From: Baolu Lu <baolu.lu@linux.intel.com>
To: "Tian, Kevin" <kevin.tian@intel.com>,
Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Jason Gunthorpe <jgg@ziepe.ca>
Cc: baolu.lu@linux.intel.com, "Zhang, Tina" <tina.zhang@intel.com>,
"Liu, Yi L" <yi.l.liu@intel.com>,
"iommu@lists.linux.dev" <iommu@lists.linux.dev>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 00/12] Consolidate domain cache invalidation
Date: Wed, 24 Apr 2024 10:46:06 +0800 [thread overview]
Message-ID: <4c8fbcc3-64cf-4add-8d82-9a2ce8dbd39d@linux.intel.com> (raw)
In-Reply-To: <BN9PR11MB52765F34E1168B538C7CEDFD8C112@BN9PR11MB5276.namprd11.prod.outlook.com>
On 4/23/24 5:06 PM, Tian, Kevin wrote:
>> From: Lu Baolu<baolu.lu@linux.intel.com>
>> Sent: Tuesday, April 16, 2024 4:07 PM
>>
>> The IOMMU hardware cache needs to be invalidated whenever the
>> mappings
>> in the domain are changed. Currently, domain cache invalidation is
>> scattered across different places, causing several issues:
>>
>> - IOMMU IOTLB Invalidation: This is done by iterating through the domain
>> IDs of each domain using the following code:
>>
>> xa_for_each(&dmar_domain->iommu_array, i, info)
>> iommu_flush_iotlb_psi(info->iommu, dmar_domain,
>> start_pfn, nrpages,
>> list_empty(&gather->freelist), 0);
>>
>> This code could theoretically cause a use-after-free problem because
>> there's no lock to protect the "info" pointer within the loop.
>>
>> - Inconsistent Invalidation Methods: Different domain types implement
>> their own cache invalidation methods, making the code difficult to
>> maintain. For example, the DMA domain, SVA domain, and nested domain
>> have similar cache invalidation code scattered across different files.
>>
>> - SVA Domain Inconsistency: The SVA domain implementation uses a
>> completely different data structure to track attached devices compared
>> to other domains. This creates unnecessary differences and, even
>> worse, leads to duplicate IOTLB invalidation when an SVA domain is
>> attached to devices belonging to a same IOMMU.
>>
>> - Nested Domain Dependency: The special overlap between a nested domain
>> and its parent domain requires a dedicated parent_domain_flush()
>> helper function to be called everywhere the parent domain's mapping
>> changes.
>>
>> - Limited Debugging Support: There are currently no debugging aids
>> available for domain cache invalidation.
>>
>> By consolidating domain cache invalidation into a common location, we
>> can address the issues mentioned above and improve the code's
>> maintainability and debuggability.
>>
> There are several small nits but overall this series looks good to me:
>
> Reviewed-by: Kevin Tian<kevin.tian@intel.com>
Thanks! I will queue this series to Joerg for wider verification.
Best regards,
baolu
prev parent reply other threads:[~2024-04-24 2:47 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-16 8:06 [PATCH v3 00/12] Consolidate domain cache invalidation Lu Baolu
2024-04-16 8:06 ` [PATCH v3 01/12] iommu/vt-d: Add cache tag assignment interface Lu Baolu
2024-04-23 8:17 ` Tian, Kevin
2024-04-24 1:48 ` Baolu Lu
2024-04-23 9:01 ` Tian, Kevin
2024-04-24 2:44 ` Baolu Lu
2024-04-16 8:06 ` [PATCH v3 02/12] iommu/vt-d: Add cache tag invalidation helpers Lu Baolu
2024-04-22 5:30 ` Baolu Lu
2024-04-23 8:42 ` Tian, Kevin
2024-04-24 1:45 ` Baolu Lu
2024-04-16 8:06 ` [PATCH v3 03/12] iommu/vt-d: Add trace events for cache tag interface Lu Baolu
2024-04-16 8:06 ` [PATCH v3 04/12] iommu/vt-d: Use cache_tag_flush_all() in flush_iotlb_all Lu Baolu
2024-04-16 8:06 ` [PATCH v3 05/12] iommu/vt-d: Use cache_tag_flush_range() in tlb_sync Lu Baolu
2024-04-16 8:06 ` [PATCH v3 06/12] iommu/vt-d: Use cache_tag_flush_range_np() in iotlb_sync_map Lu Baolu
2024-04-16 8:06 ` [PATCH v3 07/12] iommu/vt-d: Cleanup use of iommu_flush_iotlb_psi() Lu Baolu
2024-04-16 8:06 ` [PATCH v3 08/12] iommu/vt-d: Use cache_tag_flush_range() in cache_invalidate_user Lu Baolu
2024-04-16 8:06 ` [PATCH v3 09/12] iommu/vt-d: Use cache helpers in arch_invalidate_secondary_tlbs Lu Baolu
2024-04-16 8:06 ` [PATCH v3 10/12] iommu/vt-d: Remove intel_svm_dev Lu Baolu
2024-04-16 8:06 ` [PATCH v3 11/12] iommu: Add ops->domain_alloc_sva() Lu Baolu
2024-04-16 8:06 ` [PATCH v3 12/12] iommu/vt-d: Remove struct intel_svm Lu Baolu
2024-04-23 9:06 ` [PATCH v3 00/12] Consolidate domain cache invalidation Tian, Kevin
2024-04-24 2:46 ` Baolu Lu [this message]
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