From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 22 Mar 2021 04:17:33 -0400 From: "Michael S. Tsirkin" Message-ID: <20210322041414-mutt-send-email-mst@kernel.org> References: <20210318135223.1342795-1-ckuehl@redhat.com> <20210318135223.1342795-2-ckuehl@redhat.com> MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit Subject: Re: [Virtio-fs] [PATCH 1/3] virtio_ring: always warn when descriptor chain exceeds queue size List-Id: Development discussions about virtio-fs List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jason Wang Cc: miklos@szeredi.hu, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, virtio-fs@redhat.com, linux-fsdevel@vger.kernel.org, vgoyal@redhat.com On Mon, Mar 22, 2021 at 11:22:15AM +0800, Jason Wang wrote: > > 在 2021/3/18 下午9:52, Connor Kuehl 写道: > > From section 2.6.5.3.1 (Driver Requirements: Indirect Descriptors) > > of the virtio spec: > > > > "A driver MUST NOT create a descriptor chain longer than the Queue > > Size of the device." > > > > This text suggests that the warning should trigger even if > > indirect descriptors are in use. > > > So I think at least the commit log needs some tweak. > > For split virtqueue. We had: > > 2.6.5.2 Driver Requirements: The Virtqueue Descriptor Table > > Drivers MUST NOT add a descriptor chain longer than 2^32 bytes in total; > this implies that loops in the descriptor chain are forbidden! > > 2.6.5.3.1 Driver Requirements: Indirect Descriptors > > A driver MUST NOT create a descriptor chain longer than the Queue Size of > the device. > > If I understand the spec correctly, the check is only needed for a single > indirect descriptor table? > > For packed virtqueue. We had: > > 2.7.17 Driver Requirements: Scatter-Gather Support > > A driver MUST NOT create a descriptor list longer than allowed by the > device. > > A driver MUST NOT create a descriptor list longer than the Queue Size. > > 2.7.19 Driver Requirements: Indirect Descriptors > > A driver MUST NOT create a descriptor chain longer than allowed by the > device. > > So it looks to me the packed part is fine. > > Note that if I understand the spec correctly 2.7.17 implies 2.7.19. > > Thanks It would be quite strange for packed and split to differ here: so for packed would you say there's no limit on # of descriptors at all? I am guessing I just forgot to move this part from the format specific to the common part of the spec. This needs discussion in the TC mailing list - want to start a thread there? > > > > > Reported-by: Stefan Hajnoczi > > Signed-off-by: Connor Kuehl > > --- > > drivers/virtio/virtio_ring.c | 7 ++++--- > > 