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memory-device: turn alignment assert into check 

The start of the address space indicates which maximum alignment is
supported by our machine (e.g. ppc, x86 1GB). This is helpful to
catch fragmenting guest physical memory in strange fashions.

Right now we can crash QEMU by e.g. (there might be easier examples)

qemu-system-x86_64 -m 256M,maxmem=20G,slots=2 \
 -object memory-backend-file,id=mem0,size=8192M,mem-path=/dev/zero,align=8192M \
 -device pc-dimm,id=dimm1,memdev=mem0

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20180607154705.6316-2-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
David Hildenbrand 2018-06-07 17:47:04 +02:00 committed by Paolo Bonzini
parent 93d1499c81
commit 4d8938a05d
1 changed files with 7 additions and 1 deletions
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8
hw/mem/memory-device.c
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@ -116,9 +116,15 @@ uint64_t memory_device_get_free_addr(MachineState *ms, const uint64_t *hint,
address_space_start = ms->device_memory->base;
address_space_end = address_space_start +
memory_region_size(&ms->device_memory->mr);
g_assert(QEMU_ALIGN_UP(address_space_start, align) == address_space_start);
g_assert(address_space_end >= address_space_start);
/* address_space_start indicates the maximum alignment we expect */
if (QEMU_ALIGN_UP(address_space_start, align) != address_space_start) {
error_setg(errp, "the alignment (0%" PRIx64 ") is not supported",
align);
return 0;
}
memory_device_check_addable(ms, size, errp);
if (*errp) {
return 0;