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From: "Tian, Kevin" <kevin.tian@intel.com>
To: Nicolin Chen <nicolinc@nvidia.com>,
	"will@kernel.org" <will@kernel.org>,
	"robin.murphy@arm.com" <robin.murphy@arm.com>,
	"jgg@nvidia.com" <jgg@nvidia.com>,
	"suravee.suthikulpanit@amd.com" <suravee.suthikulpanit@amd.com>
Cc: "joro@8bytes.org" <joro@8bytes.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"iommu@lists.linux.dev" <iommu@lists.linux.dev>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
	"Liu, Yi L" <yi.l.liu@intel.com>,
	"eric.auger@redhat.com" <eric.auger@redhat.com>,
	"vasant.hegde@amd.com" <vasant.hegde@amd.com>,
	"jon.grimm@amd.com" <jon.grimm@amd.com>,
	"santosh.shukla@amd.com" <santosh.shukla@amd.com>,
	"Dhaval.Giani@amd.com" <Dhaval.Giani@amd.com>,
	"shameerali.kolothum.thodi@huawei.com"
	<shameerali.kolothum.thodi@huawei.com>
Subject: RE: [PATCH RFCv1 08/14] iommufd: Add IOMMU_VIOMMU_SET_DEV_ID ioctl
Date: Thu, 23 May 2024 06:42:56 +0000	[thread overview]
Message-ID: <BN9PR11MB5276A897A5386DFAC9A35F9D8CF42@BN9PR11MB5276.namprd11.prod.outlook.com> (raw)
In-Reply-To: <c97a98a72ee3498c587e5898d6b899553ccd9b27.1712978212.git.nicolinc@nvidia.com>

> From: Nicolin Chen <nicolinc@nvidia.com>
> Sent: Saturday, April 13, 2024 11:47 AM
> 
> Introduce a new ioctl to set a per-viommu device virtual id that should be
> linked to the physical device id (or just a struct device pointer).
> 
> Since a viommu (user space IOMMU instance) can have multiple devices

this is true...

> while
> it's not ideal to confine a device to one single user space IOMMU instance
> either, these two shouldn't just do a 1:1 mapping. Add two xarrays in 

...but why would one device link to multiple viommu instances?

Or is it referring to Tegra194 as arm-smmu-nvidia.c tries to support?

In any case a real example might be useful as this may not be a given
knowledge to all folks.

btw there is a check in the following code:

+	if (viommu->iommu_dev != idev->dev->iommu->iommu_dev) {
+		rc = -EINVAL;
+		goto out_put_viommu;
+	}

I vaguely remember an earlier discussion about multiple vSMMU instances
following the physical SMMU topology, but don't quite recall the exact
reason.

What is the actual technical obstacle prohibiting one to put multiple
VCMDQ's from different SMMU's into one vIOMMU instance?

  parent reply	other threads:[~2024-05-23  6:43 UTC|newest]