1 file changed, 4 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > index 71e16b53e9c1..1bc290f9ba13 100644 > > --- a/drivers/virtio/virtio_ring.c > > +++ b/drivers/virtio/virtio_ring.c > > @@ -444,11 +444,12 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, > > head = vq->free_head; > > + WARN_ON_ONCE(total_sg > vq->split.vring.num); > > + > > if (virtqueue_use_indirect(_vq, total_sg)) > > desc = alloc_indirect_split(_vq, total_sg, gfp); > > else { > > desc = NULL; > > - WARN_ON_ONCE(total_sg > vq->split.vring.num && !vq->indirect); > > } > > if (desc) { > > @@ -1118,6 +1119,8 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, > > BUG_ON(total_sg == 0); > > + WARN_ON_ONCE(total_sg > vq->packed.vring.num); > > + > > if (virtqueue_use_indirect(_vq, total_sg)) > > return virtqueue_add_indirect_packed(vq, sgs, total_sg, > > out_sgs, in_sgs, data, gfp); > > @@ -1125,8 +1128,6 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, > > head = vq->packed.next_avail_idx; > > avail_used_flags = vq->packed.avail_used_flags; > > - WARN_ON_ONCE(total_sg > vq->packed.vring.num && !vq->indirect); > > - > > desc = vq->packed.vring.desc; > > i = head; > > descs_used = total_sg; 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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 0E900C433C1 for ; Mon, 22 Mar 2021 08:17:46 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (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 742126192D for ; Mon, 22 Mar 2021 08:17:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 742126192D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=virtualization-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 18B7F40299; Mon, 22 Mar 2021 08:17:45 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 6jGdLfogU-OY; Mon, 22 Mar 2021 08:17:44 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp2.osuosl.org (Postfix) with ESMTP id 9FBA1400A9; Mon, 22 Mar 2021 08:17:43 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 73580C000A; Mon, 22 Mar 2021 08:17:43 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 72D40C0001 for ; Mon, 22 Mar 2021 08:17:42 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id 5A54A60692 for ; Mon, 22 Mar 2021 08:17:42 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp3.osuosl.org (amavisd-new); dkim=pass (1024-bit key) header.d=redhat.com Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Bo4toHTW3dD1 for ; Mon, 22 Mar 2021 08:17:41 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by smtp3.osuosl.org (Postfix) with ESMTPS id 75C4960666 for ; Mon, 22 Mar 2021 