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From: Jason Gunthorpe <jgg@nvidia.com>
To: Eric Auger <eric.auger@redhat.com>
Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>,
	Nicolin Chen <nicolinc@nvidia.com>,
	robin.murphy@arm.com, will@kernel.org, kevin.tian@intel.com,
	baolu.lu@linux.intel.com, joro@8bytes.org,
	shameerali.kolothum.thodi@huawei.com,
	linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev,
	linux-kernel@vger.kernel.org, yi.l.liu@intel.com
Subject: Re: [PATCH v1 02/14] iommufd: Add nesting related data structures for ARM SMMUv3
Date: Fri, 10 Mar 2023 08:51:36 -0400	[thread overview]
Message-ID: <ZAsn2EkRnEmsfmmp@nvidia.com> (raw)
In-Reply-To: <5288c0e9-b806-370d-e7de-8d69d5b8e902@redhat.com>

On Fri, Mar 10, 2023 at 12:33:12PM +0100, Eric Auger wrote:

> I do agree with Jean. We spent a lot of efforts all together to define
> this generic invalidation API and if there is compelling reason that
> prevents from using it, we should try to reuse it.

That's the compelling reason in a nutshell right there.

Alot of time was invested to create something that might be
general. We still don't know if it is well defined and general. Even
more time is going to be required on it before it could go forward. In
future more time will be needed for every future HW to try and fit
into it. We don't even know if it will scale to future HW. Nobody has
even checked what today's POWER and S390 HW need.

vs, this stuff was made in a few days. We know it is correct as a uAPI
since it mirrors the HW and we know it is scalable to different HW
schemes if they come up.

So I don't see a good reason to take a risk on a "general" uAPI. If we
make this wrong it could seriously damage the main goal of iommufd -
to build accelerated vIOMMU models.

Especially since the motivating reason in this thread - use it for
virtio-iommu - doesn't even want to use it as a uAPI!

If we get a vhost-virtio then we can decide what to do in-kernel and
maybe this general API returns as an in-kernel API, I dont know, we
need to see what it is this thing ends up looking like.

Jason

  reply	other threads:[~2023-03-10 12:51 UTC|newest]

