From mboxrd@z Thu Jan 1 00:00:00 1970 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 DB398C3601E for ; Thu, 10 Apr 2025 19:53:27 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1u2xxC-0003fi-Sf; Thu, 10 Apr 2025 15:52:51 -0400 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 1u2xxB-0003fT-3c for qemu-devel@nongnu.org; Thu, 10 Apr 2025 15:52:49 -0400 Received: from smtp-out1.suse.de ([195.135.223.130]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1u2xx9-0006vS-47 for qemu-devel@nongnu.org; Thu, 10 Apr 2025 15:52:48 -0400 Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 2D2982116A; Thu, 10 Apr 2025 19:52:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1744314765; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=5d2G4DBeuxDoXFNOhHrKGl+xmEH0uvr9hvSPkQvYZZU=; b=Zva2LSt/4EFC63ieeT4Dk+G2SHqBZfiBe4j5yTkT6EjrHzKB8ytVnSEfib8wlmgpyTC7Su Pu0B53h8hL1XE811j0PFgOvklGzlAAF+lPZNlhsrY8r/nWE70DAYW83UtZcN0leFF4P0GF hpZ4L/UvHxmQa/H6rjbFCQfgmmHhqKc= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1744314765; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=5d2G4DBeuxDoXFNOhHrKGl+xmEH0uvr9hvSPkQvYZZU=; b=ulBcRe8C/K30vTgYnOnPxU6Rqsf7BNHJMjqjfw/L/sQkBuWwZzffA5r/detI4sW1hQ5eUY eg7xUfIguiLt41DQ== Authentication-Results: smtp-out1.suse.de; dkim=pass header.d=suse.de header.s=susede2_rsa header.b="Zva2LSt/"; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=ulBcRe8C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1744314765; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=5d2G4DBeuxDoXFNOhHrKGl+xmEH0uvr9hvSPkQvYZZU=; b=Zva2LSt/4EFC63ieeT4Dk+G2SHqBZfiBe4j5yTkT6EjrHzKB8ytVnSEfib8wlmgpyTC7Su Pu0B53h8hL1XE811j0PFgOvklGzlAAF+lPZNlhsrY8r/nWE70DAYW83UtZcN0leFF4P0GF hpZ4L/UvHxmQa/H6rjbFCQfgmmHhqKc= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1744314765; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=5d2G4DBeuxDoXFNOhHrKGl+xmEH0uvr9hvSPkQvYZZU=; b=ulBcRe8C/K30vTgYnOnPxU6Rqsf7BNHJMjqjfw/L/sQkBuWwZzffA5r/detI4sW1hQ5eUY eg7xUfIguiLt41DQ== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 99439132D8; Thu, 10 Apr 2025 19:52:44 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 4tWiFYwh+GfPWwAAD6G6ig (envelope-from ); Thu, 10 Apr 2025 19:52:44 +0000 From: Fabiano Rosas To: Marco Cavenati , Peter Xu Cc: qemu-devel@nongnu.org, Marco Cavenati , Daniel P. =?utf-8?Q?Berrang=C3=A9?= , Prasad Pandit Subject: Re: [PATCH] migration: add FEATURE_SEEKABLE to QIOChannelBlock In-Reply-To: <20250327141451.163744-3-Marco.Cavenati@eurecom.fr> References: <20250327141451.163744-3-Marco.Cavenati@eurecom.fr> Date: Thu, 10 Apr 2025 16:52:41 -0300 Message-ID: <87jz7rhjzq.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Queue-Id: 2D2982116A X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; MISSING_XM_UA(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCPT_COUNT_FIVE(0.00)[6]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:dkim,suse.de:mid,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action Received-SPF: pass client-ip=195.135.223.130; envelope-from=farosas@suse.de; helo=smtp-out1.