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364eff6885
qemu/hw/virtio/virtio-mem.c
David Hildenbrand 364eff6885 virtio-mem: fix division by zero in virtio_mem_activate_memslots_to_plug() 
When running with "dynamic-memslots=off", we enter
virtio_mem_activate_memslots_to_plug() to return immediately again
because "vmem->dynamic_memslots == false". However, the compiler might
not optimize out calculating start_idx+end_idx, where we divide by
vmem->memslot_size. In such a configuration, the memslot size is 0 and
we'll get a division by zero:

    (qemu) qom-set vmem0 requested-size 3G
    (qemu) q35.sh: line 38: 622940 Floating point exception(core dumped)

The same is true for virtio_mem_deactivate_unplugged_memslots(), however
we never really reach that code without a prior
virtio_mem_activate_memslots_to_plug() call.

Let's fix it by simply calling these functions only with
"dynamic-memslots=on".

This was found when using a debug build of QEMU.

Message-ID: <20231023111341.219317-1-david@redhat.com>
Reprted-by: Mario Casquero <mcasquer@redhat.com>
Fixes: 177f9b1ee4 ("virtio-mem: Expose device memory dynamically via multiple memslots if enabled")
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Tested-by: Mario Casquero <mcasquer@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
2023-11-13 09:35:44 +01:00

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/*
* Virtio MEM device
*
* Copyright (C) 2020 Red Hat, Inc.
*
* Authors:
* David Hildenbrand <david@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include "qemu/iov.h"
#include "qemu/cutils.h"
#include "qemu/error-report.h"
#include "qemu/units.h"
#include "sysemu/numa.h"
#include "sysemu/sysemu.h"
#include "sysemu/reset.h"
#include "sysemu/runstate.h"
#include "hw/virtio/virtio.h"
#include "hw/virtio/virtio-bus.h"
#include "hw/virtio/virtio-mem.h"
#include "qapi/error.h"
#include "qapi/visitor.h"
#include "exec/ram_addr.h"
#include "migration/misc.h"
#include "hw/boards.h"
#include "hw/qdev-properties.h"
#include CONFIG_DEVICES
#include "trace.h"
static const VMStateDescription vmstate_virtio_mem_device_early;
/*
* We only had legacy x86 guests that did not support
* VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE. Other targets don't have legacy guests.
*/
#if defined(TARGET_X86_64) || defined(TARGET_I386)
#define VIRTIO_MEM_HAS_LEGACY_GUESTS
#endif
/*
* Let's not allow blocks smaller than 1 MiB, for example, to keep the tracking
* bitmap small.
*/
#define VIRTIO_MEM_MIN_BLOCK_SIZE ((uint32_t)(1 * MiB))
static uint32_t virtio_mem_default_thp_size(void)
{
uint32_t default_thp_size = VIRTIO_MEM_MIN_BLOCK_SIZE;
#if defined(__x86_64__) || defined(__arm__) || defined(__powerpc64__)
default_thp_size = 2 * MiB;
#elif defined(__aarch64__)
if (qemu_real_host_page_size() == 4 * KiB) {
default_thp_size = 2 * MiB;
} else if (qemu_real_host_page_size() == 16 * KiB) {
default_thp_size = 32 * MiB;
} else if (qemu_real_host_page_size() == 64 * KiB) {
default_thp_size = 512 * MiB;
}
#endif
return default_thp_size;
}
/*
* The minimum memslot size depends on this setting ("sane default"), the
* device block size, and the memory backend page size. The last (or single)
* memslot might be smaller than this constant.
*/
#define VIRTIO_MEM_MIN_MEMSLOT_SIZE (1 * GiB)
/*
* We want to have a reasonable default block size such that
* 1. We avoid splitting THPs when unplugging memory, which degrades
* performance.
* 2. We avoid placing THPs for plugged blocks that also cover unplugged
* blocks.
*
* The actual THP size might differ between Linux kernels, so we try to probe
* it. In the future (if we ever run into issues regarding 2.), we might want
* to disable THP in case we fail to properly probe the THP size, or if the
* block size is configured smaller than the THP size.
*/
static uint32_t thp_size;
#define HPAGE_PMD_SIZE_PATH "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size"
static uint32_t virtio_mem_thp_size(void)
{
gchar *content = NULL;
const char *endptr;
uint64_t tmp;
if (thp_size) {
return thp_size;
}
/*
* Try to probe the actual THP size, fallback to (sane but eventually
* incorrect) default sizes.
*/
if (g_file_get_contents(HPAGE_PMD_SIZE_PATH, &content, NULL, NULL) &&
!qemu_strtou64(content, &endptr, 0, &tmp) &&
(!endptr || *endptr == '\n')) {
/* Sanity-check the value and fallback to something reasonable. */
if (!tmp || !is_power_of_2(tmp)) {
warn_report("Read unsupported THP size: %" PRIx64, tmp);
} else {
thp_size = tmp;
}
}
if (!thp_size) {
thp_size = virtio_mem_default_thp_size();
warn_report("Could not detect THP size, falling back to %" PRIx64
" MiB.", thp_size / MiB);
}
g_free(content);
return thp_size;
}
static uint64_t virtio_mem_default_block_size(RAMBlock *rb)
{
const uint64_t page_size = qemu_ram_pagesize(rb);
/* We can have hugetlbfs with a page size smaller than the THP size. */
if (page_size == qemu_real_host_page_size()) {
return MAX(page_size, virtio_mem_thp_size());
}
return MAX(page_size, VIRTIO_MEM_MIN_BLOCK_SIZE);
}
#if defined(VIRTIO_MEM_HAS_LEGACY_GUESTS)
static bool virtio_mem_has_shared_zeropage(RAMBlock *rb)
{
/*
* We only have a guaranteed shared zeropage on ordinary MAP_PRIVATE
* anonymous RAM. In any other case, reading unplugged *can* populate a
* fresh page, consuming actual memory.
*/
return !qemu_ram_is_shared(rb) && qemu_ram_get_fd(rb) < 0 &&
qemu_ram_pagesize(rb) == qemu_real_host_page_size();
}
#endif /* VIRTIO_MEM_HAS_LEGACY_GUESTS */
/*
* Size the usable region bigger than the requested size if possible. Esp.
* Linux guests will only add (aligned) memory blocks in case they fully
* fit into the usable region, but plug+online only a subset of the pages.
* The memory block size corresponds mostly to the section size.
*
* This allows e.g., to add 20MB with a section size of 128MB on x86_64, and
* a section size of 512MB on arm64 (as long as the start address is properly
* aligned, similar to ordinary DIMMs).
*
* We can change this at any time and maybe even make it configurable if
* necessary (as the section size can change). But it's more likely that the
* section size will rather get smaller and not bigger over time.
*/
#if defined(TARGET_X86_64) || defined(TARGET_I386)
#define VIRTIO_MEM_USABLE_EXTENT (2 * (128 * MiB))
#elif defined(TARGET_ARM)
#define VIRTIO_MEM_USABLE_EXTENT (2 * (512 * MiB))
#else
#error VIRTIO_MEM_USABLE_EXTENT not defined
#endif
static bool virtio_mem_is_busy(void)
{
/*
* Postcopy cannot handle concurrent discards and we don't want to migrate
* pages on-demand with stale content when plugging new blocks.
*
* For precopy, we don't want unplugged blocks in our migration stream, and
* when plugging new blocks, the page content might differ between source
* and destination (observable by the guest when not initializing pages
* after plugging them) until we're running on the destination (as we didn't
* migrate these blocks when they were unplugged).
