From: Robin Murphy <robin.murphy@arm.com>
To: Bjorn Andersson <bjorn.andersson@linaro.org>,
Will Deacon <will@kernel.org>, Joerg Roedel <joro@8bytes.org>,
Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>,
Jordan Crouse <jcrouse@codeaurora.org>,
Rob Clark <robdclark@chromium.org>
Cc: linux-arm-msm@vger.kernel.org, iommu@lists.linux-foundation.org,
Sibi Sankar <sibis@codeaurora.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 8/8] iommu/arm-smmu-qcom: Setup identity domain for boot mappings
Date: Fri, 11 Sep 2020 18:29:23 +0100 [thread overview]
Message-ID: <34b1f9ea-fb16-faac-c288-627b51066968@arm.com> (raw)
In-Reply-To: <20200904155513.282067-9-bjorn.andersson@linaro.org>
On 2020-09-04 16:55, Bjorn Andersson wrote:
> With many Qualcomm platforms not having functional S2CR BYPASS a
> temporary IOMMU domain, without translation, needs to be allocated in
> order to allow these memory transactions.
>
> Unfortunately the boot loader uses the first few context banks, so
> rather than overwriting a active bank the last context bank is used and
> streams are diverted here during initialization.
>
> This also performs the readback of SMR registers for the Qualcomm
> platform, to trigger the mechanism.
>
> This is based on prior work by Thierry Reding and Laurentiu Tudor.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> ---
>
> Changes since v2:
> - Combined from pieces spread between the Qualcomm impl and generic code in v2.
> - Moved to use the newly introduced inherit_mapping op.
>
> drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 33 ++++++++++++++++++++++
> 1 file changed, 33 insertions(+)
>
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> index 70a1eaa52e14..a54302190932 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> @@ -12,6 +12,7 @@
> struct qcom_smmu {
> struct arm_smmu_device smmu;
> bool bypass_broken;
> + struct iommu_domain *identity;
> };
>
> static struct qcom_smmu *to_qcom_smmu(struct arm_smmu_device *smmu)
> @@ -228,6 +229,37 @@ static int qcom_smmu_cfg_probe(struct arm_smmu_device *smmu)
> return 0;
> }
>
> +static int qcom_smmu_inherit_mappings(struct arm_smmu_device *smmu)
> +{
> + struct qcom_smmu *qsmmu = to_qcom_smmu(smmu);
> + int cbndx;
> + u32 smr;
> + int i;
> +
> + qsmmu->identity = arm_smmu_alloc_identity_domain(smmu);
> + if (IS_ERR(qsmmu->identity))
> + return PTR_ERR(qsmmu->identity);
> +
> + cbndx = to_smmu_domain(qsmmu->identity)->cfg.cbndx;
I don't really get the point of going through the dance of allocating a
whole iommu_domain() just to get a context. If you don't want to simply
statically reserve a context at probe time, then just allocate from
smmu->context_map here (where AFAICS "here" should be in cfg_probe
anyway). This is entirely driver-internal, so there shouldn't be any
need for IOMMU-API-level stuff to be involved.
Robin.
> +
> + for (i = 0; i < smmu->num_mapping_groups; i++) {
> + smr = arm_smmu_gr0_read(smmu, ARM_SMMU_GR0_SMR(i));
> +
> + if (FIELD_GET(ARM_SMMU_SMR_VALID, smr)) {
> + smmu->smrs[i].id = FIELD_GET(ARM_SMMU_SMR_ID, smr);
> + smmu->smrs[i].mask = FIELD_GET(ARM_SMMU_SMR_MASK, smr);
> + smmu->smrs[i].valid = true;
> +
> + smmu->s2crs[i].type = S2CR_TYPE_TRANS;
> + smmu->s2crs[i].privcfg = S2CR_PRIVCFG_DEFAULT;
> + smmu->s2crs[i].cbndx = cbndx;
> + smmu->s2crs[i].count++;
> + }
> + }
> +
> + return 0;
> +}
> +
> static int qcom_smmu_def_domain_type(struct device *dev)
> {
> const struct of_device_id *match =
> @@ -270,6 +302,7 @@ static const struct arm_smmu_impl qcom_smmu_impl = {
> .cfg_probe = qcom_smmu_cfg_probe,
> .def_domain_type = qcom_smmu_def_domain_type,
> .reset = qcom_smmu500_reset,
> + .inherit_mappings = qcom_smmu_inherit_mappings,
> };
>
> static const struct arm_smmu_impl qcom_adreno_smmu_impl = {
>
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next prev parent reply other threads:[~2020-09-11 17:29 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-04 15:55 [PATCH v3 0/8] iommu/arm-smmu: Support maintaining bootloader mappings Bjorn Andersson
2020-09-04 15:55 ` [PATCH v3 1/8] iommu/arm-smmu: Refactor context bank allocation Bjorn Andersson
2020-09-08 18:42 ` Jordan Crouse
2020-09-08 18:46 ` Jordan Crouse
2020-09-11 8:18 ` Sai Prakash Ranjan
2020-09-04 15:55 ` [PATCH v3 2/8] iommu/arm-smmu: Delay modifying domain during init Bjorn Andersson
2020-09-11 8:20 ` Sai Prakash Ranjan
2020-09-04 15:55 ` [PATCH v3 3/8] iommu/arm-smmu: Consult context bank allocator for identify domains Bjorn Andersson
2020-09-11 8:21 ` Sai Prakash Ranjan
2020-09-11 8:24 ` Sai Prakash Ranjan
2020-09-04 15:55 ` [PATCH v3 4/8] iommu/arm-smmu-qcom: Emulate bypass by using context banks Bjorn Andersson
2020-09-11 8:25 ` Sai Prakash Ranjan
2020-09-04 15:55 ` [PATCH v3 5/8] iommu/arm-smmu-qcom: Consistently initialize stream mappings Bjorn Andersson
2020-09-11 8:26 ` Sai Prakash Ranjan
2020-09-04 15:55 ` [PATCH v3 6/8] iommu/arm-smmu: Add impl hook for inherit boot mappings Bjorn Andersson
2020-09-11 8:27 ` Sai Prakash Ranjan
2020-09-11 17:13 ` Robin Murphy
2020-09-13 3:25 ` Bjorn Andersson
2020-09-21 21:08 ` Will Deacon
2020-09-24 15:55 ` Bjorn Andersson
2020-10-12 7:31 ` Bjorn Andersson
2020-10-13 16:47 ` Robin Murphy
2020-09-04 15:55 ` [PATCH v3 7/8] iommu/arm-smmu: Provide helper for allocating identity domain Bjorn Andersson
2020-09-11 8:28 ` Sai Prakash Ranjan
2020-09-04 15:55 ` [PATCH v3 8/8] iommu/arm-smmu-qcom: Setup identity domain for boot mappings Bjorn Andersson
2020-09-11 8:29 ` Sai Prakash Ranjan
2020-09-11 17:29 ` Robin Murphy [this message]
2020-09-05 22:27 ` [PATCH v3 0/8] iommu/arm-smmu: Support maintaining bootloader mappings Rob Clark
2020-09-09 14:46 ` Laurentiu Tudor
2020-09-10 22:56 ` John Stultz
2020-09-11 8:16 ` Sai Prakash Ranjan
2020-09-11 16:10 ` Amit Pundir
2020-09-16 10:09 ` Laurentiu Tudor
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