Re: [Xen-devel] ASMedia ASM1083/1085 rev3 and Xen DMA Failure

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 10/04/2013 02:34 PM, Konrad Rzeszutek Wilk wrote:
> On Fri, Oct 04, 2013 at 11:29:58AM -0600, Bjorn Helgaas wrote:
> > [+cc Konrad, xen-devel]
> Hey Bjorn, Thanks!
> > On Wed, Oct 02, 2013 at 04:43:46PM -0400, Aaron Opfer wrote:
> > > First time submitting the kernel dev list, so if I have demonstrated
> > > gross incompetence in some way, please cut me some slack. :)
> > >
> > > I discussed with Clemens Ladisch an issue I was having that I thought
> > > was related to the driver he authored for my soundcard, but on his
> > > suggestion I experimented with other PCI devices and we have narrowed
> > > the issue to the PCI Bridge.
> > >
> > > What hints me toward DMA handling being the fault is the following
> > > message I receive during kernel initialization after rebooting from an
> > > Xen hypervisor into a baremetal-kernel, without a power-cycle:
> > >
> > > [0.012815] dmar: DRHD: handling fault status reg 3
> > > [0.012868] dmar: DMAR:[DMA Read] Request device [07:00.0] fault addr 7e00000
> > > [0.012868] DMAR:[fault reason 02] Present bit in context entry is clear
But if you powercycle the system you don't see this error?

Have you tried booting your kernel with "intel_iommu=off"?

-boris

> > Presumably 07:00.0 is your soundcard, and apparently it did a DMA
> > read to 0x7e00000, which wasn't mapped by the IOMMU.
> >
> > > In addition to other hints, such as simple IO like changing the active
> > > port on the soundcard worked (I could hear the relays clicking) but
> > > not the functions that DMA would be used (streaming audio).
> > >
> > > The PCI devices in my system are connected via this device, as listed by lspci:
> > >
> > > 06:00.0 PCI bridge: ASMedia Technology Inc. ASM1083/1085 PCIe to PCI
> > > Bridge (rev 03)
> > >
> > > This PCI bridge works under bare-metal Linux normally (w/ various
> > > debian kernels stable/unstable/testing/backports), but under Xen
> > > Hypervisor the PCI devices connected exhibit bad behavior.
> > So it fails with Xen but works otherwise?  I assume there are other
> > PCI devices, too?  Do they work?
> >
> > If you want to open a report at http://bugzilla.kernel.org, that would
> > be a handy place to attach a complete dmesg log and "lspci -vv" output
> > for more details.
> >
> > > For
> > > instance, aformentioned sound card outputs no sound and gets no
> > > microphone input at all, and an ethernet card causes a system lockup
> > > as soon as gnome's network manager attempts DHCP over it (presumably;
> > > I did not test this as thoroughly as the sound card).
> > >
> > > I've used Xen Hypervisors 4.1 and 4.2 and had the issues I described
> > > above with both of them. I was briefly running 4.3 but I did not test
> > > the device.
> So lets seperate some of these issues. The sound-card issue might be
> related to the Linux kernel Xen-SWIOTLB (fixed at some point)- so could
> you tell me what the kernel version you have?
>
> Xen 4.3 also has numerous fixes in the IOMMU path.
>
> > > Rev1 of the ASM1083 was apparently buggy to the point of being
> > > unusable, as Clemens pointed out. I would be disappointed if this
> > > device is similarly unsalvageable,but would be happier if this buggy
> > > hardware at the very least outputted warnings to users who attempt to
> > > use it (in Xen).
> > >
> > > All The Best,
> > >
> > > Aaron Opfer
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-pci" in
> > > the body of a message to majordomo@xxxxxxxxxxxxxxx
> > > More majordomo info at  http://vger.kernel.org/majordomo-info.html

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel