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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>
Subject: [PATCH v1 07/28] KVM: SVM: Duplicate pre-run ASID check for SEV and non-SEV guests
Date: Tue, 28 Jul 2026 00:35:36 +0000	[thread overview]
Message-ID: <20260728003557.1136583-8-yosry@kernel.org> (raw)
In-Reply-To: <20260728003557.1136583-1-yosry@kernel.org>

In preparation for dropping the check separately for SEV and non-SEV
VMs, duplicate the check between pre_sev_run() and pre_svm_run() (for
the non-SEV code path).

Opportunistically drop the unconditional dirtying of VMCB_ASID, as it's
only needed when the ASID is actually updated in the VMCB, not when
TLB_CONTROL is updated (as the code currently reads).

No functional change intended.

Signed-off-by: Yosry Ahmed <yosry@kernel.org>
---
 arch/x86/kvm/svm/sev.c | 6 +++++-
 arch/x86/kvm/svm/svm.c | 9 +++++----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index d1f0e42c72b27..0e5046a12a970 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3583,6 +3583,11 @@ int pre_sev_run(struct vcpu_svm *svm, int cpu)
 	/* Assign the asid allocated with this SEV guest */
 	svm->asid = asid;
 
+	if (unlikely(svm->asid != svm->vmcb->control.asid)) {
+		svm->vmcb->control.asid = asid;
+		vmcb_mark_dirty(svm->vmcb, VMCB_ASID);
+	}
+
 	/*
 	 * Flush guest TLB:
 	 *
@@ -3595,7 +3600,6 @@ int pre_sev_run(struct vcpu_svm *svm, int cpu)
 
 	sd->sev_vmcbs[asid] = svm->vmcb;
 	vmcb_set_flush_asid(svm->vmcb);
-	vmcb_mark_dirty(svm->vmcb, VMCB_ASID);
 	return 0;
 }
 
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index aff1aae5a5a32..b8f3f71f70673 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3779,6 +3779,11 @@ static int pre_svm_run(struct kvm_vcpu *vcpu)
 	if (svm->current_vmcb->asid_generation != sd->asid_generation)
 		new_asid(svm, sd);
 
+	if (unlikely(svm->asid != svm->vmcb->control.asid)) {
+		svm->vmcb->control.asid = svm->asid;
+		vmcb_mark_dirty(svm->vmcb, VMCB_ASID);
+	}
+
 	return 0;
 }
 
@@ -4515,10 +4520,6 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu, u64 run_flags)
 
 	sync_lapic_to_cr8(vcpu);
 
-	if (unlikely(svm->asid != svm->vmcb->control.asid)) {
-		svm->vmcb->control.asid = svm->asid;
-		vmcb_mark_dirty(svm->vmcb, VMCB_ASID);
-	}
 	svm->vmcb->save.cr2 = vcpu->arch.cr2;
 
 	if (guest_cpu_cap_has(vcpu, X86_FEATURE_ERAPS) &&
-- 
2.55.0.229.g6434b31f56-goog


  parent reply	other threads:[~2026-07-28  0:36 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-28  0:35 [PATCH v1 00/28] KVM: nSVM: Optimize nSVM TLB flushes Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 01/28] KVM: nSVM: Flush the TLB after forcefully leaving nested Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 02/28] KVM: SVM: Document number of ASIDs CPUID setting Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 03/28] KVM: VMX: Generalize VPID allocation to be vendor-neutral Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 04/28] KVM: x86/mmu: Support specifying reserved TLB tags Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 05/28] KVM: SVM: Add helpers to set/clear ASID flush in VMCB Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 06/28] KVM: SVM: Fallback to flush everything if FLUSHBYASID is not available Yosry Ahmed
2026-07-28  0:35 ` Yosry Ahmed [this message]
2026-07-28  0:35 ` [PATCH v1 08/28] KVM: SEV: Do ASID initialization at VMCB initialization Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 09/28] KVM: SEV: Expose sev_get_asid() outside of sev.c Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 10/28] KVM: SVM: Use a static ASID per vCPU Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 11/28] KVM: SVM: Only flush the fallback ASID when used by a different vCPU Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 12/28] KVM: nSVM: Add a placeholder ASID for L2 Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 13/28] KVM: x86: hyper-v: Rename kvm_hv_vcpu_purge_flush_tlb() Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 14/28] KVM: x86: hyper-v: Allow puring all TLB flush FIFOs Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 15/28] KVM: nSVM: Drop svm->nested.initialized Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 16/28] KVM: nSVM: Flush both L1 and L2 ASIDs on KVM_REQ_TLB_FLUSH Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 17/28] KVM: nSVM: Always switch VMCB before leaving guest mode Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 18/28] KVM: nSVM: Split nested_svm_transition_tlb_flush() into entry/exit fns Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 19/28] KVM: nSVM: Service local TLB flushes before nested transitions Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 20/28] KVM: nSVM: Handle nested TLB flush requests through TLB_CONTROL Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 21/28] KVM: nSVM: Flush the TLB if L1 changes L2's ASID in vmcb12 Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 22/28] KVM: nSVM: Do not reset TLB_CONTROL in vmcb02 on nested VM-Enter Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 23/28] KVM: x86/mmu: Rename __kvm_mmu_invalidate_addr() to kvm_mmu_sync_addr() Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 24/28] KVM: x86/mmu: Refactor kvm_mmu_invlpg() to allow skipping the GVA flush Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 25/28] KVM: nSVM: Flush L2's ASID when emulating INVLPGA Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 26/28] KVM: nSVM: Flush the ASID on nested transitions if shared by L1 and L2 Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 27/28] KVM: nSVM: Use different ASIDs for " Yosry Ahmed
2026-07-28  0:35 ` [PATCH v1 28/28] KVM: selftests: Add a test for nested TLB flushes Yosry Ahmed
2026-07-28  1:05 ` [PATCH v1 00/28] KVM: nSVM: Optimize nSVM " Yosry Ahmed
2026-07-28  1:18   ` Sean Christopherson

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