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 34674C54EED for ; Mon, 30 Jan 2023 08:05:12 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pMP8c-0001zT-Tp; Mon, 30 Jan 2023 03:03:38 -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 1pMP8V-0001v0-T7 for qemu-devel@nongnu.org; Mon, 30 Jan 2023 03:03:35 -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 1pMP8S-0000zd-T5 for qemu-devel@nongnu.org; Mon, 30 Jan 2023 03:03:31 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675065808; 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=4tyAthjyAJfKR2wxZiLS098ns/1BTHiWpLuviegbRVQ=; b=IwXtxiNXunALCe6SVl3BofNcL7hhpIkQm8J1k2LtxJqwaJ4HJhqIkb/xAgPl5BUv6V48AI QVmpQBACeC1fTW8/hsr5O2oZTpip4TxI1R2WW0cgDKiE5gWLbHi1OWDwctVR5Vz/ukG/ep ANeDHWVmTbb6R/toHGoFsa9o2p4lGno= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-244-gYtDPhBUN9SHgDG6LCXfmQ-1; Mon, 30 Jan 2023 03:03:16 -0500 X-MC-Unique: gYtDPhBUN9SHgDG6LCXfmQ-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C33EA381458C; Mon, 30 Jan 2023 08:03:15 +0000 (UTC) Received: from secure.mitica (unknown [10.39.192.57]) by smtp.corp.redhat.com (Postfix) with ESMTP id A0299492B01; Mon, 30 Jan 2023 08:03:12 +0000 (UTC) From: Juan Quintela To: qemu-devel@nongnu.org Cc: Eric Blake , John Snow , Richard Henderson , Fam Zheng , Christian Borntraeger , Thomas Huth , Alex Williamson , "Dr. David Alan Gilbert" , Stefan Hajnoczi , qemu-s390x@nongnu.org, Halil Pasic , Eric Farman , qemu-block@nongnu.org, Vladimir Sementsov-Ogievskiy , David Hildenbrand , Juan Quintela , Ilya Leoshkevich , Peter Xu , qemu-stable@nongnu.org Subject: [PULL 1/5] migration: Fix migration crash when target psize larger than host Date: Mon, 30 Jan 2023 09:03:03 +0100 Message-Id: <20230130080307.1792-2-quintela@redhat.com> In-Reply-To: <20230130080307.1792-1-quintela@redhat.com> References: <20230130080307.1792-1-quintela@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 Received-SPF: pass client-ip=170.10.133.124; envelope-from=quintela@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_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: Peter Xu Commit d9e474ea56 overlooked the case where the target psize is even larger than the host psize. One example is Alpha has 8K page size and migration will start to crash the source QEMU when running Alpha migration on x86. Fix it by detecting that case and set host start/end just to cover the single page to be migrated. This will slightly optimize the common case where host psize equals to guest psize so we don't even need to do the roundups, but that's trivial. Cc: qemu-stable@nongnu.org Reported-by: Thomas Huth Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1456 Fixes: d9e474ea56 ("migration: Teach PSS about host page") Signed-off-by: Peter Xu Reviewed-by: Thomas Huth Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela --- migration/ram.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index 334309f1c6..68a45338e3 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -2319,8 +2319,25 @@ static void pss_host_page_prepare(PageSearchStatus *pss) size_t guest_pfns = qemu_ram_pagesize(pss->block) >> TARGET_PAGE_BITS; pss->host_page_sending = true; - pss->host_page_start = ROUND_DOWN(pss->page, guest_pfns); - pss->host_page_end = ROUND_UP(pss->page + 1, guest_pfns); + if (guest_pfns <= 1) { + /* + * This covers both when guest psize == host psize, or when guest + * has larger psize than the host (guest_pfns==0). + * + * For the latter, we always send one whole guest page per + * iteration of the host page (example: an Alpha VM on x86 host + * will have guest psize 8K while host psize 4K). + */ + pss->host_page_start = pss->page; + pss->host_page_end = pss->page + 1; + } else { + /* + * The host page spans over multiple guest pages, we send them + * within the same host page iteration. + */ + pss->host_page_start = ROUND_DOWN(pss->page, guest_pfns); + pss->host_page_end = ROUND_UP(pss->page + 1, guest_pfns); + } } /* -- 2.39.1