linux-kernel - [PATCH 1/5] KVM: SVM: Drop stale comment from svm_hv_vmcb_dirty_nested

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Date:   Mon, 20 Dec 2021 16:21:35 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        Vineeth Pillai <viremana@...ux.microsoft.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/5] KVM: SVM: Drop stale comment from svm_hv_vmcb_dirty_nested_enlightenments()

Commit 3fa5e8fd0a0e4 ("KVM: SVM: delay svm_vcpu_init_msrpm after
svm->vmcb is initialized") re-arranged svm_vcpu_init_msrpm() call in
svm_create_vcpu() 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: 3fa5e8fd0a0e4 ("KVM: SVM: delay svm_vcpu_init_msrpm after svm->vmcb is initialized")
Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/kvm/svm/svm.h          | 5 -----
 arch/x86/kvm/svm/svm_onhyperv.h | 9 +--------
 2 files changed, 1 insertion(+), 13 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index daa8ca84afcc..5d197aae3a19 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -305,11 +305,6 @@ 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);
diff --git a/arch/x86/kvm/svm/svm_onhyperv.h b/arch/x86/kvm/svm/svm_onhyperv.h
index c53b8bf8d013..cdbcfc63d171 100644
--- a/arch/x86/kvm/svm/svm_onhyperv.h
+++ b/arch/x86/kvm/svm/svm_onhyperv.h
@@ -83,14 +83,7 @@ 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);
 }
 
-- 
2.33.1