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Message-ID: <be075bef-808b-4175-acbe-e26abc4a7a25@quicinc.com>
Date: Wed, 3 Jan 2024 11:54:53 +0530
From: Bibek Kumar Patro <quic_bibekkum@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: <will@...nel.org>, <robin.murphy@....com>, <joro@...tes.org>,
<konrad.dybcio@...aro.org>, <jsnitsel@...hat.com>,
<quic_bjorande@...cinc.com>, <mani@...nel.org>,
<quic_eberman@...cinc.com>, <robdclark@...omium.org>,
<u.kleine-koenig@...gutronix.de>, <robh@...nel.org>,
<vladimir.oltean@....com>, <quic_pkondeti@...cinc.com>,
<quic_molvera@...cinc.com>, <linux-arm-msm@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>, <iommu@...ts.linux.dev>,
<linux-kernel@...r.kernel.org>, <qipl.kernel.upstream@...cinc.com>
Subject: Re: [PATCH v6 3/5] iommu/arm-smmu: introduction of ACTLR for custom
prefetcher settings
On 12/21/2023 4:02 PM, Dmitry Baryshkov wrote:
> On Thu, 21 Dec 2023 at 12:02, Bibek Kumar Patro
> <quic_bibekkum@...cinc.com> wrote:
>>
>>
>>
>> On 12/21/2023 6:06 AM, Dmitry Baryshkov wrote:
>>> On Wed, 20 Dec 2023 at 15:39, Bibek Kumar Patro
>>> <quic_bibekkum@...cinc.com> wrote:
>>>>
>>>> Currently in Qualcomm SoCs the default prefetch is set to 1 which allows
>>>> the TLB to fetch just the next page table. MMU-500 features ACTLR
>>>> register which is implementation defined and is used for Qualcomm SoCs
>>>> to have a custom prefetch setting enabling TLB to prefetch the next set
>>>> of page tables accordingly allowing for faster translations.
>>>>
>>>> ACTLR value is unique for each SMR (Stream matching register) and stored
>>>> in a pre-populated table. This value is set to the register during
>>>> context bank initialisation.
>>>>
>>>> Signed-off-by: Bibek Kumar Patro <quic_bibekkum@...cinc.com>
>>>> ---
>>>> drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 45 ++++++++++++++++++++++
>>>> drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h | 6 ++-
>>>> drivers/iommu/arm/arm-smmu/arm-smmu.c | 5 ++-
>>>> drivers/iommu/arm/arm-smmu/arm-smmu.h | 5 +++
>>>> 4 files changed, 58 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
>>>> index 20c9836d859b..1cefdd0ca110 100644
>>>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
>>>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
>>>> @@ -24,6 +24,12 @@
>>>> #define CPRE (1 << 1)
>>>> #define CMTLB (1 << 0)
>>>>
>>>> +struct actlr_config {
>>>> + u16 sid;
>>>> + u16 mask;
>>>> + u32 actlr;
>>>> +};
>>>> +
>>>> static struct qcom_smmu *to_qcom_smmu(struct arm_smmu_device *smmu)
>>>> {
>>>> return container_of(smmu, struct qcom_smmu, smmu);
>>>> @@ -215,9 +221,38 @@ static bool qcom_adreno_can_do_ttbr1(struct arm_smmu_device *smmu)
>>>> return true;
>>>> }
>>>>
>>>> +static void qcom_smmu_set_actlr(struct device *dev, struct arm_smmu_device *smmu, int cbndx,
>>>> + const struct actlr_config *actlrcfg)
>>>> +{
>>>> + struct arm_smmu_master_cfg *cfg = dev_iommu_priv_get(dev);
>>>> + struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
>>>> + struct arm_smmu_smr *smr;
>>>> + u16 mask;
>>>> + int idx;
>>>> + u16 id;
>>>> + int i;
>>>> +
>>>> + for (; actlrcfg->sid || actlrcfg->mask || actlrcfg->actlr; actlrcfg++) {
>>>> + id = actlrcfg->sid;
>>>> + mask = actlrcfg->mask;
>>>> +
>>>> + for_each_cfg_sme(cfg, fwspec, i, idx) {
>>>> + smr = &smmu->smrs[idx];
>>>> + if (smr_is_subset(smr, id, mask)) {
>>>> + arm_smmu_cb_write(smmu, cbndx, ARM_SMMU_CB_ACTLR,
>>>> + actlrcfg->actlr);
>>>> + break;
>>>> + }
>>>> + }
>>>> + }
>>>> +}
>>>> +
>>>> static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain,
>>>> struct io_pgtable_cfg *pgtbl_cfg, struct device *dev)
>>>> {
>>>> + struct arm_smmu_device *smmu = smmu_domain->smmu;
>>>> + struct qcom_smmu *qsmmu = to_qcom_smmu(smmu);
>>>> + int cbndx = smmu_domain->cfg.cbndx;
>>>> struct adreno_smmu_priv *priv;
>>>>
>>>> smmu_domain->cfg.flush_walk_prefer_tlbiasid = true;
>>>> @@ -248,6 +283,9 @@ static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain,
>>>> priv->set_stall = qcom_adreno_smmu_set_stall;
>>>> priv->resume_translation = qcom_adreno_smmu_resume_translation;
>>>>
>>>> + if (qsmmu->data->actlrcfg_gfx)
>>>> + qcom_smmu_set_actlr(dev, smmu, cbndx, qsmmu->data->actlrcfg_gfx);
>>>
>>> There was a feedback point against v4 that there can be more than two
>>> (apps + gpu) SMMU devices. No, we can not use additional compat
>>> strings, the SMMU units are compatible with each other.