*/
return migration_in_incoming_postcopy() || !migration_is_idle();
}
typedef int (*virtio_mem_range_cb)(VirtIOMEM *vmem, void *arg,
uint64_t offset, uint64_t size);
static int virtio_mem_for_each_unplugged_range(VirtIOMEM *vmem, void *arg,
virtio_mem_range_cb cb)
{
unsigned long first_zero_bit, last_zero_bit;
uint64_t offset, size;
int ret = 0;
first_zero_bit = find_first_zero_bit(vmem->bitmap, vmem->bitmap_size);
while (first_zero_bit < vmem->bitmap_size) {
offset = first_zero_bit * vmem->block_size;
last_zero_bit = find_next_bit(vmem->bitmap, vmem->bitmap_size,
first_zero_bit + 1) - 1;
size = (last_zero_bit - first_zero_bit + 1) * vmem->block_size;
ret = cb(vmem, arg, offset, size);
if (ret) {
break;
}
first_zero_bit = find_next_zero_bit(vmem->bitmap, vmem->bitmap_size,
last_zero_bit + 2);
}
return ret;
}
static int virtio_mem_for_each_plugged_range(VirtIOMEM *vmem, void *arg,
virtio_mem_range_cb cb)
{
unsigned long first_bit, last_bit;
uint64_t offset, size;
int ret = 0;
first_bit = find_first_bit(vmem->bitmap, vmem->bitmap_size);
while (first_bit < vmem->bitmap_size) {
offset = first_bit * vmem->block_size;
last_bit = find_next_zero_bit(vmem->bitmap, vmem->bitmap_size,
first_bit + 1) - 1;
size = (last_bit - first_bit + 1) * vmem->block_size;
ret = cb(vmem, arg, offset, size);
if (ret) {
break;
}
first_bit = find_next_bit(vmem->bitmap, vmem->bitmap_size,
last_bit + 2);
}
return ret;
}
/*
* Adjust the memory section to cover the intersection with the given range.
*
* Returns false if the intersection is empty, otherwise returns true.
*/
static bool virtio_mem_intersect_memory_section(MemoryRegionSection *s,
uint64_t offset, uint64_t size)
{
uint64_t start = MAX(s->offset_within_region, offset);
uint64_t end = MIN(s->offset_within_region + int128_get64(s->size),
offset + size);
if (end <= start) {
return false;
}
s->offset_within_address_space += start - s->offset_within_region;
s->offset_within_region = start;
s->size = int128_make64(end - start);
return true;
}
typedef int (*virtio_mem_section_cb)(MemoryRegionSection *s, void *arg);
static int virtio_mem_for_each_plugged_section(const VirtIOMEM *vmem,
MemoryRegionSection *s,
void *arg,
virtio_mem_section_cb cb)
{
unsigned long first_bit, last_bit;
uint64_t offset, size;
int ret = 0;
first_bit = s->offset_within_region / vmem->block_size;
first_bit = find_next_bit(vmem->bitmap, vmem->bitmap_size, first_bit);
while (first_bit < vmem->bitmap_size) {
MemoryRegionSection tmp = *s;
offset = first_bit * vmem->block_size;
last_bit = find_next_zero_bit(vmem->bitmap, vmem->bitmap_size,
first_bit + 1) - 1;
size = (last_bit - first_bit + 1) * vmem->block_size;
if (!virtio_mem_intersect_memory_section(&tmp, offset, size)) {
break;
}
ret = cb(&tmp, arg);
if (ret) {
break;
}
first_bit = find_next_bit(vmem->bitmap, vmem->bitmap_size,
last_bit + 2);
}
return ret;
}
static int virtio_mem_for_each_unplugged_section(const VirtIOMEM *vmem,
MemoryRegionSection *s,
void *arg,
virtio_mem_section_cb cb)
{
unsigned long first_bit, last_bit;
uint64_t offset, size;
int ret = 0;
first_bit = s->offset_within_region / vmem->block_size;
first_bit = find_next_zero_bit(vmem->bitmap, vmem->bitmap_size, first_bit);
while (first_bit < vmem->bitmap_size) {
MemoryRegionSection tmp = *s;
offset = first_bit * vmem->block_size;
last_bit = find_next_bit(vmem->bitmap, vmem->bitmap_size,
first_bit + 1) - 1;
size = (last_bit - first_bit + 1) * vmem->block_size;
if (!virtio_mem_intersect_memory_section(&tmp, offset, size)) {
break;
}
ret = cb(&tmp, arg);
if (ret) {
break;
}
first_bit = find_next_zero_bit(vmem->bitmap, vmem->bitmap_size,
last_bit + 2);
}
return ret;
}
static int virtio_mem_notify_populate_cb(MemoryRegionSection *s, void *arg)
{
RamDiscardListener *rdl = arg;
return rdl->notify_populate(rdl, s);
}
static int virtio_mem_notify_discard_cb(MemoryRegionSection *s, void *arg)
{
RamDiscardListener *rdl = arg;
rdl->notify_discard(rdl, s);
return 0;
}
static void virtio_mem_notify_unplug(VirtIOMEM *vmem, uint64_t offset,
uint64_t size)
{
RamDiscardListener *rdl;
QLIST_FOREACH(rdl, &vmem->rdl_list, next) {
MemoryRegionSection tmp = *rdl->section;
if (!virtio_mem_intersect_memory_section(&tmp, offset, size)) {
continue;
}
rdl->notify_discard(rdl, &tmp);
}
}
static int virtio_mem_notify_plug(VirtIOMEM *vmem, uint64_t offset,
uint64_t size)
{
RamDiscardListener *rdl, *rdl2;
int ret = 0;
QLIST_FOREACH(rdl, &vmem->rdl_list, next) {
MemoryRegionSection tmp = *rdl->section;
if (!virtio_mem_intersect_memory_section(&tmp, offset, size)) {
continue;
}
ret = rdl->notify_populate(rdl, &tmp);
if (ret) {
break;
}
}
if (ret) {
/* Notify all already-notified listeners. */
QLIST_FOREACH(rdl2, &vmem->rdl_list, next) {
MemoryRegionSection tmp = *rdl2->section;
if (rdl2 == rdl) {
break;
}
if (!virtio_mem_intersect_memory_section(&tmp, offset, size)) {
continue;
}
rdl2->notify_discard(rdl2, &tmp);
}
}
return ret;
}
static void virtio_mem_notify_unplug_all(VirtIOMEM *vmem)
{
RamDiscardListener *rdl;
if (!vmem->size) {
return;
}
QLIST_FOREACH(rdl, &vmem->rdl_list, next) {
if (rdl->double_discard_supported) {
rdl->notify_discard(rdl, rdl->section);
} else {
virtio_mem_for_each_plugged_section(vmem, rdl->section, rdl,
virtio_mem_notify_discard_cb);
}
}
}
static bool virtio_mem_is_range_plugged(const VirtIOMEM *vmem,
uint64_t start_gpa, uint64_t size)
{
const unsigned long first_bit = (start_gpa - vmem->addr) / vmem->block_size;
const unsigned long last_bit = first_bit + (size / vmem->block_size) - 1;
unsigned long found_bit;
/* We fake a shorter bitmap to avoid searching too far. */
found_bit = find_next_zero_bit(vmem->bitmap, last_bit + 1, first_bit);
return found_bit > last_bit;
}
static bool virtio_mem_is_range_unplugged(const VirtIOMEM *vmem,
uint64_t start_gpa, uint64_t size)
{
const unsigned long first_bit = (start_gpa - vmem->addr) / vmem->block_size;
const unsigned long last_bit = first_bit + (size / vmem->block_size) - 1;
unsigned long found_bit;
/* We fake a shorter bitmap to avoid searching too far. */
found_bit = find_next_bit(vmem->bitmap, last_bit + 1, first_bit);
return found_bit > last_bit;
}
static void virtio_mem_set_range_plugged(VirtIOMEM *vmem, uint64_t start_gpa,
uint64_t size)
{
const unsigned long bit = (start_gpa - vmem->addr) / vmem->block_size;
const unsigned long nbits = size / vmem->block_size;
bitmap_set(vmem->bitmap, bit, nbits);
}
static void virtio_mem_set_range_unplugged(VirtIOMEM *vmem, uint64_t start_gpa,
uint64_t size)
{
const unsigned long bit = (start_gpa - vmem->addr) / vmem->block_size;
const unsigned long nbits = size / vmem->block_size;
bitmap_clear(vmem->bitmap, bit, nbits);
}
static void virtio_mem_send_response(VirtIOMEM *vmem, VirtQueueElement *elem,
struct virtio_mem_resp *resp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(vmem);
VirtQueue *vq = vmem->vq;
trace_virtio_mem_send_response(le16_to_cpu(resp->type));
iov_from_buf(elem->in_sg, elem->in_num, 0, resp, sizeof(*resp));
virtqueue_push(vq, elem, sizeof(*resp));
virtio_notify(vdev, vq);
}
static void virtio_mem_send_response_simple(VirtIOMEM *vmem,
VirtQueueElement *elem,
uint16_t type)
{
struct virtio_mem_resp resp = {
.type = cpu_to_le16(type),
};
virtio_mem_send_response(vmem, elem, &resp);
}
static bool virtio_mem_valid_range(const VirtIOMEM *vmem, uint64_t gpa,
uint64_t size)
{
if (!QEMU_IS_ALIGNED(gpa, vmem->block_size)) {
return false;
}
if (gpa + size < gpa || !size) {
return false;
}
if (gpa < vmem->addr || gpa >= vmem->addr + vmem->usable_region_size) {
return false;
}
if (gpa + size > vmem->addr + vmem->usable_region_size) {
return false;
}
return true;
}
static void virtio_mem_activate_memslot(VirtIOMEM *vmem, unsigned int idx)
{
const uint64_t memslot_offset = idx * vmem->memslot_size;
assert(vmem->memslots);
/*
* Instead of enabling/disabling memslots, we add/remove them. This should
* make address space updates faster, because we don't have to loop over
* many disabled subregions.
