Messages in this thread | | | Date | Thu, 16 Nov 2023 17:04:13 +0000 | Subject | Re: [PATCH v2 3/3] iommu/arm-smmu: re-enable context caching in smmu reset operation | From | Robin Murphy <> |
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On 16/11/2023 3:24 pm, Dmitry Baryshkov wrote: > On Thu, 16 Nov 2023 at 14:45, Bibek Kumar Patro > <quic_bibekkum@quicinc.com> wrote: >> >> >> >> On 11/15/2023 4:33 PM, Dmitry Baryshkov wrote: >>> On Wed, 15 Nov 2023 at 11:45, Bibek Kumar Patro >>> <quic_bibekkum@quicinc.com> wrote: >>>> >>>> On 11/14/2023 7:45 PM, Dmitry Baryshkov wrote: >>>>> On Tue, 14 Nov 2023 at 15:57, Bibek Kumar Patro >>>>> <quic_bibekkum@quicinc.com> wrote: >>>>>> >>>>>> Context caching is re-enabled in the prefetch buffer for Qualcomm SoCs >>>>>> through SoC specific reset ops, which is disabled in the default MMU-500 >>>>>> reset ops, but is expected for context banks using ACTLR register to >>>>>> retain the prefetch value during reset and runtime suspend. >>>>> >>>>> Please refer to Documentation/process/submitting-patches.rst and >>>>> rephrase this following the rules there. >>>>> >>>> >>>> Noted, will go through the description once and rephrase it >>>> in next version complying with rules. >>>> >>>>>> >>>>>> Signed-off-by: Bibek Kumar Patro <quic_bibekkum@quicinc.com> >>>>>> --- >>>>>> drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 25 ++++++++++++++++++---- >>>>>> 1 file changed, 21 insertions(+), 4 deletions(-) >>>>>> >>>>>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c >>>>>> index 0eaf6f2a2e49..fa867b1d9d16 100644 >>>>>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c >>>>>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c >>>>>> @@ -478,11 +478,28 @@ static int qcom_smmu_def_domain_type(struct device *dev) >>>>>> return match ? IOMMU_DOMAIN_IDENTITY : 0; >>>>>> } >>>>>> >>>>>> +static int qcom_smmu500_reset(struct arm_smmu_device *smmu) >>>>>> +{ >>>>>> + int i; >>>>>> + u32 reg; >>>>>> + >>>>>> + arm_mmu500_reset(smmu); >>>>>> + >>>>>> + /* Re-enable context caching after reset */ >>>>>> + for (i = 0; i < smmu->num_context_banks; ++i) { >>>>>> + reg = arm_smmu_cb_read(smmu, i, ARM_SMMU_CB_ACTLR); >>>>>> + reg |= CPRE; >>>>>> + arm_smmu_cb_write(smmu, i, ARM_SMMU_CB_ACTLR, reg); >>>>>> + } >>>>>> + >>>>>> + return 0; >>>>>> +} >>>>>> + >>>>>> static int qcom_sdm845_smmu500_reset(struct arm_smmu_device *smmu) >>>>>> { >>>>>> int ret; >>>>>> >>>>>> - arm_mmu500_reset(smmu); >>>>>> + qcom_smmu500_reset(smmu); >>>>> >>>>> Is this applicable for sdm845? For all other platforms supported by >>>>> qcom_smmu_500 implementation? >>>>> >>>> >>>> In arm_mmu500_reset operation drivers/iommu/arm/arm-smmu/arm-smmu-impl.c >>>> CPRE bit is reset for all SoC based on mmu500 platform, hence for all >>>> Qualcomm SoCs including sm845 we are setting back the CPRE bit. >>> >>> The errata for the CoreLink MMU-500 requires CPRE to be disabled for >>> all revisions before r2p2. Do we know whether these SoC used CoreLink >>> MMU-500 and which version of it? >>> >> >> Just checked all these SoCs are using r2p4 revision. >> So CPRE needs to be enabled back here then? > > can be enabled, yes.
There are still open errata #562869 and #1047329 which might need this workaround. I guess one could argue that we're not (knowingly) using nested translation at the moment, and also probably not running this in situations which would end up using short-descriptor format, however stuff like pKVM and IOMMUFD could potentially change those assumptions in future, so they still feel a bit sketchy to me.
Thanks, Robin.
> >> >>>> >>>>>> >>>>>> /* >>>>>> * To address performance degradation in non-real time clients, >>>>>> @@ -509,7 +526,7 @@ static const struct arm_smmu_impl qcom_smmu_500_impl = { >>>>>> .init_context = qcom_smmu_init_context, >>>>>> .cfg_probe = qcom_smmu_cfg_probe, >>>>>> .def_domain_type = qcom_smmu_def_domain_type, >>>>>> - .reset = arm_mmu500_reset, >>>>>> + .reset = qcom_smmu500_reset, >>>>>> .write_s2cr = qcom_smmu_write_s2cr, >>>>>> .tlb_sync = qcom_smmu_tlb_sync, >>>>>> }; >>>>>> @@ -528,7 +545,7 @@ static const struct arm_smmu_impl sm8550_smmu_500_impl = { >>>>>> .init_context = qcom_smmu_init_context, >>>>>> .cfg_probe = qcom_smmu_cfg_probe, >>>>>> .def_domain_type = qcom_smmu_def_domain_type, >>>>>> - .reset = arm_mmu500_reset, >>>>>> + .reset = qcom_smmu500_reset, >>>>>> .write_s2cr = qcom_smmu_write_s2cr, >>>>>> .tlb_sync = qcom_smmu_tlb_sync, >>>>>> }; >>>>>> @@ -544,7 +561,7 @@ static const struct arm_smmu_impl qcom_adreno_smmu_v2_impl = { >>>>>> static const struct arm_smmu_impl qcom_adreno_smmu_500_impl = { >>>>>> .init_context = qcom_adreno_smmu_init_context, >>>>>> .def_domain_type = qcom_smmu_def_domain_type, >>>>>> - .reset = arm_mmu500_reset, >>>>>> + .reset = qcom_smmu500_reset, >>>>>> .alloc_context_bank = qcom_adreno_smmu_alloc_context_bank, >>>>>> .write_sctlr = qcom_adreno_smmu_write_sctlr, >>>>>> .tlb_sync = qcom_smmu_tlb_sync, >>>>>> -- >>>>>> 2.17.1 >>>>>> >>>>> >>>>> >>> >>> >>> >>> -- >>> With best wishes >>> Dmitry > > >
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