From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=42143 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PmoCx-0002V9-SE for qemu-devel@nongnu.org; Tue, 08 Feb 2011 09:06:20 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PmoCw-00060K-OM for qemu-devel@nongnu.org; Tue, 08 Feb 2011 09:06:19 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42395) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PmoCw-000603-HX for qemu-devel@nongnu.org; Tue, 08 Feb 2011 09:06:18 -0500 Message-ID: <4D514E3E.6020704@redhat.com> Date: Tue, 08 Feb 2011 15:07:58 +0100 From: Kevin Wolf MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCHv2] e1000: multi-buffer packet support References: <20110203164910.GA10672@redhat.com> In-Reply-To: <20110203164910.GA10672@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: stefanha@linux.vnet.ibm.com, Jes.Sorensen@redhat.com, qemu-devel@nongnu.org, agraf@suse.de, Alex Williamson Am 03.02.2011 17:49, schrieb Michael S. Tsirkin: > e1000 supports multi-buffer packets larger than rxbuf_size. > > This fixes the following (on linux): > - in guest: ifconfig eth1 mtu 16110 > - in host: ifconfig tap0 mtu 16110 > ping -s 16082 > > Red Hat bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=602205 > > Signed-off-by: Michael S. Tsirkin > --- > > Changes from v1: > removed dead code > > hw/e1000.c | 29 +++++++++++++++++++---------- > 1 files changed, 19 insertions(+), 10 deletions(-) > > diff --git a/hw/e1000.c b/hw/e1000.c > index af101bd..3427ff3 100644 > --- a/hw/e1000.c > +++ b/hw/e1000.c > @@ -642,6 +642,8 @@ e1000_receive(VLANClientState *nc, const uint8_t *buf, size_t size) > uint16_t vlan_special = 0; > uint8_t vlan_status = 0, vlan_offset = 0; > uint8_t min_buf[MIN_BUF_SIZE]; > + size_t desc_offset; > + size_t desc_size; > > if (!(s->mac_reg[RCTL] & E1000_RCTL_EN)) > return -1; > @@ -654,12 +656,6 @@ e1000_receive(VLANClientState *nc, const uint8_t *buf, size_t size) > size = sizeof(min_buf); > } > > - if (size > s->rxbuf_size) { > - DBGOUT(RX, "packet too large for buffers (%lu > %d)\n", > - (unsigned long)size, s->rxbuf_size); > - return -1; > - } > - > if (!receive_filter(s, buf, size)) > return size; > > @@ -672,8 +668,15 @@ e1000_receive(VLANClientState *nc, const uint8_t *buf, size_t size) > } > > rdh_start = s->mac_reg[RDH]; > + desc_offset = 0; > do { > + desc_size = size - desc_offset; > + if (desc_size > s->rxbuf_size) { > + desc_size = s->rxbuf_size; > + } > if (s->mac_reg[RDH] == s->mac_reg[RDT] && s->check_rxov) { > + /* Discard all data written so far */ > + s->mac_reg[RDH] = rdh_start; > set_ics(s, 0, E1000_ICS_RXO); > return -1; > } > @@ -684,9 +687,15 @@ e1000_receive(VLANClientState *nc, const uint8_t *buf, size_t size) > desc.status |= (vlan_status | E1000_RXD_STAT_DD); > if (desc.buffer_addr) { > cpu_physical_memory_write(le64_to_cpu(desc.buffer_addr), > - (void *)(buf + vlan_offset), size); > - desc.length = cpu_to_le16(size + fcs_len(s)); > - desc.status |= E1000_RXD_STAT_EOP|E1000_RXD_STAT_IXSM; > + (void *)(buf + desc_offset + vlan_offset), > + desc_size); > + desc_offset += desc_size; > + if (desc_offset >= size) { > + desc.length = cpu_to_le16(desc_size + fcs_len(s)); I think this is not quite right: What happens if desc_size + fcs_len(s) > s->rxbuf_size? IIUC, we would seemingly overflow the guests buffer (in reality we leave the extra bytes untouched, but we may confuse the guest). Kevin