On Mon, Oct 23, 2023 at 05:35:55PM -0300, Fabiano Rosas wrote:
> From: Nikolay Borisov <nbori...@suse.com>
>
> Add the necessary code to parse the format changes for the 'fixed-ram'
> capability.
>
> One of the more notable changes in behavior is that in the 'fixed-ram'
> case ram pages are restored in one go rather than constantly looping
> through the migration stream.
>
> Signed-off-by: Nikolay Borisov <nbori...@suse.com>
> Signed-off-by: Fabiano Rosas <faro...@suse.de>
> ---
> (farosas) reused more of the common code by making the fixed-ram
> function take only one ramblock and calling it from inside
> parse_ramblock.
> ---
> migration/ram.c | 93 +++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 93 insertions(+)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index 152a03604f..cea6971ab2 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -3032,6 +3032,32 @@ static void fixed_ram_insert_header(QEMUFile *file,
> RAMBlock *block)
> qemu_put_buffer(file, (uint8_t *) header, header_size);
> }
>
> +static int fixed_ram_read_header(QEMUFile *file, struct FixedRamHeader
> *header)
> +{
> + size_t ret, header_size = sizeof(struct FixedRamHeader);
> +
> + ret = qemu_get_buffer(file, (uint8_t *)header, header_size);
> + if (ret != header_size) {
> + return -1;
> + }
> +
> + /* migration stream is big-endian */
> + be32_to_cpus(&header->version);
> +
> + if (header->version > FIXED_RAM_HDR_VERSION) {
> + error_report("Migration fixed-ram capability version mismatch
> (expected %d, got %d)",
> + FIXED_RAM_HDR_VERSION, header->version);
I know it doesn't matter a lot for now, but it'll be good to start using
Error** in new codes?
> + return -1;
> + }
> +
> + be64_to_cpus(&header->page_size);
> + be64_to_cpus(&header->bitmap_offset);
> + be64_to_cpus(&header->pages_offset);
> +
> +
> + return 0;
> +}
> +
> /*
> * Each of ram_save_setup, ram_save_iterate and ram_save_complete has
> * long-running RCU critical section. When rcu-reclaims in the code
> @@ -3932,6 +3958,68 @@ void colo_flush_ram_cache(void)
> trace_colo_flush_ram_cache_end();
> }
>
> +static void read_ramblock_fixed_ram(QEMUFile *f, RAMBlock *block,
> + long num_pages, unsigned long *bitmap)
> +{
> + unsigned long set_bit_idx, clear_bit_idx;
> + unsigned long len;
> + ram_addr_t offset;
> + void *host;
> + size_t read, completed, read_len;
> +
> + 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);
> +
> + len = TARGET_PAGE_SIZE * (clear_bit_idx - set_bit_idx);
> + offset = set_bit_idx << TARGET_PAGE_BITS;
> +
> + for (read = 0, completed = 0; completed < len; offset += read) {
> + host = host_from_ram_block_offset(block, offset);
> + read_len = MIN(len, TARGET_PAGE_SIZE);
Why MIN()? I didn't read qemu_get_buffer_at() yet, but shouldn't len
always be multiple of target page size or zero?
> +
> + read = qemu_get_buffer_at(f, host, read_len,
> + block->pages_offset + offset);
> + completed += read;
> + }
> + }
> +}
> +
> +static int parse_ramblock_fixed_ram(QEMUFile *f, RAMBlock *block, ram_addr_t
> length)
> +{
> + g_autofree unsigned long *bitmap = NULL;
> + struct FixedRamHeader header;
> + size_t bitmap_size;
> + long num_pages;
> + int ret = 0;
> +
> + ret = fixed_ram_read_header(f, &header);
> + if (ret < 0) {
> + error_report("Error reading fixed-ram header");
Same here on error handling; suggest to use Error** from the start.
> + return -EINVAL;
> + }
> +
> + block->pages_offset = header.pages_offset;
> + 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_report("Error parsing dirty bitmap");
> + return -EINVAL;
> + }
> +
> + read_ramblock_fixed_ram(f, block, num_pages, bitmap);
> +
> + /* Skip pages array */
> + qemu_set_offset(f, block->pages_offset + length, SEEK_SET);
> +
> + return ret;
> +}
> +
> static int parse_ramblock(QEMUFile *f, RAMBlock *block, ram_addr_t length)
> {
> int ret = 0;
> @@ -3940,6 +4028,10 @@ static int parse_ramblock(QEMUFile *f, RAMBlock
> *block, ram_addr_t length)
>
> assert(block);
>
> + if (migrate_fixed_ram()) {
> + return parse_ramblock_fixed_ram(f, block, length);
> + }
> +
> if (!qemu_ram_is_migratable(block)) {
> error_report("block %s should not be migrated !", block->idstr);
> return -EINVAL;
> @@ -4142,6 +4234,7 @@ static int ram_load_precopy(QEMUFile *f)
> migrate_multifd_flush_after_each_section()) {
> multifd_recv_sync_main();
> }
> +
> break;
> case RAM_SAVE_FLAG_HOOK:
> ret = rdma_registration_handle(f);
> --
> 2.35.3
>
--
Peter Xu
