The spec requires us to set the "addr" in guest physical address space to
multiples of the block size. In some cases, this is not the case right
now: For example, when starting a VM with 4 GiB boot memory and a
virtio-mem device with a block size of 2 GiB, "memaddr" will be
auto-assigned to 0x140000000 / 5 GiB.

We'll try to improve auto-assignment for memory devices next, to avoid
bailing out in case memory device code selects a bad address.

Note: The Linux driver doesn't support such big block sizes yet.

Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/virtio/virtio-mem.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hw/virtio/virtio-mem.c b/hw/virtio/virtio-mem.c
index 9b1461cf9d..878c0b4f21 100644
--- a/hw/virtio/virtio-mem.c
+++ b/hw/virtio/virtio-mem.c
@@ -532,6 +532,11 @@ static void virtio_mem_device_realize(DeviceState *dev, Error **errp)
                    ")", VIRTIO_MEM_REQUESTED_SIZE_PROP,
                    VIRTIO_MEM_BLOCK_SIZE_PROP, vmem->block_size);
         return;
+    } else if (!QEMU_IS_ALIGNED(vmem->addr, vmem->block_size)) {
+        error_setg(errp, "'%s' property has to be multiples of '%s' (0x%" PRIx64
+                   ")", VIRTIO_MEM_ADDR_PROP, VIRTIO_MEM_BLOCK_SIZE_PROP,
+                   vmem->block_size);
+        return;
     } else if (!QEMU_IS_ALIGNED(memory_region_size(&vmem->memdev->mr),
                                 vmem->block_size)) {
         error_setg(errp, "'%s' property memdev size has to be multiples of"
-- 
2.26.2