linux-kernel - [PATCH v3 51/57] KVM: x86: Drop superfluous host XSAVE check when adjusting guest XSAVES caps

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Message-ID: <20241128013424.4096668-52-seanjc@google.com>
Date: Wed, 27 Nov 2024 17:34:18 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>, Sean Christopherson <seanjc@...gle.com>, 
	Vitaly Kuznetsov <vkuznets@...hat.com>, Jarkko Sakkinen <jarkko@...nel.org>
Cc: kvm@...r.kernel.org, linux-sgx@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Maxim Levitsky <mlevitsk@...hat.com>, 
	Hou Wenlong <houwenlong.hwl@...group.com>, Xiaoyao Li <xiaoyao.li@...el.com>, 
	Kechen Lu <kechenl@...dia.com>, Oliver Upton <oliver.upton@...ux.dev>, 
	Binbin Wu <binbin.wu@...ux.intel.com>, Yang Weijiang <weijiang.yang@...el.com>, 
	Robert Hoo <robert.hoo.linux@...il.com>
Subject: [PATCH v3 51/57] KVM: x86: Drop superfluous host XSAVE check when
 adjusting guest XSAVES caps

Drop the manual boot_cpu_has() checks on XSAVE when adjusting the guest's
XSAVES capabilities now that guest cpu_caps incorporates KVM's support.
The guest's cpu_caps are initialized from kvm_cpu_caps, which are in turn
initialized from boot_cpu_data, i.e. checking guest_cpu_cap_has() also
checks host/KVM capabilities (which is the entire point of cpu_caps).

Cc: Maxim Levitsky <mlevitsk@...hat.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/svm.c | 1 -
 arch/x86/kvm/vmx/vmx.c | 3 +--
 2 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 734b3ca40311..07911ddf1efe 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4402,7 +4402,6 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 	 * the guest read/write access to the host's XSS.
 	 */
 	guest_cpu_cap_change(vcpu, X86_FEATURE_XSAVES,
-			     boot_cpu_has(X86_FEATURE_XSAVE) &&
 			     boot_cpu_has(X86_FEATURE_XSAVES) &&
 			     guest_cpu_cap_has(vcpu, X86_FEATURE_XSAVE));
 
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 6e5edaa2ba3a..cf872d8691b5 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7825,8 +7825,7 @@ void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 	 * to the guest.  XSAVES depends on CR4.OSXSAVE, and CR4.OSXSAVE can be
 	 * set if and only if XSAVE is supported.
 	 */
-	if (!boot_cpu_has(X86_FEATURE_XSAVE) ||
-	    !guest_cpu_cap_has(vcpu, X86_FEATURE_XSAVE))
+	if (!guest_cpu_cap_has(vcpu, X86_FEATURE_XSAVE))
 		guest_cpu_cap_clear(vcpu, X86_FEATURE_XSAVES);
 
 	vmx_setup_uret_msrs(vmx);
-- 
2.47.0.338.g60cca15819-goog