arm/arm64: KVM: force alignment of VGIC dist/CPU/redist addresses

Although the GIC architecture requires us to map the MMIO regions
only at page aligned addresses, we currently do not enforce this from
the kernel side.
Restrict any vGICv2 regions to be 4K aligned and any GICv3 regions
to be 64K aligned. Document this requirement.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

Documentation/virtual/kvm/devices/arm-vgic.txt

@@ -20,20 +20,24 @@ Groups:
     KVM_VGIC_V2_ADDR_TYPE_DIST (rw, 64-bit)
       Base address in the guest physical address space of the GIC distributor
       register mappings. Only valid for KVM_DEV_TYPE_ARM_VGIC_V2.
+      This address needs to be 4K aligned and the region covers 4 KByte.
 
     KVM_VGIC_V2_ADDR_TYPE_CPU (rw, 64-bit)
       Base address in the guest physical address space of the GIC virtual cpu
       interface register mappings. Only valid for KVM_DEV_TYPE_ARM_VGIC_V2.
+      This address needs to be 4K aligned and the region covers 4 KByte.
 
     KVM_VGIC_V3_ADDR_TYPE_DIST (rw, 64-bit)
       Base address in the guest physical address space of the GICv3 distributor
       register mappings. Only valid for KVM_DEV_TYPE_ARM_VGIC_V3.
+      This address needs to be 64K aligned and the region covers 64 KByte.
 
     KVM_VGIC_V3_ADDR_TYPE_REDIST (rw, 64-bit)
       Base address in the guest physical address space of the GICv3
       redistributor register mappings. There are two 64K pages for each
       VCPU and all of the redistributor pages are contiguous.
       Only valid for KVM_DEV_TYPE_ARM_VGIC_V3.
+      This address needs to be 64K aligned.
 
 
   KVM_DEV_ARM_VGIC_GRP_DIST_REGS

virt/kvm/arm/vgic.c

@@ -1683,6 +1683,7 @@ int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write)
 	struct vgic_dist *vgic = &kvm->arch.vgic;
 	int type_needed;
 	phys_addr_t *addr_ptr, block_size;
+	phys_addr_t alignment;
 
 	mutex_lock(&kvm->lock);
 	switch (type) {
@@ -1690,22 +1691,26 @@ int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write)
 		type_needed = KVM_DEV_TYPE_ARM_VGIC_V2;
 		addr_ptr = &vgic->vgic_dist_base;
 		block_size = KVM_VGIC_V2_DIST_SIZE;
+		alignment = SZ_4K;
 		break;
 	case KVM_VGIC_V2_ADDR_TYPE_CPU:
 		type_needed = KVM_DEV_TYPE_ARM_VGIC_V2;
 		addr_ptr = &vgic->vgic_cpu_base;
 		block_size = KVM_VGIC_V2_CPU_SIZE;
+		alignment = SZ_4K;
 		break;
 #ifdef CONFIG_ARM_GIC_V3
 	case KVM_VGIC_V3_ADDR_TYPE_DIST:
 		type_needed = KVM_DEV_TYPE_ARM_VGIC_V3;
 		addr_ptr = &vgic->vgic_dist_base;
 		block_size = KVM_VGIC_V3_DIST_SIZE;
+		alignment = SZ_64K;
 		break;
 	case KVM_VGIC_V3_ADDR_TYPE_REDIST:
 		type_needed = KVM_DEV_TYPE_ARM_VGIC_V3;
 		addr_ptr = &vgic->vgic_redist_base;
 		block_size = KVM_VGIC_V3_REDIST_SIZE;
+		alignment = SZ_64K;
 		break;
 #endif
 	default:
@@ -1718,10 +1723,15 @@ int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write)
 		goto out;
 	}
 
-	if (write)
-		r = vgic_ioaddr_assign(kvm, addr_ptr, *addr, block_size);
+	if (write) {
+		if (!IS_ALIGNED(*addr, alignment))
+			r = -EINVAL;
 		else
+			r = vgic_ioaddr_assign(kvm, addr_ptr, *addr,
+					       block_size);
+	} else {
 		*addr = *addr_ptr;
+	}
 
 out:
 	mutex_unlock(&kvm->lock);