linux-kernel - [PATCH v2 47/49] KVM: x86: Drop superfluous host XSAVE check when adjusting guest XSAVES caps

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Date: Fri, 17 May 2024 10:39:24 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>, Sean Christopherson <seanjc@...gle.com>, 
	Vitaly Kuznetsov <vkuznets@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Hou Wenlong <houwenlong.hwl@...group.com>, Kechen Lu <kechenl@...dia.com>, 
	Oliver Upton <oliver.upton@...ux.dev>, Maxim Levitsky <mlevitsk@...hat.com>, 
	Binbin Wu <binbin.wu@...ux.intel.com>, Yang Weijiang <weijiang.yang@...el.com>, 
	Robert Hoo <robert.hoo.linux@...il.com>
Subject: [PATCH v2 47/49] 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 06770b60c0ba..4aaffbf22531 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4340,7 +4340,6 @@ 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 741961a1edcc..6fbdf520c58b 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7833,8 +7833,7 @@ 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);
-- 
2.45.0.215.g3402c0e53f-goog