[Bug 220057] Kernel regression. Linux VMs crashing (I did not test Windows guest VMs)

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=220057

--- Comment #19 from Alex Williamson (alex.williamson@redhat.com) ---
(In reply to Adolfo from comment #16)
>
> Doesn't seam to do anything, no.
> 
> ----
> cores: 8
> cpu: host,flags=+pdpe1gb,phys-bits=39
> cpuunits: 200
> efidisk0: local-lvm:vm-200-disk-0,efitype=4m,pre-enrolled-keys=1,size=4
> ...

I'm getting that option from here:
https://pve.proxmox.com/wiki/Manual:_qm.conf

Can you find the QEMU command line in ps while the VM is running? ex. `ps aux |
grep qemu`  There should be a difference in the QEMU command line proxmox is
using with the option, and it should at least change the addresses based at
0x380000000000 in the logs.

I think the issue with the failed mappings is that you CPU physical address
width is 46-bits:

Address sizes: 46 bits physical, 48 bits virtual

But the host IOMMU width is 39-bits:

[    0.341856] DMAR: Host address width 39

Therefore the VM is giving the devices an IOVA that cannot be mapped by the
host IOMMU.  I don't know if ultimately that contributes to the issue you're
reporting, but it might.

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