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

[Okky Hendriansyah]

On November 30, 2015 at 11:31:17, Dan Ziemba (zman0900 at gmail.com) wrote:
I recently got myself a "new" (used) gpu to replace the one I was 
previously using for passthrough with vfio, and I discovered a strange 
bug during this.  With the new GPU being passed through to the guest, 
the host will "sort of" crash on guest shutdown.  Video output freezes 
and all usb devices seem to stop working, but ssh access still works 
fine.  virsh cannot be accessed over ssh though, it just hangs.  There 
is a stack trace printed in dmesg, but I don't think this is the same 
each time.  See the most recent one at the bottom. 

My VM is set up to use 8 1GB sized hugepages for memory.  By disabling 
hugepages completely, or switching to 4096 2MB hugepages, the crash is 
eliminated and the guest can be shutdown or reboot as much as I want.   
…
Hi Dan,

Hmm interesting, I found my setup to show weird white flickery things on the guest desktop when I use 1 GB hugepages. Did you notice these things on yours? Falling back to 2 MB hugepages bring things back to normal. I didn’t experience the freezing/crashing on the hypervisor host like you describe though. How do you bind the GPU? Is it pci-stub or vfio-pci? I use vfio-pci and load it statically during boot.

Best regards,
-- 
Okky Hendriansyah
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