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memory-device: Support empty memory devices

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Let's support empty memory devices -- memory devices that don't have a
memory device region in the current configuration. hv-balloon with an
optional memdev is the primary use case.

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
This commit is contained in:
David Hildenbrand 2023-06-22 12:18:23 +02:00 • committed by Maciej S. Szmigiero
parent d762bf9793
commit 6c1b28e9e4
2 changed files with 46 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

43
hw/mem/memory-device.c
View file

@ -20,6 +20,22 @@
#include "exec/address-spaces.h"
#include "trace.h"
static bool memory_device_is_empty(const MemoryDeviceState *md)
{
const MemoryDeviceClass *mdc = MEMORY_DEVICE_GET_CLASS(md);
Error *local_err = NULL;
MemoryRegion *mr;
/* dropping const here is fine as we don't touch the memory region */
mr = mdc->get_memory_region((MemoryDeviceState *)md, &local_err);
if (local_err) {
/* Not empty, we'll report errors later when ontaining the MR again. */
error_free(local_err);
return false;
}
return !mr;
}
static gint memory_device_addr_sort(gconstpointer a, gconstpointer b)
{
const MemoryDeviceState *md_a = MEMORY_DEVICE(a);
@ -249,6 +265,10 @@ static uint64_t memory_device_get_free_addr(MachineState *ms,
uint64_t next_addr;
Range tmp;
if (memory_device_is_empty(md)) {
continue;
}
range_init_nofail(&tmp, mdc->get_addr(md),
memory_device_get_region_size(md, &error_abort));
@ -292,6 +312,7 @@ MemoryDeviceInfoList *qmp_memory_device_list(void)
const MemoryDeviceClass *mdc = MEMORY_DEVICE_GET_CLASS(item->data);
MemoryDeviceInfo *info = g_new0(MemoryDeviceInfo, 1);
/* Let's query infotmation even for empty memory devices. */
mdc->fill_device_info(md, info);
QAPI_LIST_APPEND(tail, info);
@ -311,7 +332,7 @@ static int memory_device_plugged_size(Object *obj, void *opaque)
const MemoryDeviceState *md = MEMORY_DEVICE(obj);
const MemoryDeviceClass *mdc = MEMORY_DEVICE_GET_CLASS(obj);
if (dev->realized) {
if (dev->realized && !memory_device_is_empty(md)) {
*size += mdc->get_plugged_size(md, &error_abort);
}
}
@ -337,6 +358,11 @@ void memory_device_pre_plug(MemoryDeviceState *md, MachineState *ms,
uint64_t addr, align = 0;
MemoryRegion *mr;
/* We support empty memory devices even without device memory. */
if (memory_device_is_empty(md)) {
return;
}
if (!ms->device_memory) {
error_setg(errp, "the configuration is not prepared for memory devices"
" (e.g., for memory hotplug), consider specifying the"
@ -380,10 +406,17 @@ out:
void memory_device_plug(MemoryDeviceState *md, MachineState *ms)
{
const MemoryDeviceClass *mdc = MEMORY_DEVICE_GET_CLASS(md);
const unsigned int memslots = memory_device_get_memslots(md);
const uint64_t addr = mdc->get_addr(md);
unsigned int memslots;
uint64_t addr;
MemoryRegion *mr;
if (memory_device_is_empty(md)) {
return;
}
memslots = memory_device_get_memslots(md);
addr = mdc->get_addr(md);
/*
* We expect that a previous call to memory_device_pre_plug() succeeded, so
* it can't fail at this point.
@ -408,6 +441,10 @@ void memory_device_unplug(MemoryDeviceState *md, MachineState *ms)
const unsigned int memslots = memory_device_get_memslots(md);
MemoryRegion *mr;
if (memory_device_is_empty(md)) {
return;
}
/*
* We expect that a previous call to memory_device_pre_plug() succeeded, so
* it can't fail at this point.