Thread overview: 118+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-13  3:46 [PATCH RFCv1 00/14] Add Tegra241 (Grace) CMDQV Support (part 2/2) Nicolin Chen
2024-04-13  3:46 ` [PATCH RFCv1 01/14] iommufd: Move iommufd_object to public iommufd header Nicolin Chen
2024-05-12 13:21   ` Jason Gunthorpe
2024-05-12 22:40     ` Nicolin Chen
2024-05-13 22:30       ` Jason Gunthorpe
2024-04-13  3:46 ` [PATCH RFCv1 02/14] iommufd: Swap _iommufd_object_alloc and __iommufd_object_alloc Nicolin Chen
2024-05-12 13:26   ` Jason Gunthorpe
2024-05-13  2:29     ` Nicolin Chen
2024-05-13  3:44       ` Nicolin Chen
2024-05-13 22:30       ` Jason Gunthorpe
2024-04-13  3:47 ` [PATCH RFCv1 03/14] iommufd: Prepare for viommu structures and functions Nicolin Chen
2024-05-12 13:42   ` Jason Gunthorpe
2024-05-13  2:35     ` Nicolin Chen
2024-04-13  3:47 ` [PATCH RFCv1 04/14] iommufd: Add struct iommufd_viommu and iommufd_viommu_ops Nicolin Chen
2024-05-12 14:03   ` Jason Gunthorpe
2024-05-13  3:34     ` Nicolin Chen
2024-05-14 15:55       ` Jason Gunthorpe
2024-05-22  8:58         ` Tian, Kevin
2024-05-22  9:57           ` Baolu Lu
2024-05-22 13:39           ` Jason Gunthorpe
2024-05-23  1:43             ` Tian, Kevin
2024-05-23  4:01               ` Nicolin Chen
2024-05-23  5:40                 ` Tian, Kevin
2024-05-23 12:58               ` Jason Gunthorpe
2024-05-24  2:16                 ` Tian, Kevin
2024-05-24 13:03                   ` Jason Gunthorpe
2024-05-24  2:36                 ` Tian, Kevin
2024-04-13  3:47 ` [PATCH RFCv1 05/14] iommufd: Add IOMMUFD_OBJ_VIOMMU and IOMMUFD_CMD_VIOMMU_ALLOC Nicolin Chen
2024-05-12 14:27   ` Jason Gunthorpe
2024-05-13  4:33     ` Nicolin Chen
2024-05-14 15:38       ` Jason Gunthorpe
2024-05-15  1:20         ` Nicolin Chen
2024-05-21 18:05           ` Jason Gunthorpe
2024-05-22  0:13             ` Nicolin Chen
2024-05-22 16:46               ` Jason Gunthorpe
2024-04-13  3:47 ` [PATCH RFCv1 06/14] iommufd/selftest: Add IOMMU_VIOMMU_ALLOC test coverage Nicolin Chen
2024-04-13  3:47 ` [PATCH RFCv1 07/14] iommufd: Add viommu set/unset_dev_id ops Nicolin Chen
2024-05-12 14:46   ` Jason Gunthorpe
2024-05-13  4:39     ` Nicolin Chen
2024-05-14 15:53       ` Jason Gunthorpe
2024-05-15  1:59         ` Nicolin Chen
2024-05-21 18:24           ` Jason Gunthorpe
2024-05-21 22:27             ` Nicolin Chen
2024-05-22 13:59               ` Jason Gunthorpe
2024-05-23  6:19             ` Tian, Kevin
2024-05-23 15:01               ` Jason Gunthorpe
2024-05-24  2:21                 ` Tian, Kevin
2024-05-24  3:26                   ` Nicolin Chen
2024-05-24  5:24                     ` Tian, Kevin
2024-05-24  5:57                       ` Nicolin Chen
2024-05-24  7:21                         ` Tian, Kevin
2024-05-24 13:12                           ` Jason Gunthorpe
2024-05-24 13:05                   ` Jason Gunthorpe
2024-05-23  5:44       ` Tian, Kevin
2024-05-23  6:09         ` Nicolin Chen
2024-05-23  6:22           ` Tian, Kevin
2024-05-23 13:33         ` Jason Gunthorpe
2024-05-12 14:51   ` Jason Gunthorpe
2024-04-13  3:47 ` [PATCH RFCv1 08/14] iommufd: Add IOMMU_VIOMMU_SET_DEV_ID ioctl Nicolin Chen
2024-05-12 14:58   ` Jason Gunthorpe
2024-05-13  5:24     ` Nicolin Chen
2024-05-17  5:14     ` Nicolin Chen
2024-05-21 18:30       ` Jason Gunthorpe
2024-05-22  2:15         ` Nicolin Chen
2024-05-23  6:42   ` Tian, Kevin [this message]
2024-05-24  5:40     ` Nicolin Chen
2024-05-24  7:13       ` Tian, Kevin
2024-05-24 13:19         ` Jason Gunthorpe
2024-05-27  1:08           ` Tian, Kevin
2024-05-28 20:22             ` Nicolin Chen
2024-05-28 20:33               ` Nicolin Chen
2024-05-29  2:58               ` Tian, Kevin
2024-05-29  3:20                 ` Nicolin Chen
2024-05-30  0:28                   ` Tian, Kevin
2024-05-30  0:58                     ` Nicolin Chen
2024-05-30  3:05                       ` Tian, Kevin
2024-05-30  4:26                         ` Nicolin Chen
2024-06-01 21:45                       ` Jason Gunthorpe
2024-06-03  3:25                         ` Nicolin Chen
2024-06-06 18:24                           ` Jason Gunthorpe
2024-06-06 18:44                             ` Nicolin Chen
2024-06-07  0:27                               ` Jason Gunthorpe
2024-06-07  0:36                                 ` Tian, Kevin
2024-06-07 14:49                                   ` Jason Gunthorpe
2024-06-07 21:19                                     ` Nicolin Chen
2024-06-10 12:04                                       ` Jason Gunthorpe
2024-06-10 20:01                                         ` Nicolin Chen
2024-06-10 22:01                                           ` Jason Gunthorpe
2024-06-10 23:04                                             ` Nicolin Chen
2024-06-11  0:28                                               ` Jason Gunthorpe
2024-06-11  0:44                                                 ` Nicolin Chen
2024-06-11 12:17                                                   ` Jason Gunthorpe
2024-06-11 19:11                                                     ` Nicolin Chen
2024-05-28 20:30             ` Nicolin Chen
2024-05-24 13:20       ` Jason Gunthorpe
2024-04-13  3:47 ` [PATCH RFCv1 09/14] iommufd/selftest: Add IOMMU_VIOMMU_SET_DEV_ID test coverage Nicolin Chen
2024-04-13  3:47 ` [PATCH RFCv1 10/14] iommufd/selftest: Add IOMMU_TEST_OP_MV_CHECK_DEV_ID Nicolin Chen
2024-04-13  3:47 ` [PATCH RFCv1 11/14] iommufd: Add struct iommufd_vqueue and its related viommu ops Nicolin Chen
2024-04-13  3:47 ` [PATCH RFCv1 12/14] iommufd: Add IOMMUFD_OBJ_VQUEUE and IOMMUFD_CMD_VQUEUE_ALLOC Nicolin Chen
2024-05-12 15:02   ` Jason Gunthorpe
2024-05-13  4:41     ` Nicolin Chen
2024-05-13 22:36       ` Jason Gunthorpe
2024-05-23  6:57     ` Tian, Kevin
2024-05-24  4:42       ` Nicolin Chen
2024-05-24  5:26         ` Tian, Kevin
2024-05-24  6:03           ` Nicolin Chen
2024-05-23  7:05   ` Tian, Kevin
2024-04-13  3:47 ` [PATCH RFCv1 13/14] iommufd: Add mmap infrastructure Nicolin Chen
2024-05-12 15:19   ` Jason Gunthorpe
2024-05-13  4:43     ` Nicolin Chen
2024-04-13  3:47 ` [PATCH RFCv1 14/14] iommu/tegra241-cmdqv: Add user-space use support Nicolin Chen
2024-05-22  8:40 ` [PATCH RFCv1 00/14] Add Tegra241 (Grace) CMDQV Support (part 2/2) Tian, Kevin
2024-05-22 16:48   ` Jason Gunthorpe
2024-05-22 19:47     ` Nicolin Chen
2024-05-22 23:28       ` Jason Gunthorpe
2024-05-22 23:43         ` Tian, Kevin
2024-05-23  3:09           ` Nicolin Chen
2024-05-23 12:48             ` Jason Gunthorpe

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