[4/4] KVM: SVM: Enhance and clean up the vmcb tracking comment in pre_svm_run()
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Message ID 20210406171811.4043363-5-seanjc@google.com
State Accepted
Commit 44f1b5586df03b044704f3c57f529ea4120f406b
Headers show
  • KVM: SVM: A fix and cleanups for vmcb tracking
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Commit Message

Sean Christopherson April 6, 2021, 5:18 p.m. UTC
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(-)

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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;