PCI Passthrough question (xm->xl migration in Xen 4.2.2)

PCI Passthrough question (xm->xl migration in Xen 4.2.2)

[Saurabh Mishra]

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In XM toolchain, we use to put pci = [ '0000:07:11.6=0@1a' ] but looks like
in XL toolchain there is no way to specify function in the guest.

Kindly let me know.

XM  - pci = [ '0000:07:11.6=0@1a' ]
XL   - pci = [ '0000:07:11.6@1a' ]

In the guest VM we see that PCI device is getting 0 function in both the
cases however, it may not work the same way in the future.

*lspci -nn*

00:00.0 Host bridge [0600]: Intel Corporation 440FX - 82441FX PMC [Natoma]
[8086:1237] (rev 02)
00:01.0 ISA bridge [0601]: Intel Corporation 82371SB PIIX3 ISA
[Natoma/Triton II] [8086:7000]
00:01.1 IDE interface [0101]: Intel Corporation 82371SB PIIX3 IDE
[Natoma/Triton II] [8086:7010]
00:01.3 Bridge [0680]: Intel Corporation 82371AB/EB/MB PIIX4 ACPI
[8086:7113] (rev 01)
00:02.0 VGA compatible controller [0300]: Cirrus Logic GD 5446 [1013:00b8]
00:03.0 Unknown class [ff80]: XenSource, Inc. Xen Platform Device
[5853:0001] (rev 01)
*00:1a.0 Ethernet controller [0200]: Intel Corporation 82559 Ethernet
Controller Virtual Function [8086:10ed] (rev 01)*
*
*

Thanks,
/Saurabh

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Re: PCI Passthrough question (xm->xl migration in Xen 4.2.2)

[Ian Campbell]

create ^
title it xl does not support specifying virtual function for passthrough device
thanks

On Thu, 2013-10-31 at 14:29 -0700, Saurabh Mishra wrote:
> In XM toolchain, we use to put pci = [ '0000:07:11.6=0@1a' ] but looks
> like in XL toolchain there is no way to specify function in the guest.

The code is a bit confusing, but that does appear to be the case. libxl
seems to have some degree of support but I can't see any code in xl (or
the libxlu helper library function which parses the PCI options) that
would support the =N@M syntax.

Given the lack of xl support there's a good chance that the libxl
support is relatively untested.

> Kindly let me know.
> 
> 
> XM  - pci = [ '0000:07:11.6=0@1a' ]
> XL   - pci = [ '0000:07:11.6@1a' ]
> 
> 
> In the guest VM we see that PCI device is getting 0 function in both
> the cases however, it may not work the same way in the future.

Do you happen to know (or can you easily do the experiment to find out)
what happens with '0000:07:11.6@1a' on xm? Does the guest see function 0
or function 6? If it is 0 then I think we can safely say xl will not
change, but if it is 6 we'll have to have a think...

Ian.

Processed: Re: PCI Passthrough question (xm->xl migration in Xen 4.2.2)

[xen]

Processing commands for xen@bugs.xenproject.org:

> create ^
Created new bug #22 rooted at `<CAMnwyJ2W8vXJ4o7wxqcW1E1rEYK7e9zTCzESb=fQ+47dOmcmNQ@mail.gmail.com>'
Title: `Re: [Xen-devel] PCI Passthrough question (xm->xl migration in Xen 4.2.2)'
> title it xl does not support specifying virtual function for passthrough device
Set title for #22 to `xl does not support specifying virtual function for passthrough device'
> thanks
Finished processing.

Modified/created Bugs:
 - 22: http://bugs.xenproject.org/xen/bug/22 (new)

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Re: PCI Passthrough question (xm->xl migration in Xen 4.2.2)

[Sander Eikelenboom]

Monday, November 4, 2013, 4:45:25 PM, you wrote:

> create ^
> title it xl does not support specifying virtual function for passthrough device
> thanks

> On Thu, 2013-10-31 at 14:29 -0700, Saurabh Mishra wrote:
>> In XM toolchain, we use to put pci = [ '0000:07:11.6=0@1a' ] but looks
>> like in XL toolchain there is no way to specify function in the guest.

> The code is a bit confusing, but that does appear to be the case. libxl
> seems to have some degree of support but I can't see any code in xl (or
> the libxlu helper library function which parses the PCI options) that
> would support the =N@M syntax.

> Given the lack of xl support there's a good chance that the libxl
> support is relatively untested.

FYI qemu-upstream xen passhthrough currently also doesn't support specifying a request for
a certain dev/function nr.

And it is vaguely related to the lacking ability to passthrough multifunction devices as multifunction devices.
(the xm + qemu_trad require you to specify the virtual dev/func in this case, and additional some checks in libxl can't handle
the multifunction mask and bail out early)

>> Kindly let me know.
>> 
>> 
>> XM  - pci = [ '0000:07:11.6=0@1a' ]
>> XL   - pci = [ '0000:07:11.6@1a' ]
>> 
>> 
>> In the guest VM we see that PCI device is getting 0 function in both
>> the cases however, it may not work the same way in the future.

> Do you happen to know (or can you easily do the experiment to find out)
> what happens with '0000:07:11.6@1a' on xm? Does the guest see function 0
> or function 6? If it is 0 then I think we can safely say xl will not
> change, but if it is 6 we'll have to have a think...

> Ian.