From: Jason Gunthorpe <jgg@nvidia.com>
To: Nicolin Chen <nicolinc@nvidia.com>
Cc: will@kernel.org, robin.murphy@arm.com, joro@8bytes.org,
jpb@kernel.org, praan@google.com, miko.lenczewski@arm.com,
linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev,
linux-kernel@vger.kernel.org, patches@lists.linux.dev
Subject: Re: [PATCH v2 06/10] iommu/arm-smmu-v3: Allocate vmid in arm_vsmmu_init
Date: Tue, 27 Jan 2026 11:11:38 -0400 [thread overview]
Message-ID: <20260127151138.GI1134360@nvidia.com> (raw)
In-Reply-To: <aXgrsJeXB3bpFQqK@Asurada-Nvidia>
On Mon, Jan 26, 2026 at 07:06:24PM -0800, Nicolin Chen wrote:
> On Mon, Jan 26, 2026 at 05:16:36PM -0400, Jason Gunthorpe wrote:
> > On Wed, Jan 21, 2026 at 05:24:24PM -0800, Nicolin Chen wrote:
> > > VMID owned by a vSMMU should be allocated in the viommu_init callback, as
> > > HW like tegra241-cmdqv needs to setup VINTF with the VMID.
> >
> > Even the architected SMMU needs this, the VMS (not implemented in
> > Linux) should all share the same VMID for the same VM.
>
> But for standard SMMU, the allocation/sharing could happen at the
> device attachment to a nested (maybe bypass proxy) domain, right?
>
> vmid is only needed for STE (attach) and invalidation.
>
> Or do you see some other case where vmid must be allocated during
> viommu_init?
It has to be tied to the VSMMU, it doesn't matter if a single VMID is
allocated on-demand for the VSMMU or for the lifetime, it has to be a
single ID and shared across all STEs.
It is easy to understand that lifecycle by just allocating it for the
lifetime of the VSMMU..
Jason
next prev parent reply other threads:[~2026-01-27 15:11 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-22 1:24 [PATCH v2 00/10] iommu/arm-smmu-v3: Share domain across SMMU/vSMMU instances Nicolin Chen
2026-01-22 1:24 ` [PATCH v2 01/10] iommu/arm-smmu-v3: Store IOTLB cache tags in struct arm_smmu_attach_state Nicolin Chen
2026-01-26 20:44 ` Jason Gunthorpe
2026-01-27 3:23 ` Nicolin Chen
2026-01-27 15:08 ` Jason Gunthorpe
2026-01-27 16:58 ` Nicolin Chen
2026-01-22 1:24 ` [PATCH v2 02/10] iommu/arm-smmu-v3: Pass in IOTLB cache tag to CD and STE Nicolin Chen
2026-01-26 20:53 ` Jason Gunthorpe
2026-01-27 3:28 ` Nicolin Chen
2026-01-22 1:24 ` [PATCH v2 03/10] iommu/arm-smmu-v3: Look for existing iotlb tag in smmu_domain->invs Nicolin Chen
2026-01-26 21:03 ` Jason Gunthorpe
2026-01-27 2:50 ` Nicolin Chen
2026-01-22 1:24 ` [PATCH v2 04/10] iommu/arm-smmu-v3: Allocate IOTLB cache tag if no id to reuse Nicolin Chen
2026-01-26 21:06 ` Jason Gunthorpe
2026-01-26 22:23 ` Nicolin Chen
2026-01-27 16:29 ` Jason Gunthorpe
2026-01-27 16:52 ` Nicolin Chen
2026-01-22 1:24 ` [PATCH v2 05/10] iommu/arm-smmu-v3: Flush iotlb in arm_smmu_iotlb_tag_free() Nicolin Chen
2026-01-26 21:08 ` Jason Gunthorpe
2026-01-27 2:56 ` Nicolin Chen
2026-01-27 15:09 ` Jason Gunthorpe
2026-01-22 1:24 ` [PATCH v2 06/10] iommu/arm-smmu-v3: Allocate vmid in arm_vsmmu_init Nicolin Chen
2026-01-26 21:16 ` Jason Gunthorpe
2026-01-27 3:06 ` Nicolin Chen
2026-01-27 15:11 ` Jason Gunthorpe [this message]
2026-01-27 17:11 ` Nicolin Chen
2026-01-27 17:58 ` Jason Gunthorpe
2026-01-22 1:24 ` [PATCH v2 07/10] iommu/arm-smmu-v3: Pass in vsmmu to arm_smmu_domain_get_iotlb_tag() Nicolin Chen
2026-01-26 21:20 ` Jason Gunthorpe
2026-01-27 3:34 ` Nicolin Chen
2026-01-22 1:24 ` [PATCH v2 08/10] iommu/arm-smmu-v3: Introduce INV_TYPE_S2_VMID_VSMMU Nicolin Chen
2026-01-27 15:13 ` Jason Gunthorpe
2026-01-22 1:24 ` [PATCH v2 09/10] iommu/arm-smmu-v3: Remove ASID/VMID from arm_smmu_domain Nicolin Chen
2026-01-22 1:24 ` [PATCH v2 10/10] iommu/arm-smmu-v3: Allow sharing domain across SMMUs Nicolin Chen
2026-01-27 15:41 ` Jason Gunthorpe
2026-01-27 17:50 ` Nicolin Chen
2026-01-27 17:59 ` Jason Gunthorpe
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