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hv-balloon: use get_min_alignment() to express 32 GiB alignment

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Let's implement the get_min_alignment() callback for memory devices, and
copy for the device memory region the alignment of the host memory
region. This mimics what virtio-mem does, and allows for re-introducing
proper alignment checks for the memory region size (where we don't care
about additional device requirements) in memory device core.

Message-ID: <20240117135554.787344-2-david@redhat.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
This commit is contained in:
David Hildenbrand 2024-01-17 14:55:53 +01:00
parent 39a6e4f87e
commit f77c5f38f4
1 changed files with 21 additions and 16 deletions
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37
hw/hyperv/hv-balloon.c
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@ -1477,22 +1477,7 @@ static void hv_balloon_ensure_mr(HvBalloon *balloon)
balloon->mr = g_new0(MemoryRegion, 1);
memory_region_init(balloon->mr, OBJECT(balloon), TYPE_HV_BALLOON,
memory_region_size(hostmem_mr));
/*
* The VM can indicate an alignment up to 32 GiB. Memory device core can
* usually only handle/guarantee 1 GiB alignment. The user will have to
* specify a larger maxmem eventually.
*
* The memory device core will warn the user in case maxmem might have to be
* increased and will fail plugging the device if there is not sufficient
* space after alignment.
*
* TODO: we could do the alignment ourselves in a slightly bigger region.
* But this feels better, although the warning might be annoying. Maybe
* we can optimize that in the future (e.g., with such a device on the
* cmdline place/size the device memory region differently.
*/
balloon->mr->align = MAX(32 * GiB, memory_region_get_alignment(hostmem_mr));
balloon->mr->align = memory_region_get_alignment(hostmem_mr);
}
static void hv_balloon_free_mr(HvBalloon *balloon)
@ -1654,6 +1639,25 @@ static MemoryRegion *hv_balloon_md_get_memory_region(MemoryDeviceState *md,
return balloon->mr;
}
static uint64_t hv_balloon_md_get_min_alignment(const MemoryDeviceState *md)
{
/*
* The VM can indicate an alignment up to 32 GiB. Memory device core can
* usually only handle/guarantee 1 GiB alignment. The user will have to
* specify a larger maxmem eventually.
*
* The memory device core will warn the user in case maxmem might have to be
* increased and will fail plugging the device if there is not sufficient
* space after alignment.
*
* TODO: we could do the alignment ourselves in a slightly bigger region.
* But this feels better, although the warning might be annoying. Maybe
* we can optimize that in the future (e.g., with such a device on the
* cmdline place/size the device memory region differently.
*/
return 32 * GiB;
}
static void hv_balloon_md_fill_device_info(const MemoryDeviceState *md,
MemoryDeviceInfo *info)
{
@ -1766,5 +1770,6 @@ static void hv_balloon_class_init(ObjectClass *klass, void *data)
mdc->get_memory_region = hv_balloon_md_get_memory_region;
mdc->decide_memslots = hv_balloon_decide_memslots;
mdc->get_memslots = hv_balloon_get_memslots;
mdc->get_min_alignment = hv_balloon_md_get_min_alignment;
mdc->fill_device_info = hv_balloon_md_fill_device_info;
}