From: Robin Murphy <robin.murphy@arm.com>
To: Joerg Roedel <joro@8bytes.org>, Sibi Sankar <sibis@codeaurora.org>
Cc: ohad@wizery.com, devicetree@vger.kernel.org,
linux-kernel-owner@vger.kernel.org,
linux-arm-msm@vger.kernel.org, linux-remoteproc@vger.kernel.org,
linux-kernel@vger.kernel.org, bjorn.andersson@linaro.org,
iommu@lists.linux-foundation.org, robh+dt@kernel.org,
agross@kernel.org
Subject: Re: [PATCH 0/3] Request direct mapping for modem firmware subdevice
Date: Tue, 10 Mar 2020 16:44:12 +0000 [thread overview]
Message-ID: <a50040a9-54fe-f682-dd7e-b2991b48d633@arm.com> (raw)
In-Reply-To: <20200310162320.GL3794@8bytes.org>
On 10/03/2020 4:23 pm, Joerg Roedel wrote:
> On Tue, Mar 10, 2020 at 07:30:50PM +0530, Sibi Sankar wrote:
>> The accesses are initiated by the firmware
>> and they access modem reserved regions.
>> However as explained in ^^ any accesses
>> outside the region will result in a violation
>> and is controlled through XPUs (protection units).
>
> Okay, this sounds like a case for arm_smmu_get_resv_region(). It should
> return an entry for the reserved memory region the firmware needs to
> access, so that generic iommu can setup this mapping.
>
> Note that it should return that entry only for your device, not for all
> devices. Maybe there is a property in DT or IORT you can set to
> transport this information into the arm-smmu driver.
>
> This is pretty similar to RMRR mapping on the Intel VT-d IOMMU or
> Unity-mapped ranges in the AMD-Vi IOMMU.
Yup, a way to describe boot-time memory regions in IORT is in the
process of being specced out; the first attempt at an equivalent for DT
is here:
https://lore.kernel.org/linux-iommu/20191209150748.2471814-1-thierry.reding@gmail.com/
If that's not enough and the SMMU still needs to treat certain Stream
IDs specially because they may be untranslatable (due to having direct
access to memory as a side-channel), then that should be handled in the
SoC-specific corner of the SMMU driver, not delegated to individual
endpoint drivers.
Robin.
next prev parent reply other threads:[~2020-03-10 16:44 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-09 18:22 [PATCH 0/3] Request direct mapping for modem firmware subdevice Sibi Sankar
2020-03-09 18:22 ` [PATCH 1/3] iommu: Export "iommu_request_dm_for_dev" Sibi Sankar
2020-03-09 18:22 ` [PATCH 2/3] dt-bindings: remoteproc: qcom: Add modem-firmware bindings Sibi Sankar
2020-03-09 18:22 ` [PATCH 3/3] remoteproc: qcom_q6v5_mss: Request direct mapping for firmware subdevice Sibi Sankar
2020-03-10 11:23 ` [PATCH 0/3] Request direct mapping for modem " Joerg Roedel
2020-03-10 14:00 ` Sibi Sankar
2020-03-10 16:23 ` Joerg Roedel
2020-03-10 16:44 ` Robin Murphy [this message]
2020-03-12 6:28 ` Sai Prakash Ranjan
2020-03-12 12:05 ` Robin Murphy
2020-03-23 9:43 ` Sai Prakash Ranjan
2020-03-16 15:50 ` Christoph Hellwig
2020-03-16 16:37 ` Sibi Sankar
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