*/
if (memory_region_is_mapped(&vmem->memslots[idx])) {
return;
}
memory_region_add_subregion(vmem->mr, memslot_offset, &vmem->memslots[idx]);
}
static void virtio_mem_deactivate_memslot(VirtIOMEM *vmem, unsigned int idx)
{
assert(vmem->memslots);
if (!memory_region_is_mapped(&vmem->memslots[idx])) {
return;
}
memory_region_del_subregion(vmem->mr, &vmem->memslots[idx]);
}
static void virtio_mem_activate_memslots_to_plug(VirtIOMEM *vmem,
uint64_t offset, uint64_t size)
{
const unsigned int start_idx = offset / vmem->memslot_size;
const unsigned int end_idx = (offset + size + vmem->memslot_size - 1) /
vmem->memslot_size;
unsigned int idx;
assert(vmem->dynamic_memslots);
/* Activate all involved memslots in a single transaction. */
memory_region_transaction_begin();
for (idx = start_idx; idx < end_idx; idx++) {
virtio_mem_activate_memslot(vmem, idx);
}
memory_region_transaction_commit();
}
static void virtio_mem_deactivate_unplugged_memslots(VirtIOMEM *vmem,
uint64_t offset,
uint64_t size)
{
const uint64_t region_size = memory_region_size(&vmem->memdev->mr);
const unsigned int start_idx = offset / vmem->memslot_size;
const unsigned int end_idx = (offset + size + vmem->memslot_size - 1) /
vmem->memslot_size;
unsigned int idx;
assert(vmem->dynamic_memslots);
/* Deactivate all memslots with unplugged blocks in a single transaction. */
memory_region_transaction_begin();
for (idx = start_idx; idx < end_idx; idx++) {
const uint64_t memslot_offset = idx * vmem->memslot_size;
uint64_t memslot_size = vmem->memslot_size;
/* The size of the last memslot might be smaller. */
if (idx == vmem->nb_memslots - 1) {
memslot_size = region_size - memslot_offset;
}
/*
* Partially covered memslots might still have some blocks plugged and
* have to remain active if that's the case.
*/
if (offset > memslot_offset ||
offset + size < memslot_offset + memslot_size) {
const uint64_t gpa = vmem->addr + memslot_offset;
if (!virtio_mem_is_range_unplugged(vmem, gpa, memslot_size)) {
continue;
}
}
virtio_mem_deactivate_memslot(vmem, idx);
}
memory_region_transaction_commit();
}
static int virtio_mem_set_block_state(VirtIOMEM *vmem, uint64_t start_gpa,
uint64_t size, bool plug)
{
const uint64_t offset = start_gpa - vmem->addr;
RAMBlock *rb = vmem->memdev->mr.ram_block;
int ret = 0;
if (virtio_mem_is_busy()) {
return -EBUSY;
}
if (!plug) {
if (ram_block_discard_range(rb, offset, size)) {
return -EBUSY;
}
virtio_mem_notify_unplug(vmem, offset, size);
virtio_mem_set_range_unplugged(vmem, start_gpa, size);
/* Deactivate completely unplugged memslots after updating the state. */
if (vmem->dynamic_memslots) {
virtio_mem_deactivate_unplugged_memslots(vmem, offset, size);
}
return 0;
}
if (vmem->prealloc) {
void *area = memory_region_get_ram_ptr(&vmem->memdev->mr) + offset;
int fd = memory_region_get_fd(&vmem->memdev->mr);
Error *local_err = NULL;
qemu_prealloc_mem(fd, area, size, 1, NULL, &local_err);
if (local_err) {
static bool warned;
/*
* Warn only once, we don't want to fill the log with these
* warnings.
*/
if (!warned) {
warn_report_err(local_err);
warned = true;
} else {
error_free(local_err);
}
ret = -EBUSY;
}
}
if (!ret) {
/*
* Activate before notifying and rollback in case of any errors.
*
* When activating a yet inactive memslot, memory notifiers will get
* notified about the added memory region and can register with the
* RamDiscardManager; this will traverse all plugged blocks and skip the
* blocks we are plugging here. The following notification will inform
* registered listeners about the blocks we're plugging.
*/
if (vmem->dynamic_memslots) {
virtio_mem_activate_memslots_to_plug(vmem, offset, size);
}
ret = virtio_mem_notify_plug(vmem, offset, size);
if (ret && vmem->dynamic_memslots) {
virtio_mem_deactivate_unplugged_memslots(vmem, offset, size);
}
}
if (ret) {
/* Could be preallocation or a notifier populated memory. */
ram_block_discard_range(vmem->memdev->mr.ram_block, offset, size);
return -EBUSY;
}
virtio_mem_set_range_plugged(vmem, start_gpa, size);
return 0;
}
static int virtio_mem_state_change_request(VirtIOMEM *vmem, uint64_t gpa,
uint16_t nb_blocks, bool plug)
{
const uint64_t size = nb_blocks * vmem->block_size;
int ret;
if (!virtio_mem_valid_range(vmem, gpa, size)) {
return VIRTIO_MEM_RESP_ERROR;
}
if (plug && (vmem->size + size > vmem->requested_size)) {
return VIRTIO_MEM_RESP_NACK;
}
/* test if really all blocks are in the opposite state */
if ((plug && !virtio_mem_is_range_unplugged(vmem, gpa, size)) ||
(!plug && !virtio_mem_is_range_plugged(vmem, gpa, size))) {
return VIRTIO_MEM_RESP_ERROR;
}
ret = virtio_mem_set_block_state(vmem, gpa, size, plug);
if (ret) {
return VIRTIO_MEM_RESP_BUSY;
}
if (plug) {
vmem->size += size;
} else {
vmem->size -= size;
}
notifier_list_notify(&vmem->size_change_notifiers, &vmem->size);
return VIRTIO_MEM_RESP_ACK;
}
static void virtio_mem_plug_request(VirtIOMEM *vmem, VirtQueueElement *elem,
struct virtio_mem_req *req)
{
const uint64_t gpa = le64_to_cpu(req->u.plug.addr);
const uint16_t nb_blocks = le16_to_cpu(req->u.plug.nb_blocks);
uint16_t type;
trace_virtio_mem_plug_request(gpa, nb_blocks);
type = virtio_mem_state_change_request(vmem, gpa, nb_blocks, true);
virtio_mem_send_response_simple(vmem, elem, type);
}
static void virtio_mem_unplug_request(VirtIOMEM *vmem, VirtQueueElement *elem,
struct virtio_mem_req *req)
{
const uint64_t gpa = le64_to_cpu(req->u.unplug.addr);
const uint16_t nb_blocks = le16_to_cpu(req->u.unplug.nb_blocks);
uint16_t type;
trace_virtio_mem_unplug_request(gpa, nb_blocks);
type = virtio_mem_state_change_request(vmem, gpa, nb_blocks, false);
virtio_mem_send_response_simple(vmem, elem, type);
}
static void virtio_mem_resize_usable_region(VirtIOMEM *vmem,
uint64_t requested_size,
bool can_shrink)
{
uint64_t newsize = MIN(memory_region_size(&vmem->memdev->mr),
requested_size + VIRTIO_MEM_USABLE_EXTENT);
/* The usable region size always has to be multiples of the block size. */
newsize = QEMU_ALIGN_UP(newsize, vmem->block_size);
if (!requested_size) {
newsize = 0;
}
if (newsize < vmem->usable_region_size && !can_shrink) {
return;
}
trace_virtio_mem_resized_usable_region(vmem->usable_region_size, newsize);
vmem->usable_region_size = newsize;
}
static int virtio_mem_unplug_all(VirtIOMEM *vmem)
{
