Re: [RFC PATCH 1/3] powerpc/pseries/iommu: Bring back userspace view for single level TCE tables

[Timothy Pearson]

----- Original Message -----
> From: "Jason Gunthorpe" <jgg@xxxxxxxx>
> To: "Shivaprasad G Bhat" <sbhat@xxxxxxxxxxxxx>
> Cc: "Timothy Pearson" <tpearson@xxxxxxxxxxxxxxxxxxxxx>, "Alex Williamson" <alex.williamson@xxxxxxxxxx>, "linuxppc-dev"
> <linuxppc-dev@xxxxxxxxxxxxxxxx>, "Michael Ellerman" <mpe@xxxxxxxxxxxxxx>, "npiggin" <npiggin@xxxxxxxxx>, "christophe
> leroy" <christophe.leroy@xxxxxxxxxx>, "aneesh kumar" <aneesh.kumar@xxxxxxxxxx>, "naveen n rao"
> <naveen.n.rao@xxxxxxxxxxxxx>, "gbatra" <gbatra@xxxxxxxxxxxxxxxxxx>, brking@xxxxxxxxxxxxxxxxxx, "Alexey Kardashevskiy"
> <aik@xxxxxxxxx>, robh@xxxxxxxxxx, "linux-kernel" <linux-kernel@xxxxxxxxxxxxxxx>, "kvm" <kvm@xxxxxxxxxxxxxxx>, "aik"
> <aik@xxxxxxx>, msuchanek@xxxxxxx, "jroedel" <jroedel@xxxxxxx>, "vaibhav" <vaibhav@xxxxxxxxxxxxx>, svaidy@xxxxxxxxxxxxx
> Sent: Tuesday, March 19, 2024 9:32:02 AM
> Subject: Re: [RFC PATCH 1/3] powerpc/pseries/iommu: Bring back userspace view for single level TCE tables

> On Tue, Mar 12, 2024 at 01:14:20PM -0500, Shivaprasad G Bhat wrote:
>> The commit 090bad39b237a ("powerpc/powernv: Add indirect levels to
>> it_userspace") which implemented the tce indirect levels
>> support for PowerNV ended up removing the single level support
>> which existed by default(generic tce_iommu_userspace_view_alloc/free()
>> calls). On pSeries the TCEs are single level, and the allocation
>> of userspace view is lost with the removal of generic code.
> 
> :( :(
> 
> If this has been broken since 2018 and nobody cared till now can we
> please go in a direction of moving this code to the new iommu APIs
> instead of doubling down on more of this old stuff that apparently
> almost nobody cares about ??
> 
> Jason

Just FYI Raptor is working on porting things over to the new APIs.  RFC patches should be posted in the next week or two.