Commit 4a41e43c authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: SVM: Document the ASID logic in svm_flush_tlb() 



Add a comment in svm_flush_tlb() to document why it flushes only the
current ASID, even when it is invoked when flushing remote TLBs.

Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200320212833.3507-22-sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 33d19ec9

arch/x86/kvm/svm/svm.c

+7 −0
Original line number Diff line number Diff line
@@ -3157,6 +3157,13 @@ void svm_flush_tlb(struct kvm_vcpu *vcpu) 
{

	struct vcpu_svm *svm = to_svm(vcpu);



	/*

	 * Flush only the current ASID even if the TLB flush was invoked via

	 * kvm_flush_remote_tlbs().  Although flushing remote TLBs requires all

	 * ASIDs to be flushed, KVM uses a single ASID for L1 and L2, and

	 * unconditionally does a TLB flush on both nested VM-Enter and nested

	 * VM-Exit (via kvm_mmu_reset_context()).

	 */

	if (static_cpu_has(X86_FEATURE_FLUSHBYASID))

		svm->vmcb->control.tlb_ctl = TLB_CONTROL_FLUSH_ASID;

	else