From patchwork Mon Mar 4 01:26:19 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Xu X-Patchwork-Id: 13579935 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9E861C48BF6 for ; Mon, 4 Mar 2024 01:29:19 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rgx7L-0001XQ-Pp; Sun, 03 Mar 2024 20:27:48 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rgx7J-0001Vu-Op for qemu-devel@nongnu.org; Sun, 03 Mar 2024 20:27:45 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rgx7D-0002Mw-F8 for qemu-devel@nongnu.org; Sun, 03 Mar 2024 20:27:45 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1709515658; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=wOw9cV6G1FdBgmpEqntI7YB8cm83Rvin9BHTLXvzNUg=; b=JR2DxA8wSjPP2v5TDtBGnmSYWf77buhtC2BYYLAvFo3weRlHwi7SY2uYzhs96N6Kd31WLP uRNWAA2K0d4NR47CIJASwa9iPfY5TBYoTbEh2uAggtOIFj99iZCI2tsEbgQeh35ONyUMg4 /Ywn74p673c1sGAJ13myORiYNceDp58= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-490-k8h3Ra-WMguixpHVj4FoTA-1; Sun, 03 Mar 2024 20:27:35 -0500 X-MC-Unique: k8h3Ra-WMguixpHVj4FoTA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id A9AF487A9EC; Mon, 4 Mar 2024 01:27:34 +0000 (UTC) Received: from x1n.redhat.com (unknown [10.72.116.2]) by smtp.corp.redhat.com (Postfix) with ESMTP id 319A940C6EBA; Mon, 4 Mar 2024 01:27:30 +0000 (UTC) From: peterx@redhat.com To: qemu-devel@nongnu.org, Peter Maydell Cc: peterx@redhat.com, =?utf-8?q?Daniel_P_=2E_Berrang=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 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org 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; 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 */ +/* + * 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; /* used by the search for pages to send */ @@ -1126,12 +1138,18 @@ static int save_zero_page(RAMState *rs, PageSearchStatus *pss, return 0; } + 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 += save_page_header(pss, file, pss->block, offset | RAM_SAVE_FLAG_ZERO); qemu_put_byte(file, 0); len += 1; ram_release_page(pss->block->idstr, offset); - - stat64_add(&mig_stats.zero_pages, 1); ram_transferred_add(len); /* @@ -1189,14 +1207,20 @@ static int save_normal_page(PageSearchStatus *pss, RAMBlock *block, { QEMUFile *file = pss->pss_channel; - 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 = NULL; g_free(block->bmap); block->bmap = NULL; + g_free(block->file_bmap); + block->file_bmap = NULL; } xbzrle_cleanup(); @@ -2778,6 +2804,9 @@ static void ram_list_init_bitmaps(void) */ block->bmap = bitmap_new(pages); bitmap_set(block->bmap, 0, pages); + if (migrate_mapped_ram()) { + block->file_bmap = bitmap_new(pages); + } block->clear_bmap_shift = shift; block->clear_bmap = bitmap_new(clear_bmap_size(pages, shift)); } @@ -2915,6 +2944,60 @@ void qemu_guest_free_page_hint(void *addr, size_t len) } } +#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 = NULL; + size_t header_size, bitmap_size; + long num_pages; + + header = g_new0(MappedRamHeader, 1); + header_size = sizeof(MappedRamHeader); + + num_pages = block->used_length >> TARGET_PAGE_BITS; + bitmap_size = 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 = qemu_get_offset(file) + header_size; + block->pages_offset = ROUND_UP(block->bitmap_offset + + bitmap_size, + MAPPED_RAM_FILE_OFFSET_ALIGNMENT); + + header->version = cpu_to_be32(MAPPED_RAM_HDR_VERSION); + header->page_size = cpu_to_be64(TARGET_PAGE_SIZE); + header->bitmap_offset = cpu_to_be64(block->bitmap_offset); + header->pages_offset = 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_SET); +} + /* * 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); + } } } @@ -2997,6 +3084,20 @@ static int ram_save_setup(QEMUFile *f, void *opaque) return qemu_fflush(f); } +static void ram_save_file_bmap(QEMUFile *f) +{ + RAMBlock *block; + + RAMBLOCK_FOREACH_MIGRATABLE(block) { + long num_pages = block->used_length >> TARGET_PAGE_BITS; + long bitmap_size = BITS_TO_LONGS(num_pages) * sizeof(unsigned long); + + 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 *opaque) return ret; } + if (migrate_mapped_ram()) { + ram_save_file_bmap(f); + + if (qemu_file_get_error(f)) { + Error *local_err = NULL; + int err = 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); }