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bh=wOw9cV6G1FdBgmpEqntI7YB8cm83Rvin9BHTLXvzNUg=; b=JR2DxA8wSjPP2v5TDtBGnmSYWf77buhtC2BYYLAvFo3weRlHwi7SY2uYzhs96N6Kd31WLP uRNWAA2K0d4NR47CIJASwa9iPfY5TBYoTbEh2uAggtOIFj99iZCI2tsEbgQeh35ONyUMg4 /Ywn74p673c1sGAJ13myORiYNceDp58= X-MC-Unique: k8h3Ra-WMguixpHVj4FoTA-1 From: peterx@redhat.com To: qemu-devel@nongnu.org, Peter Maydell Cc: peterx@redhat.com, =?UTF-8?q?Daniel=20P=20=2E=20Berrang=C3=A9?= , Prasad Pandit , Fabiano Rosas , Nikolay Borisov Subject: [PULL 12/27] migration/ram: Add outgoing 'mapped-ram' migration Date: Mon, 4 Mar 2024 09:26:19 +0800 Message-ID: <20240304012634.95520-13-peterx@redhat.com> In-Reply-To: <20240304012634.95520-1-peterx@redhat.com> References: <20240304012634.95520-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.589, 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=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01, T_SPF_HELO_TEMPERROR=0.01 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: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1709515761213100001 Content-Type: text/plain; charset="utf-8" From: Fabiano Rosas Implement the outgoing migration side for the 'mapped-ram' capability. A bitmap is introduced to track which pages have been written in the migration file. Pages are written at a fixed location for every ramblock. Zero pages are ignored as they'd be zero in the destination migration as well. The migration stream is altered to put the dirty pages for a ramblock after its header instead of having a sequential stream of pages that follow the ramblock headers. Without mapped-ram (current): With mapped-ram (new): --------------------- -------------------------------- | ramblock 1 header | | ramblock 1 header | --------------------- -------------------------------- | ramblock 2 header | | ramblock 1 mapped-ram header | --------------------- -------------------------------- | ... | | padding to next 1MB boundary | --------------------- | ... | | ramblock n header | -------------------------------- --------------------- | ramblock 1 pages | | RAM_SAVE_FLAG_EOS | | ... | --------------------- -------------------------------- | stream of pages | | ramblock 2 header | | (iter 1) | -------------------------------- | ... | | ramblock 2 mapped-ram header | --------------------- -------------------------------- | RAM_SAVE_FLAG_EOS | | padding to next 1MB boundary | --------------------- | ... | | stream of pages | -------------------------------- | (iter 2) | | ramblock 2 pages | | ... | | ... | --------------------- -------------------------------- | ... | | ... | --------------------- -------------------------------- | RAM_SAVE_FLAG_EOS | -------------------------------- | ... | -------------------------------- where: - ramblock header: the generic information for a ramblock, such as idstr, used_len, etc. - ramblock mapped-ram header: the new information added by this feature: bitmap of pages written, bitmap size and offset of pages in the migration file. Signed-off-by: Nikolay Borisov Reviewed-by: Peter Xu Signed-off-by: Fabiano Rosas Link: https://lore.kernel.org/r/20240229153017.2221-10-farosas@suse.de Signed-off-by: Peter Xu --- include/exec/ramblock.h | 13 ++++ migration/ram.c | 131 +++++++++++++++++++++++++++++++++++++--- 2 files changed, 135 insertions(+), 9 deletions(-) diff --git a/include/exec/ramblock.h