From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: iommu@lists.linux-foundation.org, devicetree@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org,
linux-mm@kvack.org
Cc: joro@8bytes.org, catalin.marinas@arm.com, will@kernel.org,
robin.murphy@arm.com, kevin.tian@intel.com,
baolu.lu@linux.intel.com, Jonathan.Cameron@huawei.com,
jacob.jun.pan@linux.intel.com, christian.koenig@amd.com,
zhangfei.gao@linaro.org, jgg@ziepe.ca, xuzaibo@huawei.com,
Jean-Philippe Brucker <jean-philippe@linaro.org>,
Rob Herring <robh@kernel.org>
Subject: [PATCH v5 21/25] dt-bindings: document stall property for IOMMU masters
Date: Tue, 14 Apr 2020 19:02:49 +0200 [thread overview]
Message-ID: <20200414170252.714402-22-jean-philippe@linaro.org> (raw)
In-Reply-To: <20200414170252.714402-1-jean-philippe@linaro.org>
On ARM systems, some platform devices behind an IOMMU may support stall,
which is the ability to recover from page faults. Let the firmware tell us
when a device supports stall.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
.../devicetree/bindings/iommu/iommu.txt | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/Documentation/devicetree/bindings/iommu/iommu.txt b/Documentation/devicetree/bindings/iommu/iommu.txt
index 3c36334e4f942..26ba9e530f138 100644
--- a/Documentation/devicetree/bindings/iommu/iommu.txt
+++ b/Documentation/devicetree/bindings/iommu/iommu.txt
@@ -92,6 +92,24 @@ Optional properties:
tagging DMA transactions with an address space identifier. By default,
this is 0, which means that the device only has one address space.
+- dma-can-stall: When present, the master can wait for a transaction to
+ complete for an indefinite amount of time. Upon translation fault some
+ IOMMUs, instead of aborting the translation immediately, may first
+ notify the driver and keep the transaction in flight. This allows the OS
+ to inspect the fault and, for example, make physical pages resident
+ before updating the mappings and completing the transaction. Such IOMMU
+ accepts a limited number of simultaneous stalled transactions before
+ having to either put back-pressure on the master, or abort new faulting
+ transactions.
+
+ Firmware has to opt-in stalling, because most buses and masters don't
+ support it. In particular it isn't compatible with PCI, where
+ transactions have to complete before a time limit. More generally it
+ won't work in systems and masters that haven't been designed for
+ stalling. For example the OS, in order to handle a stalled transaction,
+ may attempt to retrieve pages from secondary storage in a stalled
+ domain, leading to a deadlock.
+
Notes:
======
--
2.26.0
next prev parent reply other threads:[~2020-04-14 17:05 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-14 17:02 [PATCH v5 00/25] iommu: Shared Virtual Addressing and SMMUv3 support Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 01/25] mm/mmu_notifiers: pass private data down to alloc_notifier() Jean-Philippe Brucker
2020-04-14 18:09 ` Jason Gunthorpe
2020-04-14 17:02 ` [PATCH v5 02/25] iommu/sva: Manage process address spaces Jean-Philippe Brucker
2020-04-16 7:28 ` Christoph Hellwig
2020-04-16 8:54 ` Jean-Philippe Brucker
2020-04-16 12:13 ` Christoph Hellwig
2020-04-20 7:42 ` Jean-Philippe Brucker
2020-04-20 8:10 ` Christoph Hellwig
2020-04-20 11:44 ` Christian König
2020-04-20 11:55 ` Christoph Hellwig
2020-04-20 12:40 ` Christian König
2020-04-20 15:00 ` Felix Kuehling
2020-04-20 17:44 ` Jacob Pan
2020-04-20 13:57 ` Jason Gunthorpe
2020-04-20 17:48 ` Jacob Pan
2020-04-20 18:14 ` Fenghua Yu
2020-04-21 8:55 ` Christoph Hellwig
2020-04-14 17:02 ` [PATCH v5 03/25] iommu: Add a page fault handler Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 04/25] iommu/sva: Search mm by PASID Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 05/25] iommu/iopf: Handle mm faults Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 06/25] iommu/sva: Register page fault handler Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 07/25] arm64: mm: Add asid_gen_match() helper Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 08/25] arm64: mm: Pin down ASIDs for sharing mm with devices Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 09/25] iommu/io-pgtable-arm: Move some definitions to a header Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 10/25] iommu/arm-smmu-v3: Manage ASIDs with xarray Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 11/25] arm64: cpufeature: Export symbol read_sanitised_ftr_reg() Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 12/25] iommu/arm-smmu-v3: Share process page tables Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 13/25] iommu/arm-smmu-v3: Seize private ASID Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 14/25] iommu/arm-smmu-v3: Add support for VHE Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 15/25] iommu/arm-smmu-v3: Enable broadcast TLB maintenance Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 16/25] iommu/arm-smmu-v3: Add SVA feature checking Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 17/25] iommu/arm-smmu-v3: Implement mm operations Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 18/25] iommu/arm-smmu-v3: Hook up ATC invalidation to mm ops Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 19/25] iommu/arm-smmu-v3: Add support for Hardware Translation Table Update Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 20/25] iommu/arm-smmu-v3: Maintain a SID->device structure Jean-Philippe Brucker
2020-04-14 17:02 ` Jean-Philippe Brucker [this message]
2020-04-14 17:02 ` [PATCH v5 22/25] iommu/arm-smmu-v3: Add stall support for platform devices Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 23/25] PCI/ATS: Add PRI stubs Jean-Philippe Brucker
2020-04-14 18:03 ` Kuppuswamy, Sathyanarayanan
2020-04-14 17:02 ` [PATCH v5 24/25] PCI/ATS: Export PRI functions Jean-Philippe Brucker
2020-04-14 18:03 ` Kuppuswamy, Sathyanarayanan
2020-04-14 17:02 ` [PATCH v5 25/25] iommu/arm-smmu-v3: Add support for PRI Jean-Philippe Brucker
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