Re: [Xen-devel] Xen-unstable: AMD-Vi: update_paging_mode Try to access pdev_list without aquiring pcidevs_lock.

[Jan Beulich <jbeulich@xxxxxxxx>]

On 31.10.2019 21:48, Sander Eikelenboom wrote:
>     - The usb3 controller malfunctioning seems indeed to be a separate issue 
> (which seems unfortunate, 
>       because a bisect seems to become even nastier with all the intertwined 
> pci-passthrough issues).
>       
>       Perhaps this one is then related to the only *once* occuring message: 
>           (XEN) [2019-10-31 20:39:30.746] AMD-Vi: INVALID_DEV_REQUEST 
> 00000800 8a000000 f8000840 000000fd
>      
>       While in the guest it is endlessly repeating:
>           [  231.385566] xhci_hcd 0000:00:05.0: Max number of devices this 
> xHCI host supports is 32.
>           [  231.407351] usb usb1-port2: couldn't allocate usb_device

I'm uncertain whether there's a correlation: The device the Xen
message is about is 08:00.0; please let us know what kind of device
that is (the hypervisor log alone don't allow me to guess).

The specific type is described as "Posted write to the Interrupt/EOI
range from an I/O device that has IntCtl=00b in the device’s DTE."
This would make me guess 1b00c16bdf ("AMD/IOMMU: pre-fill all DTEs
right after table allocation") is the culprit here, and I may need
to hand you a debugging patch to gain some insight. But let me first
take a look at sufficiently verbose lspci output from that system.

Jan

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