const uint64_t region_size = memory_region_size(&vmem->memdev->mr);
RAMBlock *rb = vmem->memdev->mr.ram_block;
if (vmem->size) {
if (virtio_mem_is_busy()) {
return -EBUSY;
}
if (ram_block_discard_range(rb, 0, qemu_ram_get_used_length(rb))) {
return -EBUSY;
}
virtio_mem_notify_unplug_all(vmem);
bitmap_clear(vmem->bitmap, 0, vmem->bitmap_size);
vmem->size = 0;
notifier_list_notify(&vmem->size_change_notifiers, &vmem->size);
/* Deactivate all memslots after updating the state. */
if (vmem->dynamic_memslots) {
virtio_mem_deactivate_unplugged_memslots(vmem, 0, region_size);
}
}
trace_virtio_mem_unplugged_all();
virtio_mem_resize_usable_region(vmem, vmem->requested_size, true);
return 0;
}
static void virtio_mem_unplug_all_request(VirtIOMEM *vmem,
VirtQueueElement *elem)
{
trace_virtio_mem_unplug_all_request();
if (virtio_mem_unplug_all(vmem)) {
virtio_mem_send_response_simple(vmem, elem, VIRTIO_MEM_RESP_BUSY);
} else {
virtio_mem_send_response_simple(vmem, elem, VIRTIO_MEM_RESP_ACK);
}
}
static void virtio_mem_state_request(VirtIOMEM *vmem, VirtQueueElement *elem,
struct virtio_mem_req *req)
{
const uint16_t nb_blocks = le16_to_cpu(req->u.state.nb_blocks);
const uint64_t gpa = le64_to_cpu(req->u.state.addr);
const uint64_t size = nb_blocks * vmem->block_size;
struct virtio_mem_resp resp = {
.type = cpu_to_le16(VIRTIO_MEM_RESP_ACK),
};
trace_virtio_mem_state_request(gpa, nb_blocks);
if (!virtio_mem_valid_range(vmem, gpa, size)) {
virtio_mem_send_response_simple(vmem, elem, VIRTIO_MEM_RESP_ERROR);
return;
}
if (virtio_mem_is_range_plugged(vmem, gpa, size)) {
resp.u.state.state = cpu_to_le16(VIRTIO_MEM_STATE_PLUGGED);
} else if (virtio_mem_is_range_unplugged(vmem, gpa, size)) {
resp.u.state.state = cpu_to_le16(VIRTIO_MEM_STATE_UNPLUGGED);
} else {
resp.u.state.state = cpu_to_le16(VIRTIO_MEM_STATE_MIXED);
}
trace_virtio_mem_state_response(le16_to_cpu(resp.u.state.state));
virtio_mem_send_response(vmem, elem, &resp);
}
static void virtio_mem_handle_request(VirtIODevice *vdev, VirtQueue *vq)
{
const int len = sizeof(struct virtio_mem_req);
VirtIOMEM *vmem = VIRTIO_MEM(vdev);
VirtQueueElement *elem;
struct virtio_mem_req req;
uint16_t type;
while (true) {
elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
if (!elem) {
return;
}
if (iov_to_buf(elem->out_sg, elem->out_num, 0, &req, len) < len) {
virtio_error(vdev, "virtio-mem protocol violation: invalid request"
" size: %d", len);
virtqueue_detach_element(vq, elem, 0);
g_free(elem);
return;
}
if (iov_size(elem->in_sg, elem->in_num) <
sizeof(struct virtio_mem_resp)) {
virtio_error(vdev, "virtio-mem protocol violation: not enough space"
" for response: %zu",
iov_size(elem->in_sg, elem->in_num));
virtqueue_detach_element(vq, elem, 0);
g_free(elem);
return;
}
type = le16_to_cpu(req.type);
switch (type) {
case VIRTIO_MEM_REQ_PLUG:
virtio_mem_plug_request(vmem, elem, &req);
break;
case VIRTIO_MEM_REQ_UNPLUG:
virtio_mem_unplug_request(vmem, elem, &req);
break;
case VIRTIO_MEM_REQ_UNPLUG_ALL:
virtio_mem_unplug_all_request(vmem, elem);
break;
case VIRTIO_MEM_REQ_STATE:
virtio_mem_state_request(vmem, elem, &req);
break;
default:
virtio_error(vdev, "virtio-mem protocol violation: unknown request"
" type: %d", type);
virtqueue_detach_element(vq, elem, 0);
g_free(elem);
return;
}
g_free(elem);
}
}
static void virtio_mem_get_config(VirtIODevice *vdev, uint8_t *config_data)
{
VirtIOMEM *vmem = VIRTIO_MEM(vdev);
struct virtio_mem_config *config = (void *) config_data;
config->block_size = cpu_to_le64(vmem->block_size);
config->node_id = cpu_to_le16(vmem->node);
config->requested_size = cpu_to_le64(vmem->requested_size);
config->plugged_size = cpu_to_le64(vmem->size);
config->addr = cpu_to_le64(vmem->addr);
config->region_size = cpu_to_le64(memory_region_size(&vmem->memdev->mr));
config->usable_region_size = cpu_to_le64(vmem->usable_region_size);
}
static uint64_t virtio_mem_get_features(VirtIODevice *vdev, uint64_t features,
Error **errp)
{
MachineState *ms = MACHINE(qdev_get_machine());
VirtIOMEM *vmem = VIRTIO_MEM(vdev);
if (ms->numa_state) {
#if defined(CONFIG_ACPI)
virtio_add_feature(&features, VIRTIO_MEM_F_ACPI_PXM);
#endif
}
assert(vmem->unplugged_inaccessible != ON_OFF_AUTO_AUTO);
if (vmem->unplugged_inaccessible == ON_OFF_AUTO_ON) {
virtio_add_feature(&features, VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE);
}
return features;
}
static int virtio_mem_validate_features(VirtIODevice *vdev)
{
if (virtio_host_has_feature(vdev, VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE) &&
!virtio_vdev_has_feature(vdev, VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE)) {
return -EFAULT;
}
return 0;
}
static void virtio_mem_system_reset(void *opaque)
{
VirtIOMEM *vmem = VIRTIO_MEM(opaque);
/*
* During usual resets, we will unplug all memory and shrink the usable
* region size. This is, however, not possible in all scenarios. Then,
* the guest has to deal with this manually (VIRTIO_MEM_REQ_UNPLUG_ALL).
*/
virtio_mem_unplug_all(vmem);
}
static void virtio_mem_prepare_mr(VirtIOMEM *vmem)
{
const uint64_t region_size = memory_region_size(&vmem->memdev->mr);
assert(!vmem->mr && vmem->dynamic_memslots);
vmem->mr = g_new0(MemoryRegion, 1);
memory_region_init(vmem->mr, OBJECT(vmem), "virtio-mem",
region_size);
vmem->mr->align = memory_region_get_alignment(&vmem->memdev->mr);
}
static void virtio_mem_prepare_memslots(VirtIOMEM *vmem)
{
const uint64_t region_size = memory_region_size(&vmem->memdev->mr);
unsigned int idx;
g_assert(!vmem->memslots && vmem->nb_memslots && vmem->dynamic_memslots);
vmem->memslots = g_new0(MemoryRegion, vmem->nb_memslots);
/* Initialize our memslots, but don't map them yet. */
for (idx = 0; idx < vmem->nb_memslots; idx++) {
const uint64_t memslot_offset = idx * vmem->memslot_size;
uint64_t memslot_size = vmem->memslot_size;
char name[20];
/* The size of the last memslot might be smaller. */
if (idx == vmem->nb_memslots - 1) {
memslot_size = region_size - memslot_offset;
}
snprintf(name, sizeof(name), "memslot-%u", idx);
memory_region_init_alias(&vmem->memslots[idx], OBJECT(vmem), name,
&vmem->memdev->mr, memslot_offset,
memslot_size);
/*
* We want to be able to atomically and efficiently activate/deactivate
* individual memslots without affecting adjacent memslots in memory
* notifiers.
