Re: DMAR fault with qemu 7.2 and Ubuntu 22.04 base image

[Klaus Jensen]

On Feb 14 17:34, Major Saheb wrote:
> Thanks Peter for the reply. I tried to connect gdb to qemu and able to
> break 'vtd_iova_to_slpte()', I dumped the following with both Ubuntu
> 20.04 base image container which is the success case and Ubuntu 22.04
> base image container which is failure case
> One thing I observed is the NvmeSQueue::dma_addr is correctly set to
> '0x800000000', however in failure case this value is 0x1196b1000. A
> closer look indicates more fields in NvmeSQueue might be corrupted,
> for example we are setting admin queue size as 512 but in failure case
> it is showing 32.
> 

Hi Major,

It's obviously pretty bad if hw/nvme somehow corrupts the SQ structure,
but it's difficult to say from this output.

Are you configuring shadow doorbells (the db_addr and ei_addr's are
set in both cases)?

> > > Following is the partial qemu command line that I am using
> > >
> > > -device 
> > > intel-iommu,intremap=on,caching-mode=on,eim=on,device-iotlb=on,aw-bits=48
> > >

I'm not sure if caching-mode=on and device-iotlb=on leads to any issues
here? As far as I understand, this is mostly used with stuff like vhost.
I've tested and developed vfio-based drivers against hw/nvme excessively
and I'm not using anything besides `-device intel-iommu`.

Do I undestand correctly that your setup is "just" a Ubuntu 22.04 guest
with a container and a user-space driver to interact with the nvme
devices available on the guest? No nested virtualization with vfio
passthrough?

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