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From: "Michael S. Tsirkin" <mst@redhat.com>
To: David Miller <davem@davemloft.net>
Cc: brouer@redhat.com, shrijeet@gmail.com, tom@herbertland.com,
	netdev@vger.kernel.org, shm@cumulusnetworks.com,
	roopa@cumulusnetworks.com, nikolay@cumulusnetworks.com
Subject: Re: [PATCH net-next RFC WIP] Patch for XDP support for virtio_net
Date: Wed, 26 Oct 2016 20:07:19 +0300	[thread overview]
Message-ID: <20161026200153-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20161026.125245.1630138589657247338.davem@davemloft.net>

On Wed, Oct 26, 2016 at 12:52:45PM -0400, David Miller wrote:
> From: "Michael S. Tsirkin" <mst@redhat.com>
> Date: Wed, 26 Oct 2016 19:36:45 +0300
> 
> > On Wed, Oct 26, 2016 at 03:52:02PM +0200, Jesper Dangaard Brouer wrote:
> >> On Sat, 22 Oct 2016 04:07:23 +0000
> >> Shrijeet Mukherjee <shrijeet@gmail.com> wrote:
> >> 
> >> > This patch adds support for xdp ndo and also inserts the xdp program
> >> > call into the merged RX buffers and big buffers paths
> >> 
> >> I really appreciate you are doing this for virtio_net.
> >> 
> >> My first question is: Is the (packet) page data writable?
> >> (MST might be able to answer?)
> >> 
> >> As this is currently an XDP requirement[1].  
> > 
> > I'm not sure I understand what does writable mean.
> > Could you explain a bit more pls?
> > We do copy data into skb ATM but I plan to change that.
> 
> The packet data area must be writable,

This is the part I don't fully understand.
It's in RAM so of course it's writeable.

> and the page it lives in must
> not be shared with any other entity in the system.

We share pages between arbitrary multiple packets. I think that's
OK - or is there an assumption that multiple programs
will be attached with different priveledges?

> This is because the eBPF program that executes via XDP must be able
> to modify and read arbitrary parts of the packet area.

-- 
MST

  reply	other threads:[~2016-10-26 17:07 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-22  4:07 [PATCH net-next RFC WIP] Patch for XDP support for virtio_net Shrijeet Mukherjee
2016-10-23 16:38 ` Stephen Hemminger
2016-10-24  1:51   ` Shrijeet Mukherjee
2016-10-25  1:10     ` Alexei Starovoitov
2016-10-25 17:36 ` Jakub Kicinski
2016-10-26 13:52 ` Jesper Dangaard Brouer
2016-10-26 16:36   ` Michael S. Tsirkin
2016-10-26 16:52     ` David Miller
2016-10-26 17:07       ` Michael S. Tsirkin [this message]
2016-10-26 17:11         ` David Miller
2016-10-27  8:55           ` Jesper Dangaard Brouer
2016-10-27 21:09             ` John Fastabend
2016-10-27 21:30               ` Michael S. Tsirkin
2016-10-27 21:42                 ` David Miller
2016-10-27 22:25                   ` Michael S. Tsirkin
2016-10-28  1:35                     ` David Miller
2016-10-28  1:43                       ` Alexander Duyck
2016-10-28  2:10                         ` David Miller
2016-10-28 15:56                           ` John Fastabend
2016-10-28 16:18                             ` Jakub Kicinski
2016-10-28 18:22                               ` Alexei Starovoitov
2016-10-28 20:35                                 ` Alexander Duyck
2016-10-28 20:42                                   ` Jakub Kicinski
2016-10-28 20:36                                 ` Jakub Kicinski
2016-10-29  3:51                                 ` Shrijeet Mukherjee
2016-10-29 11:25                                   ` Thomas Graf
2016-11-02 14:27                                     ` Jesper Dangaard Brouer
2016-11-03  1:28                                       ` Shrijeet Mukherjee
2016-11-03  4:11                                         ` Michael S. Tsirkin
2016-11-03  6:44                                           ` John Fastabend
2016-11-03 22:20                                             ` John Fastabend
2016-11-03 22:42                                             ` Michael S. Tsirkin
2016-11-03 23:29                                               ` John Fastabend
2016-11-04  0:34                                                 ` Michael S. Tsirkin
2016-11-04 23:05                                                   ` John Fastabend
2016-11-06  6:50                                                     ` Michael S. Tsirkin
2016-10-28 17:11                             ` David Miller
2016-10-30 22:53                               ` Michael S. Tsirkin
2016-11-02 14:01                               ` Jesper Dangaard Brouer
2016-11-02 16:06                                 ` Alexander Duyck
2016-10-28  0:02               ` Shrijeet Mukherjee
2016-10-28  0:46                 ` Shrijeet Mukherjee

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