[PULL,05/38] memory-device: Support big alignment requirements

Commit Message

Michael S. Tsirkin Nov. 3, 2020, 2:34 p.m. UTC

From: David Hildenbrand <[e-mail]>

Let's warn instead of bailing out - the worst thing that can happen is
that we'll fail hot/coldplug later. The user got warned, and this should
be rare.

This will be necessary for memory devices with rather big (user-defined)
alignment requirements - say a virtio-mem device with a 2G block size -
which will become important, for example, when supporting vfio in the
future.

Reviewed-by: Pankaj Gupta <[e-mail]>
Cc: "Michael S. Tsirkin" <[e-mail]>
Cc: Wei Yang <[e-mail]>
Cc: Dr. David Alan Gilbert <[e-mail]>
Cc: Igor Mammedov <[e-mail]>
Cc: Pankaj Gupta <[e-mail]>
Signed-off-by: David Hildenbrand <[e-mail]>
Message-Id: <[e-mail]>
Reviewed-by: Michael S. Tsirkin <[e-mail]>
Signed-off-by: Michael S. Tsirkin <[e-mail]>
---
 hw/mem/memory-device.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

Patch

diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
index 4bc9cf0917..8a736f1a26 100644
--- a/hw/mem/memory-device.c
+++ b/hw/mem/memory-device.c
@@ -119,9 +119,10 @@  static uint64_t memory_device_get_free_addr(MachineState *ms,
 
     /* start of address space indicates the maximum alignment we expect */
     if (!QEMU_IS_ALIGNED(range_lob(&as), align)) {
-        error_setg(errp, "the alignment (0x%" PRIx64 ") is not supported",
-                   align);
-        return 0;
+        warn_report("the alignment (0x%" PRIx64 ") exceeds the expected"
+                    " maximum alignment, memory will get fragmented and not"
+                    " all 'maxmem' might be usable for memory devices.",
+                    align);
     }
 
     memory_device_check_addable(ms, size, &err);
@@ -151,7 +152,7 @@  static uint64_t memory_device_get_free_addr(MachineState *ms,
             return 0;
         }
     } else {
-        if (range_init(&new, range_lob(&as), size)) {
+        if (range_init(&new, QEMU_ALIGN_UP(range_lob(&as), align), size)) {
             error_setg(errp, "can't add memory device, device too big");
             return 0;
         }