diff mbox series

[46/67] iommu/amd: KVM: SVM: Set pCPU info in IRTE when setting vCPU affinity

Message ID 20250404193923.1413163-47-seanjc@google.com (mailing list archive)
State New
Headers show
Series KVM: iommu: Overhaul device posted IRQs support | expand

Commit Message

Sean Christopherson April 4, 2025, 7:39 p.m. UTC 
Now that setting vCPU affinity is guarded with ir_list_lock, i.e. now that
avic_physical_id_entry can be safely accessed, set the pCPU info
straight-away when setting vCPU affinity.  Putting the IRTE into posted
mode, and then immediately updating the IRTE a second time if the target
vCPU is running is wasteful and confusing.

This also fixes a flaw where a posted IRQ that arrives between putting
the IRTE into guest_mode and setting the correct destination could cause
the IOMMU to ring the doorbell on the wrong pCPU.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/include/asm/irq_remapping.h |  1 +
 arch/x86/kvm/svm/avic.c              | 26 ++++++++++++++------------
 drivers/iommu/amd/iommu.c            |  6 ++++--
 include/linux/amd-iommu.h            |  4 ++--
 4 files changed, 21 insertions(+), 16 deletions(-)
diff mbox series

Patch

diff --git a/arch/x86/include/asm/irq_remapping.h b/arch/x86/include/asm/irq_remapping.h
index 2dbc9cb61c2f..4c75a17632f6 100644
--- a/arch/x86/include/asm/irq_remapping.h
+++ b/arch/x86/include/asm/irq_remapping.h
@@ -35,6 +35,7 @@  struct amd_iommu_pi_data {
 	u64 vapic_addr;		/* Physical address of the vCPU's vAPIC. */
 	u32 ga_tag;
 	u32 vector;		/* Guest vector of the interrupt */
+	int cpu;
 	bool is_guest_mode;
 	void *ir_data;
 };
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 3fcec297e3e3..086139e85242 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -735,6 +735,7 @@  void avic_apicv_post_state_restore(struct kvm_vcpu *vcpu)
 
 static int avic_set_pi_irte_mode(struct kvm_vcpu *vcpu, bool activate)
 {
+	int apic_id = kvm_cpu_get_apicid(vcpu->cpu);
 	int ret = 0;
 	unsigned long flags;
 	struct amd_svm_iommu_ir *ir;
@@ -754,7 +755,7 @@  static int avic_set_pi_irte_mode(struct kvm_vcpu *vcpu, bool activate)
 
 	list_for_each_entry(ir, &svm->ir_list, node) {
 		if (activate)
-			ret = amd_iommu_activate_guest_mode(ir->data);
+			ret = amd_iommu_activate_guest_mode(ir->data, apic_id);
 		else
 			ret = amd_iommu_deactivate_guest_mode(ir->data);
 		if (ret)
@@ -819,6 +820,18 @@  int avic_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm,
 		 */
 		guard(spinlock_irqsave)(&svm->ir_list_lock);
 
+		/*
+		 * Update the target pCPU for IOMMU doorbells if the vCPU is
+		 * running.  If the vCPU is NOT running, i.e. is blocking or
+		 * scheduled out, KVM will update the pCPU info when the vCPU
+		 * is awakened and/or scheduled in.  See also avic_vcpu_load().
+		 */
+		entry = svm->avic_physical_id_entry;
+		if (entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK)
+			pi_data.cpu = entry & AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK;
+		else
+			pi_data.cpu = -1;
+
 		ret = irq_set_vcpu_affinity(host_irq, &pi_data);
 		if (ret)
 			return ret;
@@ -833,17 +846,6 @@  int avic_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm,
 			return -EIO;
 		}
 
-		/*
-		 * Update the target pCPU for IOMMU doorbells if the vCPU is
-		 * running.  If the vCPU is NOT running, i.e. is blocking or
-		 * scheduled out, KVM will update the pCPU info when the vCPU
-		 * is awakened and/or scheduled in.  See also avic_vcpu_load().
-		 */
-		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,
-					    pi_data.ir_data);
-
 		irqfd->irq_bypass_data = pi_data.ir_data;
 		list_add(&irqfd->vcpu_list, &svm->ir_list);
 		return 0;
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 4fdf1502be69..b0b4c5ca16a8 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3807,7 +3807,7 @@  int amd_iommu_update_ga(int cpu, void *data)
 }
 EXPORT_SYMBOL(amd_iommu_update_ga);
 
-int amd_iommu_activate_guest_mode(void *data)
+int amd_iommu_activate_guest_mode(void *data, int cpu)
 {
 	struct amd_ir_data *ir_data = (struct amd_ir_data *)data;
 	struct irte_ga *entry = (struct irte_ga *) ir_data->entry;
@@ -3828,6 +3828,8 @@  int amd_iommu_activate_guest_mode(void *data)
 	entry->hi.fields.vector            = ir_data->ga_vector;
 	entry->lo.fields_vapic.ga_tag      = ir_data->ga_tag;
 
+	__amd_iommu_update_ga(entry, cpu);
+
 	return modify_irte_ga(ir_data->iommu, ir_data->irq_2_irte.devid,
 			      ir_data->irq_2_irte.index, entry);
 }
@@ -3894,7 +3896,7 @@  static int amd_ir_set_vcpu_affinity(struct irq_data *data, void *info)
 		ir_data->ga_root_ptr = (pi_data->vapic_addr >> 12);
 		ir_data->ga_vector = pi_data->vector;
 		ir_data->ga_tag = pi_data->ga_tag;
-		ret = amd_iommu_activate_guest_mode(ir_data);
+		ret = amd_iommu_activate_guest_mode(ir_data, pi_data->cpu);
 	} else {
 		ret = amd_iommu_deactivate_guest_mode(ir_data);
 	}
diff --git a/include/linux/amd-iommu.h b/include/linux/amd-iommu.h
index fe0e16ffe0e5..c9f2df0c4596 100644
--- a/include/linux/amd-iommu.h
+++ b/include/linux/amd-iommu.h
@@ -32,7 +32,7 @@  extern int amd_iommu_register_ga_log_notifier(int (*notifier)(u32));
 
 extern int amd_iommu_update_ga(int cpu, void *data);
 
-extern int amd_iommu_activate_guest_mode(void *data);
+extern int amd_iommu_activate_guest_mode(void *data, int cpu);
 extern int amd_iommu_deactivate_guest_mode(void *data);
 
 #else /* defined(CONFIG_AMD_IOMMU) && defined(CONFIG_IRQ_REMAP) */
@@ -48,7 +48,7 @@  static inline int amd_iommu_update_ga(int cpu, void *data)
 	return 0;
 }
 
-static inline int amd_iommu_activate_guest_mode(void *data)
+static inline int amd_iommu_activate_guest_mode(void *data, int cpu)
 {
 	return 0;
 }