08:17:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616401060; 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=PsZodVPsWs6YP/fF4pvWwqUUa+rr5N0r5iTqRaFVfOc=; b=BewU5VbKrORLE5g/udttKpgTNVG8KPm7CEqyETnDNzYAAniACWLVJjjBFJR9HIh0Ardyts w6ixXegh1EgafXGFzpHNiREd2sU24qQa/i1ZH+0VPGIb7hll706iTAvWdR4hEn9RUoRI2/ M2BAtruWT3fi5qeElQ/MN6AOsx972mg= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-250-Fw8iaDLiNTqlfSj8MjWl0w-1; Mon, 22 Mar 2021 04:17:38 -0400 X-MC-Unique: Fw8iaDLiNTqlfSj8MjWl0w-1 Received: by mail-wr1-f71.google.com with SMTP id m23so20582634wrh.7 for ; Mon, 22 Mar 2021 01:17:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=PsZodVPsWs6YP/fF4pvWwqUUa+rr5N0r5iTqRaFVfOc=; b=UDw5WObFjNiuXRAboDZqEp/KhA7F/cQNLT+rbiU4ndbCUR/8RVMTFu+s7Lcy6pGAcA eojSD/fmXuFbv/ZDDtsqfVmYbkPpIz67RkdJbg3EbBYwqKNfzUS07kN7oBuaISZXaRaK ye63Y+ExutYncwGWVdtforQ1Yyr6/XWmG/U9jlX1F2ligq8EbtM0OcECH4qC8iznQRMG m54DQ7+wZvx1sOt/qDrxVHaEyMXwka+3FJ5ezS7ZM9OB9eMpSc+2zZKnwJHJmoF5q0eC LViaI3MsM3RfAR6hfo1tHlD3LC3w5ym/GgtO62OeYB5UkIMS00RtY/XWdDWnibVtrNvQ +sgA== X-Gm-Message-State: AOAM531mXmpZp00fPZwj6bp1NH1OufBVYBYMUuNyMyyO42ql7dslLm0U /Q+dTB883zxn076m9kfHIcZlbQk5aODFU1lpviESWiv0hpRDrdqteVTTQT6K17NcWEk5GyF891g ec6IGaeWW2TRbb4iv0637R0aKCw7MigbDioApyXAt8A== X-Received: by 2002:a5d:4ecf:: with SMTP id s15mr17188156wrv.222.1616401057445; Mon, 22 Mar 2021 01:17:37 -0700 (PDT) X-Google-Smtp-Source: ABdhPJylZqhTCHG8w045DowIsxunwGOileNP81Z98LrDX9nf428OhlNQeHBKBDDVXpT/YRj5Vf8BjA== X-Received: by 2002:a5d:4ecf:: with SMTP id s15mr17188137wrv.222.1616401057261; Mon, 22 Mar 2021 01:17:37 -0700 (PDT) Received: from redhat.com ([2a10:800e:f0d3:0:b69b:9fb8:3947:5636]) by smtp.gmail.com with ESMTPSA id a14sm20018493wrg.84.2021.03.22.01.17.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Mar 2021 01:17:36 -0700 (PDT) Date: Mon, 22 Mar 2021 04:17:33 -0400 From: "Michael S. Tsirkin" To: Jason Wang Subject: Re: [PATCH 1/3] virtio_ring: always warn when descriptor chain exceeds queue size Message-ID: <20210322041414-mutt-send-email-mst@kernel.org> References: <20210318135223.1342795-1-ckuehl@redhat.com> <20210318135223.1342795-2-ckuehl@redhat.com> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Cc: miklos@szeredi.hu, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, virtio-fs@redhat.com, stefanha@redhat.com, linux-fsdevel@vger.kernel.org, vgoyal@redhat.com X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" T24gTW9uLCBNYXIgMjIsIDIwMjEgYXQgMTE6MjI6MTVBTSArMDgwMCwgSmFzb24gV2FuZyB3cm90 ZToKPiAKPiDlnKggMjAyMS8zLzE4IOS4i+WNiDk6NTIsIENvbm5vciBLdWVobCDlhpnpgZM6Cj4g PiAgRnJvbSBzZWN0aW9uIDIuNi41LjMuMSAoRHJpdmVyIFJlcXVpcmVtZW50czogSW5kaXJlY3Qg