Date: Fri, 03 May 2013 11:55:17 +0200
Message-ID: <s5hmwscxu9m.wl%tiwai@suse.de>
From: Takashi Iwai <tiwai@suse.de>
To: Mike Travis <travis@sgi.com>
Cc: David Henningsson <david.henningsson@canonical.com>,
        Stephen Warren <swarren@nvidia.com>, Jaroslav Kysela <perex@perex.cz>,
        Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
        alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org,
        Russ Anderson <rja@sgi.com>
Subject: Re: [PATCH]: x86_64, audio: Fix system panic when DMA > 40 bits
In-Reply-To: <51820968.7080303@sgi.com>
References: <1367435048-66137-1-git-send-email-travis@sgi.com>
	<518205A9.1050409@canonical.com>
	<51820968.7080303@sgi.com>
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At Wed, 01 May 2013 23:36:24 -0700,
Mike Travis wrote:
> 
> 
> 
> On 5/1/2013 11:20 PM, David Henningsson wrote:
> > On 05/01/2013 09:04 PM, Mike Travis wrote:
> >> The audio driver mistakenly allows 64 bit addresses to be created for
> >> the audio driver on Nvidia GPUs.  Unfortunately, the hardware normally
> >> only supports up to 40 bits of DMA.  This can cause system panics as
> >> well as misdirected data when the address is > 40 bits as the upper
> >> part the address is truncated.
> > 
> > Thanks for this patch. Stephen Warren, is this something you can
> > confirm/deny, and do you know what range of hardware this actually
> > applies to?
> 
> The dma_mask can be read from the gpu device's pci entry.

Well, this assumes that the graphics driver is initialized before the
audio driver, right?

>  I know it's
> a stretch to try to link to that but past history has shown that it
> ranges from 36 to 40 bits.

Looking through nouveau drivers, even 32bit dma_bits is used for some
devices, too, so a safe bid would be simply 32bit.  Of course, if we
have a table of DMA bits, we can use the more exact values.

I'll apply your original patch as a quick fix for now.


thanks,

Takashi

> > 
> >>
> >> Signed-off-by: Mike Travis <travis@sgi.com>
> >> Reviewed-by: Mike Habeck <habeck@sgi.com>
> >> ---
> >>   sound/pci/hda/hda_intel.c | 2 +-
> >>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> >> index bcd40ee..45eb165 100644
> >> --- a/sound/pci/hda/hda_intel.c
> >> +++ b/sound/pci/hda/hda_intel.c
> >> @@ -615,7 +615,7 @@ enum {
> >>   /* quirks for Nvidia */
> >>   #define AZX_DCAPS_PRESET_NVIDIA \
> >>       (AZX_DCAPS_NVIDIA_SNOOP | AZX_DCAPS_RIRB_DELAY |
> >> AZX_DCAPS_NO_MSI |\
> >> -     AZX_DCAPS_ALIGN_BUFSIZE)
> >> +     AZX_DCAPS_ALIGN_BUFSIZE | AZX_DCAPS_NO_64BIT)
> >>
> >>   #define AZX_DCAPS_PRESET_CTHDA \
> >>       (AZX_DCAPS_NO_MSI | AZX_DCAPS_POSFIX_LPIB |
> >> AZX_DCAPS_4K_BDLE_BOUNDARY)
> >>
> > 
> > 
> > 
> 
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