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migration/ram: Add incoming 'mapped-ram' migration

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Add the necessary code to parse the format changes for the
'mapped-ram' capability.

One of the more notable changes in behavior is that in the
'mapped-ram' case ram pages are restored in one go rather than
constantly looping through the migration stream.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240229153017.2221-11-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>
This commit is contained in:
Fabiano Rosas 2024-02-29 12:30:04 -03:00 committed by Peter Xu
parent c2d5c4a7cb
commit 2f6b8826a5
1 changed files with 141 additions and 2 deletions
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143
migration/ram.c
View file

@ -106,6 +106,12 @@
*/
#define MAPPED_RAM_FILE_OFFSET_ALIGNMENT 0x100000
/*
* When doing mapped-ram migration, this is the amount we read from
* the pages region in the migration file at a time.
*/
#define MAPPED_RAM_LOAD_BUF_SIZE 0x100000
XBZRLECacheStats xbzrle_counters;
/* used by the search for pages to send */
@ -2998,6 +3004,35 @@ static void mapped_ram_setup_ramblock(QEMUFile *file, RAMBlock *block)
qemu_set_offset(file, block->pages_offset + block->used_length, SEEK_SET);
}
static bool mapped_ram_read_header(QEMUFile *file, MappedRamHeader *header,
Error **errp)
{
size_t ret, header_size = sizeof(MappedRamHeader);
ret = qemu_get_buffer(file, (uint8_t *)header, header_size);
if (ret != header_size) {
error_setg(errp, "Could not read whole mapped-ram migration header "
"(expected %zd, got %zd bytes)", header_size, ret);
return false;
}
/* migration stream is big-endian */
header->version = be32_to_cpu(header->version);
if (header->version > MAPPED_RAM_HDR_VERSION) {
error_setg(errp, "Migration mapped-ram capability version not "
"supported (expected <= %d, got %d)", MAPPED_RAM_HDR_VERSION,
header->version);
return false;
}
header->page_size = be64_to_cpu(header->page_size);
header->bitmap_offset = be64_to_cpu(header->bitmap_offset);
header->pages_offset = be64_to_cpu(header->pages_offset);
return true;
}
/*
* Each of ram_save_setup, ram_save_iterate and ram_save_complete has
* long-running RCU critical section. When rcu-reclaims in the code
@ -3899,22 +3934,126 @@ void colo_flush_ram_cache(void)
trace_colo_flush_ram_cache_end();
}
static bool read_ramblock_mapped_ram(QEMUFile *f, RAMBlock *block,
long num_pages, unsigned long *bitmap,
Error **errp)
{
ERRP_GUARD();
unsigned long set_bit_idx, clear_bit_idx;
ram_addr_t offset;
void *host;
size_t read, unread, size;
for (set_bit_idx = find_first_bit(bitmap, num_pages);
set_bit_idx < num_pages;
set_bit_idx = find_next_bit(bitmap, num_pages, clear_bit_idx + 1)) {
clear_bit_idx = find_next_zero_bit(bitmap, num_pages, set_bit_idx + 1);
unread = TARGET_PAGE_SIZE * (clear_bit_idx - set_bit_idx);
offset = set_bit_idx << TARGET_PAGE_BITS;
while (unread > 0) {
host = host_from_ram_block_offset(block, offset);
if (!host) {
error_setg(errp, "page outside of ramblock %s range",
block->idstr);
return false;
}
size = MIN(unread, MAPPED_RAM_LOAD_BUF_SIZE);
read = qemu_get_buffer_at(f, host, size,
block->pages_offset + offset);
if (!read) {
goto err;
}
offset += read;
unread -= read;
}
}
return true;
err:
qemu_file_get_error_obj(f, errp);
error_prepend(errp, "(%s) failed to read page " RAM_ADDR_FMT
"from file offset %" PRIx64 ": ", block->idstr, offset,
block->pages_offset + offset);
return false;
}
static void parse_ramblock_mapped_ram(QEMUFile *f, RAMBlock *block,
ram_addr_t length, Error **errp)
{
g_autofree unsigned long *bitmap = NULL;
MappedRamHeader header;
size_t bitmap_size;
long num_pages;
if (!mapped_ram_read_header(f, &header, errp)) {
return;
}
block->pages_offset = header.pages_offset;
/*
* Check the alignment of the file region that contains pages. We
* don't enforce MAPPED_RAM_FILE_OFFSET_ALIGNMENT to allow that
* value to change in the future. Do only a sanity check with page
* size alignment.
*/
if (!QEMU_IS_ALIGNED(block->pages_offset, TARGET_PAGE_SIZE)) {
error_setg(errp,
"Error reading ramblock %s pages, region has bad alignment",
block->idstr);
return;
}
num_pages = length / header.page_size;
bitmap_size = BITS_TO_LONGS(num_pages) * sizeof(unsigned long);
bitmap = g_malloc0(bitmap_size);
if (qemu_get_buffer_at(f, (uint8_t *)bitmap, bitmap_size,
header.bitmap_offset) != bitmap_size) {
error_setg(errp, "Error reading dirty bitmap");
return;
}
if (!read_ramblock_mapped_ram(f, block, num_pages, bitmap, errp)) {
return;
}
/* Skip pages array */
qemu_set_offset(f, block->pages_offset + length, SEEK_SET);
return;
}
static int parse_ramblock(QEMUFile *f, RAMBlock *block, ram_addr_t length)
{
int ret = 0;
/* ADVISE is earlier, it shows the source has the postcopy capability on */
bool postcopy_advised = migration_incoming_postcopy_advised();
Error *local_err = NULL;
assert(block);
if (migrate_mapped_ram()) {
parse_ramblock_mapped_ram(f, block, length, &local_err);
if (local_err) {
error_report_err(local_err);
return -EINVAL;
}
return 0;
}
if (!qemu_ram_is_migratable(block)) {
error_report("block %s should not be migrated !", block->idstr);
return -EINVAL;
}
if (length != block->used_length) {
Error *local_err = NULL;
ret = qemu_ram_resize(block, length, &local_err);
if (local_err) {
error_report_err(local_err);