From nobody Sat May 4 20:01:54 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=virtuozzo.com ARC-Seal: i=1; a=rsa-sha256; t=1617206003; cv=none; d=zohomail.com; s=zohoarc; b=NFvGcLGPvLXi9FD6JuyXEuLaT8L8yEIbMMS3aXR0U2eoD7ruLyhdEyJUrN9z/1FB2i0Jqv3C6Mc0iK4CrU3q1QiSIvZkeGMmyeDf4iSw3EmZWgTyl117HrQj7cTI+wvyxE0uYgYnsrw6IEoSZClImZ5SPbgrVPlR1DE0Z94xF+w= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1617206003; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=xU32CofsJay/rU4iEOor0ZWeLxqyVfFbC56XhPawbjY=; b=WnMkcq1RvTiIdhNdVkeni6s423itdwaPVvSjjlaR1L/nn/RmXYL4KHpsUomWNuXvmGkddXRM4tOWqkqiPcR11E2ZCDogCpr0kPRkCynlU2Hlv9NlaEmXyz2T8yWUdQrjwtgPKAhOhX+pcm3x5xitw3xZIfQ1Ly9VKOedbF4yYpk= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 16172060039501000.0075243493716; Wed, 31 Mar 2021 08:53:23 -0700 (PDT) Received: from localhost ([::1]:49264 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lRd9m-0007Vg-T7 for importer@patchew.org; Wed, 31 Mar 2021 11:53:22 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60786) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lRd4s-0002eJ-LC for qemu-devel@nongnu.org; Wed, 31 Mar 2021 11:48:18 -0400 Received: from relay.sw.ru ([185.231.240.75]:58774) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lRd4p-0003NE-26 for qemu-devel@nongnu.org; Wed, 31 Mar 2021 11:48:18 -0400 Received: from [192.168.15.162] (helo=andrey-MS-7B54.sw.ru) by relay.sw.ru with esmtp (Exim 4.94) (envelope-from ) id 1lRd4k-000CqQ-En; Wed, 31 Mar 2021 18:48:10 +0300 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=virtuozzo.com; s=relay; h=MIME-Version:Message-Id:Date:Subject:From: Content-Type; bh=xU32CofsJay/rU4iEOor0ZWeLxqyVfFbC56XhPawbjY=; b=c+jUt3t3YQzY bkikmQNJMIor6UHO0UxfxmKX2TOZg+BuknhckneKiO1JlRLUZ8lrn6+J/1yIQbFWAEgzfbRLyd5Sl nsRH7LTbl8R2VAL3cpPxjXnVWAK7alvF0DtiDGCrS0WtGX/dRQNQ5mwCO3WPl56MtT9Q6wgjyJLRw yIxGw=; From: Andrey Gruzdev To: qemu-devel@nongnu.org Cc: Den Lunev , Eric Blake , Paolo Bonzini , Juan Quintela , "Dr . David Alan Gilbert" , Markus Armbruster , Peter Xu , David Hildenbrand , Andrey Gruzdev Subject: [PATCH v2 1/3] migration: Fix missing qemu_fflush() on buffer file in bg_migration_thread Date: Wed, 31 Mar 2021 18:48:07 +0300 Message-Id: <20210331154809.86052-2-andrey.gruzdev@virtuozzo.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210331154809.86052-1-andrey.gruzdev@virtuozzo.com> References: <20210331154809.86052-1-andrey.gruzdev@virtuozzo.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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=185.231.240.75; envelope-from=andrey.gruzdev@virtuozzo.com; helo=relay.sw.ru 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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, 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: 2.1.23 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" X-ZohoMail-DKIM: pass (identity @virtuozzo.com) Content-Type: text/plain; charset="utf-8" Added missing qemu_fflush() on buffer file holding precopy device state. Increased initial QIOChannelBuffer allocation to 512KB to avoid reallocs. Typical configurations often require >200KB for device state and VMDESC. Signed-off-by: Andrey Gruzdev --- migration/migration.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/migration/migration.c b/migration/migration.c index ca8b97baa5..00e13f9d58 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -3812,7 +3812,7 @@ static void *bg_migration_thread(void *opaque) * with vCPUs running and, finally, write stashed non-RAM part of * the vmstate from the buffer to the migration stream. */ - s->bioc =3D qio_channel_buffer_new(128 * 1024); + s->bioc =3D qio_channel_buffer_new(512 * 1024); qio_channel_set_name(QIO_CHANNEL(s->bioc), "vmstate-buffer"); fb =3D qemu_fopen_channel_output(QIO_CHANNEL(s->bioc)); object_unref(OBJECT(s->bioc)); @@ -3866,6 +3866,12 @@ static void *bg_migration_thread(void *opaque) if (qemu_savevm_state_complete_precopy_non_iterable(fb, false, false))= { goto fail; } + /* + * Since we are going to get non-iterable state data directly + * from s->bioc->data, explicit flush is needed here. + */ + qemu_fflush(fb); + /* Now initialize UFFD context and start tracking RAM writes */ if (ram_write_tracking_start()) { goto fail; --=20 2.27.0 From nobody Sat May 4 20:01:54 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=virtuozzo.com ARC-Seal: i=1; a=rsa-sha256; t=1617205822; cv=none; d=zohomail.com; s=zohoarc; b=GoovOgUx6tHUH9AnW79jbVL1aLw0bngTPuahFAXFvfJntlARBHirizAq/ecyD285n1nhppUJ6usHZygYFuw09yKGhH4yND0jYp3dAS0csoyFT6ZS0GKe/NEMiFMatNafVvlcVYf7dOGASeXpI2bUBbK+A1dE9BKUG8BROtjb2Ts= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1617205822; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=x4VDWe6YAqHdgNV8XWbseXtLo9cDhGE9q422M0+V8is=; b=gTVWW3ZeNoPnxOrlupqvP0fvufIcI5wzxnTdVt31SsPzLJlZzepZqwpVHh8D6+CbL6t7E9lV7w8S3zCkfMOsYFLpMhKD58pqV/KA04TTjTKTBbi/evvlYDc0DAsxLXI9DkPinEdvhQF20GrECCl+hxUe7um4j7lqjn/BNhMvsVY= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1617205822509516.2374086713572; Wed, 31 Mar 2021 08:50:22 -0700 (PDT) Received: from localhost ([::1]:42988 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lRd6r-0004lo-BM for importer@patchew.org; Wed, 31 Mar 2021 11:50:21 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60766) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lRd4r-0002cA-Nj for qemu-devel@nongnu.org; Wed, 31 Mar 2021 11:48:17 -0400 Received: from relay.sw.ru ([185.231.240.75]:58772) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lRd4p-0003ND-4A for qemu-devel@nongnu.org; Wed, 31 Mar 2021 11:48:17 -0400 Received: from [192.168.15.162] (helo=andrey-MS-7B54.sw.ru) by relay.sw.ru with esmtp (Exim 4.94) (envelope-from ) id 1lRd4k-000CqQ-IX; Wed, 31 Mar 2021 18:48:10 +0300 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=virtuozzo.com; s=relay; h=MIME-Version:Message-Id:Date:Subject:From: Content-Type; bh=x4VDWe6YAqHdgNV8XWbseXtLo9cDhGE9q422M0+V8is=; b=fx+JhPZ+Ydgf WdVJoavqr9g1pUGjzplz6UnZpQ4RZqHJLZpOBEBQn6rzzEiCVDFTfJ63aurANAoMszWQlorBVZoUF IRCdGC6jE8S+bOr4zLwAyeJgN0/v/apdPR4hgDHWyUtyf8b20Z8CbHa+5FtnzDhkde482AnhJ72yK ug34M=; From: Andrey Gruzdev To: qemu-devel@nongnu.org Cc: Den Lunev , Eric Blake , Paolo Bonzini , Juan Quintela , "Dr . David Alan Gilbert" , Markus Armbruster , Peter Xu , David Hildenbrand , Andrey Gruzdev Subject: [PATCH v2 2/3] migration: Inhibit virtio-balloon for the duration of background snapshot Date: Wed, 31 Mar 2021 18:48:08 +0300 Message-Id: <20210331154809.86052-3-andrey.gruzdev@virtuozzo.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210331154809.86052-1-andrey.gruzdev@virtuozzo.com> References: <20210331154809.86052-1-andrey.gruzdev@virtuozzo.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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=185.231.240.75; envelope-from=andrey.gruzdev@virtuozzo.com; helo=relay.sw.ru 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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, 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: 2.1.23 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" X-ZohoMail-DKIM: pass (identity @virtuozzo.com) Content-Type: text/plain; charset="utf-8" The same thing as for incoming postcopy - we cannot deal with concurrent RAM discards when using background snapshot feature in outgoing migration. Signed-off-by: Andrey Gruzdev Reviewed-by: David Hildenbrand --- hw/virtio/virtio-balloon.c | 8 ++++++-- include/migration/misc.h | 2 ++ migration/migration.c | 8 ++++++++ 3 files changed, 16 insertions(+), 2 deletions(-) diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index