RGVzY3JpcHRvcnMpCj4gPiBvZiB0aGUgdmlydGlvIHNwZWM6Cj4gPiAKPiA+ICAgICJBIGRyaXZl ciBNVVNUIE5PVCBjcmVhdGUgYSBkZXNjcmlwdG9yIGNoYWluIGxvbmdlciB0aGFuIHRoZSBRdWV1 ZQo+ID4gICAgU2l6ZSBvZiB0aGUgZGV2aWNlLiIKPiA+IAo+ID4gVGhpcyB0ZXh0IHN1Z2dlc3Rz IHRoYXQgdGhlIHdhcm5pbmcgc2hvdWxkIHRyaWdnZXIgZXZlbiBpZgo+ID4gaW5kaXJlY3QgZGVz Y3JpcHRvcnMgYXJlIGluIHVzZS4KPiAKPiAKPiBTbyBJIHRoaW5rIGF0IGxlYXN0IHRoZSBjb21t aXQgbG9nIG5lZWRzIHNvbWUgdHdlYWsuCj4gCj4gRm9yIHNwbGl0IHZpcnRxdWV1ZS4gV2UgaGFk Ogo+IAo+IDIuNi41LjIgRHJpdmVyIFJlcXVpcmVtZW50czogVGhlIFZpcnRxdWV1ZSBEZXNjcmlw dG9yIFRhYmxlCj4gCj4gRHJpdmVycyBNVVNUIE5PVCBhZGQgYSBkZXNjcmlwdG9yIGNoYWluIGxv bmdlciB0aGFuIDJeMzIgYnl0ZXMgaW4gdG90YWw7Cj4gdGhpcyBpbXBsaWVzIHRoYXQgbG9vcHMg aW4gdGhlIGRlc2NyaXB0b3IgY2hhaW4gYXJlIGZvcmJpZGRlbiEKPiAKPiAyLjYuNS4zLjEgRHJp dmVyIFJlcXVpcmVtZW50czogSW5kaXJlY3QgRGVzY3JpcHRvcnMKPiAKPiBBIGRyaXZlciBNVVNU IE5PVCBjcmVhdGUgYSBkZXNjcmlwdG9yIGNoYWluIGxvbmdlciB0aGFuIHRoZSBRdWV1ZSBTaXpl IG9mCj4gdGhlIGRldmljZS4KPiAKPiBJZiBJIHVuZGVyc3RhbmQgdGhlIHNwZWMgY29ycmVjdGx5 LCB0aGUgY2hlY2sgaXMgb25seSBuZWVkZWQgZm9yIGEgc2luZ2xlCj4gaW5kaXJlY3QgZGVzY3Jp cHRvciB0YWJsZT8KPiAKPiBGb3IgcGFja2VkIHZpcnRxdWV1ZS4gV2UgaGFkOgo+IAo+IDIuNy4x NyBEcml2ZXIgUmVxdWlyZW1lbnRzOiBTY2F0dGVyLUdhdGhlciBTdXBwb3J0Cj4gCj4gQSBkcml2 ZXIgTVVTVCBOT1QgY3JlYXRlIGEgZGVzY3JpcHRvciBsaXN0IGxvbmdlciB0aGFuIGFsbG93ZWQg YnkgdGhlCj4gZGV2aWNlLgo+IAo+IEEgZHJpdmVyIE1VU1QgTk9UIGNyZWF0ZSBhIGRlc2NyaXB0 b3IgbGlzdCBsb25nZXIgdGhhbiB0aGUgUXVldWUgU2l6ZS4KPiAKPiAyLjcuMTkgRHJpdmVyIFJl cXVpcmVtZW50czogSW5kaXJlY3QgRGVzY3JpcHRvcnMKPiAKPiBBIGRyaXZlciBNVVNUIE5PVCBj cmVhdGUgYSBkZXNjcmlwdG9yIGNoYWluIGxvbmdlciB0aGFuIGFsbG93ZWQgYnkgdGhlCj4gZGV2 aWNlLgo+IAo+IFNvIGl0IGxvb2tzIHRvIG1lIHRoZSBwYWNrZWQgcGFydCBpcyBmaW5lLgo+IAo+ IE5vdGUgdGhhdCBpZiBJIHVuZGVyc3RhbmQgdGhlIHNwZWMgY29ycmVjdGx5IDIuNy4xNyBpbXBs aWVzIDIuNy4xOS4KPiAKPiBUaGFua3MKCkl0IHdvdWxkIGJlIHF1aXRlIHN0cmFuZ2UgZm9yIHBh Y2tlZCBhbmQgc3BsaXQgdG8gZGlmZmVyIGhlcmU6CnNvIGZvciBwYWNrZWQgd291bGQgeW91IHNh eSB0aGVyZSdzIG5vIGxpbWl0IG9uICMgb2YgZGVzY3JpcHRvcnMgYXQgYWxsPwoKSSBhbSBndWVz c2luZyBJIGp1c3QgZm9yZ290IHRvIG1vdmUgdGhpcyBwYXJ0IGZyb20KdGhlIGZvcm1hdCBzcGVj aWZpYyB0byB0aGUgY29tbW9uIHBhcnQgb2YgdGhlIHNwZWMuCgpUaGlzIG5lZWRzIGRpc2N1c3Np b24gaW4gdGhlIFRDIG1haWxpbmcgbGlzdCAtIHdhbnQgdG8gc3RhcnQgYSB0aHJlYWQKdGhlcmU/ CgoKCj4gCj4gPiAKPiA+IFJlcG9ydGVkLWJ5OiBTdGVmYW4gSGFqbm9jemkgPHN0ZWZhbmhhQHJl ZGhhdC5jb20+Cj4gPiBTaWduZWQtb2ZmLWJ5OiBDb25ub3IgS3VlaGwgPGNrdWVobEByZWRoYXQu Y29tPgo+ID4gLS0tCj4gPiAgIGRyaXZlcnMvdmlydGlvL3ZpcnRpb19yaW5nLmMgfCA3ICsrKyst LS0KPiA+ICAgMSBmaWxlIGNoYW5nZWQsIDQgaW5zZXJ0aW9ucygrKSwgMyBkZWxldGlvbnMoLSkK PiA+IAo+ID4gZGlmZiAtLWdpdCBhL2RyaXZlcnMvdmlydGlvL3ZpcnRpb19yaW5nLmMgYi9kcml2 