*/
memory_region_set_unmergeable(&vmem->memslots[idx], true);
}
}
static void virtio_mem_device_realize(DeviceState *dev, Error **errp)
{
MachineState *ms = MACHINE(qdev_get_machine());
int nb_numa_nodes = ms->numa_state ? ms->numa_state->num_nodes : 0;
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtIOMEM *vmem = VIRTIO_MEM(dev);
uint64_t page_size;
RAMBlock *rb;
int ret;
if (!vmem->memdev) {
error_setg(errp, "'%s' property is not set", VIRTIO_MEM_MEMDEV_PROP);
return;
} else if (host_memory_backend_is_mapped(vmem->memdev)) {
error_setg(errp, "'%s' property specifies a busy memdev: %s",
VIRTIO_MEM_MEMDEV_PROP,
object_get_canonical_path_component(OBJECT(vmem->memdev)));
return;
} else if (!memory_region_is_ram(&vmem->memdev->mr) ||
memory_region_is_rom(&vmem->memdev->mr) ||
!vmem->memdev->mr.ram_block) {
error_setg(errp, "'%s' property specifies an unsupported memdev",
VIRTIO_MEM_MEMDEV_PROP);
return;
} else if (vmem->memdev->prealloc) {
error_setg(errp, "'%s' property specifies a memdev with preallocation"
" enabled: %s. Instead, specify 'prealloc=on' for the"
" virtio-mem device. ", VIRTIO_MEM_MEMDEV_PROP,
object_get_canonical_path_component(OBJECT(vmem->memdev)));
return;
}
if ((nb_numa_nodes && vmem->node >= nb_numa_nodes) ||
(!nb_numa_nodes && vmem->node)) {
error_setg(errp, "'%s' property has value '%" PRIu32 "', which exceeds"
"the number of numa nodes: %d", VIRTIO_MEM_NODE_PROP,
vmem->node, nb_numa_nodes ? nb_numa_nodes : 1);
return;
}
if (enable_mlock) {
error_setg(errp, "Incompatible with mlock");
return;
}
rb = vmem->memdev->mr.ram_block;
page_size = qemu_ram_pagesize(rb);
#if defined(VIRTIO_MEM_HAS_LEGACY_GUESTS)
switch (vmem->unplugged_inaccessible) {
case ON_OFF_AUTO_AUTO:
if (virtio_mem_has_shared_zeropage(rb)) {
vmem->unplugged_inaccessible = ON_OFF_AUTO_OFF;
} else {
vmem->unplugged_inaccessible = ON_OFF_AUTO_ON;
}
break;
case ON_OFF_AUTO_OFF:
if (!virtio_mem_has_shared_zeropage(rb)) {
warn_report("'%s' property set to 'off' with a memdev that does"
" not support the shared zeropage.",
VIRTIO_MEM_UNPLUGGED_INACCESSIBLE_PROP);
}
break;
default:
break;
}
#else /* VIRTIO_MEM_HAS_LEGACY_GUESTS */
vmem->unplugged_inaccessible = ON_OFF_AUTO_ON;
#endif /* VIRTIO_MEM_HAS_LEGACY_GUESTS */
if (vmem->dynamic_memslots &&
vmem->unplugged_inaccessible != ON_OFF_AUTO_ON) {
error_setg(errp, "'%s' property set to 'on' requires '%s' to be 'on'",
VIRTIO_MEM_DYNAMIC_MEMSLOTS_PROP,
VIRTIO_MEM_UNPLUGGED_INACCESSIBLE_PROP);
return;
}
/*
* If the block size wasn't configured by the user, use a sane default. This
* allows using hugetlbfs backends of any page size without manual
* intervention.
*/
if (!vmem->block_size) {
vmem->block_size = virtio_mem_default_block_size(rb);
}
if (vmem->block_size < page_size) {
error_setg(errp, "'%s' property has to be at least the page size (0x%"
PRIx64 ")", VIRTIO_MEM_BLOCK_SIZE_PROP, page_size);
return;
} else if (vmem->block_size < virtio_mem_default_block_size(rb)) {
warn_report("'%s' property is smaller than the default block size (%"
PRIx64 " MiB)", VIRTIO_MEM_BLOCK_SIZE_PROP,
virtio_mem_default_block_size(rb) / MiB);
}
if (!QEMU_IS_ALIGNED(vmem->requested_size, vmem->block_size)) {
error_setg(errp, "'%s' property has to be multiples of '%s' (0x%" PRIx64
")", VIRTIO_MEM_REQUESTED_SIZE_PROP,
VIRTIO_MEM_BLOCK_SIZE_PROP, vmem->block_size);
return;
} else if (!QEMU_IS_ALIGNED(vmem->addr, vmem->block_size)) {
error_setg(errp, "'%s' property has to be multiples of '%s' (0x%" PRIx64
")", VIRTIO_MEM_ADDR_PROP, VIRTIO_MEM_BLOCK_SIZE_PROP,
vmem->block_size);
return;
} else if (!QEMU_IS_ALIGNED(memory_region_size(&vmem->memdev->mr),
vmem->block_size)) {
error_setg(errp, "'%s' property memdev size has to be multiples of"
"'%s' (0x%" PRIx64 ")", VIRTIO_MEM_MEMDEV_PROP,
VIRTIO_MEM_BLOCK_SIZE_PROP, vmem->block_size);
return;
}
if (ram_block_coordinated_discard_require(true)) {
error_setg(errp, "Discarding RAM is disabled");
return;
}
/*
* We don't know at this point whether shared RAM is migrated using
* QEMU or migrated using the file content. "x-ignore-shared" will be
* configured after realizing the device. So in case we have an
* incoming migration, simply always skip the discard step.
*
* Otherwise, make sure that we start with a clean slate: either the
* memory backend might get reused or the shared file might still have
* memory allocated.
*/
if (!runstate_check(RUN_STATE_INMIGRATE)) {
ret = ram_block_discard_range(rb, 0, qemu_ram_get_used_length(rb));
if (ret) {
error_setg_errno(errp, -ret, "Unexpected error discarding RAM");
ram_block_coordinated_discard_require(false);
return;
}
}
virtio_mem_resize_usable_region(vmem, vmem->requested_size, true);
vmem->bitmap_size = memory_region_size(&vmem->memdev->mr) /
vmem->block_size;
vmem->bitmap = bitmap_new(vmem->bitmap_size);
virtio_init(vdev, VIRTIO_ID_MEM, sizeof(struct virtio_mem_config));
vmem->vq = virtio_add_queue(vdev, 128, virtio_mem_handle_request);
/*
* With "dynamic-memslots=off" (old behavior) we always map the whole
* RAM memory region directly.
*/
if (vmem->dynamic_memslots) {
if (!vmem->mr) {
virtio_mem_prepare_mr(vmem);
}
if (vmem->nb_memslots <= 1) {
vmem->nb_memslots = 1;
vmem->memslot_size = memory_region_size(&vmem->memdev->mr);
}
if (!vmem->memslots) {
virtio_mem_prepare_memslots(vmem);
}
} else {
assert(!vmem->mr && !vmem->nb_memslots && !vmem->memslots);
}
host_memory_backend_set_mapped(vmem->memdev, true);
vmstate_register_ram(&vmem->memdev->mr, DEVICE(vmem));
if (vmem->early_migration) {
vmstate_register_any(VMSTATE_IF(vmem),
&vmstate_virtio_mem_device_early, vmem);
}
qemu_register_reset(virtio_mem_system_reset, vmem);
/*
* Set ourselves as RamDiscardManager before the plug handler maps the
* memory region and exposes it via an address space.
*/
memory_region_set_ram_discard_manager(&vmem->memdev->mr,
RAM_DISCARD_MANAGER(vmem));
}
static void virtio_mem_device_unrealize(DeviceState *dev)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtIOMEM *vmem = VIRTIO_MEM(dev);
/*
* The unplug handler unmapped the memory region, it cannot be
* found via an address space anymore. Unset ourselves.
*/
memory_region_set_ram_discard_manager(&vmem->memdev->mr, NULL);
qemu_unregister_reset(virtio_mem_system_reset, vmem);
if (vmem->early_migration) {
vmstate_unregister(VMSTATE_IF(vmem), &vmstate_virtio_mem_device_early,
vmem);
}
vmstate_unregister_ram(&vmem->memdev->mr, DEVICE(vmem));
host_memory_backend_set_mapped(vmem->memdev, false);
virtio_del_queue(vdev, 0);
virtio_cleanup(vdev);
g_free(vmem->bitmap);
ram_block_coordinated_discard_require(false);
}
static int virtio_mem_discard_range_cb(VirtIOMEM *vmem, void *arg,
uint64_t offset, uint64_t size)
{
RAMBlock *rb = vmem->memdev->mr.ram_block;
return ram_block_discard_range(rb, offset, size) ? -EINVAL : 0;
}
static int virtio_mem_restore_unplugged(VirtIOMEM *vmem)
{
/* Make sure all memory is really discarded after migration. */
return virtio_mem_for_each_unplugged_range(vmem, NULL,
virtio_mem_discard_range_cb);
}
static int virtio_mem_activate_memslot_range_cb(VirtIOMEM *vmem, void *arg,
uint64_t offset, uint64_t size)
{
virtio_mem_activate_memslots_to_plug(vmem, offset, size);
return 0;
}
static int virtio_mem_post_load_bitmap(VirtIOMEM *vmem)
{
RamDiscardListener *rdl;
int ret;
/*
* We restored the bitmap and updated the requested size; activate all
* memslots (so listeners register) before notifying about plugged blocks.