>>
>> Just to understand better, did you mean if in the below check
>> [inside arm-smmu-qcom.c file during qcom_smmu_create()], "else" has two
>> things? (Currently adreno_impl for gpu smmu, else for only
>> apps smmu)
>
> qcom,adreno-smmu is quite unique here, this is the only distinctive
> substring. We do not have such compat strings for any other of SMMU
> nodes.
>
Apologies for the delayed response, I was on leave and could
not monitor the replies.
for other SMMUs (except qcom-adreno-smmu) we would
need to use the IO address matching.
>>
>> if (np && of_device_is_compatible(np, "qcom,adreno-smmu"))
>> impl = data->adreno_impl;
>> else
>> impl = data->impl;
>>
>>> Please add
>>> matching between the smmu and particular actlr table using the IO
>>> address of the SMMU block.
>>>
>>
>> The ACTLR table for each smmu will have A IO address attached, so based
>> on IO address we can apply ACTLR.
>> Is this your proposal((IMO hardcoding IO in driver won't be viable,
>> isn't it?), or in smmu DT we would need to set the IO?
>
> Unfortunately, I meant exactly that: hardcoding addresses of the SMMU
> register spaces. see drivers/gpu/drm/msm/dsi_cfg.c
> Then during device probe the driver can match the IO address to the
> list of the per-platform ACTLR tables and select the correct one.
> Then you don't even need a special actlrcfg_gfx. The GFX will fall
> into the main schema.
>
Thanks for the reference, I will check once and try to evaluate a
similar implementation for ACTLR table as well.
Thanks,
Bibek
>>
>>
>> Thanks & regards,
>> Bibek
>>
>>>> +
>>>> return 0;
>>>> }
>>>>
>>>> @@ -274,6 +312,13 @@ static const struct of_device_id qcom_smmu_client_of_match[] __maybe_unused = {
>>>> static int qcom_smmu_init_context(struct arm_smmu_domain *smmu_domain,
>>>> struct io_pgtable_cfg *pgtbl_cfg, struct device *dev)
>>>> {
>>>> + struct arm_smmu_device *smmu = smmu_domain->smmu;
>>>> + struct qcom_smmu *qsmmu = to_qcom_smmu(smmu);
>>>> + int cbndx = smmu_domain->cfg.cbndx;
>>>> +
>>>> + if (qsmmu->data->actlrcfg)
>>>> + qcom_smmu_set_actlr(dev, smmu, cbndx, qsmmu->data->actlrcfg);
>>>> +
>>>
>>> One issue occured to me, while I was reviewing the patchset. The ACTLR
>>> settings are related to the whole SMMU setup, but we are applying them
>>> each time there is an SMMU context init (in other words, one per each
>>> domain). Is that correct? Or it's just that there is no better place
>>> for initialising the global register set? Would it be better to
>>> reprogram the ACTLR registers which are related just to this
>>> particular domain?
>>>
>>>> smmu_domain->cfg.flush_walk_prefer_tlbiasid = true;
>>>>
>>>> return 0;
>>>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h
>>>> index f3b91963e234..cb4cb402c202 100644
>>>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h
>>>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h
>>>> @@ -1,6 +1,6 @@
>>>> /* SPDX-License-Identifier: GPL-2.0-only */
>>>> /*
>>>> - * Copyright (c) 2022, Qualcomm Innovation Center, Inc. All rights reserved.
>>>> + * Copyright (c) 2023, Qualcomm Innovation Center, Inc. All rights reserved.
>>>> */
>>>>
>>>> #ifndef _ARM_SMMU_QCOM_H
>>>> @@ -24,7 +24,11 @@ struct qcom_smmu_config {
>>>> const u32 *reg_offset;
>>>> };
>>>>
>>>> +struct actlr_config;
>>>> +
>>>> struct qcom_smmu_match_data {
>>>> + const struct actlr_config *actlrcfg;
>>>> + const struct actlr_config *actlrcfg_gfx;
>>>> const struct qcom_smmu_config *cfg;
>>>> const struct arm_smmu_impl *impl;
>>>> const struct arm_smmu_impl *adreno_impl;
>>>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
>>>> index d6d1a2a55cc0..0c7f700b27dd 100644
>>>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
>>>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
>>>> @@ -990,9 +990,10 @@ static int arm_smmu_find_sme(struct arm_smmu_device *smmu, u16 id, u16 mask)
>>>> * expect simply identical entries for this case, but there's
>>>> * no harm in accommodating the generalisation.
>>>> */
>>>> - if ((mask & smrs[i].mask) == mask &&
>>>> - !((id ^ smrs[i].id) & ~smrs[i].mask))
>>>> +
>>>> + if (smr_is_subset(&smrs[i], id, mask))
>>>> return i;
>>>> +
>>>> /*
>>>> * If the new entry has any other overlap with an existing one,
>>>> * though, then there always exists at least one stream ID
>>>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/arm/arm-smmu/arm-smmu.h
>>>> index 703fd5817ec1..2e4f65412c6b 100644
>>>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
>>>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
>>>> @@ -501,6 +501,11 @@ static inline void arm_smmu_writeq(struct arm_smmu_device *smmu, int page,
>>>> writeq_relaxed(val, arm_smmu_page(smmu, page) + offset);
>>>> }
>>>>
>>>> +static inline bool smr_is_subset(struct arm_smmu_smr *smrs, u16 id, u16 mask)
>>>> +{
>>>> + return (mask & smrs->mask) == mask && !((id ^ smrs->id) & ~smrs->mask);
>>>> +}
>>>> +
>>>> #define ARM_SMMU_GR0 0
>>>> #define ARM_SMMU_GR1 1
>>>> #define ARM_SMMU_CB(s, n) ((s)->numpage + (n))
>>>> --
>>>> 2.17.1
>>>>
>>>
>>>
>
>
>
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