Thread overview: 165+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-09 10:53 [PATCH v1 00/14] Add Nested Translation Support for SMMUv3 Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 01/14] iommu: Add iommu_get_unmanaged_domain helper Nicolin Chen
2023-03-09 12:51   ` Robin Murphy
2023-03-09 14:19     ` Jason Gunthorpe
2023-03-09 19:04       ` Robin Murphy
2023-03-10  0:23         ` Jason Gunthorpe
2023-03-10  8:41     ` Eric Auger
2023-03-10 15:55       ` Jason Gunthorpe
2023-03-16  1:21         ` Nicolin Chen
2023-03-16 18:42           ` Robin Murphy
2023-03-16 20:01             ` Nicolin Chen
2023-03-20 12:51             ` Jason Gunthorpe
2023-03-10 10:14   ` Eric Auger
2023-03-10 15:33     ` Jason Gunthorpe
2023-03-10 15:44       ` Shameerali Kolothum Thodi
2023-03-10 15:56         ` Jason Gunthorpe
2023-03-10 16:07           ` Shameerali Kolothum Thodi
2023-03-10 16:21             ` Jason Gunthorpe
2023-03-10 16:30               ` Shameerali Kolothum Thodi
2023-03-10 17:03                 ` Jason Gunthorpe
2023-03-22 16:07                   ` Eric Auger
2023-03-22 17:02                     ` Jason Gunthorpe
2023-03-22 17:41                       ` Eric Auger
2023-03-22 18:07                         ` Jason Gunthorpe
2023-03-16 19:51                 ` Nicolin Chen
2023-03-16 19:56                   ` Shameerali Kolothum Thodi
2023-03-22 15:44                     ` Eric Auger
2023-03-09 10:53 ` [PATCH v1 02/14] iommufd: Add nesting related data structures for ARM SMMUv3 Nicolin Chen
2023-03-09 13:42   ` Jean-Philippe Brucker
2023-03-09 14:48     ` Jason Gunthorpe
2023-03-09 18:26       ` Jean-Philippe Brucker
2023-03-09 21:01         ` Jason Gunthorpe
2023-03-10 12:16           ` Jean-Philippe Brucker
2023-03-10 14:52           ` Robin Murphy
2023-03-10 15:25             ` Jason Gunthorpe
2023-03-10 15:57               ` Robin Murphy
2023-03-10 16:03                 ` Jason Gunthorpe
2023-03-17 10:10                   ` Tian, Kevin
2023-03-17 10:04                 ` Tian, Kevin
2023-03-10  4:50       ` Nicolin Chen
2023-03-10 12:54         ` Jean-Philippe Brucker
2023-03-10 14:00           ` Jason Gunthorpe
2023-03-10 16:06         ` Jason Gunthorpe
2023-03-16  0:59           ` Nicolin Chen
2023-03-09 15:26     ` Shameerali Kolothum Thodi
2023-03-09 15:40       ` Jason Gunthorpe
2023-03-09 15:51         ` Shameerali Kolothum Thodi
2023-03-09 15:59           ` Jason Gunthorpe
2023-03-09 16:07             ` Shameerali Kolothum Thodi
2023-03-10  5:26               ` Nicolin Chen
2023-03-10  5:36                 ` Nicolin Chen
2023-03-10 12:55                   ` Jason Gunthorpe
2023-03-10  5:18         ` Nicolin Chen
2023-03-10  5:04     ` Nicolin Chen
2023-03-10 11:33     ` Eric Auger
2023-03-10 12:51       ` Jason Gunthorpe [this message]
2023-03-17 10:17         ` Tian, Kevin
2023-03-09 10:53 ` [PATCH v1 03/14] iommufd/device: Setup MSI on kernel-managed domains Nicolin Chen
2023-03-10 16:45   ` Eric Auger
2023-03-11  0:17     ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 04/14] iommu/arm-smmu-v3: Add arm_smmu_hw_info Nicolin Chen
2023-03-09 13:03   ` Robin Murphy
2023-03-10  1:17     ` Nicolin Chen
2023-03-10 15:28       ` Robin Murphy
2023-03-16  0:13         ` Nicolin Chen
2023-03-16 15:19           ` Robin Murphy
2023-03-16 20:06             ` Nicolin Chen
2023-04-12  7:47               ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 05/14] iommu/arm-smmu-v3: Remove ARM_SMMU_DOMAIN_NESTED Nicolin Chen
2023-03-10 16:39   ` Eric Auger
2023-03-10 17:05     ` Jason Gunthorpe
2023-03-11  0:24       ` Nicolin Chen
2023-03-11  0:23     ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 06/14] iommu/arm-smmu-v3: Unset corresponding STE fields when s2_cfg is NULL Nicolin Chen
2023-03-09 13:13   ` Robin Murphy
2023-03-09 18:24     ` Shameerali Kolothum Thodi
2023-03-10  1:54       ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 07/14] iommu/arm-smmu-v3: Add STRTAB_STE_0_CFG_NESTED for 2-stage translation Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 08/14] iommu/arm-smmu-v3: Prepare for nested domain support Nicolin Chen
2023-03-10 20:39   ` Robin Murphy
2023-03-11 12:40     ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 09/14] iommu/arm-smmu-v3: Implement arm_smmu_get_unmanaged_domain Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 10/14] iommu/arm-smmu-v3: Pass in user_cfg to arm_smmu_domain_finalise Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 11/14] iommu/arm-smmu-v3: Add arm_smmu_domain_alloc_user Nicolin Chen
