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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 78C8AC433F5 for ; Mon, 11 Oct 2021 18:14:28 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 3E71760F11 for ; Mon, 11 Oct 2021 18:14:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 3E71760F11 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:33122 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mZzoh-00049U-Bn for qemu-devel@archiver.kernel.org; Mon, 11 Oct 2021 14:14:27 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60328) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mZzYw-0002n5-Md for qemu-devel@nongnu.org; Mon, 11 Oct 2021 13:58:10 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:46185) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mZzYu-0004Iq-Uw for qemu-devel@nongnu.org; Mon, 11 Oct 2021 13:58:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1633975088; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=io/zt988Dg8S6Zu9Ne0KKC+57ohEf+yYEI9rI8GQI+c=; b=fVMVtoslXas2tIoU0vhi1JbIid5hqwj00+pZypgpCAU6olZtGUyEX5G+r+v2uTlDt4JUoo wldmBLHTyRu4t6A2S97T9yy/APUdEboDNUtQPgBeiF60VzXdmTkIj6Y+GUabigBUQgSUn3 wpjZ/c1wpmIeqmL1hPDRWssH4QUWd4Y= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-317-L8EfT7s8PgWm6hHF8aL-xA-1; Mon, 11 Oct 2021 13:58:05 -0400 X-MC-Unique: L8EfT7s8PgWm6hHF8aL-xA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 109CA801A92; Mon, 11 Oct 2021 17:58:04 +0000 (UTC) Received: from t480s.redhat.com (unknown [10.39.192.99]) by smtp.corp.redhat.com (Postfix) with ESMTP id E5C6319E7E; Mon, 11 Oct 2021 17:57:33 +0000 (UTC) From: David Hildenbrand To: qemu-devel@nongnu.org Subject: [PATCH v1 8/9] migration/ram: Factor out populating pages readable in ram_block_populate_pages() Date: Mon, 11 Oct 2021 19:53:45 +0200 Message-Id: <20211011175346.15499-9-david@redhat.com> In-Reply-To: <20211011175346.15499-1-david@redhat.com> References: <20211011175346.15499-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII" Received-SPF: pass client-ip=216.205.24.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.049, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eduardo Habkost , "Michael S. Tsirkin" , Pankaj Gupta , Juan Quintela , David Hildenbrand , "Dr. David Alan Gilbert" , Peter Xu , Marek Kedzierski , Alex Williamson , teawater , Paolo Bonzini , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Andrey Gruzdev , Wei Yang Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Let's factor out prefaulting/populating to make further changes easier to review and add a comment what we are actually expecting to happen. While at it, use the actual page size of the ramblock, which defaults to qemu_real_host_page_size for anonymous memory. Further, rename ram_block_populate_pages() to ram_block_populate_read() as well, to make it clearer what we are doing. In the future, we might want to use MADV_POPULATE_READ to speed up population. Reviewed-by: Peter Xu Signed-off-by: David Hildenbrand --- migration/ram.c | 35 ++++++++++++++++++++++------------- 1 file changed, 22 insertions(+), 13 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index b225ec7507..c212081f85 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1639,26 +1639,35 @@ out: return ret; } +static inline void populate_read_range(RAMBlock *block, ram_addr_t offset, + ram_addr_t size) +{ + /* + * We read one byte of each page; this will preallocate page tables if + * required and populate the shared zeropage on MAP_PRIVATE anonymous memory + * where no page was populated yet. This might require adaption when + * supporting other mappings, like shmem. + */ + for (; offset < size; offset += block->page_size) { + char tmp = *((char *)block->host + offset); + + /* Don't optimize the read out */ + asm volatile("" : "+r" (tmp)); + } +} + /* - * ram_block_populate_pages: populate memory in the RAM block by reading - * an integer from the beginning of each page. + * ram_block_populate_read: preallocate page tables and populate pages in the + * RAM block by reading a byte 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. * * @block: RAM block to populate */ -static void ram_block_populate_pages(RAMBlock *block) +static void ram_block_populate_read(RAMBlock *block) { - char *ptr = (char *) block->host; - - for (ram_addr_t offset = 0; offset < block->used_length; - offset += qemu_real_host_page_size) { - char tmp = *(ptr + offset); - - /* Don't optimize the read out */ - asm volatile("" : "+r" (tmp)); - } + populate_read_range(block, 0, block->used_length); } /* @@ -1684,7 +1693,7 @@ void ram_write_tracking_prepare(void) * UFFDIO_WRITEPROTECT_MODE_WP mode setting would silently skip * pages with pte_none() entries in page table. */ - ram_block_populate_pages(block); + ram_block_populate_read(block); } } -- 2.31.1