by Vivek Gautam

[permalink] [raw]

Subject: Re: [PATCH v2 1/4] firmware: qcom_scm-64: Add atomic version of qcom_scm_call

On 3/26/2019 2:39 AM, Bjorn Andersson wrote:
> On Sun 09 Sep 23:25 PDT 2018, Vivek Gautam wrote:
>
>> There are scnenarios where drivers are required to make a
>> scm call in atomic context, such as in one of the qcom's
>> arm-smmu-500 errata [1].
>>
>> [1] ("https://source.codeaurora.org/quic/la/kernel/msm-4.9/
>> tree/drivers/iommu/arm-smmu.c?h=msm-4.9#n4842")
>>
>> Signed-off-by: Vivek Gautam <[email protected]>
> Reviewed-by: Bjorn Andersson <[email protected]>

Thanks Bjorn for reviewing and testing this series.
I will repost the series on latest head.

Best regards
Vivek

>
> Regards,
> Bjorn
>
>> ---
>> drivers/firmware/qcom_scm-64.c | 136 ++++++++++++++++++++++++++++-------------
>> 1 file changed, 92 insertions(+), 44 deletions(-)
>>
>> diff --git a/drivers/firmware/qcom_scm-64.c b/drivers/firmware/qcom_scm-64.c
>> index 688525dd4aee..3a8c867cdf51 100644
>> --- a/drivers/firmware/qcom_scm-64.c
>> +++ b/drivers/firmware/qcom_scm-64.c
>> @@ -70,32 +70,71 @@ static DEFINE_MUTEX(qcom_scm_lock);
>> #define FIRST_EXT_ARG_IDX 3
>> #define N_REGISTER_ARGS (MAX_QCOM_SCM_ARGS - N_EXT_QCOM_SCM_ARGS + 1)
>>
>> -/**
>> - * qcom_scm_call() - Invoke a syscall in the secure world
>> - * @dev: device
>> - * @svc_id: service identifier
>> - * @cmd_id: command identifier
>> - * @desc: Descriptor structure containing arguments and return values
>> - *
>> - * Sends a command to the SCM and waits for the command to finish processing.
>> - * This should *only* be called in pre-emptible context.
>> -*/
>> -static int qcom_scm_call(struct device *dev, u32 svc_id, u32 cmd_id,
>> - const struct qcom_scm_desc *desc,
>> - struct arm_smccc_res *res)
>> +static void __qcom_scm_call_do(const struct qcom_scm_desc *desc,
>> + struct arm_smccc_res *res, u32 fn_id,
>> + u64 x5, u32 type)
>> +{
>> + u64 cmd;
>> + struct arm_smccc_quirk quirk = {.id = ARM_SMCCC_QUIRK_QCOM_A6};
>> +
>> + cmd = ARM_SMCCC_CALL_VAL(type, qcom_smccc_convention,
>> + ARM_SMCCC_OWNER_SIP, fn_id);
>> +
>> + quirk.state.a6 = 0;
>> +
>> + do {
>> + arm_smccc_smc_quirk(cmd, desc->arginfo, desc->args[0],
>> + desc->args[1], desc->args[2], x5,
>> + quirk.state.a6, 0, res, &quirk);
>> +
>> + if (res->a0 == QCOM_SCM_INTERRUPTED)
>> + cmd = res->a0;
>> +
>> + } while (res->a0 == QCOM_SCM_INTERRUPTED);
>> +}
>> +
>> +static void qcom_scm_call_do(const struct qcom_scm_desc *desc,
>> + struct arm_smccc_res *res, u32 fn_id,
>> + u64 x5, bool atomic)
>> +{
>> + int retry_count = 0;
>> +
>> + if (!atomic) {
>> + do {
>> + mutex_lock(&qcom_scm_lock);
>> +
>> + __qcom_scm_call_do(desc, res, fn_id, x5,
>> + ARM_SMCCC_STD_CALL);
>> +
>> + mutex_unlock(&qcom_scm_lock);
>> +
>> + if (res->a0 == QCOM_SCM_V2_EBUSY) {
>> + if (retry_count++ > QCOM_SCM_EBUSY_MAX_RETRY)
>> + break;
>> + msleep(QCOM_SCM_EBUSY_WAIT_MS);
>> + }
>> + } while (res->a0 == QCOM_SCM_V2_EBUSY);
>> + } else {
>> + __qcom_scm_call_do(desc, res, fn_id, x5, ARM_SMCCC_FAST_CALL);
>> + }
>> +}
>> +
>> +static int ___qcom_scm_call(struct device *dev, u32 svc_id, u32 cmd_id,
>> + const struct qcom_scm_desc *desc,
>> + struct arm_smccc_res *res, bool atomic)
>> {
>> int arglen = desc->arginfo & 0xf;
