[RFC,17/24] KVM: nSVM: Flush both L1 and L2 ASIDs on KVM_REQ_TLB_FLUSH

Commit Message

Yosry Ahmed March 26, 2025, 7:36 p.m. UTC

KVM_REQ_TLB_FLUSH is used to flush all TLB entries for all contexts
(e.g. in kvm_flush_remote_tlbs()). Flush both L1 and L2 ASIDs in
svm_flush_tlb_all() to handle it appropriately.

This is currently not required as nested transitions do unconditional
TLB flushes, but this is a step toward eliminating that.

Signed-off-by: Yosry Ahmed <[e-mail]>
---
 arch/x86/kvm/svm/nested.c |  1 -
 arch/x86/kvm/svm/svm.c    | 10 ++--------
 2 files changed, 2 insertions(+), 9 deletions(-)

Patch

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index c336ab63c6da3..56a4ff480bb3d 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -491,7 +491,6 @@  static void nested_svm_entry_tlb_flush(struct kvm_vcpu *vcpu)
 	 * TODO: optimize unconditional TLB flush/MMU sync.  A partial list of
 	 * things to fix before this can be conditional:
 	 *
-	 *  - Flush TLBs for both L1 and L2 remote TLB flush
 	 *  - Honor L1's request to flush an ASID on nested VMRUN
 	 *  - Sync nested NPT MMU on VMRUN that flushes L2's ASID[*]
 	 *  - Don't crush a pending TLB flush in vmcb02 on nested VMRUN
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index fb6b9f88a1504..4cad1085936bb 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4064,14 +4064,8 @@  static void svm_flush_tlb_all(struct kvm_vcpu *vcpu)
 	if (WARN_ON_ONCE(svm_hv_is_enlightened_tlb_enabled(vcpu)))
 		hv_flush_remote_tlbs(vcpu->kvm);
 
-	/*
-	 * 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()).
-	 */
-	svm_flush_tlb_asid(vcpu, is_guest_mode(vcpu));
+	svm_flush_tlb_asid(vcpu, false);
+	svm_flush_tlb_asid(vcpu, true);
 }
 
 static void svm_flush_tlb_gva(struct kvm_vcpu *vcpu, gva_t gva)