linux-kernel - [PATCH 44/67] iommu/amd: KVM: SVM: Infer IsRun from validity of pCPU destination

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Message-ID: <20250404193923.1413163-45-seanjc@google.com>
Date: Fri,  4 Apr 2025 12:38:59 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	Joerg Roedel <joro@...tes.org>, David Woodhouse <dwmw2@...radead.org>, 
	Lu Baolu <baolu.lu@...ux.intel.com>
Cc: kvm@...r.kernel.org, iommu@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	Maxim Levitsky <mlevitsk@...hat.com>, Joao Martins <joao.m.martins@...cle.com>, 
	David Matlack <dmatlack@...gle.com>
Subject: [PATCH 44/67] iommu/amd: KVM: SVM: Infer IsRun from validity of pCPU destination

Infer whether or not a vCPU should be marked running from the validity of
the pCPU on which it is running.  amd_iommu_update_ga() already skips the
IRTE update if the pCPU is invalid, i.e. passing %true for is_run with an
invalid pCPU would be a blatant and egregrious KVM bug.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/avic.c   | 11 +++++------
 drivers/iommu/amd/iommu.c |  6 ++++--
 include/linux/amd-iommu.h |  6 ++----
 3 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 4dbbb5a6cacc..3fcec297e3e3 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -842,7 +842,7 @@ int avic_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm,
 		entry = svm->avic_physical_id_entry;
 		if (entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK)
 			amd_iommu_update_ga(entry & AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK,
-					    true, pi_data.ir_data);
+					    pi_data.ir_data);
 
 		irqfd->irq_bypass_data = pi_data.ir_data;
 		list_add(&irqfd->vcpu_list, &svm->ir_list);
@@ -851,8 +851,7 @@ int avic_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm,
 	return irq_set_vcpu_affinity(host_irq, NULL);
 }
 
-static inline int
-avic_update_iommu_vcpu_affinity(struct kvm_vcpu *vcpu, int cpu, bool r)
+static inline int avic_update_iommu_vcpu_affinity(struct kvm_vcpu *vcpu, int cpu)
 {
 	int ret = 0;
 	struct amd_svm_iommu_ir *ir;
@@ -871,7 +870,7 @@ avic_update_iommu_vcpu_affinity(struct kvm_vcpu *vcpu, int cpu, bool r)
 		return 0;
 
 	list_for_each_entry(ir, &svm->ir_list, node) {
-		ret = amd_iommu_update_ga(cpu, r, ir->data);
+		ret = amd_iommu_update_ga(cpu, ir->data);
 		if (ret)
 			return ret;
 	}
@@ -933,7 +932,7 @@ void avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 
 	WRITE_ONCE(kvm_svm->avic_physical_id_table[vcpu->vcpu_id], entry);
 
-	avic_update_iommu_vcpu_affinity(vcpu, h_physical_id, true);
+	avic_update_iommu_vcpu_affinity(vcpu, h_physical_id);
 
 	spin_unlock_irqrestore(&svm->ir_list_lock, flags);
 }
@@ -973,7 +972,7 @@ void avic_vcpu_put(struct kvm_vcpu *vcpu)
 	 */
 	spin_lock_irqsave(&svm->ir_list_lock, flags);
 
-	avic_update_iommu_vcpu_affinity(vcpu, -1, 0);
+	avic_update_iommu_vcpu_affinity(vcpu, -1);
 
 	entry &= ~AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK;
 	svm->avic_physical_id_entry = entry;
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index bc6f7eb2f04b..ba3a1a403cb2 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3957,7 +3957,7 @@ int amd_iommu_create_irq_domain(struct amd_iommu *iommu)
 	return 0;
 }
 
-int amd_iommu_update_ga(int cpu, bool is_run, void *data)
+int amd_iommu_update_ga(int cpu, void *data)
 {
 	struct amd_ir_data *ir_data = (struct amd_ir_data *)data;
 	struct irte_ga *entry = (struct irte_ga *) ir_data->entry;
@@ -3974,8 +3974,10 @@ int amd_iommu_update_ga(int cpu, bool is_run, void *data)
 					APICID_TO_IRTE_DEST_LO(cpu);
 		entry->hi.fields.destination =
 					APICID_TO_IRTE_DEST_HI(cpu);
+		entry->lo.fields_vapic.is_run = true;
+	} else {
+		entry->lo.fields_vapic.is_run = false;
 	}
-	entry->lo.fields_vapic.is_run = is_run;
 
 	return __modify_irte_ga(ir_data->iommu, ir_data->irq_2_irte.devid,
 				ir_data->irq_2_irte.index, entry);
diff --git a/include/linux/amd-iommu.h b/include/linux/amd-iommu.h
index 99b4fa9a0296..fe0e16ffe0e5 100644
--- a/include/linux/amd-iommu.h
+++ b/include/linux/amd-iommu.h
@@ -30,8 +30,7 @@ static inline void amd_iommu_detect(void) { }
 /* IOMMU AVIC Function */
 extern int amd_iommu_register_ga_log_notifier(int (*notifier)(u32));
 
-extern int
-amd_iommu_update_ga(int cpu, bool is_run, void *data);
+extern int amd_iommu_update_ga(int cpu, void *data);
 
 extern int amd_iommu_activate_guest_mode(void *data);
 extern int amd_iommu_deactivate_guest_mode(void *data);
@@ -44,8 +43,7 @@ amd_iommu_register_ga_log_notifier(int (*notifier)(u32))
 	return 0;
 }
 
-static inline int
-amd_iommu_update_ga(int cpu, bool is_run, void *data)
+static inline int amd_iommu_update_ga(int cpu, void *data)
 {
 	return 0;
 }
-- 
2.49.0.504.g3bcea36a83-goog