2023-03-24 15:28   ` Eric Auger
2023-03-24 17:40     ` Nicolin Chen
2023-03-24 17:50       ` Jason Gunthorpe
2023-03-24 18:00         ` Nicolin Chen
2023-03-24 15:33   ` Eric Auger
2023-03-24 17:43     ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 12/14] iommu/arm-smmu-v3: Support IOMMU_DOMAIN_NESTED type of allocations Nicolin Chen
2023-03-09 13:20   ` Robin Murphy
2023-03-09 14:28     ` Robin Murphy
2023-03-10  1:34       ` Nicolin Chen
2023-03-24 15:44   ` Eric Auger
2023-03-24 16:30     ` Jason Gunthorpe
2023-03-24 17:50     ` Nicolin Chen
2023-03-24 17:51       ` Jason Gunthorpe
2023-03-24 17:55         ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 13/14] iommu/arm-smmu-v3: Add CMDQ_OP_TLBI_NH_VAA and CMDQ_OP_TLBI_NH_ALL Nicolin Chen
2023-03-09 13:44   ` Robin Murphy
2023-03-10  1:19     ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 14/14] iommu/arm-smmu-v3: Add arm_smmu_cache_invalidate_user Nicolin Chen
2023-03-09 14:49   ` Robin Murphy
2023-03-09 15:31     ` Jason Gunthorpe
2023-03-10  4:20       ` Nicolin Chen
2023-03-10 16:19         ` Jason Gunthorpe
2023-03-11 11:56           ` Nicolin Chen
2023-03-11 12:53             ` Nicolin Chen
2023-03-20 13:03             ` Jason Gunthorpe
2023-03-20 15:56               ` Nicolin Chen
2023-03-20 16:04                 ` Jason Gunthorpe
2023-03-20 16:59                   ` Nicolin Chen
2023-03-20 18:45                     ` Jason Gunthorpe
2023-03-20 21:22                       ` Nicolin Chen
2023-03-20 22:19                         ` Jason Gunthorpe
2023-03-22 20:57                           ` Nicolin Chen
2023-03-23 12:17                             ` Jason Gunthorpe
2023-03-17  9:41           ` Tian, Kevin
2023-03-17 14:24             ` Nicolin Chen
2023-03-20 12:59             ` Jason Gunthorpe
2023-03-20 16:12               ` Nicolin Chen
2023-03-20 18:00                 ` Jason Gunthorpe
2023-03-21  8:34                   ` Tian, Kevin
2023-03-21 11:48                     ` Jason Gunthorpe
2023-03-22  6:42                       ` Nicolin Chen
2023-03-22 12:43                         ` Jason Gunthorpe
2023-03-22 17:11                           ` Nicolin Chen
2023-03-22 17:28                             ` Jason Gunthorpe
2023-03-22 19:21                               ` Nicolin Chen
2023-03-22 19:41                                 ` Jason Gunthorpe
2023-03-22 20:43                                   ` Nicolin Chen
2023-03-23 12:16                                     ` Jason Gunthorpe
2023-03-23 18:13                                       ` Nicolin Chen
2023-03-23 18:27                                         ` Jason Gunthorpe
2023-03-24  9:02                         ` Tian, Kevin
2023-03-24 14:57                           ` Jason Gunthorpe
2023-03-24 17:35                             ` Nicolin Chen
2023-03-28  3:03                               ` Tian, Kevin
2023-03-24  8:47                       ` Tian, Kevin
2023-03-24 14:44                         ` Jason Gunthorpe
2023-03-28  2:48                           ` Tian, Kevin
2023-03-28 12:26                             ` Jason Gunthorpe
2023-03-31  8:09                               ` Tian, Kevin
2023-03-17  9:24       ` Tian, Kevin
2023-03-10  3:51     ` Nicolin Chen
2023-03-10 17:53       ` Robin Murphy
2023-03-10 18:49         ` Jason Gunthorpe
2023-03-11 12:38         ` Nicolin Chen
2023-03-13 13:07           ` Robin Murphy
2023-03-16  0:01             ` Nicolin Chen
2023-03-16 14:58               ` Robin Murphy
2023-03-16 21:09                 ` Nicolin Chen
2023-03-20  1:32                   ` Nicolin Chen
2023-03-20 13:11                     ` Jason Gunthorpe
2023-03-20 15:28                       ` Nicolin Chen
2023-03-20 16:01                         ` Jason Gunthorpe
2023-03-20 16:35                           ` Nicolin Chen
2023-03-20 18:07                             ` Jason Gunthorpe
2023-03-20 20:46                               ` Nicolin Chen
2023-03-20 22:14                                 ` Jason Gunthorpe
2023-03-22  5:14                                   ` Nicolin Chen
2023-03-24  8:55                                     ` Tian, Kevin
2023-03-17  9:47     ` Tian, Kevin
2023-03-17 14:16       ` Nicolin Chen

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