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 7A226C05027 for ; Tue, 7 Feb 2023 00:58:15 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pPCIw-0003CM-WA; Mon, 06 Feb 2023 19:57:51 -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 1pPCIv-0003BZ-S2 for qemu-devel@nongnu.org; Mon, 06 Feb 2023 19:57:49 -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 1pPCIu-0003hZ-9w for qemu-devel@nongnu.org; Mon, 06 Feb 2023 19:57:49 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675731466; 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=qzSBIR6LRz6N4Dl8hXA3eueT1HX6gOU9Tw+HrG3oo/w=; b=HK4nUVmS3MeObKUt56U9uuMMKIjvvuraCn4e0QdLQWX6PPO2+Xngf8IJETP10dv7lqO606 7n1WurIt4NQOH68XTYnnqnywBxWm0KcV3HwSoHxK2iti0NthrmqPhoICmJIEQ3iOk/Cn6k JYFxCBQRjt0ZAPuza8QcMR3mJKvcZ/M= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-657-GR52TcoOO6qY4ikAJib3BQ-1; Mon, 06 Feb 2023 19:57:43 -0500 X-MC-Unique: GR52TcoOO6qY4ikAJib3BQ-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 9F65A85A588; Tue, 7 Feb 2023 00:57:42 +0000 (UTC) Received: from secure.mitica (unknown [10.39.192.29]) by smtp.corp.redhat.com (Postfix) with ESMTP id DAF28492C3C; Tue, 7 Feb 2023 00:57:37 +0000 (UTC) From: Juan Quintela To: qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, Stefan Berger , Stefan Hajnoczi , Halil Pasic , John Snow , David Hildenbrand , Fam Zheng , Thomas Huth , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , Laurent Vivier , Vladimir Sementsov-Ogievskiy , qemu-s390x@nongnu.org, Christian Borntraeger , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , "Michael S. Tsirkin" , Juan Quintela , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , "Dr. David Alan Gilbert" , Marcel Apfelbaum , Coiby Xu , Ilya Leoshkevich , Eduardo Habkost , Yanan Wang , Richard Henderson , Markus Armbruster , Paolo Bonzini , Alex Williamson , Eric Blake , Eric Farman , Peter Xu Subject: [PULL 09/30] migration/ram: Don't explicitly unprotect when unregistering uffd-wp Date: Tue, 7 Feb 2023 01:56:29 +0100 Message-Id: <20230207005650.1810-10-quintela@redhat.com> In-Reply-To: <20230207005650.1810-1-quintela@redhat.com> References: <20230207005650.1810-1-quintela@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Received-SPF: pass client-ip=170.10.129.124; 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: David Hildenbrand When unregistering uffd-wp, older kernels before commit f369b07c86143 ("mm/uffd:reset write protection when unregister with wp-mode") won't clear the uffd-wp PTE bit. When re-registering uffd-wp, the previous uffd-wp PTE bits would trigger again. With above commit, the kernel will clear the uffd-wp PTE bits when unregistering itself. Consequently, we'll clear the uffd-wp PTE bits now twice -- whereby we don't care about clearing them at all: a new background snapshot will re-register uffd-wp and re-protect all memory either way. So let's skip the manual clearing of uffd-wp. If ever relevant, we could clear conditionally in uffd_unregister_memory() -- we just need a way to figure out more recent kernels. Reviewed-by: Peter Xu Reviewed-by: Juan Quintela Signed-off-by: David Hildenbrand Signed-off-by: Juan Quintela --- migration/ram.c | 9 --------- 1 file changed, 9 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index 73e5ca93e5..efaae07dd8 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1918,12 +1918,6 @@ fail: if ((block->flags & RAM_UF_WRITEPROTECT) == 0) { continue; } - /* - * In case some memory block failed to be write-protected - * remove protection and unregister all succeeded RAM blocks - */ - uffd_change_protection(rs->uffdio_fd, block->host, block->max_length, - false, false); uffd_unregister_memory(rs->uffdio_fd, block->host, block->max_length); /* Cleanup flags and remove reference */ block->flags &= ~RAM_UF_WRITEPROTECT; @@ -1949,9 +1943,6 @@ void ram_write_tracking_stop(void) if ((block->flags & RAM_UF_WRITEPROTECT) == 0) { continue; } - /* Remove protection and unregister all affected RAM blocks */ - uffd_change_protection(rs->uffdio_fd, block->host, block->max_length, - false, false); uffd_unregister_memory(rs->uffdio_fd, block->host, block->max_length); trace_ram_write_tracking_ramblock_stop(block->idstr, block->page_size, -- 2.39.1