Let's rewrite it properly using ranges. This fixes certain overflows that
are right now possible. E.g.
qemu-system-x86_64 -m 4G,slots=20,maxmem=40G -M pc \
-object memory-backend-file,id=mem1,share,mem-path=/dev/zero,size=2G
-device pc-dimm,memdev=mem1,id=dimm1,addr=-0x40000000
Now properly reports an error instead of succeeding.
"can't add memory device [0xffffffffc0000000:0x80000000], range overflow"
Signed-off-by: David Hildenbrand <da...@redhat.com>
---
hw/mem/memory-device.c | 56 +++++++++++++++++++++++++-----------------
1 file changed, 33 insertions(+), 23 deletions(-)
diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
index 8be63c8032..1ca9c8e410 100644
--- a/hw/mem/memory-device.c
+++ b/hw/mem/memory-device.c
@@ -100,9 +100,8 @@ static uint64_t memory_device_get_free_addr(MachineState
*ms,
uint64_t align, uint64_t size,
Error **errp)
{
- uint64_t address_space_start, address_space_end;
GSList *list = NULL, *item;
- uint64_t new_addr = 0;
+ Range as, new = range_empty;
if (!ms->device_memory) {
error_setg(errp, "memory devices (e.g. for memory hotplug) are not "
@@ -115,13 +114,11 @@ static uint64_t memory_device_get_free_addr(MachineState
*ms,
"enabled, please specify the maxmem option");
return 0;
}
- address_space_start = ms->device_memory->base;
- address_space_end = address_space_start +
- memory_region_size(&ms->device_memory->mr);
- g_assert(address_space_end >= address_space_start);
+ range_init(&as, ms->device_memory->base,
+ memory_region_size(&ms->device_memory->mr));
- /* address_space_start indicates the maximum alignment we expect */
- if (!QEMU_IS_ALIGNED(address_space_start, align)) {
+ /* 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;
@@ -145,20 +142,26 @@ static uint64_t memory_device_get_free_addr(MachineState
*ms,
}
if (hint) {
- new_addr = *hint;
- if (new_addr < address_space_start) {
+ if (!range_valid(*hint, size)) {
error_setg(errp, "can't add memory device [0x%" PRIx64 ":0x%"
PRIx64
- "] before 0x%" PRIx64, new_addr, size,
- address_space_start);
+ "], range overflow", *hint, size);
return 0;
- } else if ((new_addr + size) > address_space_end) {
+ }
+ range_init(&new, *hint, size);
+ if (range_starts_before_range(&new, &as)) {
+ error_setg(errp, "can't add memory device [0x%" PRIx64 ":0x%"
PRIx64
+ "] before 0x%" PRIx64, range_lob(&new),
range_size(&new),
+ range_lob(&as));
+ return 0;
+ } else if (range_ends_after_range(&new, &as)) {
error_setg(errp, "can't add memory device [0x%" PRIx64 ":0x%"
PRIx64
- "] beyond 0x%" PRIx64, new_addr, size,
- address_space_end);
+ "] beyond 0x%" PRIx64, range_lob(&new),
range_size(&new),
+ range_upb(&as));
return 0;
}
} else {
- new_addr = address_space_start;
+ /* our previous size checks make sure that this never overflows */
+ range_init(&new, range_lob(&as), size);
}
/* find address range that will fit new memory device */
@@ -166,30 +169,37 @@ static uint64_t memory_device_get_free_addr(MachineState
*ms,
for (item = list; item; item = g_slist_next(item)) {
const MemoryDeviceState *md = item->data;
const MemoryDeviceClass *mdc = MEMORY_DEVICE_GET_CLASS(OBJECT(md));
- uint64_t md_size, md_addr;
+ uint64_t next_addr;
+ Range tmp;
- md_addr = mdc->get_addr(md);
- md_size = memory_device_get_region_size(md, &error_abort);
+ range_init(&tmp, mdc->get_addr(md),
+ memory_device_get_region_size(md, &error_abort));
- if (ranges_overlap(md_addr, md_size, new_addr, size)) {
+ if (range_overlaps_range(&tmp, &new)) {
if (hint) {
const DeviceState *d = DEVICE(md);
error_setg(errp, "address range conflicts with memory device"
" id='%s'", d->id ? d->id : "(unnamed)");
goto out;
}
- new_addr = QEMU_ALIGN_UP(md_addr + md_size, align);
+
+ next_addr = QEMU_ALIGN_UP(range_upb(&tmp) + 1, align);
+ if (!range_valid(next_addr, size)) {
+ range_make_empty(&new);
+ break;
+ }
+ range_init(&new, next_addr, size);
}
}
- if (new_addr + size > address_space_end) {
+ if (!range_contains_range(&as, &new)) {
error_setg(errp, "could not find position in guest address space for "
"memory device - memory fragmented due to alignments");
goto out;
}
out:
g_slist_free(list);
- return new_addr;
+ return range_lob(&new);
}
MemoryDeviceInfoList *qmp_memory_device_list(void)
--
2.17.1