e770955176..d120bf8f43 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -66,8 +66,12 @@ static bool virtio_balloon_pbp_matches(PartiallyBalloone= dPage *pbp, =20 static bool virtio_balloon_inhibited(void) { - /* Postcopy cannot deal with concurrent discards, so it's special. */ - return ram_block_discard_is_disabled() || migration_in_incoming_postco= py(); + /* + * Postcopy cannot deal with concurrent discards, + * so it's special, as well as background snapshots. + */ + return ram_block_discard_is_disabled() || migration_in_incoming_postco= py() || + migration_in_bg_snapshot(); } =20 static void balloon_inflate_page(VirtIOBalloon *balloon, diff --git a/include/migration/misc.h b/include/migration/misc.h index bccc1b6b44..738675ef52 100644 --- a/include/migration/misc.h +++ b/include/migration/misc.h @@ -70,6 +70,8 @@ bool migration_in_postcopy_after_devices(MigrationState *= ); void migration_global_dump(Monitor *mon); /* True if incomming migration entered POSTCOPY_INCOMING_DISCARD */ bool migration_in_incoming_postcopy(void); +/* True if background snapshot is active */ +bool migration_in_bg_snapshot(void); =20 /* migration/block-dirty-bitmap.c */ void dirty_bitmap_mig_init(void); diff --git a/migration/migration.c b/migration/migration.c index 00e13f9d58..be4729e7c8 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -1976,6 +1976,14 @@ bool migration_in_incoming_postcopy(void) return ps >=3D POSTCOPY_INCOMING_DISCARD && ps < POSTCOPY_INCOMING_END; } =20 +bool migration_in_bg_snapshot(void) +{ + MigrationState *s =3D migrate_get_current(); + + return migrate_background_snapshot() && + migration_is_setup_or_active(s->state); +} + bool migration_is_idle(void) { MigrationState *s =3D current_migration; --=20 2.27.0 From nobody Sat May 4 20:01:54 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=virtuozzo.com ARC-Seal: i=1; a=rsa-sha256; t=1617206292; cv=none; d=zohomail.com; s=zohoarc; b=GnnIG4B5gB5Txb7lNTK1wDwNaDA/Wqjy3kFYg0+EnWEJVbeo/fXGEwemwmmqEohZDuHGGvqGtnNpZDCuxaDX1B6tnr+n7h8oB+Vli3U/LHgAUGz2S3icrYvFU0iDraH/3FxOo9Ktw8i5Ie5IrYlhK+OR5to58uwBDuT3R7KxmUM= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1617206292; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=1AaVatpZSlATx99e4rvSYANsjd/KI7S4MT1FQQLheok=; b=iAfVDEsUhf1yl4Akg4Xg00p+6ORF/lR3HaCfOyGeU37hnJP4/EyXNJ5ttwCsGvT+eF3Xvpu9KySUGuBrtOe+Nst8q5w+GFUghyw+wHA9oiqROPI4G8C7I6EQiuD5jw41wsWUAPoslJePjFxfKB5FHv6lSunk2WDT6pVzgFuqnNU= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1617206291999944.4852126977534; Wed, 31 Mar 2021 08:58:11 -0700 (PDT) Received: from localhost ([::1]:33384 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lRdER-0004LT-0o for importer@patchew.org; Wed, 31 Mar 2021 11:58:11 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60790) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lRd4s-0002em-TG for qemu-devel@nongnu.org; Wed, 31 Mar 2021 11:48:18 -0400 Received: from relay.sw.ru ([185.231.240.75]:58776) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lRd4p-0003NC-Fl for qemu-devel@nongnu.org; Wed, 31 Mar 2021 11:48:18 -0400 Received: from [192.168.15.162] (helo=andrey-MS-7B54.sw.ru) by relay.sw.ru with esmtp (Exim 4.94) (envelope-from ) id 1lRd4k-000CqQ-Mi; Wed, 31 Mar 2021 18:48:10 +0300 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=virtuozzo.com; s=relay; h=MIME-Version:Message-Id:Date:Subject:From: Content-Type; bh=1AaVatpZSlATx99e4rvSYANsjd/KI7S4MT1FQQLheok=; b=QRJ1oY6XzCu+ 1IBaL7+no9494ZWc1Wrs4hsfAPJjRA6B3TckZZFbzU3XabB9WdZGEiObPkARoKmeKTpKv/Vjp412s 7EVkOKec8e0oYHkiqx9vxvUaLkDBp8WvbFtShvYcYzOILd9IQGiDMBR1fyi24FSH8i1PPvxWI1fNY xNMhs=; From: Andrey Gruzdev To: qemu-devel@nongnu.org Cc: Den Lunev , Eric Blake , Paolo Bonzini , Juan Quintela , "Dr . David Alan Gilbert" , Markus Armbruster , Peter Xu , David Hildenbrand , Andrey Gruzdev Subject: [PATCH v2 3/3] migration: Pre-fault memory before starting background snasphot Date: Wed, 31 Mar 2021 18:48:09 +0300 Message-Id: <20210331154809.86052-4-andrey.gruzdev@virtuozzo.