linux-kernel - Re: [RFC 2/5] virtio_ring: introduce virtqueue_map/unmap

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: <CAJaqyWfpVfm6JgSanRBKrsprpKR6Nc+YsyFmsYzoNwBb+uZW-Q@mail.gmail.com>
Date: Thu, 23 Jan 2025 08:31:52 +0100
From: Eugenio Perez Martin <eperezma@...hat.com>
To: Jason Wang <jasowang@...hat.com>
Cc: linux-kernel@...r.kernel.org, mst@...hat.com, 
	Hanna Reitz <hreitz@...hat.com>, Stefano Garzarella <sgarzare@...hat.com>, 
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, Vivek Goyal <vgoyal@...hat.com>, 
	Miklos Szeredi <miklos@...redi.hu>, German Maglione <gmaglione@...hat.com>, 
	Stefan Hajnoczi <stefanha@...hat.com>, virtualization@...ts.linux.dev
Subject: Re: [RFC 2/5] virtio_ring: introduce virtqueue_map/unmap_sgs()

On Thu, Jan 23, 2025 at 2:51 AM Jason Wang <jasowang@...hat.com> wrote:
>
> On Thu, Jan 23, 2025 at 12:32 AM Eugenio Pérez <eperezma@...hat.com> wrote:
> >
> > From: Jason Wang <jasowang@...hat.com>
> >
> > Introduce new virtqueue DMA operations which allows the drivers that
> > want to make use of the premapping API but operate at the sg level.
> >
> > Note that we still follow the assumtions if virtqueue_add() so
> > dma_map_sg() is not used. This could be optimized in the future.
> > Signed-off-by: Jason Wang <jasowang@...hat.com>
> > Signed-off-by: Eugenio Pérez <eperezma@...hat.com>
> > --
> > Eugenio's changes: Remove blank
> > TODO: Should we call directly dma_map instead of this? XDP do the direct
> > call.
>
> Note that we should have an indirection layer as the device is not
> necessarily DMA capable.
>

Can you expand on this? virtqueue_map_sgs calls directly to
dma_map_page for each entry in the sg. This indirection layer should
be in the device's callback for DMA, isn't it?

> And we probably need to rename the virtqueue_dma_map_XXX() to
> virtqueue_map_XXX()
>

Ok so maybe these functions are already enough without using
dma_map_sgs. I"m ok with renaming these, but that should be done in a
separate series, isn't it?

Thanks!