RE: [PATCH v3 1/3] PCI: Allow ATS to be always on for CXL.cache capable devices

[Tian, Kevin]

> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Friday, April 10, 2026 6:53 AM
> 
> On Thu, Apr 09, 2026 at 03:45:26PM -0700, Nicolin Chen wrote:
> 
> > One question regarding VM case: if a device is ats_always_on, while
> > VM somehow doesn't set nested_domain->enable_ats. Should the kernel
> > at least spit a warning, given that it would surely fail the device?
> 
> No, just let break, the resulting failure has to be contained to the
> VM or the platform is broken..
> 
> The HV can't turn on ATS because we it can't know what invalidations
> to push so not much other choice.
> 

Taking about in theory - host can append a devtlb invalidation cmd
after iotlb invalidation (if vcmdq is not used)?