From patchwork Thu Jan 5 12:45:27 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13089783 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 948C5C3DA7D for ; Thu, 5 Jan 2023 12:46:49 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pDPd6-0000dA-0D; Thu, 05 Jan 2023 07:45:56 -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 1pDPcv-0000YW-13 for qemu-devel@nongnu.org; Thu, 05 Jan 2023 07:45:45 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pDPcr-0005ob-9y for qemu-devel@nongnu.org; Thu, 05 Jan 2023 07:45:44 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1672922740; 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=OKjPvhnoNBzLZXaSESBUhCck4dzrCgas7ZbjAuGp4CU=; b=GlhMQfbwSGtF3nYtz+BNXDoKTZGGdFD9yppc4NbH/+CHgL5/V0lj/uUtJQf1El3sTfnlYp DbCCeJbTOCik22XkPIcddYb1a+auV6Xh+iNDIZa+/KThjA2bej/cQL/l2/faTJEkBTEiat aiBY9Y9DSfCPf4okU8x1MD7sixVCJw8= 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-297-15utGDaQMXqAuac0AH87-A-1; Thu, 05 Jan 2023 07:45:38 -0500 X-MC-Unique: 15utGDaQMXqAuac0AH87-A-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8706D3C0D18E; Thu, 5 Jan 2023 12:45:38 +0000 (UTC) Received: from t480s.redhat.com (unknown [10.39.192.193]) by smtp.corp.redhat.com (Postfix) with ESMTP id 514D01121314; Thu, 5 Jan 2023 12:45:37 +0000 (UTC) From: David Hildenbrand To: qemu-devel@nongnu.org Cc: David Hildenbrand , Juan Quintela , "Dr. David Alan Gilbert" , Peter Xu , Andrey Gruzdev Subject: [PATCH v1 4/5] migration/ram: Rely on used_length for uffd_change_protection() Date: Thu, 5 Jan 2023 13:45:27 +0100 Message-Id: <20230105124528.93813-5-david@redhat.com> In-Reply-To: <20230105124528.93813-1-david@redhat.com> References: <20230105124528.93813-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 Received-SPF: pass client-ip=170.10.129.124; envelope-from=david@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=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 ram_mig_ram_block_resized() will abort migration (including background snapshots) when resizing a RAMBlock. ram_block_populate_read() will only populate RAM up to used_length, so at least for anonymous memory protecting everything between used_length and max_length won't actually be protected and is just a NOP. So let's only protect everything up to used_length. Note: it still makes sense to register uffd-wp for max_length, such that RAM_UF_WRITEPROTECT is independent of a changing used_length. Signed-off-by: David Hildenbrand Reviewed-by: Juan Quintela --- migration/ram.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/migration/ram.c b/migration/ram.c index 6a3dbee2c3..73a443f683 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1901,7 +1901,7 @@ int ram_write_tracking_start(void) /* Apply UFFD write protection to the block memory range */ if (uffd_change_protection(rs->uffdio_fd, block->host, - block->max_length, true, false)) { + block->used_length, true, false)) { goto fail; }