From: Jason Gunthorpe <jgg@ziepe.ca>
To: Baolu Lu <baolu.lu@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Kevin Tian <kevin.tian@intel.com>,
Tina Zhang <tina.zhang@intel.com>, Yi Liu <yi.l.liu@intel.com>,
iommu@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 12/12] iommu/vt-d: Retire struct intel_svm
Date: Thu, 11 Apr 2024 10:07:59 -0300 [thread overview]
Message-ID: <20240411130759.GJ223006@ziepe.ca> (raw)
In-Reply-To: <b24f3380-1ac3-41c4-9163-56c1dcff6297@linux.intel.com>
On Thu, Apr 11, 2024 at 03:55:50PM +0800, Baolu Lu wrote:
> > > @@ -4388,14 +4386,8 @@ static void intel_iommu_remove_dev_pasid(struct device *dev, ioasid_t pasid)
> > > WARN_ON_ONCE(!dev_pasid);
> > > spin_unlock_irqrestore(&dmar_domain->lock, flags);
> > > - /*
> > > - * The SVA implementation needs to handle its own stuffs like the mm
> > > - * notification. Before consolidating that code into iommu core, let
> > > - * the intel sva code handle it.
> > > - */
> > > if (domain->type == IOMMU_DOMAIN_SVA) {
> > > cache_tag_unassign_domain(dmar_domain, FLPT_DEFAULT_DID, dev, pasid);
> > > - intel_svm_remove_dev_pasid(domain);
> > > } else {
> > > did = domain_id_iommu(dmar_domain, iommu);
> > > cache_tag_unassign_domain(dmar_domain, did, dev, pasid);
> >
> > It seems very strange that SVA has a different DID scheme, why is
> > this? PASID and SVA should not be different at this layer.
>
> The VT-d spec recommends that all SVA domains share a single domain ID.
> The PASID is unique to each SVA domain, hence the cache tags are unique.
> Currently, the Intel IOMMU driver assigns different domain IDs for all
> domains except the SVA type.
>
> Sharing a domain ID is not specific to SVA. In general, for devices
> under a single IOMMU, domains with unique PASIDs can share the same
> domain ID.
>
> In the long term (also on my task list), we will extend the cache tag
> code to support sharing domain IDs and remove the domain type check from
> the main code. This will also benefit the nesting case, where user
> domains nested on the same parent could share a domain ID.
Okay, that makes sense
> +static void intel_mm_free_notifier(struct mmu_notifier *mn)
> +{
> + kfree(container_of(mn, struct dmar_domain, notifier));
> +}
> +
> static const struct mmu_notifier_ops intel_mmuops = {
> .release = intel_mm_release,
> .arch_invalidate_secondary_tlbs =
> intel_arch_invalidate_secondary_tlbs,
> + .free_notifier = intel_mm_free_notifier,
> };
>
> static int intel_svm_set_dev_pasid(struct iommu_domain *domain,
> @@ -598,10 +604,8 @@ static void intel_svm_domain_free(struct iommu_domain
> *domain)
> {
> struct dmar_domain *dmar_domain = to_dmar_domain(domain);
>
> - if (dmar_domain->notifier.ops)
> - mmu_notifier_unregister(&dmar_domain->notifier, domain->mm);
> -
> - kfree(dmar_domain);
> + /* dmar_domain free is defered to the mmu free_notifier callback. */
> + mmu_notifier_put(&dmar_domain->notifier);
> }
Yeah, that is better.
Also you need to have mmu notifier call on module unload when using
this scheme.
Jason
next prev parent reply other threads:[~2024-04-11 13:08 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-10 2:08 [PATCH v2 00/12] Consolidate domain cache invalidation Lu Baolu
2024-04-10 2:08 ` [PATCH v2 01/12] iommu/vt-d: Add cache tag assignment interface Lu Baolu
2024-04-10 2:08 ` [PATCH v2 02/12] iommu/vt-d: Add cache tag invalidation helpers Lu Baolu
2024-04-15 4:15 ` Zhang, Tina
2024-04-15 5:06 ` Baolu Lu
2024-04-15 6:46 ` Zhang, Tina
2024-04-10 2:08 ` [PATCH v2 03/12] iommu/vt-d: Add trace events for cache tag interface Lu Baolu
2024-04-10 2:08 ` [PATCH v2 04/12] iommu/vt-d: Use cache_tag_flush_all() in flush_iotlb_all Lu Baolu
2024-04-10 2:08 ` [PATCH v2 05/12] iommu/vt-d: Use cache_tag_flush_range() in tlb_sync Lu Baolu
2024-04-10 2:08 ` [PATCH v2 06/12] iommu/vt-d: Use cache_tag_flush_range_np() in iotlb_sync_map Lu Baolu
2024-04-10 2:08 ` [PATCH v2 07/12] iommu/vt-d: Cleanup use of iommu_flush_iotlb_psi() Lu Baolu
2024-04-10 2:08 ` [PATCH v2 08/12] iommu/vt-d: Use cache_tag_flush_range() in cache_invalidate_user Lu Baolu
2024-04-10 2:08 ` [PATCH v2 09/12] iommu/vt-d: Use cache helpers in arch_invalidate_secondary_tlbs Lu Baolu
2024-04-10 15:55 ` Jason Gunthorpe
2024-04-11 8:10 ` Baolu Lu
2024-04-10 2:08 ` [PATCH v2 10/12] iommu/vt-d: Retire intel_svm_dev Lu Baolu
2024-04-10 2:08 ` [PATCH v2 11/12] iommu: Add ops->domain_alloc_sva() Lu Baolu
2024-04-10 2:08 ` [PATCH v2 12/12] iommu/vt-d: Retire struct intel_svm Lu Baolu
2024-04-10 15:49 ` Jason Gunthorpe
2024-04-11 7:55 ` Baolu Lu
2024-04-11 8:32 ` Tian, Kevin
2024-04-11 10:42 ` Baolu Lu
2024-04-11 13:07 ` Jason Gunthorpe [this message]
2024-04-11 13:13 ` Baolu Lu
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