linux-kernel - Re: [PATCH 1/3] KVM: x86: Finalize kvm_cpu_caps setup from {svm,vmx}_set_cpu

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Message-ID: <204d5234-9afd-4745-b40a-4355afad1e6b@intel.com>
Date: Tue, 27 Jan 2026 23:12:30 +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,
 Mathias Krause <minipli@...ecurity.net>, John Allen <john.allen@....com>,
 Rick Edgecombe <rick.p.edgecombe@...el.com>, Chao Gao <chao.gao@...el.com>,
 Binbin Wu <binbin.wu@...ux.intel.com>, Jim Mattson <jmattson@...gle.com>
Subject: Re: [PATCH 1/3] KVM: x86: Finalize kvm_cpu_caps setup from
 {svm,vmx}_set_cpu_caps()

On 1/24/2026 6:15 AM, Sean Christopherson wrote:
...
> +void kvm_finalize_cpu_caps(void)

It also finalizes the kvm_caps, at least kvm_caps.supported_xss, which 
seems not consistent with the name.

Even more, just look at the function body, the name 
"kvm_finalize_supported_xss" seems to fit better while clearing SHSTK 
and IBT just the side effect of the finalized kvm_caps.supported_xss.



> +{
> +	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
> +		kvm_caps.supported_xss = 0;
> +
> +	if (!kvm_cpu_cap_has(X86_FEATURE_SHSTK) &&
> +	    !kvm_cpu_cap_has(X86_FEATURE_IBT))
> +		kvm_caps.supported_xss &= ~XFEATURE_MASK_CET_ALL;
> +
> +	if ((kvm_caps.supported_xss & XFEATURE_MASK_CET_ALL) != XFEATURE_MASK_CET_ALL) {
> +		kvm_cpu_cap_clear(X86_FEATURE_SHSTK);
> +		kvm_cpu_cap_clear(X86_FEATURE_IBT);
> +		kvm_caps.supported_xss &= ~XFEATURE_MASK_CET_ALL;
> +	}
> +}