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@redhat.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20241128013424.4096668-52-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: sean-jc

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));
 

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);