b/include/exec/ramblock.h index 3eb79723c6..848915ea5b 100644 --- a/include/exec/ramblock.h +++ b/include/exec/ramblock.h @@ -44,6 +44,19 @@ struct RAMBlock { size_t page_size; /* dirty bitmap used during migration */ unsigned long *bmap; + + /* + * Below fields are only used by mapped-ram migration + */ + /* bitmap of pages present in the migration file */ + unsigned long *file_bmap; + /* + * offset in the file pages belonging to this ramblock are saved, + * used only during migration to a file. + */ + off_t bitmap_offset; + uint64_t pages_offset; + /* bitmap of already received pages in postcopy */ unsigned long *receivedmap; =20 diff --git a/migration/ram.c b/migration/ram.c index 45a00b45ed..f807824d49 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -94,6 +94,18 @@ #define RAM_SAVE_FLAG_MULTIFD_FLUSH 0x200 /* We can't use any flag that is bigger than 0x200 */ =20 +/* + * mapped-ram migration supports O_DIRECT, so we need to make sure the + * userspace buffer, the IO operation size and the file offset are + * aligned according to the underlying device's block size. The first + * two are already aligned to page size, but we need to add padding to + * the file to align the offset. We cannot read the block size + * dynamically because the migration file can be moved between + * different systems, so use 1M to cover most block sizes and to keep + * the file offset aligned at page size as well. + */ +#define MAPPED_RAM_FILE_OFFSET_ALIGNMENT 0x100000 + XBZRLECacheStats xbzrle_counters; =20 /* used by the search for pages to send */ @@ -1126,12 +1138,18 @@ static int save_zero_page(RAMState *rs, PageSearchS= tatus *pss, return 0; } =20 + stat64_add(&mig_stats.zero_pages, 1); + + if (migrate_mapped_ram()) { + /* zero pages are not transferred with mapped-ram */ + clear_bit(offset >> TARGET_PAGE_BITS, pss->block->file_bmap); + return 1; + } + len +=3D save_page_header(pss, file, pss->block, offset | RAM_SAVE_FLA= G_ZERO); qemu_put_byte(file, 0); len +=3D 1; ram_release_page(pss->block->idstr, offset); - - stat64_add(&mig_stats.zero_pages, 1); ram_transferred_add(len); =20 /* @@ -1189,14 +1207,20 @@ static int save_normal_page(PageSearchStatus *pss, = RAMBlock *block, { QEMUFile *file =3D pss->pss_channel; =20 - ram_transferred_add(save_page_header(pss, pss->pss_channel, block, - offset | RAM_SAVE_FLAG_PAGE)); - if (async) { - qemu_put_buffer_async(file, buf, TARGET_PAGE_SIZE, - migrate_release_ram() && - migration_in_postcopy()); + if (migrate_mapped_ram()) { + qemu_put_buffer_at(file, buf, TARGET_PAGE_SIZE, + block->pages_offset + offset); + set_bit(offset >> TARGET_PAGE_BITS, block->file_bmap); } else { - qemu_put_buffer(file, buf, TARGET_PAGE_SIZE); + ram_transferred_add(save_page_header(pss, pss->pss_channel, block, + offset | RAM_SAVE_FLAG_PAGE)); + if (async) { + qemu_put_buffer_async(file, buf, TARGET_PAGE_SIZE, + migrate_release_ram() && + migration_in_postcopy()); + } else { + qemu_put_buffer(file, buf, TARGET_PAGE_SIZE); + } } ram_transferred_add(TARGET_PAGE_SIZE); stat64_add(&mig_stats.normal_pages, 1); @@ -2411,6 +2435,8 @@ static void ram_save_cleanup(void *opaque) block->clear_bmap =3D NULL; g_free(block->bmap); block->bmap =3D NULL; + g_free(block->file_bmap); + block->file_bmap =3D NULL; } =20 xbzrle_cleanup(); @@ -2778,6 +2804,9 @@ static void ram_list_init_bitmaps(void) */ block->bmap =3D