[RFC PATCH 04/13] KVM: arm64: Implement vLPI QUERY ioctl for per-vCPU vLPI injection API

[Maximilian Dittgen <mdittgen@amazon.de>]

Implement kvm_vgic_query_vcpu_vlpi, which handles the KVM_QUERY_VCPU_VLPI
ioctl to query whether a vCPU is currently initialized to handle LPIs via
direct vLPI injection. This function checks whether the vCPU's entry in
the VM's vPE array is populated.

Signed-off-by: Maximilian Dittgen <mdittgen@amazon.com>
---
 arch/arm64/kvm/arm.c          | 13 +++++++++++--
 arch/arm64/kvm/vgic/vgic-v4.c | 15 +++++++++++++++
 arch/arm64/kvm/vgic/vgic.h    |  1 +
 include/linux/kvm_host.h      | 11 +++++++++++
 4 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 31db3ccb3296..afb04162e0cf 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1959,8 +1959,17 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
 		return -ENOSYS;
 	}
 	case KVM_QUERY_VCPU_VLPI: {
-		/* TODO: create ioctl handler function */
-		return -ENOSYS;
+		int vcpu_id;
+		struct kvm_vcpu *vcpu;
+
+		if (copy_from_user(&vcpu_id, argp, sizeof(vcpu_id)))
+			return -EFAULT;
+
+		vcpu = kvm_get_vcpu_by_id(kvm, vcpu_id);
+		if (!vcpu)
+			return -EINVAL;
+
+		return kvm_vgic_query_vcpu_vlpi(vcpu);
 	}
 	default:
 		return -EINVAL;
diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c
index 4a1825a1a5d7..cebcb9175572 100644
--- a/arch/arm64/kvm/vgic/vgic-v4.c
+++ b/arch/arm64/kvm/vgic/vgic-v4.c
@@ -617,3 +617,18 @@ void kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int host_irq)
 	raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
 	vgic_put_irq(kvm, irq);
 }
+
+/* query whether vLPI direct injection is enabled on a specific vCPU.
+ * return 0 if disabled, 1 if enabled, -EINVAL if vCPU non-existant or GIC
+ * uninitialized
+ */
+int kvm_vgic_query_vcpu_vlpi(struct kvm_vcpu *vcpu)
+{
+	struct kvm *kvm = vcpu->kvm;
+	struct vgic_dist *dist = &kvm->arch.vgic;
+	int i = kvm_idx_from_vcpu(kvm, vcpu);
+
+	if (i == UINT_MAX || !dist->its_vm.vpes)
+		return -EINVAL; /* vCPU non-existant or uninitialized */
+	return dist->its_vm.vpes[i] != NULL;
+}
diff --git a/arch/arm64/kvm/vgic/vgic.h b/arch/arm64/kvm/vgic/vgic.h
index 99894806a4e9..295088913c26 100644
--- a/arch/arm64/kvm/vgic/vgic.h
+++ b/arch/arm64/kvm/vgic/vgic.h
@@ -468,5 +468,6 @@ int vgic_its_debug_init(struct kvm_device *dev);
 void vgic_its_debug_destroy(struct kvm_device *dev);
 
 bool kvm_per_vcpu_vlpi_supported(void);
+int kvm_vgic_query_vcpu_vlpi(struct kvm_vcpu *vcpu);
 
 #endif
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 5bd76cf394fa..bc7001f8c5dd 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1030,6 +1030,17 @@ static inline struct kvm_vcpu *kvm_get_vcpu_by_id(struct kvm *kvm, int id)
 	return NULL;
 }
 
+static inline unsigned int kvm_idx_from_vcpu(struct kvm *kvm, struct kvm_vcpu *target_vcpu)
+{
+	struct kvm_vcpu *vcpu;
+	unsigned long i;
+
+	kvm_for_each_vcpu(i, vcpu, kvm)
+		if (vcpu == target_vcpu)
+			return i;
+	return UINT_MAX;
+}
+
 void kvm_destroy_vcpus(struct kvm *kvm);
 
 int kvm_trylock_all_vcpus(struct kvm *kvm);
-- 
2.50.1 (Apple Git-155)




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