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 4/4] KVM: SVM: Enhance and clean up the vmcb tracking comment in pre_svm_run()
Date: Tue, 6 Apr 2021 10:18:11 -0700 [thread overview]
Message-ID: <20210406171811.4043363-5-seanjc@google.com> (raw)
In-Reply-To: <20210406171811.4043363-1-seanjc@google.com>
Explicitly document why a vmcb must be marked dirty and assigned a new
asid when it will be run on a different cpu. The "what" is relatively
obvious, whereas the "why" requires reading the APM and/or KVM code.
Opportunistically remove a spurious period and several unnecessary
newlines in the comment.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/svm/svm.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index f62c56adf7c9..afc275ba5d59 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3336,11 +3336,10 @@ static void pre_svm_run(struct kvm_vcpu *vcpu)
struct vcpu_svm *svm = to_svm(vcpu);
/*
- * If the previous vmrun of the vmcb occurred on
- * a different physical cpu then we must mark the vmcb dirty.
- * and assign a new asid.
- */
-
+ * If the previous vmrun of the vmcb occurred on a different physical
+ * cpu, then mark the vmcb dirty and assign a new asid. Hardware's
+ * vmcb clean bits are per logical CPU, as are KVM's asid assignments.
+ */
if (unlikely(svm->current_vmcb->cpu != vcpu->cpu)) {
svm->current_vmcb->asid_generation = 0;
vmcb_mark_all_dirty(svm->vmcb);
--
2.31.0.208.g409f899ff0-goog
next prev 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 ` [PATCH 2/4] KVM: SVM: Drop vcpu_svm.vmcb_pa Sean Christopherson
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 ` Sean Christopherson [this message]
2021-04-17 12:50 ` [PATCH 0/4] KVM: SVM: A fix and cleanups for vmcb tracking Paolo Bonzini
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