Re: AMD integrated graphics passthrough to KVM guest

[Alex Williamson <alex.williamson@redhat.com>]

On Fri, 2013-07-12 at 18:13 +0200, Gustav Sorenson wrote:
> Hello Alex,
> 
> thank you very much for your answer.
> 
> > VGA assignment should only even be attempted on non-primary displays at
> > this point (unless of course you want to work on adding support).
> 
> I assume when you say "non-primary," you refer to graphics adapters
> that are not used to display POST and kernel messages?

Yes

> Although I know C, I've never worked on hardware-related tasks, so I'm
> afraid I won't be of much help in adding support, unless you think
> it's a task that is suitable for a newcomer. In any case, I'd be happy
> to help by testing suggestions by you or others.
> 
> >> Next, I took a really old PCIe graphics card, installed it and set it
> >> to be my primary graphics adapter in BIOS (or rather UEFI?), so that I
> >> now saw POST and kernel messages via the dedicated GPU. Surprisingly
> >> to me, I was able to pass-through the dedicated PCIe card to a KVM
> >> guest, but still not the now supposedly unused integrated GPU, still
> >> getting the same message when I tried.
> >
> > What is the plugin graphics card?
> 
> I've pulled that card out of an old computer that I haven't bought.
> It's manufactured by MSI, but other than that, I haven't found make or
> model names. lspci says it's an "ATI RV515 [Radeon X1300]."

Ok, I have an X500 and I've never been able to get it to work correctly
for passthrough.  It has additional quirks required beyond what either
my HD5450 or HD7850 require.  Also, these old devices have a weird
co-processor secondary function (see 01:00.1 in your lspci).  It
probably needs to be co-assigned, but I'm not really sure what it does.
FWIW, I don't think it's worth bothering to add support for anything
older than a Radeon HD5xxx (I'd say HD6xxx, but I happen to have the
HD5450 and it works, so...)

> > Please provide 'sudo lspci -vvv'.  Thanks,
> lspci -vvv with the graphics card built into the first PCIe slot:
> http://pastebin.com/92Q6uFwa
> lspci -vvv without the graphics card: http://pastebin.com/RAAsXxF3

One reason you're probably not getting any output is because the device
doesn't have a ROM (ie. there's no video BIOS to run to get seabios to
POST the device).  You'll either need to find a VBIOS for the device or
use it as a secondary graphics device in the guest.  In some cases you
can rip this out of the system ROM or ACPI tables.

I don't think that using the vfio-vga-reset branches is helping you
since it's a root complex device and we can't do a reset even if we knew
how and if you use it as a secondary device, you might not even need the
x-vga=on option for VFIO (ie. VFIO would handle this just like any
regular PCI device).  Thanks,

Alex