ZXJzL3ZpcnRpby92aXJ0aW9fcmluZy5jCj4gPiBpbmRleCA3MWUxNmI1M2U5YzEuLjFiYzI5MGY5 YmExMyAxMDA2NDQKPiA+IC0tLSBhL2RyaXZlcnMvdmlydGlvL3ZpcnRpb19yaW5nLmMKPiA+ICsr KyBiL2RyaXZlcnMvdmlydGlvL3ZpcnRpb19yaW5nLmMKPiA+IEBAIC00NDQsMTEgKzQ0NCwxMiBA QCBzdGF0aWMgaW5saW5lIGludCB2aXJ0cXVldWVfYWRkX3NwbGl0KHN0cnVjdCB2aXJ0cXVldWUg Kl92cSwKPiA+ICAgCWhlYWQgPSB2cS0+ZnJlZV9oZWFkOwo+ID4gKwlXQVJOX09OX09OQ0UodG90 YWxfc2cgPiB2cS0+c3BsaXQudnJpbmcubnVtKTsKPiA+ICsKPiA+ICAgCWlmICh2aXJ0cXVldWVf dXNlX2luZGlyZWN0KF92cSwgdG90YWxfc2cpKQo+ID4gICAJCWRlc2MgPSBhbGxvY19pbmRpcmVj dF9zcGxpdChfdnEsIHRvdGFsX3NnLCBnZnApOwo+ID4gICAJZWxzZSB7Cj4gPiAgIAkJZGVzYyA9 IE5VTEw7Cj4gPiAtCQlXQVJOX09OX09OQ0UodG90YWxfc2cgPiB2cS0+c3BsaXQudnJpbmcubnVt ICYmICF2cS0+aW5kaXJlY3QpOwo+ID4gICAJfQo+ID4gICAJaWYgKGRlc2MpIHsKPiA+IEBAIC0x MTE4LDYgKzExMTksOCBAQCBzdGF0aWMgaW5saW5lIGludCB2aXJ0cXVldWVfYWRkX3BhY2tlZChz dHJ1Y3QgdmlydHF1ZXVlICpfdnEsCj4gPiAgIAlCVUdfT04odG90YWxfc2cgPT0gMCk7Cj4gPiAr CVdBUk5fT05fT05DRSh0b3RhbF9zZyA+IHZxLT5wYWNrZWQudnJpbmcubnVtKTsKPiA+ICsKPiA+ ICAgCWlmICh2aXJ0cXVldWVfdXNlX2luZGlyZWN0KF92cSwgdG90YWxfc2cpKQo+ID4gICAJCXJl dHVybiB2aXJ0cXVldWVfYWRkX2luZGlyZWN0X3BhY2tlZCh2cSwgc2dzLCB0b3RhbF9zZywKPiA+ ICAgCQkJCW91dF9zZ3MsIGluX3NncywgZGF0YSwgZ2ZwKTsKPiA+IEBAIC0xMTI1LDggKzExMjgs NiBAQCBzdGF0aWMgaW5saW5lIGludCB2aXJ0cXVldWVfYWRkX3BhY2tlZChzdHJ1Y3QgdmlydHF1 ZXVlICpfdnEsCj4gPiAgIAloZWFkID0gdnEtPnBhY2tlZC5uZXh0X2F2YWlsX2lkeDsKPiA+ICAg CWF2YWlsX3VzZWRfZmxhZ3MgPSB2cS0+cGFja2VkLmF2YWlsX3VzZWRfZmxhZ3M7Cj4gPiAtCVdB Uk5fT05fT05DRSh0b3RhbF9zZyA+IHZxLT5wYWNrZWQudnJpbmcubnVtICYmICF2cS0+aW5kaXJl Y3QpOwo+ID4gLQo+ID4gICAJZGVzYyA9IHZxLT5wYWNrZWQudnJpbmcuZGVzYzsKPiA+ICAgCWkg PSBoZWFkOwo+ID4gICAJZGVzY3NfdXNlZCA9IHRvdGFsX3NnOwoKX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX18KVmlydHVhbGl6YXRpb24gbWFpbGluZyBsaXN0 ClZpcnR1YWxpemF0aW9uQGxpc3RzLmxpbnV4LWZvdW5kYXRpb24ub3JnCmh0dHBzOi8vbGlzdHMu bGludXhmb3VuZGF0aW9uLm9yZy9tYWlsbWFuL2xpc3RpbmZvL3ZpcnR1YWxpemF0aW9u 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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 8FE51C433DB for ; Mon, 22 Mar 2021 08:18:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4FD546196C for ; Mon, 22 Mar 2021 08:18:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229870AbhCVIR5 (ORCPT ); Mon, 22 Mar 2021 04:17:57 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:48104 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229986AbhCVIRn (ORCPT ); Mon, 22 Mar 2021 04:17:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616401062; 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=PsZodVPsWs6YP/fF4pvWwqUUa+rr5N0r5iTqRaFVfOc=; b=TzZYZnseo0UXY2jKOuyeERGuiWc9bPPAxn1YgYAIgwTcsE1BR+YHkOsiYtvCnszWqnak3m 