bitmap_new(pages); bitmap_set(block->bmap, 0, pages); + if (migrate_mapped_ram()) { + block->file_bmap =3D bitmap_new(pages); + } block->clear_bmap_shift =3D shift; block->clear_bmap =3D bitmap_new(clear_bmap_size(pages, shift)= ); } @@ -2915,6 +2944,60 @@ void qemu_guest_free_page_hint(void *addr, size_t le= n) } } =20 +#define MAPPED_RAM_HDR_VERSION 1 +struct MappedRamHeader { + uint32_t version; + /* + * The target's page size, so we know how many pages are in the + * bitmap. + */ + uint64_t page_size; + /* + * The offset in the migration file where the pages bitmap is + * stored. + */ + uint64_t bitmap_offset; + /* + * The offset in the migration file where the actual pages (data) + * are stored. + */ + uint64_t pages_offset; +} QEMU_PACKED; +typedef struct MappedRamHeader MappedRamHeader; + +static void mapped_ram_setup_ramblock(QEMUFile *file, RAMBlock *block) +{ + g_autofree MappedRamHeader *header =3D NULL; + size_t header_size, bitmap_size; + long num_pages; + + header =3D g_new0(MappedRamHeader, 1); + header_size =3D sizeof(MappedRamHeader); + + num_pages =3D block->used_length >> TARGET_PAGE_BITS; + bitmap_size =3D BITS_TO_LONGS(num_pages) * sizeof(unsigned long); + + /* + * Save the file offsets of where the bitmap and the pages should + * go as they are written at the end of migration and during the + * iterative phase, respectively. + */ + block->bitmap_offset =3D qemu_get_offset(file) + header_size; + block->pages_offset =3D ROUND_UP(block->bitmap_offset + + bitmap_size, + MAPPED_RAM_FILE_OFFSET_ALIGNMENT); + + header->version =3D cpu_to_be32(MAPPED_RAM_HDR_VERSION); + header->page_size =3D cpu_to_be64(TARGET_PAGE_SIZE); + header->bitmap_offset =3D cpu_to_be64(block->bitmap_offset); + header->pages_offset =3D cpu_to_be64(block->pages_offset); + + qemu_put_buffer(file, (uint8_t *) header, header_size); + + /* prepare offset for next ramblock */ + qemu_set_offset(file, block->pages_offset + block->used_length, SEEK_S= ET); +} + /* * Each of ram_save_setup, ram_save_iterate and ram_save_complete has * long-running RCU critical section. When rcu-reclaims in the code @@ -2964,6 +3047,10 @@ static int ram_save_setup(QEMUFile *f, void *opaque) if (migrate_ignore_shared()) { qemu_put_be64(f, block->mr->addr); } + + if (migrate_mapped_ram()) { + mapped_ram_setup_ramblock(f, block); + } } } =20 @@ -2997,6 +3084,20 @@ static int ram_save_setup(QEMUFile *f, void *opaque) return qemu_fflush(f); } =20 +static void ram_save_file_bmap(QEMUFile *f) +{ + RAMBlock *block; + + RAMBLOCK_FOREACH_MIGRATABLE(block) { + long num_pages =3D block->used_length >> TARGET_PAGE_BITS; + long bitmap_size =3D BITS_TO_LONGS(num_pages) * sizeof(unsigned lo= ng); + + qemu_put_buffer_at(f, (uint8_t *)block->file_bmap, bitmap_size, + block->bitmap_offset); + ram_transferred_add(bitmap_size); + } +} + /** * ram_save_iterate: iterative stage for migration * @@ -3186,6 +3287,18 @@ static int ram_save_complete(QEMUFile *f, void *opaq= ue) return ret; } =20 + if (migrate_mapped_ram()) { + ram_save_file_bmap(f); + + if (qemu_file_get_error(f)) { + Error *local_err =3D NULL; + int err =3D qemu_file_get_error_obj(f, &local_err); + + error_reportf_err(local_err, "Failed to write bitmap to file: = "); + return -err; + } + } + if (migrate_multifd() && !migrate_multifd_flush_after_each_section()) { qemu_put_be64(f, RAM_SAVE_FLAG_MULTIFD_FLUSH); } --=20 2.44.0