Hi Shameer, On 5/13/20 5:57 PM, Shameerali Kolothum Thodi wrote: > Hi Eric, > >> -----Original Message----- >> From: Auger Eric [mailto:eric.au...@redhat.com] >> Sent: 13 May 2020 14:29 >> To: Shameerali Kolothum Thodi <shameerali.kolothum.th...@huawei.com>; >> Zhangfei Gao <zhangfei....@linaro.org>; eric.auger....@gmail.com; >> io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org; >> k...@vger.kernel.org; kvm...@lists.cs.columbia.edu; w...@kernel.org; >> j...@8bytes.org; m...@kernel.org; robin.mur...@arm.com >> Cc: jean-phili...@linaro.org; alex.william...@redhat.com; >> jacob.jun....@linux.intel.com; yi.l....@intel.com; peter.mayd...@linaro.org; >> t...@semihalf.com; bbhush...@marvell.com >> Subject: Re: [PATCH v11 00/13] SMMUv3 Nested Stage Setup (IOMMU part) >> > [...] > >>>>> Yes that's normal this series is not meant to support vSVM at this stage. >>>>> >>>>> I intend to add the missing pieces during the next weeks. >>>> >>>> Thanks for that. I have made an attempt to add the vSVA based on >>>> your v10 + JPBs sva patches. The host kernel and Qemu changes can >>>> be found here[1][2]. >>>> >>>> This basically adds multiple pasid support on top of your changes. >>>> I have done some basic sanity testing and we have some initial success >>>> with the zip vf dev on our D06 platform. Please note that the STALL event >>>> is >>>> not yet supported though, but works fine if we mlock() guest usr mem. >>> >>> I have added STALL support for our vSVA prototype and it seems to be >>> working(on our hardware). I have updated the kernel and qemu branches >> with >>> the same[1][2]. I should warn you though that these are prototype code and I >> am pretty >>> much re-using the VFIO_IOMMU_SET_PASID_TABLE interface for almost >> everything. >>> But thought of sharing, in case if it is useful somehow!. >> >> Thank you again for sharing the POC. I looked at the kernel and QEMU >> branches. >> >> Here are some preliminary comments: >> - "arm-smmu-v3: Reset S2TTB while switching back from nested stage": as >> you mentionned S2TTB reset now is featured in v11 > > Yes. > >> - "arm-smmu-v3: Add support for multiple pasid in nested mode": I could >> easily integrate this into my series. Update the iommu api first and >> pass multiple CD info in a separate patch > > Ok. in v12, I added [PATCH v12 14/15] iommu/smmuv3: Accept configs with more than one context descriptor
I don't think you need to add s1cdmax addition as we already have pasid_bits which should do the job. >> - "arm-smmu-v3: Add support to Invalidate CD": CD invalidation should be >> cascaded to host through the PASID cache invalidation uapi (no pb you >> warned us for the POC you simply used VFIO_IOMMU_SET_PASID_TABLE). I >> think I should add this support in my original series although it does >> not seem to trigger any issue up to now. > > Agree. Cache invalidation uapi is a better interface for this. Also I don’t > think > this matters for non-vsva cases as Guest kernel table/CD(pasid 0) will never > get invalidated. in v12 I added [PATCH v12 15/15] iommu/smmuv3: Add PASID cache invalidation per PASID. I have not tested it though. > >> - "arm-smmu-v3: Remove duplication of fault propagation". I understand >> the transcode is done somewhere else with SVA but we still need to do it >> if a single CD is used, right? I will review the SVA code to better >> understand. Since I have rebase on 5.10-rc4 you will still have this duplication to handle. > > Hmm..not sure. Need to take another look to see whether we need a special > handling for single CD or not. > >> - for the STALL response injection I would tend to use a new VFIO region >> for responses. At the moment there is a single VFIO region for reporting >> the fault. in v12 I added a new VFIO region to inject your fault. This was tested with dummy event injection, this should work properly. If we clearly identify all the public dependencies needed for vSVA/ARM I can help you respinning on top of them Thanks Eric > > Sure. That will be much cleaner and probably improve the context switch > latency. Another thing I noted with STALL is that pasid_valid flag needs to be > taken care in the SVA kernel path. > > "iommu: Remove pasid validity check for STALL model page response msg" > Not sure this one is a proper way to handle this. > >> On QEMU side: >> - I am currently working on 3.2 range invalidation support which is >> needed for DPDK/VFIO >> - While at it I will look at how to incrementally introduce some of the >> features you need in this series. > > Ok. > > Thanks for taking a look at the POC. > > Cheers, > Shameer >
