From patchwork Fri Jul 19 16:01:18 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11050297 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3E32E746 for ; Fri, 19 Jul 2019 16:04:28 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2AB0C285D1 for ; Fri, 19 Jul 2019 16:04:28 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1B515205C0; Fri, 19 Jul 2019 16:04:28 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 8AF27205C0 for ; Fri, 19 Jul 2019 16:04:27 +0000 (UTC) Received: from localhost ([::1]:46840 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hoVMw-00032T-O5 for patchwork-qemu-devel@patchwork.kernel.org; Fri, 19 Jul 2019 12:04:26 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38125) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hoVMn-0002bC-G8 for qemu-devel@nongnu.org; Fri, 19 Jul 2019 12:04:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hoVMe-00058P-Q5 for qemu-devel@nongnu.org; Fri, 19 Jul 2019 12:04:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43156) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hoVMX-0003Z7-Nh for qemu-devel@nongnu.org; Fri, 19 Jul 2019 12:04:05 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9B54B317915D; Fri, 19 Jul 2019 16:01:31 +0000 (UTC) Received: from t460s.redhat.com (ovpn-116-220.ams2.redhat.com [10.36.116.220]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1441F1001B02; Fri, 19 Jul 2019 16:01:29 +0000 (UTC) From: David Hildenbrand To: qemu-devel@nongnu.org Date: Fri, 19 Jul 2019 18:01:18 +0200 Message-Id: <20190719160120.26581-2-david@redhat.com> In-Reply-To: <20190719160120.26581-1-david@redhat.com> References: <20190719160120.26581-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Fri, 19 Jul 2019 16:01:31 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v1 1/3] virtio-balloon: simplify deflate with pbp 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: Igor Mammedov , David Gibson , "Michael S . Tsirkin" , Stefan Hajnoczi , David Hildenbrand Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP Let's simplify this - the case we are optimizing for is very hard to trigger and not worth the effort. If we're switching from inflation to deflation, let's reset the pbp. Signed-off-by: David Hildenbrand Acked-by: David Gibson --- hw/virtio/virtio-balloon.c | 24 ++++-------------------- 1 file changed, 4 insertions(+), 20 deletions(-) diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index 9de3c030bf..287d5d4c97 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -121,7 +121,7 @@ static void balloon_deflate_page(VirtIOBalloon *balloon, void *addr = memory_region_get_ram_ptr(mr) + offset; RAMBlock *rb; size_t rb_page_size; - ram_addr_t ram_offset, host_page_base; + ram_addr_t ram_offset; void *host_addr; int ret; @@ -129,26 +129,10 @@ static void balloon_deflate_page(VirtIOBalloon *balloon, * host address? */ rb = qemu_ram_block_from_host(addr, false, &ram_offset); rb_page_size = qemu_ram_pagesize(rb); - host_page_base = ram_offset & ~(rb_page_size - 1); - - if (balloon->pbp - && rb == balloon->pbp->rb - && host_page_base == balloon->pbp->base) { - int subpages = rb_page_size / BALLOON_PAGE_SIZE; - /* - * This means the guest has asked to discard some of the 4kiB - * subpages of a host page, but then changed its mind and - * asked to keep them after all. It's exceedingly unlikely - * for a guest to do this in practice, but handle it anyway, - * since getting it wrong could mean discarding memory the - * guest is still using. */ - clear_bit((ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE, - balloon->pbp->bitmap); - - if (bitmap_empty(balloon->pbp->bitmap, subpages)) { - virtio_balloon_reset_pbp(balloon); - } + if (balloon->pbp) { + /* Let's play safe and always reset the pbp on deflation requests. */ + virtio_balloon_reset_pbp(balloon); } host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1));