4tLhbBsFQpI7ixtDHsmRPCXBNcu65hEarfGBQNGL8Nzip8pDvrv2fGrPh9VnVM2PDjPbti 1YWLbk1GIhMjuA/s9diVBouDGrR8eZI= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-471-Td2R3ir2OxuB3soEFeLADg-1; Mon, 22 Mar 2021 04:17:38 -0400 X-MC-Unique: Td2R3ir2OxuB3soEFeLADg-1 Received: by mail-wr1-f72.google.com with SMTP id r12so25663686wro.15 for ; Mon, 22 Mar 2021 01:17:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=PsZodVPsWs6YP/fF4pvWwqUUa+rr5N0r5iTqRaFVfOc=; b=sHMgGNNcsnuaWE4+B6He8VNjWIcpuSsp91Fg+WAVW7vSqlv22vBcFIj4ICT+pe8j27 3gsWuCjZNIotjVKMNZPdq9VHmDQKvm4O7iwnnBneVIkQFUZygVv8NboTc9synS1vkPh7 rCmvMc1jPCt/opQ3P//tGXWqsG3euoDHnpRg/henyGVzfTgMHMYGKlRD14jYJowZ3jxO AwOR8CN5AN5w4BohzvdqbsAjc2eFqVgbtmyMdIn1o8DtSH9a/3spYU+pFFJ2ZDtoiWuu ds9+fP6h2LJgTjLsmQzo0qsLuB3I+xJiEui0N6CDLhZv8LzloYvT7I14aowXlB6qnERn NFnw== X-Gm-Message-State: AOAM530g83/P1n5USi735xy4sJul/bfE0rqtcP1qNLAylNB+gLusjBfk CE36sh6IhN+nIPvLsVuPyriDlLgjQq8njppIfgfz9P0Q01/aLiUMF8GbO+ePWBfEvm3C7lewJ6N cgFJGIzp1wl8XgNvCD3tzMNEzgg== X-Received: by 2002:a5d:4ecf:: with SMTP id s15mr17188161wrv.222.1616401057494; Mon, 22 Mar 2021 01:17:37 -0700 (PDT) X-Google-Smtp-Source: ABdhPJylZqhTCHG8w045DowIsxunwGOileNP81Z98LrDX9nf428OhlNQeHBKBDDVXpT/YRj5Vf8BjA== X-Received: by 2002:a5d:4ecf:: with SMTP id s15mr17188137wrv.222.1616401057261; Mon, 22 Mar 2021 01:17:37 -0700 (PDT) Received: from redhat.com ([2a10:800e:f0d3:0:b69b:9fb8:3947:5636]) by smtp.gmail.com with ESMTPSA id a14sm20018493wrg.84.2021.03.22.01.17.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Mar 2021 01:17:36 -0700 (PDT) Date: Mon, 22 Mar 2021 04:17:33 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: Connor Kuehl , virtio-fs@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, stefanha@redhat.com, vgoyal@redhat.com, miklos@szeredi.hu Subject: Re: [PATCH 1/3] virtio_ring: always warn when descriptor chain exceeds queue size Message-ID: <20210322041414-mutt-send-email-mst@kernel.org> References: <20210318135223.1342795-1-ckuehl@redhat.com> <20210318135223.1342795-2-ckuehl@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Mar 22, 2021 at 11:22:15AM +0800, Jason Wang wrote: > > 在 2021/3/18 下午9:52, Connor Kuehl 写道: > > From section 2.6.5.3.1 (Driver Requirements: Indirect Descriptors) > > of the virtio spec: > > > > "A driver MUST NOT create a descriptor chain longer than the Queue > > Size of the device." > > > > This text suggests that the warning should trigger even if > > indirect descriptors are in use. > > > So I think at least the commit log needs some tweak. > > For split virtqueue. We had: > > 