Re: [Xen-devel] Atheros WiFi - memory paging failure on driver load

[Andrey Grodzovsky <andrey2805@xxxxxxxxx>]

Thank you for your comments !

As a question , will disabling MSI enable bit in the card  and switching back to legacy interrupt method might resolve the issue ?

On Mon, Jul 18, 2016 at 2:22 PM, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:

On 18/07/16 04:29, Andrey Grodzovsky wrote:

On Fri, Jul 15, 2016 at 11:45 PM, Andrey Grodzovsky <andrey2805@xxxxxxxxx> wrote:

On Fri, Jul 15, 2016 at 6:04 AM, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:

On 12/07/16 04:59, Andrey Grodzovsky wrote:

Hello

Some background -

We are trying to run Qualcomm Atheros AR928X Wireless Network Adapter and have a crash right on driver load, following are our observations and questions.

Jurgen's observation - 

" The Atheros card "Qualcomm Atheros AR928X Wireless Network Adapter (PCI-Express) (rev 01)"  is plugged into the host system (datatron).
When I attach it to the DomU - the module "ath9k" is automatically loaded, but it gives an exception "iowrite32+0x2b/0x30".

No idea what the issue is (tried also with another Atheros Card (ath10k) - similar problem). When I try an Intel card, it works.
(the card also works on the Dom0 - so the Linux driver and HW is OK)."

Debugging - 

After some investigation with kgdb and iommu trace on DomU it seems the iomap of PCI BAR for the device returns a a mapping f which first 0x1000 bytes are read only and that causes access violation when trying to write registers mapped to this area (all the regs with offset < 0x1000) - why this happens i still don't know. Register writes with offsets > 0x1000 are fine.

Your card is not PCI spec compliant.

The Spec mandates that nothing may exist in any 4k aligned block covering part of the MSI-X table, precisely so read-only tricks like this can be done trap&intercept MSI-X updates.

Running same driver on Dom0 is totally fine

This is curious.  Dom0 and DomU should be treated identically in this regard.

~Andrew

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