From: Auger Eric <eric.auger@redhat.com>
To: Jean-Philippe Brucker <jean-philippe@linaro.org>,
joro@8bytes.org, will@kernel.org
Cc: devicetree@vger.kernel.org, kevin.tian@intel.com,
vivek.gautam@arm.com, guohanjun@huawei.com, rjw@rjwysocki.net,
linux-acpi@vger.kernel.org, iommu@lists.linux-foundation.org,
robh+dt@kernel.org, linux-accelerators@lists.ozlabs.org,
sudeep.holla@arm.com, zhangfei.gao@linaro.org,
robin.murphy@arm.com, Rob Herring <robh@kernel.org>,
linux-arm-kernel@lists.infradead.org, lenb@kernel.org
Subject: Re: [PATCH v12 08/10] dt-bindings: document stall property for IOMMU masters
Date: Mon, 1 Feb 2021 08:28:06 +0100 [thread overview]
Message-ID: <fa61a670-e11d-0493-a38f-132482b54e35@redhat.com> (raw)
In-Reply-To: <20210127154322.3959196-9-jean-philippe@linaro.org>
Hi Jean-Philippe,
On 1/27/21 4:43 PM, Jean-Philippe Brucker wrote:
> 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>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Eric
> ---
> .../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 3c36334e4f94..26ba9e530f13 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:
> ======
>
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2021-02-01 7:28 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-27 15:43 [PATCH v12 00/10] iommu: I/O page faults for SMMUv3 Jean-Philippe Brucker
2021-01-27 15:43 ` [PATCH v12 01/10] iommu: Fix comment for struct iommu_fwspec Jean-Philippe Brucker
2021-01-27 15:43 ` [PATCH v12 02/10] iommu/arm-smmu-v3: Use device properties for pasid-num-bits Jean-Philippe Brucker
2021-02-01 7:30 ` Auger Eric
2021-01-27 15:43 ` [PATCH v12 03/10] iommu: Separate IOMMU_DEV_FEAT_IOPF from IOMMU_DEV_FEAT_SVA Jean-Philippe Brucker
2021-02-01 7:35 ` Auger Eric
2021-01-27 15:43 ` [PATCH v12 04/10] iommu/vt-d: Support IOMMU_DEV_FEAT_IOPF Jean-Philippe Brucker
2021-01-27 15:43 ` [PATCH v12 05/10] uacce: Enable IOMMU_DEV_FEAT_IOPF Jean-Philippe Brucker
2021-01-27 15:43 ` [PATCH v12 06/10] iommu: Add a page fault handler Jean-Philippe Brucker
2021-01-31 18:29 ` Auger Eric
2021-02-02 5:51 ` Shenming Lu
2021-01-27 15:43 ` [PATCH v12 07/10] iommu/arm-smmu-v3: Maintain a SID->device structure Jean-Philippe Brucker
2021-01-27 15:43 ` [PATCH v12 08/10] dt-bindings: document stall property for IOMMU masters Jean-Philippe Brucker
2021-02-01 7:28 ` Auger Eric [this message]
2021-01-27 15:43 ` [PATCH v12 09/10] ACPI/IORT: Enable stall support for platform devices Jean-Philippe Brucker
2021-01-27 15:43 ` [PATCH v12 10/10] iommu/arm-smmu-v3: Add " Jean-Philippe Brucker
2021-01-31 18:29 ` Auger Eric
2021-02-01 11:12 ` Jean-Philippe Brucker
2021-02-01 13:16 ` Auger Eric
2021-02-01 15:19 ` Jean-Philippe Brucker
2021-02-01 1:18 ` Zhou Wang
2021-02-01 11:14 ` Jean-Philippe Brucker
2021-02-01 12:53 ` Zhou Wang
2021-02-26 9:43 ` Zhou Wang
2021-02-26 16:29 ` Jean-Philippe Brucker
2021-02-27 3:40 ` Zhou Wang
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