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Wed, 25 Oct 2023 09:43:17 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.154]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 36F64492BD9; Wed, 25 Oct 2023 09:43:16 +0000 (UTC) Date: Wed, 25 Oct 2023 10:43:14 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Fabiano Rosas Cc: qemu-devel@nongnu.org, armbru@redhat.com, Juan Quintela , Peter Xu , Leonardo Bras , Claudio Fontana , Nikolay Borisov Subject: Re: [PATCH v2 16/29] migration/ram: Add support for 'fixed-ram' migration restore Message-ID: References: <20231023203608.26370-1-farosas@suse.de> <20231023203608.26370-17-farosas@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20231023203608.26370-17-farosas@suse.de> User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, Oct 23, 2023 at 05:35:55PM -0300, Fabiano Rosas wrote: > From: Nikolay Borisov > > 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 > Signed-off-by: Fabiano Rosas > --- > (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); > + 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); > + > + 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"); > + return -EINVAL; > + } > + > + block->pages_offset = header.pages_offset; Do you think it is worth sanity checking that 'pages_offset' is aligned in some way. It is nice that we have flexibility to change the alignment in future if we find 1 MB is not optimal, so I wouldn't want to force 1MB align check htere. Perhaps we could at least sanity check for alignment at TARGET_PAGE_SIZE, to detect a gross data corruption problem ? > + 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"); s/parsing/reading/ since we're not actually parsing any semantic info here. > + 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; Spurious whitespace > case RAM_SAVE_FLAG_HOOK: > ret = rdma_registration_handle(f); > -- > 2.35.3 > With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|