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

[Timothy Pearson <tpearson@raptorengineering.com>]

----- Original Message -----
> From: "Jason Gunthorpe" <jgg@ziepe.ca>
> To: "Shivaprasad G Bhat" <sbhat@linux.ibm.com>
> Cc: "Timothy Pearson" <tpearson@raptorengineering.com>, "Alex Williamson" <alex.williamson@redhat.com>, "linuxppc-dev"
> <linuxppc-dev@lists.ozlabs.org>, "Michael Ellerman" <mpe@ellerman.id.au>, "npiggin" <npiggin@gmail.com>, "christophe
> leroy" <christophe.leroy@csgroup.eu>, "aneesh kumar" <aneesh.kumar@kernel.org>, "naveen n rao"
> <naveen.n.rao@linux.ibm.com>, "gbatra" <gbatra@linux.vnet.ibm.com>, brking@linux.vnet.ibm.com, "Alexey Kardashevskiy"
> <aik@ozlabs.ru>, robh@kernel.org, "linux-kernel" <linux-kernel@vger.kernel.org>, "kvm" <kvm@vger.kernel.org>, "aik"
> <aik@amd.com>, msuchanek@suse.de, "jroedel" <jroedel@suse.de>, "vaibhav" <vaibhav@linux.ibm.com>, svaidy@linux.ibm.com
> 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.