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 X-Spam-Level: X-Spam-Status: No, score=-12.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7F0E8C433E0 for ; Thu, 16 Jul 2020 08:25:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F482206C1 for ; Thu, 16 Jul 2020 08:25:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726832AbgGPIZL convert rfc822-to-8bit (ORCPT ); Thu, 16 Jul 2020 04:25:11 -0400 Received: from out30-133.freemail.mail.aliyun.com ([115.124.30.133]:50431 "EHLO out30-133.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725922AbgGPIZK (ORCPT ); Thu, 16 Jul 2020 04:25:10 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04357;MF=teawaterz@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0U2shvgI_1594887901; Received: from 127.0.0.1(mailfrom:teawaterz@linux.alibaba.com fp:SMTPD_---0U2shvgI_1594887901) by smtp.aliyun-inc.com(127.0.0.1); Thu, 16 Jul 2020 16:25:05 +0800 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.80.23.2.2\)) Subject: Re: [RFC for Linux v4 1/2] virtio_balloon: Add VIRTIO_BALLOON_F_CONT_PAGES and inflate_cont_vq From: teawater In-Reply-To: <20200716024114-mutt-send-email-mst@kernel.org> Date: Thu, 16 Jul 2020 16:25:00 +0800 Cc: Hui Zhu , David Hildenbrand , Jason Wang , Andrew Morton , Linux Virtualization , linux-kernel@vger.kernel.org, linux-mm@kvack.org, qemu-devel@nongnu.org, virtio-dev@lists.oasis-open.org Content-Transfer-Encoding: 8BIT Message-Id: References: <1594867315-8626-1-git-send-email-teawater@gmail.com> <1594867315-8626-2-git-send-email-teawater@gmail.com> <20200716024114-mutt-send-email-mst@kernel.org> To: "Michael S. Tsirkin" X-Mailer: Apple Mail (2.3608.80.23.2.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > 2020年7月16日 14:43，Michael S. Tsirkin 写道： > > On Thu, Jul 16, 2020 at 10:41:51AM +0800, Hui Zhu wrote: >> diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h >> index dc3e656..4d0151a 100644 >> --- a/include/uapi/linux/virtio_balloon.h >> +++ b/include/uapi/linux/virtio_balloon.h >> @@ -37,6 +37,7 @@ >> #define VIRTIO_BALLOON_F_FREE_PAGE_HINT 3 /* VQ to report free pages */ >> #define VIRTIO_BALLOON_F_PAGE_POISON 4 /* Guest is using page poisoning */ >> #define VIRTIO_BALLOON_F_REPORTING 5 /* Page reporting virtqueue */ >> +#define VIRTIO_BALLOON_F_CONT_PAGES 6 /* VQ to report continuous pages */ >> >> /* Size of a PFN in the balloon interface. */ >> #define VIRTIO_BALLOON_PFN_SHIFT 12 > > So how does the guest/host interface look like? > Could you write up something about it? Continuous pages are report by num_pfns and pfns in virtio_balloon too. The function to set pfns is set_page_pfns_size in https://github.com/teawater/linux/blob/balloon_conts/drivers/virtio/virtio_balloon.c#L221 static void set_page_pfns_size(struct virtio_balloon *vb, __virtio32 pfns[], struct page *page, size_t size) { /* Set the first pfn of the continuous pages. */ pfns[0] = cpu_to_virtio32(vb->vdev, page_to_balloon_pfn(page)); /* Set the size of the continuous pages. */ pfns[1] = (__virtio32) size; } Each of continuous pages need 2 pfn. The first pfn of the pages is set to pfns[0]. The size of the pages is set to pfns[1]. The pfn is 32 bits. So the max order of inflate continuous pages is VIRTIO_BALLOON_INFLATE_MAX_ORDER. #define VIRTIO_BALLOON_INFLATE_MAX_ORDER min((int) (sizeof(__virtio32) * BITS_PER_BYTE - \ 1 - PAGE_SHIFT), (MAX_ORDER-1)) The max page number of deflate continuous pages is VIRTIO_BALLOON_DEFLATE_MAX_PAGES_NUM. #define VIRTIO_BALLOON_DEFLATE_MAX_PAGES_NUM (((__virtio32)~0U) >> PAGE_SHIFT) Best, Hui