From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753696AbdFQWfa (ORCPT ); Sat, 17 Jun 2017 18:35:30 -0400 Received: from omzsmtpe03.verizonbusiness.com ([199.249.25.208]:14451 "EHLO omzsmtpe03.verizonbusiness.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753324AbdFQWZ5 (ORCPT ); Sat, 17 Jun 2017 18:25:57 -0400 X-IronPort-Anti-Spam-Filtered: false From: "Levin, Alexander (Sasha Levin)" Cc: "Michael S. Tsirkin" , John Fastabend , "David S . Miller" , "Levin, Alexander (Sasha Levin)" X-IronPort-AV: E=Sophos;i="5.39,316,1493683200"; d="scan'208";a="372653794" To: "stable@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: [PATCH for v4.9 LTS 45/86] virtio_net: fix PAGE_SIZE > 64k Thread-Topic: [PATCH for v4.9 LTS 45/86] virtio_net: fix PAGE_SIZE > 64k Thread-Index: AQHS57iE1Y4XwZCoKUWeZJ4b8qkN+Q== Date: Sat, 17 Jun 2017 22:24:43 +0000 Message-ID: <20170617222420.19316-45-alexander.levin@verizon.com> References: <20170617222420.19316-1-alexander.levin@verizon.com> In-Reply-To: <20170617222420.19316-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id v5HMZsiL022831 From: "Michael S. Tsirkin" [ Upstream commit d0fa28f00052391b5df328f502fbbdd4444938b7 ] I don't have any guests with PAGE_SIZE > 64k but the code seems to be clearly broken in that case as PAGE_SIZE / MERGEABLE_BUFFER_ALIGN will need more than 8 bit and so the code in mergeable_ctx_to_buf_address does not give us the actual true size. Cc: John Fastabend Signed-off-by: Michael S. Tsirkin Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/virtio_net.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 7ca99899972e..1568aedddfc9 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -47,8 +47,16 @@ module_param(gso, bool, 0444); */ DECLARE_EWMA(pkt_len, 1, 64) +/* With mergeable buffers we align buffer address and use the low bits to + * encode its true size. Buffer size is up to 1 page so we need to align to + * square root of page size to ensure we reserve enough bits to encode the true + * size. + */ +#define MERGEABLE_BUFFER_MIN_ALIGN_SHIFT ((PAGE_SHIFT + 1) / 2) + /* Minimum alignment for mergeable packet buffers. */ -#define MERGEABLE_BUFFER_ALIGN max(L1_CACHE_BYTES, 256) +#define MERGEABLE_BUFFER_ALIGN max(L1_CACHE_BYTES, \ + 1 << MERGEABLE_BUFFER_MIN_ALIGN_SHIFT) #define VIRTNET_DRIVER_VERSION "1.0.0" -- 2.11.0