Re: [Xen-devel] [PATCH] x86/msi: Validate the guest-identified PCI devices in pci_prepare_msix()

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.01.14 at 22:40, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
> On Wed, Jan 22, 2014 at 12:08:42PM +0000, Jan Beulich wrote:
>> "Fixing the wrong thing" presumably, after taking a closer look at
>> Konrad's second crash: The device in question really appears to
>> be MSI-X capable, yet alloc_pdev() didn't recognize it as such. I
>> wonder whether the capability gets displayed/hidden dynamically
>> based on some other enabling the driver may be doing on the
>> device. In which case we'd need to allocate the structure on
>> demand.
> 
> The device in question (02:00.1) is an SR-IOV 82576:
> 
> 02:00.0 Ethernet controller: Intel Corporation 82576 Gigabit Network 
> Connection (rev 01)
> 02:00.1 Ethernet controller: Intel Corporation 82576 Gigabit Network 
> Connection (rev 01)
> 
> -bash-4.1# lspci -s 02:00.1 -v | more
> 02:00.1 Ethernet controller: Intel Corporation 82576 Gigabit Network 
> Connection (rev 01)
>         Subsystem: Intel Corporation Gigabit ET Dual Port Server Adapter
>         Flags: fast devsel, IRQ 18
>         Memory at f1400000 (32-bit, non-prefetchable) [disabled] [size=128K]
>         Memory at f0800000 (32-bit, non-prefetchable) [disabled] [size=4M]
>         I/O ports at d000 [disabled] [size=32]
>         Memory at f1440000 (32-bit, non-prefetchable) [disabled] [size=16K]
>         Expansion ROM at f0400000 [disabled] [size=4M]
>         Capabilities: [40] Power Management version 3
>         Capabilities: [50] MSI: Enable- Count=1/1 Maskable+ 64bit+
>         Capabilities: [70] MSI-X: Enable- Count=10 Masked-
>         Capabilities: [a0] Express Endpoint, MSI 00
>         Capabilities: [100] Advanced Error Reporting
>         Capabilities: [140] Device Serial Number 00-1b-21-ff-ff-45-d9-ac
>         Capabilities: [150] Alternative Routing-ID Interpretation (ARI)
>         Capabilities: [160] Single Root I/O Virtualization (SR-IOV)
>         Kernel driver in use: pciback
>         Kernel modules: igb

So is this state with igb never having been bound to the device,
or was it unbound before the device got handed to igb. I'm asking
because I'm trying to understand why alloc_pdev() didn't find the
MSI-X capability structure, and I continue to suspect that the
driver may have done something to the device to make it visible.

Jan


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