*/
if (vmem->dynamic_memslots) {
/*
* We don't expect any active memslots at this point to deactivate: no
* memory was plugged on the migration destination.
*/
virtio_mem_for_each_plugged_range(vmem, NULL,
virtio_mem_activate_memslot_range_cb);
}
/*
* We started out with all memory discarded and our memory region is mapped
* into an address space. Replay, now that we updated the bitmap.
*/
QLIST_FOREACH(rdl, &vmem->rdl_list, next) {
ret = virtio_mem_for_each_plugged_section(vmem, rdl->section, rdl,
virtio_mem_notify_populate_cb);
if (ret) {
return ret;
}
}
return 0;
}
static int virtio_mem_post_load(void *opaque, int version_id)
{
VirtIOMEM *vmem = VIRTIO_MEM(opaque);
int ret;
if (!vmem->early_migration) {
ret = virtio_mem_post_load_bitmap(vmem);
if (ret) {
return ret;
}
}
/*
* If shared RAM is migrated using the file content and not using QEMU,
* don't mess with preallocation and postcopy.
*/
if (migrate_ram_is_ignored(vmem->memdev->mr.ram_block)) {
return 0;
}
if (vmem->prealloc && !vmem->early_migration) {
warn_report("Proper preallocation with migration requires a newer QEMU machine");
}
if (migration_in_incoming_postcopy()) {
return 0;
}
return virtio_mem_restore_unplugged(vmem);
}
static int virtio_mem_prealloc_range_cb(VirtIOMEM *vmem, void *arg,
uint64_t offset, uint64_t size)
{
void *area = memory_region_get_ram_ptr(&vmem->memdev->mr) + offset;
int fd = memory_region_get_fd(&vmem->memdev->mr);
Error *local_err = NULL;
qemu_prealloc_mem(fd, area, size, 1, NULL, &local_err);
if (local_err) {
error_report_err(local_err);
return -ENOMEM;
}
return 0;
}
static int virtio_mem_post_load_early(void *opaque, int version_id)
{
VirtIOMEM *vmem = VIRTIO_MEM(opaque);
RAMBlock *rb = vmem->memdev->mr.ram_block;
int ret;
if (!vmem->prealloc) {
goto post_load_bitmap;
}
/*
* If shared RAM is migrated using the file content and not using QEMU,
* don't mess with preallocation and postcopy.
*/
if (migrate_ram_is_ignored(rb)) {
goto post_load_bitmap;
}
/*
* We restored the bitmap and verified that the basic properties
* match on source and destination, so we can go ahead and preallocate
* memory for all plugged memory blocks, before actual RAM migration starts
* touching this memory.
*/
ret = virtio_mem_for_each_plugged_range(vmem, NULL,
virtio_mem_prealloc_range_cb);
if (ret) {
return ret;
}
/*
* This is tricky: postcopy wants to start with a clean slate. On
* POSTCOPY_INCOMING_ADVISE, postcopy code discards all (ordinarily
* preallocated) RAM such that postcopy will work as expected later.
*
* However, we run after POSTCOPY_INCOMING_ADVISE -- but before actual
* RAM migration. So let's discard all memory again. This looks like an
* expensive NOP, but actually serves a purpose: we made sure that we
* were able to allocate all required backend memory once. We cannot
* guarantee that the backend memory we will free will remain free
* until we need it during postcopy, but at least we can catch the
* obvious setup issues this way.
*/
if (migration_incoming_postcopy_advised()) {
if (ram_block_discard_range(rb, 0, qemu_ram_get_used_length(rb))) {
return -EBUSY;
}
}
post_load_bitmap:
/* Finally, update any other state to be consistent with the new bitmap. */
return virtio_mem_post_load_bitmap(vmem);
}
typedef struct VirtIOMEMMigSanityChecks {
VirtIOMEM *parent;
uint64_t addr;
uint64_t region_size;
uint64_t block_size;
uint32_t node;
} VirtIOMEMMigSanityChecks;
static int virtio_mem_mig_sanity_checks_pre_save(void *opaque)
{
VirtIOMEMMigSanityChecks *tmp = opaque;
VirtIOMEM *vmem = tmp->parent;
tmp->addr = vmem->addr;
tmp->region_size = memory_region_size(&vmem->memdev->mr);
tmp->block_size = vmem->block_size;
tmp->node = vmem->node;
return 0;
}
static int virtio_mem_mig_sanity_checks_post_load(void *opaque, int version_id)
{
VirtIOMEMMigSanityChecks *tmp = opaque;
VirtIOMEM *vmem = tmp->parent;
const uint64_t new_region_size = memory_region_size(&vmem->memdev->mr);
if (tmp->addr != vmem->addr) {
error_report("Property '%s' changed from 0x%" PRIx64 " to 0x%" PRIx64,
VIRTIO_MEM_ADDR_PROP, tmp->addr, vmem->addr);
return -EINVAL;
}
/*
* Note: Preparation for resizable memory regions. The maximum size
* of the memory region must not change during migration.
*/
if (tmp->region_size != new_region_size) {
error_report("Property '%s' size changed from 0x%" PRIx64 " to 0x%"
PRIx64, VIRTIO_MEM_MEMDEV_PROP, tmp->region_size,
new_region_size);
return -EINVAL;
}
if (tmp->block_size != vmem->block_size) {
error_report("Property '%s' changed from 0x%" PRIx64 " to 0x%" PRIx64,
VIRTIO_MEM_BLOCK_SIZE_PROP, tmp->block_size,
vmem->block_size);
return -EINVAL;
}
if (tmp->node != vmem->node) {
error_report("Property '%s' changed from %" PRIu32 " to %" PRIu32,
VIRTIO_MEM_NODE_PROP, tmp->node, vmem->node);
return -EINVAL;
}
return 0;
}
static const VMStateDescription vmstate_virtio_mem_sanity_checks = {
.name = "virtio-mem-device/sanity-checks",
.pre_save = virtio_mem_mig_sanity_checks_pre_save,
.post_load = virtio_mem_mig_sanity_checks_post_load,
.fields = (VMStateField[]) {
VMSTATE_UINT64(addr, VirtIOMEMMigSanityChecks),
VMSTATE_UINT64(region_size, VirtIOMEMMigSanityChecks),
VMSTATE_UINT64(block_size, VirtIOMEMMigSanityChecks),
VMSTATE_UINT32(node, VirtIOMEMMigSanityChecks),
VMSTATE_END_OF_LIST(),
},
};
static bool virtio_mem_vmstate_field_exists(void *opaque, int version_id)
{
const VirtIOMEM *vmem = VIRTIO_MEM(opaque);
/* With early migration, these fields were already migrated. */
return !vmem->early_migration;
}
static const VMStateDescription vmstate_virtio_mem_device = {
.name = "virtio-mem-device",
.minimum_version_id = 1,
.version_id = 1,
.priority = MIG_PRI_VIRTIO_MEM,
.post_load = virtio_mem_post_load,
.fields = (VMStateField[]) {
VMSTATE_WITH_TMP_TEST(VirtIOMEM, virtio_mem_vmstate_field_exists,
VirtIOMEMMigSanityChecks,
vmstate_virtio_mem_sanity_checks),
VMSTATE_UINT64(usable_region_size, VirtIOMEM),
VMSTATE_UINT64_TEST(size, VirtIOMEM, virtio_mem_vmstate_field_exists),
VMSTATE_UINT64(requested_size, VirtIOMEM),
VMSTATE_BITMAP_TEST(bitmap, VirtIOMEM, virtio_mem_vmstate_field_exists,
0, bitmap_size),
VMSTATE_END_OF_LIST()
},
};
/*
* Transfer properties that are immutable while migration is active early,
* such that we have have this information around before migrating any RAM
* content.
*
* Note that virtio_mem_is_busy() makes sure these properties can no longer
* change on the migration source until migration completed.
*
* With QEMU compat machines, we transmit these properties later, via
* vmstate_virtio_mem_device instead -- see virtio_mem_vmstate_field_exists().
*/
static const VMStateDescription vmstate_virtio_mem_device_early = {
.name = "virtio-mem-device-early",
.minimum_version_id = 1,
.version_id = 1,
.early_setup = true,
.post_load = virtio_mem_post_load_early,
.fields = (VMStateField[]) {
VMSTATE_WITH_TMP(VirtIOMEM, VirtIOMEMMigSanityChecks,
vmstate_virtio_mem_sanity_checks),
VMSTATE_UINT64(size, VirtIOMEM),
VMSTATE_BITMAP(bitmap, VirtIOMEM, 0, bitmap_size),
VMSTATE_END_OF_LIST()
},
};
static const VMStateDescription vmstate_virtio_mem = {
.name = "virtio-mem",
.minimum_version_id = 1,
.version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_VIRTIO_DEVICE,
VMSTATE_END_OF_LIST()
},
};
static void virtio_mem_fill_device_info(const VirtIOMEM *vmem,
VirtioMEMDeviceInfo *vi)
{
vi->memaddr = vmem->addr;
vi->node = vmem->node;
vi->requested_size = vmem->requested_size;
vi->size = vmem->size;
vi->max_size = memory_region_size(&vmem->memdev->mr);
vi->block_size = vmem->block_size;
vi->memdev = object_get_canonical_path(OBJECT(vmem->memdev));
}
static MemoryRegion *virtio_mem_get_memory_region(VirtIOMEM *vmem, Error **errp)
{
if (!vmem->memdev) {
error_setg(errp, "'%s' property must be set", VIRTIO_MEM_MEMDEV_PROP);
return NULL;
} else if (vmem->dynamic_memslots) {
if (!vmem->mr) {
virtio_mem_prepare_mr(vmem);
}
return vmem->mr;
}
return &vmem->memdev->mr;
}
static void virtio_mem_decide_memslots(VirtIOMEM *vmem, unsigned int limit)
{
uint64_t region_size, memslot_size, min_memslot_size;
unsigned int memslots;
RAMBlock *rb;
if (!vmem->dynamic_memslots) {
return;
}
/* We're called exactly once, before realizing the device. */
assert(!vmem->nb_memslots);
/* If realizing the device will fail, just assume a single memslot. */
if (limit <= 1 || !vmem->memdev || !vmem->memdev->mr.ram_block) {
vmem->nb_memslots = 1;
return;
}
rb = vmem->memdev->mr.ram_block;
region_size = memory_region_size(&vmem->memdev->mr);
/*
* Determine the default block size now, to determine the minimum memslot
* size. We want the minimum slot size to be at least the device block size.
*/
if (!vmem->block_size) {
vmem->block_size = virtio_mem_default_block_size(rb);
}
/* If realizing the device will fail, just assume a single memslot. */
if (vmem->block_size < qemu_ram_pagesize(rb) ||
!QEMU_IS_ALIGNED(region_size, vmem->block_size)) {
vmem->nb_memslots = 1;
return;
}
/*
* All memslots except the last one have a reasonable minimum size, and
* and all memslot sizes are aligned to the device block size.
*/
memslot_size = QEMU_ALIGN_UP(region_size / limit, vmem->block_size);
min_memslot_size = MAX(vmem->block_size, VIRTIO_MEM_MIN_MEMSLOT_SIZE);
memslot_size = MAX(memslot_size, min_memslot_size);
memslots = QEMU_ALIGN_UP(region_size, memslot_size) / memslot_size;
if (memslots != 1) {
vmem->memslot_size = memslot_size;
}
vmem->nb_memslots = memslots;
}
static unsigned int virtio_mem_get_memslots(VirtIOMEM *vmem)
{
if (!vmem->dynamic_memslots) {
/* Exactly one static RAM memory region. */
return 1;
}
/* We're called after instructed to make a decision. */
g_assert(vmem->nb_memslots);
return vmem->nb_memslots;
}
static void virtio_mem_add_size_change_notifier(VirtIOMEM *vmem,
Notifier *notifier)
{
notifier_list_add(&vmem->size_change_notifiers, notifier);
}
static void virtio_mem_remove_size_change_notifier(VirtIOMEM *vmem,
Notifier *notifier)
{
notifier_remove(notifier);
}
static void virtio_mem_get_size(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
const VirtIOMEM *vmem = VIRTIO_MEM(obj);
uint64_t value = vmem->size;
visit_type_size(v, name, &value, errp);
}
static void virtio_mem_get_requested_size(Object *obj, Visitor *v,
const char *name, void *opaque,
Error **errp)
{
const VirtIOMEM *vmem = VIRTIO_MEM(obj);
uint64_t value = vmem->requested_size;
visit_type_size(v, name, &value, errp);
}
static void virtio_mem_set_requested_size(Object *obj, Visitor *v,
const char *name, void *opaque,
Error **errp)
{
VirtIOMEM *vmem = VIRTIO_MEM(obj);
uint64_t value;
if (!visit_type_size(v, name, &value, errp)) {
return;
}
/*
* The block size and memory backend are not fixed until the device was
* realized. realize() will verify these properties then.
*/
if (DEVICE(obj)->realized) {
if (!QEMU_IS_ALIGNED(value, vmem->block_size)) {
error_setg(errp, "'%s' has to be multiples of '%s' (0x%" PRIx64
")", name, VIRTIO_MEM_BLOCK_SIZE_PROP,
vmem->block_size);
return;
} else if (value > memory_region_size(&vmem->memdev->mr)) {
error_setg(errp, "'%s' cannot exceed the memory backend size"
"(0x%" PRIx64 ")", name,
memory_region_size(&vmem->memdev->mr));
return;
}
if (value != vmem->requested_size) {
virtio_mem_resize_usable_region(vmem, value, false);
vmem->requested_size = value;
}
/*
* Trigger a config update so the guest gets notified. We trigger
* even if the size didn't change (especially helpful for debugging).
*/
virtio_notify_config(VIRTIO_DEVICE(vmem));
} else {
vmem->requested_size = value;
}
}
static void virtio_mem_get_block_size(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
const VirtIOMEM *vmem = VIRTIO_MEM(obj);
uint64_t value = vmem->block_size;
/*
* If not configured by the user (and we're not realized yet), use the
* default block size we would use with the current memory backend.
*/
if (!value) {
if (vmem->memdev && memory_region_is_ram(&vmem->memdev->mr)) {
value = virtio_mem_default_block_size(vmem->memdev->mr.ram_block);
} else {
value = virtio_mem_thp_size();
}
}
visit_type_size(v, name, &value, errp);
}
static void virtio_mem_set_block_size(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
VirtIOMEM *vmem = VIRTIO_MEM(obj);
uint64_t value;
if (DEVICE(obj)->realized) {
error_setg(errp, "'%s' cannot be changed", name);
return;
}
if (!visit_type_size(v, name, &value, errp)) {
return;
}
if (value < VIRTIO_MEM_MIN_BLOCK_SIZE) {
error_setg(errp, "'%s' property has to be at least 0x%" PRIx32, name,
VIRTIO_MEM_MIN_BLOCK_SIZE);
return;
} else if (!is_power_of_2(value)) {
error_setg(errp, "'%s' property has to be a power of two", name);
return;
}
vmem->block_size = value;
}
static void virtio_mem_instance_init(Object *obj)
{
VirtIOMEM *vmem = VIRTIO_MEM(obj);
notifier_list_init(&vmem->size_change_notifiers);
QLIST_INIT(&vmem->rdl_list);
object_property_add(obj, VIRTIO_MEM_SIZE_PROP, "size", virtio_mem_get_size,
NULL, NULL, NULL);
object_property_add(obj, VIRTIO_MEM_REQUESTED_SIZE_PROP, "size",
virtio_mem_get_requested_size,
virtio_mem_set_requested_size, NULL, NULL);
object_property_add(obj, VIRTIO_MEM_BLOCK_SIZE_PROP, "size",
virtio_mem_get_block_size, virtio_mem_set_block_size,
NULL, NULL);
}
static void virtio_mem_instance_finalize(Object *obj)
{
VirtIOMEM *vmem = VIRTIO_MEM(obj);
/*
* Note: the core already dropped the references on all memory regions
* (it's passed as the owner to memory_region_init_*()) and finalized
* these objects. We can simply free the memory.