>> - int retry_count = 0, i;
>> + int i;
>> u32 fn_id = QCOM_SCM_FNID(svc_id, cmd_id);
>> - u64 cmd, x5 = desc->args[FIRST_EXT_ARG_IDX];
>> + u64 x5 = desc->args[FIRST_EXT_ARG_IDX];
>> dma_addr_t args_phys = 0;
>> void *args_virt = NULL;
>> size_t alloc_len;
>> - struct arm_smccc_quirk quirk = {.id = ARM_SMCCC_QUIRK_QCOM_A6};
>> + gfp_t flag = atomic ? GFP_ATOMIC : GFP_KERNEL;
>>
>> if (unlikely(arglen > N_REGISTER_ARGS)) {
>> alloc_len = N_EXT_QCOM_SCM_ARGS * sizeof(u64);
>> - args_virt = kzalloc(PAGE_ALIGN(alloc_len), GFP_KERNEL);
>> + args_virt = kzalloc(PAGE_ALIGN(alloc_len), flag);
>>
>> if (!args_virt)
>> return -ENOMEM;
>> @@ -125,33 +164,7 @@ static int qcom_scm_call(struct device *dev, u32 svc_id, u32 cmd_id,
>> x5 = args_phys;
>> }
>>
>> - do {
>> - mutex_lock(&qcom_scm_lock);
>> -
>> - cmd = ARM_SMCCC_CALL_VAL(ARM_SMCCC_STD_CALL,
>> - qcom_smccc_convention,
>> - ARM_SMCCC_OWNER_SIP, fn_id);
>> -
>> - quirk.state.a6 = 0;
>> -
>> - do {
>> - arm_smccc_smc_quirk(cmd, desc->arginfo, desc->args[0],
>> - desc->args[1], desc->args[2], x5,
>> - quirk.state.a6, 0, res, &quirk);
>> -
>> - if (res->a0 == QCOM_SCM_INTERRUPTED)
>> - cmd = res->a0;
>> -
>> - } while (res->a0 == QCOM_SCM_INTERRUPTED);
>> -
>> - mutex_unlock(&qcom_scm_lock);
>> -
>> - if (res->a0 == QCOM_SCM_V2_EBUSY) {
>> - if (retry_count++ > QCOM_SCM_EBUSY_MAX_RETRY)
>> - break;
>> - msleep(QCOM_SCM_EBUSY_WAIT_MS);
>> - }
>> - } while (res->a0 == QCOM_SCM_V2_EBUSY);
>> + qcom_scm_call_do(desc, res, fn_id, x5, atomic);
>>
>> if (args_virt) {
>> dma_unmap_single(dev, args_phys, alloc_len, DMA_TO_DEVICE);
>> @@ -164,6 +177,41 @@ static int qcom_scm_call(struct device *dev, u32 svc_id, u32 cmd_id,
>> return 0;
>> }
>>
>> +/**
>> + * qcom_scm_call() - Invoke a syscall in the secure world
>> + * @dev: device
>> + * @svc_id: service identifier
>> + * @cmd_id: command identifier
>> + * @desc: Descriptor structure containing arguments and return values
>> + *
>> + * Sends a command to the SCM and waits for the command to finish processing.
>> + * This should *only* be called in pre-emptible context.
>> + */
>> +static int qcom_scm_call(struct device *dev, u32 svc_id, u32 cmd_id,
>> + const struct qcom_scm_desc *desc,
>> + struct arm_smccc_res *res)
>> +{
>> + return ___qcom_scm_call(dev, svc_id, cmd_id, desc, res, false);
>> +}
>> +
>> +/**
>> + * qcom_scm_call_atomic() - atomic variation of qcom_scm_call()
>> + * @dev: device
>> + * @svc_id: service identifier
>> + * @cmd_id: command identifier
>> + * @desc: Descriptor structure containing arguments and return values
>> + * @res: Structure containing results from SMC/HVC call
>> + *
>> + * Sends a command to the SCM and waits for the command to finish processing.
>> + * This should be called in atomic context only.
>> + */
>> +static int qcom_scm_call_atomic(struct device *dev, u32 svc_id, u32 cmd_id,
>> + const struct qcom_scm_desc *desc,
>> + struct arm_smccc_res *res)
>> +{
>> + return ___qcom_scm_call(dev, svc_id, cmd_id, desc, res, true);
>> +}
>> +
>> /**
>> * qcom_scm_set_cold_boot_addr() - Set the cold boot address for cpus
>> * @entry: Entry point function for the cpus
>> --
>> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
>> of Code Aurora Forum, hosted by The Linux Foundation
>>