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From: Yosry Ahmed <yosry@kernel.org>
To: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Jim Mattson <jmattson@google.com>,
	Maxim Levitsky <mlevitsk@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Yosry Ahmed <yosry@kernel.org>,
	stable@vger.kernel.org
Subject: [PATCH v3 01/27] KVM: nSVM: Flush the TLB after forcefully leaving nested
Date: Mon, 12 Oct 2026 23:36:12 +0000	[thread overview]
Message-ID: <20261012233638.2546339-2-yosry@kernel.org> (raw)
In-Reply-To: <20261012233638.2546339-1-yosry@kernel.org>

KVM flushes the TLB on nested VM-Enter and nested VM-Exit, but not when
forcefully leaving nested. In this case, L2 TLB entries can leak into
L1. Flush the TLB after forcefully exiting L2, similar to nested
VM-Exits.

Note that vmx_leave_nested() handles this correctly, as it reuses
nested_vmx_vmexit(), which handles the necessary TLB flushes on an L2 ->
L1 transition.

Cc: stable@vger.kernel.org
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
---
 arch/x86/kvm/svm/nested.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index af0ef678433d7..2bfc9d2c341b1 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -1558,6 +1558,8 @@ void svm_leave_nested(struct kvm_vcpu *vcpu)
 
 		svm_switch_vmcb(svm, &svm->vmcb01);
 
+		nested_svm_transition_tlb_flush(vcpu);
+
 		nested_svm_uninit_mmu_context(vcpu);
 		vmcb_mark_all_dirty(svm->vmcb);
 
-- 
2.56.0.385.gd3acb90ef8-goog


  reply	other threads:[~2026-10-12 23:36 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-12 23:36 [PATCH v3 00/27] KVM: nSVM: Optimize nSVM TLB flushes Yosry Ahmed
2026-10-12 23:36 ` Yosry Ahmed [this message]
2026-10-12 23:36 ` [PATCH v3 02/27] KVM: SVM: Document number of ASIDs CPUID setting Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 03/27] KVM: VMX: Generalize VPID allocation to be vendor-neutral Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 04/27] KVM: x86/mmu: Support specifying reserved TLB tags Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 05/27] KVM: SVM: Add helpers to set/clear ASID flush in VMCB Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 06/27] KVM: SVM: Fallback to flush everything if FLUSHBYASID is not available Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 07/27] KVM: SEV: Do ASID initialization at VMCB initialization Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 08/27] KVM: SEV: Expose sev_get_asid() outside of sev.c Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 09/27] KVM: SEV: Explicitly initialize the per vCPU ASID on SEV VM migration Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 10/27] KVM: SVM: Use a static ASID per vCPU Yosry Ahmed
2026-10-12 23:54   ` sashiko-bot
2026-10-12 23:55     ` Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 11/27] KVM: SVM: Only flush the fallback ASID when used by a different vCPU Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 12/27] KVM: nSVM: Drop svm->nested.initialized Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 13/27] KVM: nSVM: Add a placeholder ASID for L2 Yosry Ahmed
2026-10-13  0:01   ` sashiko-bot
2026-10-12 23:36 ` [PATCH v3 14/27] KVM: x86: hyper-v: Rename kvm_hv_vcpu_purge_flush_tlb() Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 15/27] KVM: x86: hyper-v: Allow purging all TLB flush FIFOs Yosry Ahmed
2026-10-12 23:56   ` sashiko-bot
2026-10-12 23:36 ` [PATCH v3 16/27] KVM: nSVM: Flush both L1 and L2 ASIDs on KVM_REQ_TLB_FLUSH Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 17/27] KVM: nSVM: Always switch VMCB before leaving guest mode Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 18/27] KVM: nSVM: Split nested_svm_transition_tlb_flush() into entry/exit fns Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 19/27] KVM: nSVM: Service local TLB flushes before nested transitions Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 20/27] KVM: x86: Add KVM_REQ_MMU_SYNC_ALL_ROOTS Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 21/27] KVM: nSVM: Handle nested TLB flush requests through TLB_CONTROL Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 22/27] KVM: nSVM: Flush the TLB if L1 changes L2's ASID in vmcb12 Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 23/27] KVM: nSVM: Do not reset TLB_CONTROL in vmcb02 on nested VM-Enter Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 24/27] KVM: nSVM: Flush L2's ASID when emulating INVLPGA Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 25/27] KVM: nSVM: Flush the ASID on nested transitions if shared by L1 and L2 Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 26/27] KVM: nSVM: Use different ASIDs for " Yosry Ahmed
2026-10-12 23:36 ` [PATCH v3 27/27] KVM: selftests: Add a test for nested TLB flushes Yosry Ahmed

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