec6b2b79157f26dd43bc368b8 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -903,7 +903,7 @@ unsigned int __vmx_vcpu_run_flags(struct vcpu_vmx *vmx)
>  	if (!msr_write_intercepted(vmx, MSR_IA32_SPEC_CTRL))
>  		flags |= VMX_RUN_SAVE_SPEC_CTRL;
>  
> -	if (static_branch_unlikely(&cpu_buf_vm_clear) &&
> +	if (static_branch_unlikely(&cpu_buf_vm_clear_mmio_only) &&
>  	    kvm_vcpu_can_access_host_mmio(&vmx->vcpu))
>  		flags |= VMX_RUN_CLEAR_CPU_BUFFERS_FOR_MMIO;

The use in vmx_vcpu_enter_exit() needs to be renamed as well.  The code gets
dropped in patch 3, but intermediate builds will fail.