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From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Cathy Avery <cavery@redhat.com>,
	Maxim Levitsky <mlevitsk@redhat.com>
Subject: [PATCH 2/4] KVM: SVM: Drop vcpu_svm.vmcb_pa
Date: Tue,  6 Apr 2021 10:18:09 -0700	[thread overview]
Message-ID: <20210406171811.4043363-3-seanjc@google.com> (raw)
In-Reply-To: <20210406171811.4043363-1-seanjc@google.com>

Remove vmcb_pa from vcpu_svm and simply read current_vmcb->pa directly in
the one path where it is consumed.  Unlike svm->vmcb, use of the current
vmcb's address is very limited, as evidenced by the fact that its use
can be trimmed to a single dereference.

Opportunistically add a comment about using vmcb01 for VMLOAD/VMSAVE, at
first glance using vmcb01 instead of vmcb_pa looks wrong.

No functional change intended.

Cc: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/svm/svm.c | 12 +++++++++---
 arch/x86/kvm/svm/svm.h |  1 -
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 89619cc52cf4..f62c56adf7c9 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1310,7 +1310,6 @@ void svm_switch_vmcb(struct vcpu_svm *svm, struct kvm_vmcb_info *target_vmcb)
 {
 	svm->current_vmcb = target_vmcb;
 	svm->vmcb = target_vmcb->ptr;
-	svm->vmcb_pa = target_vmcb->pa;
 }
 
 static int svm_create_vcpu(struct kvm_vcpu *vcpu)
@@ -3704,6 +3703,7 @@ static fastpath_t svm_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
 static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
+	unsigned long vmcb_pa = svm->current_vmcb->pa;
 
 	/*
 	 * VMENTER enables interrupts (host state), but the kernel state is
@@ -3726,12 +3726,18 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu)
 	lockdep_hardirqs_on(CALLER_ADDR0);
 
 	if (sev_es_guest(vcpu->kvm)) {
-		__svm_sev_es_vcpu_run(svm->vmcb_pa);
+		__svm_sev_es_vcpu_run(vmcb_pa);
 	} else {
 		struct svm_cpu_data *sd = per_cpu(svm_data, vcpu->cpu);
 
+		/*
+		 * Use a single vmcb (vmcb01 because it's always valid) for
+		 * context switching guest state via VMLOAD/VMSAVE, that way
+		 * the state doesn't need to be copied between vmcb01 and
+		 * vmcb02 when switching vmcbs for nested virtualization.
+		 */
 		vmload(svm->vmcb01.pa);
-		__svm_vcpu_run(svm->vmcb_pa, (unsigned long *)&vcpu->arch.regs);
+		__svm_vcpu_run(vmcb_pa, (unsigned long *)&vcpu->arch.regs);
 		vmsave(svm->vmcb01.pa);
 
 		vmload(__sme_page_pa(sd->save_area));
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 02f8ece8c741..2173fe985104 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -112,7 +112,6 @@ struct svm_nested_state {
 struct vcpu_svm {
 	struct kvm_vcpu vcpu;
 	struct vmcb *vmcb;
-	unsigned long vmcb_pa;
 	struct kvm_vmcb_info vmcb01;
 	struct kvm_vmcb_info *current_vmcb;
 	struct svm_cpu_data *svm_data;
-- 
2.31.0.208.g409f899ff0-goog


  parent reply	other threads:[~2021-04-06 17:18 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-06 17:18 [PATCH 0/4] KVM: SVM: A fix and cleanups for vmcb tracking Sean Christopherson
2021-04-06 17:18 ` [PATCH 1/4] KVM: SVM: Don't set current_vmcb->cpu when switching vmcb Sean Christopherson
2021-04-06 17:18 ` Sean Christopherson [this message]
2021-04-06 17:18 ` [PATCH 3/4] KVM: SVM: Add a comment to clarify what vcpu_svm.vmcb points at Sean Christopherson
2021-04-06 17:18 ` [PATCH 4/4] KVM: SVM: Enhance and clean up the vmcb tracking comment in pre_svm_run() Sean Christopherson
2021-04-17 12:50 ` [PATCH 0/4] KVM: SVM: A fix and cleanups for vmcb tracking Paolo Bonzini

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