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210331154809.86052-1-andrey.gruzdev@virtuozzo.com> References: <20210331154809.86052-1-andrey.gruzdev@virtuozzo.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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=185.231.240.75; envelope-from=andrey.gruzdev@virtuozzo.com; helo=relay.sw.ru 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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, 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: 2.1.23 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" X-ZohoMail-DKIM: pass (identity @virtuozzo.com) Content-Type: text/plain; charset="utf-8" This commit solves the issue with userfault_fd WP feature that background snapshot is based on. For any never poluated or discarded memory page, the UFFDIO_WRITEPROTECT ioctl() would skip updating PTE for that page, thereby loosing WP setting for it. So we need to pre-fault pages for each RAM block to be protected before making a userfault_fd wr-protect ioctl(). Signed-off-by: Andrey Gruzdev --- migration/migration.c | 6 ++++++ migration/ram.c | 48 +++++++++++++++++++++++++++++++++++++++++++ migration/ram.h | 1 + 3 files changed, 55 insertions(+) diff --git a/migration/migration.c b/migration/migration.c index be4729e7c8..71bce15a1b 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -3827,6 +3827,12 @@ static void *bg_migration_thread(void *opaque) =20 update_iteration_initial_status(s); =20 + /* + * Prepare for tracking memory writes with UFFD-WP - populate + * RAM pages before protecting. + */ + ram_write_tracking_prepare(); + qemu_savevm_state_header(s->to_dst_file); qemu_savevm_state_setup(s->to_dst_file); =20 diff --git a/migration/ram.c b/migration/ram.c index 40e78952ad..24c8627214 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1560,6 +1560,54 @@ out: return ret; } =20 +/* + * ram_block_populate_pages: populate memory in the RAM block by reading + * an integer from the beginning of each page. + * + * Since it's solely used for userfault_fd WP feature, here we just + * hardcode page size to qemu_real_host_page_size. + * + * @bs: RAM block to populate + */ +static void ram_block_populate_pages(RAMBlock *bs) +{ + char *ptr =3D (char *) bs->host; + + for (ram_addr_t offset =3D 0; offset < bs->used_length; + offset +=3D qemu_real_host_page_size) { + char tmp =3D *(ptr + offset); + /* Don't optimize the read out */ + asm volatile("" : "+r" (tmp)); + } +} + +/* + * ram_write_tracking_prepare: prepare for UFFD-WP memory tracking + */ +void ram_write_tracking_prepare(void) +{ + RAMBlock *bs; + + RCU_READ_LOCK_GUARD(); + + RAMBLOCK_FOREACH_NOT_IGNORED(bs) { + /* Nothing to do with read-only and MMIO-writable regions */ + if (bs->mr->readonly || bs->mr->rom_device) { + continue; + } + + /* + * Populate pages of the RAM block before enabling userfault_fd + * write protection. + * + * This stage is required since ioctl(UFFDIO_WRITEPROTECT) with + * UFFDIO_WRITEPROTECT_MODE_WP mode setting would silently skip + * pages with pte_none() entries in page table. + */ + ram_block_populate_pages(bs); + } +} + /* * ram_write_tracking_start: start UFFD-WP memory tracking * diff --git a/migration/ram.h b/migration/ram.h index 6378bb3ebc..4833e9fd5b 100644 --- a/migration/ram.h +++ b/migration/ram.h @@ -82,6 +82,7 @@ void colo_incoming_start_dirty_log(void); /* Background snapshot */ bool ram_write_tracking_available(void); bool ram_write_tracking_compatible(void); +void ram_write_tracking_prepare(void); int ram_write_tracking_start(void); void ram_write_tracking_stop(void); =20 --=20 2.27.0