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From: Ingo Molnar <mingo@kernel.org>
To: Amit Shah <amit.shah@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>,
	x86@kernel.org, virtualization@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org,
	"Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH] virtio_console: Stop doing DMA on the stack
Date: Thu, 8 Sep 2016 08:49:43 +0200	[thread overview]
Message-ID: <20160908064943.GA25876@gmail.com> (raw)
In-Reply-To: <20160906070343.GD3100@amit-lp.rh>


* Amit Shah <amit.shah@redhat.com> 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@kernel.org>
> 
> Looks fine,
> 
> Reviewed-by: Amit Shah <amit.shah@redhat.com>
> 
> > ---
> > 
> > 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

  parent reply	other threads:[~2016-09-08  6:49 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-30 15:04 [PATCH] virtio_console: Stop doing DMA on the stack Andy Lutomirski
2016-08-30 15:04 ` Andy Lutomirski
2016-09-06  7:03 ` Amit Shah
2016-09-06  7:03   ` Amit Shah
2016-09-08  6:49   ` Ingo Molnar
2016-09-08  6:49   ` Ingo Molnar [this message]
2016-09-09 18:10     ` Michael S. Tsirkin
2016-09-09 18:10       ` Michael S. Tsirkin
2016-09-10  4:33       ` Ingo Molnar
2016-09-10  4:33         ` Ingo Molnar
2016-09-08  9:47 ` [tip:x86/asm] " tip-bot for Andy Lutomirski

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