linux-kernel - Re: [RFC net-next 1/4] net: Allow non parent devices to be used for ZC DMA

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250702113208.5adafe79@kernel.org>
Date: Wed, 2 Jul 2025 11:32:08 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Dragos Tatulea <dtatulea@...dia.com>
Cc: <almasrymina@...gle.com>, <asml.silence@...il.com>, Andrew Lunn
 <andrew+netdev@...n.ch>, "David S. Miller" <davem@...emloft.net>, "Eric
 Dumazet" <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, Simon
 Horman <horms@...nel.org>, Saeed Mahameed <saeedm@...dia.com>,
 <tariqt@...dia.com>, <cratiu@...dia.com>, <netdev@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>
Subject: Re: [RFC net-next 1/4] net: Allow non parent devices to be used for
 ZC DMA

On Wed, 2 Jul 2025 20:24:23 +0300 Dragos Tatulea wrote:
> For zerocopy (io_uring, devmem), there is an assumption that the
> parent device can do DMA. However that is not always the case:
> for example mlx5 SF devices have an auxiliary device as a parent.

Noob question -- I thought that the point of SFs was that you can pass
them thru to a VM. How do they not have DMA support? Is it added on
demand by the mediated driver or some such?