On Thu, Aug 13, 2020 at 07:40:55PM -0700, Rob Clark wrote:
From: Rob Clark robdclark@chromium.org
NOTE: Since Jordan was out today, and I wanted to keep things moving on this, I took the liberty of respinning his series (originally titled "iommu/arm-smmu: Add Adreno SMMU specific implementation") with updates based on Will's review comments, and some fixes and extra bits that I found in stress testing the series. Original commit msg and updated version history below.
In general I like the private interface between adreno-smmu and the GPU driver. It should make for a more straightforward way to extend things to optimize TLB invalidation in the future, for example, rather than shoe-horning everything thru domain attrs. And it lets us describe the get_ttbr1_cfg/set_ttrb0_cfg dance more clearly. Although it is going to make landing this via iommu vs drm tree a bit more difficult. Maybe there are some arm-smmu parts of this series that could be pulled out to make it not conflicty to land the private interface and adreno-smmu bits via the drm tree? (But I'm jumping a bit ahead here. Just wanted to point out that issue.) The complete series can be found at: https://gitlab.freedesktop.org/drm/msm/-/commits/msm-next-pgtablesThis series adds an Adreno SMMU implementation to arm-smmu to allow GPU hardware pagetable switching.
The Adreno GPU has built in capabilities to switch the TTBR0 pagetable during runtime to allow each individual instance or application to have its own pagetable. In order to take advantage of the HW capabilities there are certain requirements needed of the SMMU hardware.
This series adds support for an Adreno specific arm-smmu implementation. The new implementation 1) ensures that the GPU domain is always assigned context bank 0, 2) enables split pagetable support (TTBR1) so that the instance specific pagetable can be swapped while the global memory remains in place and 3) shares the current pagetable configuration with the GPU driver to allow it to create its own io-pgtable instances.
The series then adds the drm/msm code to enable these features. For targets that support it allocate new pagetables using the io-pgtable configuration shared by the arm-smmu driver and swap them in during runtime.
This version of the series merges the previous patchset(s) [1] and [2] with the following improvements:
v13: (Respin by Rob)
- Switch to a private interface between adreno-smmu and GPU driver, dropping the custom domain attr (Will Deacon)
- Rework the SCTLR.HUPCF patch to add new fields in smmu_domain->cfg rather than adding new impl hook (Will Deacon)
- Drop for_each_cfg_sme() in favor of plain for() loop (Will Deacon)
- Fix context refcnt'ing issue which was causing problems with GPU crash recover stress testing.
- Spiff up $debugfs/gem to show process information associated with VMAs
I'll add the tags to Rob's code but in general I ack all these changes. I also like the private interface - it gives us the most flexibility without either changing the IOMMU API or giving up entirely and making an internal SMMU implementation inside drm/msm.
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Jordan