2.6.5.2 Driver Requirements: The Virtqueue Descriptor Table > > Drivers MUST NOT add a descriptor chain longer than 2^32 bytes in total; > this implies that loops in the descriptor chain are forbidden! > > 2.6.5.3.1 Driver Requirements: Indirect Descriptors > > A driver MUST NOT create a descriptor chain longer than the Queue Size of > the device. > > If I understand the spec correctly, the check is only needed for a single > indirect descriptor table? > > For packed virtqueue. We had: > > 2.7.17 Driver Requirements: Scatter-Gather Support > > A driver MUST NOT create a descriptor list longer than allowed by the > device. > > A driver MUST NOT create a descriptor list longer than the Queue Size. > > 2.7.19 Driver Requirements: Indirect Descriptors > > A driver MUST NOT create a descriptor chain longer than allowed by the > device. > > So it looks to me the packed part is fine. > > Note that if I understand the spec correctly 2.7.17 implies 2.7.19. > > Thanks It would be quite strange for packed and split to differ here: so for packed would you say there's no limit on # of descriptors at all? I am guessing I just forgot to move this part from the format specific to the common part of the spec. This needs discussion in the TC mailing list - want to start a thread there? > > > > > Reported-by: Stefan Hajnoczi > > Signed-off-by: Connor Kuehl > > --- > > drivers/virtio/virtio_ring.c | 7 ++++--- > > 1 file changed, 4 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > index 71e16b53e9c1..1bc290f9ba13 100644 > > --- a/drivers/virtio/virtio_ring.c > > +++ b/drivers/virtio/virtio_ring.c > > @@ -444,11 +444,12 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, > > head = vq->free_head; > > + WARN_ON_ONCE(total_sg > vq->split.vring.num); > > + > > if (virtqueue_use_indirect(_vq, total_sg)) > > desc = alloc_indirect_split(_vq, total_sg, gfp); > > else { > > desc = NULL; > > - WARN_ON_ONCE(total_sg > vq->split.vring.num && !vq->indirect); > > } > > if (desc) { > > @@ -1118,6 +1119,8 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, > > BUG_ON(total_sg == 0); > > + WARN_ON_ONCE(total_sg > vq->packed.vring.num); > > + > > if (virtqueue_use_indirect(_vq, total_sg)) > > return virtqueue_add_indirect_packed(vq, sgs, total_sg, > > out_sgs, in_sgs, data, gfp); > > @@ -1125,8 +1128,6 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, > > head = vq->packed.next_avail_idx; > > avail_used_flags = vq->packed.avail_used_flags; > > - WARN_ON_ONCE(total_sg > vq->packed.vring.num && !vq->indirect); > > - > > desc = vq->packed.vring.desc; > > i = head; > > descs_used = total_sg;