KVM: arm64: vgic-v3: Consolidate MAINT_IRQ handling

Consolidate the duplicated handling of the VGICv3 maintenance IRQ
attribute as a regular GICv3 attribute, as it is neither a register nor
a common attribute. As this is now handled separately from the VGIC
registers, the locking is relaxed to only acquire the intended
config_lock.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250724062805.2658919-3-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

1 files changed, 25 insertions, 26 deletions

diff --git a/arch/arm64/kvm/vgic/vgic-kvm-device.c b/arch/arm64/kvm/vgic/vgic-kvm-device.c
index f9ae790163fb..00c011cc8627 100644
--- a/arch/arm64/kvm/vgic/vgic-kvm-device.c
+++ b/arch/arm64/kvm/vgic/vgic-kvm-device.c
@@ -303,12 +303,6 @@ static int vgic_get_common_attr(struct kvm_device *dev,
 			     VGIC_NR_PRIVATE_IRQS, uaddr);
 		break;
 	}
-	case KVM_DEV_ARM_VGIC_GRP_MAINT_IRQ: {
-		u32 __user *uaddr = (u32 __user *)(long)attr->addr;
-
-		r = put_user(dev->kvm->arch.vgic.mi_intid, uaddr);
-		break;
-	}
 	}
 
 	return r;
@@ -523,7 +517,7 @@ static int vgic_v3_attr_regs_access(struct kvm_device *dev,
 	struct vgic_reg_attr reg_attr;
 	gpa_t addr;
 	struct kvm_vcpu *vcpu;
-	bool uaccess, post_init = true;
+	bool uaccess;
 	u32 val;
 	int ret;
 
@@ -539,9 +533,6 @@ static int vgic_v3_attr_regs_access(struct kvm_device *dev,
 		/* Sysregs uaccess is performed by the sysreg handling code */
 		uaccess = false;
 		break;
-	case KVM_DEV_ARM_VGIC_GRP_MAINT_IRQ:
-		post_init = false;
-		fallthrough;
 	default:
 		uaccess = true;
 	}
@@ -561,7 +552,7 @@ static int vgic_v3_attr_regs_access(struct kvm_device *dev,
 
 	mutex_lock(&dev->kvm->arch.config_lock);
 
-	if (post_init != vgic_initialized(dev->kvm)) {
+	if (!vgic_initialized(dev->kvm)) {
 		ret = -EBUSY;
 		goto out;
 	}
@@ -591,19 +582,6 @@ static int vgic_v3_attr_regs_access(struct kvm_device *dev,
 		}
 		break;
 	}
-	case KVM_DEV_ARM_VGIC_GRP_MAINT_IRQ:
-		if (!is_write) {
-			val = dev->kvm->arch.vgic.mi_intid;
-			ret = 0;
-			break;
-		}
-
-		ret = -EINVAL;
-		if ((val < VGIC_NR_PRIVATE_IRQS) && (val >= VGIC_NR_SGIS)) {
-			dev->kvm->arch.vgic.mi_intid = val;
-			ret = 0;
-		}
-		break;
 	default:
 		ret = -EINVAL;
 		break;
@@ -630,8 +608,24 @@ static int vgic_v3_set_attr(struct kvm_device *dev,
 	case KVM_DEV_ARM_VGIC_GRP_REDIST_REGS:
 	case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS:
 	case KVM_DEV_ARM_VGIC_GRP_LEVEL_INFO:
-	case KVM_DEV_ARM_VGIC_GRP_MAINT_IRQ:
 		return vgic_v3_attr_regs_access(dev, attr, true);
+	case KVM_DEV_ARM_VGIC_GRP_MAINT_IRQ: {
+		u32 __user *uaddr = (u32 __user *)attr->addr;
+		u32 val;
+
+		if (get_user(val, uaddr))
+			return -EFAULT;
+
+		guard(mutex)(&dev->kvm->arch.config_lock);
+		if (vgic_initialized(dev->kvm))
+			return -EBUSY;
+
+		if (!irq_is_ppi(val))
+			return -EINVAL;
+
+		dev->kvm->arch.vgic.mi_intid = val;
+		return 0;
+	}
 	default:
 		return vgic_set_common_attr(dev, attr);
 	}
@@ -645,8 +639,13 @@ static int vgic_v3_get_attr(struct kvm_device *dev,
 	case KVM_DEV_ARM_VGIC_GRP_REDIST_REGS:
 	case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS:
 	case KVM_DEV_ARM_VGIC_GRP_LEVEL_INFO:
-	case KVM_DEV_ARM_VGIC_GRP_MAINT_IRQ:
 		return vgic_v3_attr_regs_access(dev, attr, false);
+	case KVM_DEV_ARM_VGIC_GRP_MAINT_IRQ: {
+		u32 __user *uaddr = (u32 __user *)(long)attr->addr;
+
+		guard(mutex)(&dev->kvm->arch.config_lock);
+		return put_user(dev->kvm->arch.vgic.mi_intid, uaddr);
+	}
 	default:
 		return vgic_get_common_attr(dev, attr);
 	}