KVM: SVM: drop unnecessary code in svm_hv_vmcb_dirty_nested_enlightenments()

Commit 3fa5e8fd ("KVM: SVM: delay svm_vcpu_init_msrpm after
svm->vmcb is initialized") re-arranged svm_vcpu_init_msrpm() call in
svm_create_vcpu(), thus making the comment about vmcb being NULL
obsolete. Drop it.

While on it, drop superfluous vmcb_is_clean() check: vmcb_mark_dirty()
is a bit flip, an extra check is unlikely to bring any performance gain.
Drop now-unneeded vmcb_is_clean() helper as well.

Fixes: 3fa5e8fd ("KVM: SVM: delay svm_vcpu_init_msrpm after svm->vmcb is initialized")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211220152139.418372-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/svm.h

@@ -304,11 +304,6 @@ static inline void vmcb_mark_all_clean(struct vmcb *vmcb)
 			       & ~VMCB_ALWAYS_DIRTY_MASK;
 }
 
-static inline bool vmcb_is_clean(struct vmcb *vmcb, int bit)
-{
-	return (vmcb->control.clean & (1 << bit));
-}
-
 static inline void vmcb_mark_dirty(struct vmcb *vmcb, int bit)
 {
 	vmcb->control.clean &= ~(1 << bit);

arch/x86/kvm/svm/svm_onhyperv.h

@@ -86,14 +86,7 @@ static inline void svm_hv_vmcb_dirty_nested_enlightenments(
 	struct hv_enlightenments *hve =
 		(struct hv_enlightenments *)vmcb->control.reserved_sw;
 
-	/*
-	 * vmcb can be NULL if called during early vcpu init.
-	 * And its okay not to mark vmcb dirty during vcpu init
-	 * as we mark it dirty unconditionally towards end of vcpu
-	 * init phase.
-	 */
-	if (vmcb_is_clean(vmcb, VMCB_HV_NESTED_ENLIGHTENMENTS) &&
-	    hve->hv_enlightenments_control.msr_bitmap)
+	if (hve->hv_enlightenments_control.msr_bitmap)
 		vmcb_mark_dirty(vmcb, VMCB_HV_NESTED_ENLIGHTENMENTS);
 }