[vfio-users] 1 GB hugepages cause host crash on guest shutdown with some GPUs

[Okky Hendriansyah]

On December 8, 2015 at 15:02:08, Hristo Iliev (hristo at hiliev.eu) wrote:
Hi Okky, 

My linux-lts is 4.1.13-1 from the core repo. I took some time over the 
weekend to examine the situation more carefully and discovered that it is 
actually the complete reverse of what I've written in my last email. 

When I shut down the host completely and then boot it with linux-lts, the 
VM boots up fine. I can reboot or shut down the VM and then boot it up again 
multiple times without any issues. But should I reboot the host without 
shutting it down, the VM would reliably hang on the OVMF splash. It's 
really perplexing. Something I haven't tried yet though is to disable the 
huge pages guest memory backing and see if it has any effect. 

Perhaps, I should simply replace the reboot action of my display manager 
with shutdown and declare it a solution :) 
Hmm, probably the passed through GPU didn’t properly reinitialize/ejected during forced host reboot, since the handle still on the guest. I’m not really sure about this. Why do you reboot the host without shutting down the guest? Probably you need to configure something like pre-reboot hook script to properly shutdown all guests first.

Pretty sure I meant linux-lts. 
OK, I think I was confused myself since you got reversed.

Again, I've got this in reverse. The VM actually boots on linux-lts after a 
complete shutdown of the host. It doesn't boot after the host is rebooted 
with linux-lts, no matter what kernel ran before the reboot.
So the linux-vfio-lts kernel can boot the guest after the reboot?

...

I'm actually taking issue with the AUR and the fact that I have to always 
abort yaourt after the vfio kernel is compiled once. It produces three 
packages at once (kernel, headers, docs), but once those are installed, it 
proceeds to recompiling the kernel again in order to produce the headers 
package, which was already produced in the previous step... Anyway, Arch is 
pretty new to me, so I guess I will find a fix (or the proper way to handle 
it) soon. Maybe Dan could shed some light here. 
When yaourt asked you the first time, just answer that you want to compile all of them. I think by default it only compiles one component, hence you have to compile like 3 times although you already done that in the first step.


-- 
Okky Hendriansyah
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