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,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 2FDBCC76188 for ; Tue, 23 Jul 2019 05:20:19 +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 EDA782238E for ; Tue, 23 Jul 2019 05:20:16 +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="HKNh3lk2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EDA782238E 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]:39186 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hpnDg-00056p-5L for qemu-devel@archiver.kernel.org; Tue, 23 Jul 2019 01:20:12 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39683) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hpnCd-0000s3-Mv 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-0003mh-8a for qemu-devel@nongnu.org; Tue, 23 Jul 2019 01:19:07 -0400 Received: from bilbo.ozlabs.org ([2401:3900:2:1::2]:53983 helo=ozlabs.org) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hpnCb-0003gO-Dv; Tue, 23 Jul 2019 01:19:06 -0400 Received: by ozlabs.org (Postfix, from userid 1007) id 45t6G80qYSz9sDB; Tue, 23 Jul 2019 15:18:55 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1563859136; bh=kAm+4MYG6VWkj52D/DjrfIg4F5Dv271zrXHZGQuPVc4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=HKNh3lk2k5AaYXGe2G237ayDScOzeJLy5EzttgmArCf3+qXSozuTMsEYn5QV4reyg 3Lqec/QcAL66iyOfFDobLqdM2ItDfnhHmJH96WTN1kUsAAslTEzvyU54FX7Uj/KcLH KBMxnGxNpveGL0wpUtql0M55yvR8PYxose9wsZE0= Date: Tue, 23 Jul 2019 12:54:22 +1000 From: David Gibson To: David Hildenbrand Message-ID: <20190723025422.GL25073@umbus.fritz.box> References: <20190722134108.22151-1-david@redhat.com> <20190722134108.22151-6-david@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="RNGrj7vazCqBHNw7" Content-Disposition: inline In-Reply-To: <20190722134108.22151-6-david@redhat.com> User-Agent: Mutt/1.12.0 (2019-05-25) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2401:3900:2:1::2 Subject: Re: [Qemu-devel] [PATCH-for-4.1 v3 5/6] virtio-balloon: Rework pbp tracking data 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" --RNGrj7vazCqBHNw7 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jul 22, 2019 at 03:41:07PM +0200, David Hildenbrand wrote: > Using the address of a RAMBlock to test for a matching pbp is not really > safe. Instead, let's use the guest physical address of the base page > along with the page size (via the number of subpages). >=20 > Also, let's allocate the bitmap separately. This makes the code > easier to read and maintain - we can reuse bitmap_new(). >=20 > Prepare the code to move the PBP out of the device. >=20 > Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE < > host page size") > Fixes: b27b32391404 ("virtio-balloon: Fix possible guest memory corruption > with inflates & deflates") > Cc: qemu-stable@nongnu.org #v4.0.0 > Signed-off-by: David Hildenbrand > --- > hw/virtio/virtio-balloon.c | 69 +++++++++++++++++++++++++------------- > 1 file changed, 46 insertions(+), 23 deletions(-) >=20 > diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c > index f206cc8bf7..40d493a31a 100644 > --- a/hw/virtio/virtio-balloon.c > +++ b/hw/virtio/virtio-balloon.c > @@ -35,16 +35,44 @@ > #define BALLOON_PAGE_SIZE (1 << VIRTIO_BALLOON_PFN_SHIFT) > =20 > struct PartiallyBalloonedPage { > - RAMBlock *rb; > - ram_addr_t base; > - unsigned long bitmap[]; > + ram_addr_t base_gpa; > + long subpages; > + unsigned long *bitmap; > }; > =20 > +static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp) > +{ > + if (!pbp) { > + return; > + } > + g_free(pbp->bitmap); > + g_free(pbp); > +} > + > +static PartiallyBalloonedPage *virtio_balloon_pbp_alloc(ram_addr_t base_= gpa, > + long subpages) > +{ > + PartiallyBalloonedPage *pbp =3D g_new0(PartiallyBalloonedPage, 1); > + > + pbp->base_gpa =3D base_gpa; > + pbp->subpages =3D subpages; > + pbp->bitmap =3D bitmap_new(subpages); > + > + return pbp; > +} > + > +static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp, > + ram_addr_t base_gpa, long subpage= s) > +{ > + return pbp->subpages =3D=3D subpages && pbp->base_gpa =3D=3D base_gp= a; I think the test on subpages is pointless here. You've (reasonably) rejected handling the edge case of a ramblock being removed and replugged - but the only thing this handles is an edge case of that edge case. Otherwise, LGTM. > +} > + > static void balloon_inflate_page(VirtIOBalloon *balloon, > MemoryRegion *mr, hwaddr mr_offset) > { > void *addr =3D memory_region_get_ram_ptr(mr) + mr_offset; > - ram_addr_t rb_offset, rb_aligned_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; > @@ -75,39 +103,34 @@ static void balloon_inflate_page(VirtIOBalloon *ball= oon, > =20 > rb_aligned_offset =3D QEMU_ALIGN_DOWN(rb_offset, rb_page_size); > subpages =3D rb_page_size / BALLOON_PAGE_SIZE; > + base_gpa =3D memory_region_get_ram_addr(mr) + mr_offset - > + (rb_offset - rb_aligned_offset); > =20 > - if (balloon->pbp > - && (rb !=3D balloon->pbp->rb > - || rb_aligned_offset !=3D balloon->pbp->base)) { > + if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa, subpages)) { > /* We've partially ballooned part of a host page, but now > * we're trying to balloon part of a different one. Too hard, > * give up on the old partial page */ > - g_free(balloon->pbp); > - balloon->pbp =3D NULL; > + virtio_balloon_pbp_free(*pbp); > + *pbp =3D NULL; > } > =20 > - if (!balloon->pbp) { > - /* Starting on a new host page */ > - size_t bitlen =3D BITS_TO_LONGS(subpages) * sizeof(unsigned long= ); > - balloon->pbp =3D g_malloc0(sizeof(PartiallyBalloonedPage) + bitl= en); > - balloon->pbp->rb =3D rb; > - balloon->pbp->base =3D rb_aligned_offset; > + if (!*pbp) { > + *pbp =3D virtio_balloon_pbp_alloc(base_gpa, subpages); > } > =20 > - set_bit((rb_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE, > - balloon->pbp->bitmap); > + set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE, > + (*pbp)->bitmap); > =20 > - if (bitmap_full(balloon->pbp->bitmap, subpages)) { > + if (bitmap_full((*pbp)->bitmap, subpages)) { > /* We've accumulated a full host page, we can actually discard > * it now */ > =20 > - ram_block_discard_range(rb, balloon->pbp->base, rb_page_size); > + ram_block_discard_range(rb, rb_aligned_offset, rb_page_size); > /* We ignore errors from ram_block_discard_range(), because it > * has already reported them, and failing to discard a balloon > * page is not fatal */ > - > - g_free(balloon->pbp); > - balloon->pbp =3D NULL; > + virtio_balloon_pbp_free(*pbp); > + *pbp =3D NULL; > } > } > =20 > @@ -128,7 +151,7 @@ static void balloon_deflate_page(VirtIOBalloon *ballo= on, > =20 > if (balloon->pbp) { > /* Let's play safe and always reset the pbp on deflation request= s. */ > - g_free(balloon->pbp); > + virtio_balloon_pbp_free(balloon->pbp); > balloon->pbp =3D NULL; > } > =20 --=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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