linux-kernel - [PATCH 06/23] KVM: nSVM: do not mark all VMCB01 fields dirty on nested vmexit

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Message-Id: <20210302193343.313318-7-pbonzini@redhat.com>
Date:   Tue,  2 Mar 2021 14:33:26 -0500
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     seanjc@...gle.com
Subject: [PATCH 06/23] KVM: nSVM: do not mark all VMCB01 fields dirty on nested vmexit

Since L1 and L2 now use different VMCBs, most of the fields remain
the same from one L1 run to the next.  svm_set_cr0 and other functions
called by nested_svm_vmexit already take care of clearing the
corresponding clean bits; only the TSC offset is special.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/svm/nested.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index f88d0614d9b8..4fc742ba1f1f 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -698,8 +698,11 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
 	svm_set_gif(svm, false);
 	svm->vmcb->control.exit_int_info = 0;
 
-	svm->vmcb->control.tsc_offset = svm->vcpu.arch.tsc_offset =
-		svm->vcpu.arch.l1_tsc_offset;
+	svm->vcpu.arch.tsc_offset = svm->vcpu.arch.l1_tsc_offset;
+	if (svm->vmcb->control.tsc_offset != svm->vcpu.arch.tsc_offset) {
+		svm->vmcb->control.tsc_offset = svm->vcpu.arch.tsc_offset;
+		vmcb_mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
+	}
 
 	svm->nested.ctl.nested_cr3 = 0;
 
@@ -717,8 +720,6 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
 	svm->vcpu.arch.dr7 = DR7_FIXED_1;
 	kvm_update_dr7(&svm->vcpu);
 
-	vmcb_mark_all_dirty(svm->vmcb);
-
 	trace_kvm_nested_vmexit_inject(vmcb12->control.exit_code,
 				       vmcb12->control.exit_info_1,
 				       vmcb12->control.exit_info_2,
-- 
2.26.2