[PATCH 5/6] block/nvme: Align block pages queue to host page size

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

In nvme_create_queue_pair() we create a page list using
qemu_blockalign(), then map it with qemu_vfio_dma_map():

  q->prp_list_pages = qemu_blockalign0(bs, s->page_size * NVME_QUEUE_SIZE);
  r = qemu_vfio_dma_map(s->vfio, q->prp_list_pages,
                        s->page_size * NVME_QUEUE_SIZE, ...);

With:

  s->page_size = MAX(4096, 1 << (12 + ((cap >> 48) & 0xF)));

The qemu_vfio_dma_map() documentation says "The caller need
to make sure the area is aligned to page size". While we use
multiple s->page_size as alignment, it might be not sufficient
on some hosts. Use the qemu_real_host_page_size value to be
sure the host alignment is respected.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
Cc: Cédric Le Goater <clg@kaod.org>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Laurent Vivier <lvivier@redhat.com>
---
 block/nvme.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/nvme.c b/block/nvme.c
index 7b7c0cc5d6..bde0d28b39 100644
--- a/block/nvme.c
+++ b/block/nvme.c
@@ -627,7 +627,7 @@ static int nvme_init(BlockDriverState *bs, const char *device, int namespace,
 
     s->page_size = MAX(4096, 1 << (12 + ((cap >> 48) & 0xF)));
     s->doorbell_scale = (4 << (((cap >> 32) & 0xF))) / sizeof(uint32_t);
-    bs->bl.opt_mem_alignment = s->page_size;
+    bs->bl.opt_mem_alignment = MAX(qemu_real_host_page_size, s->page_size);
     timeout_ms = MIN(500 * ((cap >> 24) & 0xFF), 30000);
 
     /* Reset device to get a clean state. */
-- 
2.21.3