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@xxxxxxx>
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
arch/x86/kvm/svm.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index dfa3b53f8437..8c3700b44eb4 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5630,6 +5630,13 @@ static 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
--
2.24.1