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Marco Cavenati writes: > Enable the use of the mapped-ram migration feature with savevm/loadvm > snapshots by adding the QIO_CHANNEL_FEATURE_SEEKABLE feature to > QIOChannelBlock. Implement io_preadv and io_pwritev methods to provide > positioned I/O capabilities that don't modify the channel's position > pointer. We'll need to add the infrastructure to reject multifd and direct-io before this. The rest of the capabilities should not affect mapped-ram, so it's fine (for now) if we don't honor them. What about zero page handling? Mapped-ram doesn't send zero pages because the file will always have zeroes in it and the migration destination is guaranteed to not have been running previously. I believe loading a snapshot in a VM that's already been running would leave stale data in the guest's memory. > > Signed-off-by: Marco Cavenati > --- > Hello, > Please note that this depends on my previous fix [0] (which has already > been reviewed) in order to work. > > The code in this patch is inspired by commit > 0478b030fa2530cbbfc4d6432e8e39a16d06865b that adds the same feature to > QIOChannelFile. > > Thank you, > Regards > Marco > > [0] [PATCH] migration: fix SEEK_CUR offset calculation in > qio_channel_block_seek https://lore.kernel.org/all/20250326162230.3323199-1-Marco.Cavenati@eurecom.fr/t/#u > --- > migration/channel-block.c | 48 +++++++++++++++++++++++++++++++++++++++ > 1 file changed, 48 insertions(+) > > diff --git a/migration/channel-block.c b/migration/channel-block.c > index fff8d87094..741cf6f31b 100644 > --- a/migration/channel-block.c > +++ b/migration/channel-block.c > @@ -30,6 +30,7 @@ qio_channel_block_new(BlockDriverState *bs) > QIOChannelBlock *ioc; > > ioc = QIO_CHANNEL_BLOCK(object_new(TYPE_QIO_CHANNEL_BLOCK)); > + qio_channel_set_feature(QIO_CHANNEL(ioc), QIO_CHANNEL_FEATURE_SEEKABLE); > > bdrv_ref(bs); > ioc->bs = bs; > @@ -96,6 +97,49 @@ qio_channel_block_writev(QIOChannel *ioc, > return qiov.size; > } > > +#ifdef CONFIG_PREADV > +static ssize_t > +qio_channel_block_preadv(QIOChannel *ioc, > + const struct iovec *iov, > + size_t niov, > + off_t offset, > + Error **errp) > +{ > + QIOChannelBlock *bioc = QIO_CHANNEL_BLOCK(ioc); > + QEMUIOVector qiov; > + int ret; > + > + qemu_iovec_init_external(&qiov, (struct iovec *)iov, niov); > + ret = bdrv_readv_vmstate(bioc->bs, &qiov, offset); > + if (ret < 0) { > + error_setg_errno(errp, -ret, "bdrv_readv_vmstate failed"); > + return -1; > + } > + > + return qiov.size; > +} > + > +static ssize_t > +qio_channel_block_pwritev(QIOChannel *ioc, > + const struct iovec *iov, > + size_t niov, > + off_t offset, > + Error **errp) > +{ > + QIOChannelBlock *bioc = QIO_CHANNEL_BLOCK(ioc); > + QEMUIOVector qiov; > + int ret; > + > + qemu_iovec_init_external(&qiov, (struct iovec *)iov, niov); > + ret = bdrv_writev_vmstate(bioc->bs, &qiov, offset); > + if (ret < 0) { > + error_setg_errno(errp, -ret, "bdrv_writev_vmstate failed"); > + return -1; > + } > + > + return qiov.size; > +} > +#endif /* CONFIG_PREADV */ > > static int > qio_channel_block_set_blocking(QIOChannel *ioc, > @@ -177,6 +221,10 @@ qio_channel_block_class_init(ObjectClass *klass, > ioc_klass->io_writev = qio_channel_block_writev; > ioc_klass->io_readv = qio_channel_block_readv; > ioc_klass->io_set_blocking = qio_channel_block_set_blocking; > +#ifdef CONFIG_PREADV > + ioc_klass->io_preadv = qio_channel_block_preadv; > + ioc_klass->io_pwritev = qio_channel_block_pwritev; > +#endif > ioc_klass->io_seek = qio_channel_block_seek; > ioc_klass->io_close = qio_channel_block_close; > ioc_klass->io_set_aio_fd_handler = qio_channel_block_set_aio_fd_handler;