*/
g_free(vmem->memslots);
vmem->memslots = NULL;
g_free(vmem->mr);
vmem->mr = NULL;
}
static Property virtio_mem_properties[] = {
DEFINE_PROP_UINT64(VIRTIO_MEM_ADDR_PROP, VirtIOMEM, addr, 0),
DEFINE_PROP_UINT32(VIRTIO_MEM_NODE_PROP, VirtIOMEM, node, 0),
DEFINE_PROP_BOOL(VIRTIO_MEM_PREALLOC_PROP, VirtIOMEM, prealloc, false),
DEFINE_PROP_LINK(VIRTIO_MEM_MEMDEV_PROP, VirtIOMEM, memdev,
TYPE_MEMORY_BACKEND, HostMemoryBackend *),
#if defined(VIRTIO_MEM_HAS_LEGACY_GUESTS)
DEFINE_PROP_ON_OFF_AUTO(VIRTIO_MEM_UNPLUGGED_INACCESSIBLE_PROP, VirtIOMEM,
unplugged_inaccessible, ON_OFF_AUTO_ON),
#endif
DEFINE_PROP_BOOL(VIRTIO_MEM_EARLY_MIGRATION_PROP, VirtIOMEM,
early_migration, true),
DEFINE_PROP_BOOL(VIRTIO_MEM_DYNAMIC_MEMSLOTS_PROP, VirtIOMEM,
dynamic_memslots, false),
DEFINE_PROP_END_OF_LIST(),
};
static uint64_t virtio_mem_rdm_get_min_granularity(const RamDiscardManager *rdm,
const MemoryRegion *mr)
{
const VirtIOMEM *vmem = VIRTIO_MEM(rdm);
g_assert(mr == &vmem->memdev->mr);
return vmem->block_size;
}
static bool virtio_mem_rdm_is_populated(const RamDiscardManager *rdm,
const MemoryRegionSection *s)
{
const VirtIOMEM *vmem = VIRTIO_MEM(rdm);
uint64_t start_gpa = vmem->addr + s->offset_within_region;
uint64_t end_gpa = start_gpa + int128_get64(s->size);
g_assert(s->mr == &vmem->memdev->mr);
start_gpa = QEMU_ALIGN_DOWN(start_gpa, vmem->block_size);
end_gpa = QEMU_ALIGN_UP(end_gpa, vmem->block_size);
if (!virtio_mem_valid_range(vmem, start_gpa, end_gpa - start_gpa)) {
return false;
}
return virtio_mem_is_range_plugged(vmem, start_gpa, end_gpa - start_gpa);
}
struct VirtIOMEMReplayData {
void *fn;
void *opaque;
};
static int virtio_mem_rdm_replay_populated_cb(MemoryRegionSection *s, void *arg)
{
struct VirtIOMEMReplayData *data = arg;
return ((ReplayRamPopulate)data->fn)(s, data->opaque);
}
static int virtio_mem_rdm_replay_populated(const RamDiscardManager *rdm,
MemoryRegionSection *s,
ReplayRamPopulate replay_fn,
void *opaque)
{
const VirtIOMEM *vmem = VIRTIO_MEM(rdm);
struct VirtIOMEMReplayData data = {
.fn = replay_fn,
.opaque = opaque,
};
g_assert(s->mr == &vmem->memdev->mr);
return virtio_mem_for_each_plugged_section(vmem, s, &data,
virtio_mem_rdm_replay_populated_cb);
}
static int virtio_mem_rdm_replay_discarded_cb(MemoryRegionSection *s,
void *arg)
{
struct VirtIOMEMReplayData *data = arg;
((ReplayRamDiscard)data->fn)(s, data->opaque);
return 0;
}
static void virtio_mem_rdm_replay_discarded(const RamDiscardManager *rdm,
MemoryRegionSection *s,
ReplayRamDiscard replay_fn,
void *opaque)
{
const VirtIOMEM *vmem = VIRTIO_MEM(rdm);
struct VirtIOMEMReplayData data = {
.fn = replay_fn,
.opaque = opaque,
};
g_assert(s->mr == &vmem->memdev->mr);
virtio_mem_for_each_unplugged_section(vmem, s, &data,
virtio_mem_rdm_replay_discarded_cb);
}
static void virtio_mem_rdm_register_listener(RamDiscardManager *rdm,
RamDiscardListener *rdl,
MemoryRegionSection *s)
{
VirtIOMEM *vmem = VIRTIO_MEM(rdm);
int ret;
g_assert(s->mr == &vmem->memdev->mr);
rdl->section = memory_region_section_new_copy(s);
QLIST_INSERT_HEAD(&vmem->rdl_list, rdl, next);
ret = virtio_mem_for_each_plugged_section(vmem, rdl->section, rdl,
virtio_mem_notify_populate_cb);
if (ret) {
error_report("%s: Replaying plugged ranges failed: %s", __func__,
strerror(-ret));
}
}
static void virtio_mem_rdm_unregister_listener(RamDiscardManager *rdm,
RamDiscardListener *rdl)
{
VirtIOMEM *vmem = VIRTIO_MEM(rdm);
g_assert(rdl->section->mr == &vmem->memdev->mr);
if (vmem->size) {
if (rdl->double_discard_supported) {
rdl->notify_discard(rdl, rdl->section);
} else {
virtio_mem_for_each_plugged_section(vmem, rdl->section, rdl,
virtio_mem_notify_discard_cb);
}
}
memory_region_section_free_copy(rdl->section);
rdl->section = NULL;
QLIST_REMOVE(rdl, next);
}
static void virtio_mem_unplug_request_check(VirtIOMEM *vmem, Error **errp)
{
if (vmem->unplugged_inaccessible == ON_OFF_AUTO_OFF) {
/*
* We could allow it with a usable region size of 0, but let's just
* not care about that legacy setting.
*/
error_setg(errp, "virtio-mem device cannot get unplugged while"
" '" VIRTIO_MEM_UNPLUGGED_INACCESSIBLE_PROP "' != 'on'");
return;
}
if (vmem->size) {
error_setg(errp, "virtio-mem device cannot get unplugged while"
" '" VIRTIO_MEM_SIZE_PROP "' != '0'");
return;
}
if (vmem->requested_size) {
error_setg(errp, "virtio-mem device cannot get unplugged while"
" '" VIRTIO_MEM_REQUESTED_SIZE_PROP "' != '0'");
return;
}
}
static void virtio_mem_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
VirtIOMEMClass *vmc = VIRTIO_MEM_CLASS(klass);
RamDiscardManagerClass *rdmc = RAM_DISCARD_MANAGER_CLASS(klass);
device_class_set_props(dc, virtio_mem_properties);
dc->vmsd = &vmstate_virtio_mem;
set_bit(DEVICE_CATEGORY_MISC, dc->categories);
vdc->realize = virtio_mem_device_realize;
vdc->unrealize = virtio_mem_device_unrealize;
vdc->get_config = virtio_mem_get_config;
vdc->get_features = virtio_mem_get_features;
vdc->validate_features = virtio_mem_validate_features;
vdc->vmsd = &vmstate_virtio_mem_device;
vmc->fill_device_info = virtio_mem_fill_device_info;
vmc->get_memory_region = virtio_mem_get_memory_region;
vmc->decide_memslots = virtio_mem_decide_memslots;
vmc->get_memslots = virtio_mem_get_memslots;
vmc->add_size_change_notifier = virtio_mem_add_size_change_notifier;
vmc->remove_size_change_notifier = virtio_mem_remove_size_change_notifier;
vmc->unplug_request_check = virtio_mem_unplug_request_check;
rdmc->get_min_granularity = virtio_mem_rdm_get_min_granularity;
rdmc->is_populated = virtio_mem_rdm_is_populated;
rdmc->replay_populated = virtio_mem_rdm_replay_populated;
rdmc->replay_discarded = virtio_mem_rdm_replay_discarded;
rdmc->register_listener = virtio_mem_rdm_register_listener;
rdmc->unregister_listener = virtio_mem_rdm_unregister_listener;
}
static const TypeInfo virtio_mem_info = {
.name = TYPE_VIRTIO_MEM,
.parent = TYPE_VIRTIO_DEVICE,
.instance_size = sizeof(VirtIOMEM),
.instance_init = virtio_mem_instance_init,
.instance_finalize = virtio_mem_instance_finalize,
.class_init = virtio_mem_class_init,
.class_size = sizeof(VirtIOMEMClass),
.interfaces = (InterfaceInfo[]) {
{ TYPE_RAM_DISCARD_MANAGER },
{ }
},
};
static void virtio_register_types(void)
{
type_register_static(&virtio_mem_info);
}
type_init(virtio_register_types)
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