Re: [PATCH] virtio_console: Stop doing DMA on the stack

[Ingo Molnar]

* Amit Shah <amit.shah@xxxxxxxxxx> wrote:

> On (Tue) 30 Aug 2016 [08:04:15], Andy Lutomirski wrote:
> > virtio_console uses a small DMA buffer for control requests.  Move
> > that buffer into heap memory.
> > 
> > Doing virtio DMA on the stack is normally okay on non-DMA-API virtio
> > systems (which is currently most of them), but it breaks completely
> > if the stack is virtually mapped.
> > 
> > Tested by typing both directions using picocom aimed at /dev/hvc0.
> > 
> > Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
> 
> Looks fine,
> 
> Reviewed-by: Amit Shah <amit.shah@xxxxxxxxxx>
> 
> > ---
> > 
> > Hi all-
> > 
> > This is currently broken in tip:x86/asm.  If you (Amit) like this patch,
> > would it make sense for Ingo to add it to -tip?
> 
> Yes, I'm fine with that.

Thanks! FYI, this patch now lives as:

  9472fe7040bb ("virtio_console: Stop doing DMA on the stack")

in tip:x86/asm, and is targeted for a v4.9 merge.

Thanks,

	Ingo