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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 13998C76188 for ; Tue, 23 Jul 2019 05:20:36 +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 D7FE02238E for ; Tue, 23 Jul 2019 05:20:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.b="kASVw9mo" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D7FE02238E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:39198 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hpnE2-0006il-Rf for qemu-devel@archiver.kernel.org; Tue, 23 Jul 2019 01:20:34 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39686) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hpnCd-0000s4-Ny for qemu-devel@nongnu.org; Tue, 23 Jul 2019 01:19:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hpnCc-0003mX-8G for qemu-devel@nongnu.org; Tue, 23 Jul 2019 01:19:07 -0400 Received: from ozlabs.org ([203.11.71.1]:59119) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hpnCb-0003gI-7f; Tue, 23 Jul 2019 01:19:06 -0400 Received: by ozlabs.org (Postfix, from userid 1007) id 45t6G83DD8z9sNT; Tue, 23 Jul 2019 15:18:56 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1563859136; bh=tfyq+j0/fRoJB2Cdzgd4s+TGPHpD2ApevN6sfMmA7Ac=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kASVw9mozLpLsbYTVurY01h/Je+kk1/KIFw6B8Nsz/KegrX94+P84edpy1SeUYkfV M0sQmD7alWsoxdx4AgTqXe5q1AjFVnJCiBJDiu2nZSUdq5oFStgoqiIAtRGUJwpBj1 2NOEEx8KBOKVtKdIAml2nNP8dqaxj1OcLRbxQ5vk= Date: Tue, 23 Jul 2019 13:22:19 +1000 From: David Gibson To: David Hildenbrand Message-ID: <20190723032219.GM25073@umbus.fritz.box> References: <20190722134108.22151-1-david@redhat.com> <20190722134108.22151-7-david@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Aaj1jBvBEV7KRjLi" Content-Disposition: inline In-Reply-To: <20190722134108.22151-7-david@redhat.com> User-Agent: Mutt/1.12.0 (2019-05-25) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 203.11.71.1 Subject: Re: [Qemu-devel] [PATCH-for-4.1 v3 6/6] virtio-balloon: Use temporary PBP only 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 , qemu-stable@nongnu.org, qemu-devel@nongnu.org, Stefan Hajnoczi , "Michael S . Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --Aaj1jBvBEV7KRjLi Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jul 22, 2019 at 03:41:08PM +0200, David Hildenbrand wrote: > We still have multiple issues in the current code > - The PBP is not freed during unrealize() > - The PBP is not reset on device resets: After a reset, the PBP is stale. > - We are not indicating VIRTIO_BALLOON_F_MUST_TELL_HOST, therefore > guests (esp. legacy guests) will reuse pages without deflating, > turning the PBP stale. Adding that would require compat handling. >=20 > Instead, let's use the PBP only temporarily, when processing one bulk of > inflation requests. This will keep guest_page_size > 4k working (with > Linux guests). There is nothing to do for deflation requests anymore. > The pbp is only used for a limited amount of time. >=20 > Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE < > host page size") > Cc: qemu-stable@nongnu.org #v4.0.0 > Suggested-by: Michael S. Tsirkin > Signed-off-by: David Hildenbrand Ah, nice idea. =20 Acked-by: David Gibson > --- > hw/virtio/virtio-balloon.c | 21 +++++++++------------ > include/hw/virtio/virtio-balloon.h | 3 --- > 2 files changed, 9 insertions(+), 15 deletions(-) >=20 > diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c > index 40d493a31a..a6282d58d4 100644 > --- a/hw/virtio/virtio-balloon.c > +++ b/hw/virtio/virtio-balloon.c > @@ -34,11 +34,11 @@ > =20 > #define BALLOON_PAGE_SIZE (1 << VIRTIO_BALLOON_PFN_SHIFT) > =20 > -struct PartiallyBalloonedPage { > +typedef struct PartiallyBalloonedPage { > ram_addr_t base_gpa; > long subpages; > unsigned long *bitmap; > -}; > +} PartiallyBalloonedPage; > =20 > static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp) > { > @@ -68,11 +68,11 @@ static bool virtio_balloon_pbp_matches(PartiallyBallo= onedPage *pbp, > } > =20 > static void balloon_inflate_page(VirtIOBalloon *balloon, > - MemoryRegion *mr, hwaddr mr_offset) > + MemoryRegion *mr, hwaddr mr_offset, > + PartiallyBalloonedPage **pbp) > { > void *addr =3D memory_region_get_ram_ptr(mr) + mr_offset; > ram_addr_t rb_offset, rb_aligned_offset, base_gpa; > - PartiallyBalloonedPage **pbp =3D &balloon->pbp; > RAMBlock *rb; > size_t rb_page_size; > int subpages; > @@ -149,12 +149,6 @@ static void balloon_deflate_page(VirtIOBalloon *ball= oon, > rb =3D qemu_ram_block_from_host(addr, false, &rb_offset); > rb_page_size =3D qemu_ram_pagesize(rb); > =20 > - if (balloon->pbp) { > - /* Let's play safe and always reset the pbp on deflation request= s. */ > - virtio_balloon_pbp_free(balloon->pbp); > - balloon->pbp =3D NULL; > - } > - > host_addr =3D (void *)((uintptr_t)addr & ~(rb_page_size - 1)); > =20 > /* When a page is deflated, we hint the whole host page it lives > @@ -336,6 +330,7 @@ static void balloon_stats_set_poll_interval(Object *o= bj, Visitor *v, > static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *= vq) > { > VirtIOBalloon *s =3D VIRTIO_BALLOON(vdev); > + PartiallyBalloonedPage *pbp =3D NULL; > VirtQueueElement *elem; > MemoryRegionSection section; > =20 > @@ -344,7 +339,7 @@ static void virtio_balloon_handle_output(VirtIODevice= *vdev, VirtQueue *vq) > uint32_t pfn; > elem =3D virtqueue_pop(vq, sizeof(VirtQueueElement)); > if (!elem) { > - return; > + break; > } > =20 > while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) = =3D=3D 4) { > @@ -373,7 +368,7 @@ static void virtio_balloon_handle_output(VirtIODevice= *vdev, VirtQueue *vq) > if (!qemu_balloon_is_inhibited()) { > if (vq =3D=3D s->ivq) { > balloon_inflate_page(s, section.mr, > - section.offset_within_region); > + section.offset_within_region, &= pbp); > } else if (vq =3D=3D s->dvq) { > balloon_deflate_page(s, section.mr, section.offset_w= ithin_region); > } else { > @@ -387,6 +382,8 @@ static void virtio_balloon_handle_output(VirtIODevice= *vdev, VirtQueue *vq) > virtio_notify(vdev, vq); > g_free(elem); > } > + > + virtio_balloon_pbp_free(pbp); > } > =20 > static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *= vq) > diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virti= o-balloon.h > index 5a99293a45..d1c968d237 100644 > --- a/include/hw/virtio/virtio-balloon.h > +++ b/include/hw/virtio/virtio-balloon.h > @@ -33,8 +33,6 @@ typedef struct virtio_balloon_stat_modern { > uint64_t val; > } VirtIOBalloonStatModern; > =20 > -typedef struct PartiallyBalloonedPage PartiallyBalloonedPage; > - > enum virtio_balloon_free_page_report_status { > FREE_PAGE_REPORT_S_STOP =3D 0, > FREE_PAGE_REPORT_S_REQUESTED =3D 1, > @@ -70,7 +68,6 @@ typedef struct VirtIOBalloon { > int64_t stats_last_update; > int64_t stats_poll_interval; > uint32_t host_features; > - PartiallyBalloonedPage *pbp; > =20 > bool qemu_4_0_config_size; > } VirtIOBalloon; --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. 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