linux-kernel - [RFC PATCH 08/13] KVM: nSVM: Flush both L1 and L2 ASIDs on KVM_REQ_TLB

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Message-ID: <20250205182402.2147495-9-yosry.ahmed@linux.dev>
Date: Wed,  5 Feb 2025 18:23:57 +0000
From: Yosry Ahmed <yosry.ahmed@...ux.dev>
To: Sean Christopherson <seanjc@...gle.com>,
	Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [RFC PATCH 08/13] KVM: nSVM: Flush both L1 and L2 ASIDs on KVM_REQ_TLB_FLUSH

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 <yosry.ahmed@...ux.dev>
---
 arch/x86/kvm/svm/nested.c | 1 -
 arch/x86/kvm/svm/svm.c    | 4 +++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 0e9b0592c1f83..0735177b95a1d 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 9e29f87d3bd93..8342c7eadbba8 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4044,7 +4044,9 @@ 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);
 
-	svm_flush_tlb_asid(vcpu, svm->current_vmcb);
+	svm_flush_tlb_asid(vcpu, &svm->vmcb01);
+	if (svm->nested.initialized)
+		svm_flush_tlb_asid(vcpu, &svm->nested.vmcb02);
 }
 
 static void svm_flush_tlb_gva(struct kvm_vcpu *vcpu, gva_t gva)
-- 
2.48.1.362.g079036d154-goog