Re: [PATCH v10 15/16] iommu: Make iopf_group_response() return void

Baolu Lu
2024-01-26T06:44:05Z

On 2024/1/26 0:27, Joel Granados wrote:
> On Mon, Jan 22, 2024 at 01:43:07PM +0800, Lu Baolu wrote:
>> The iopf_group_response() should return void, as nothing can do anything
>> with the failure. This implies that ops->page_response() must also return
>> void; this is consistent with what the drivers do. The failure paths,
>> which are all integrity validations of the fault, should be WARN_ON'd,
>> not return codes.
>>
>> If the iommu core fails to enqueue the fault, it should respond the fault
>> directly by calling ops->page_response() instead of returning an error
>> number and relying on the iommu drivers to do so. Consolidate the error
>> fault handling code in the core.
>>
>> Co-developed-by: Jason Gunthorpe<jgg@nvidia.com>
>> Signed-off-by: Jason Gunthorpe<jgg@nvidia.com>
>> Signed-off-by: Lu Baolu<baolu.lu@linux.intel.com>
>> ---
>> include/linux/iommu.h | 14 +--
>> drivers/iommu/intel/iommu.h | 4 +-
>> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 50 +++-----
>> drivers/iommu/intel/svm.c | 18 +--
>> drivers/iommu/io-pgfault.c | 132 +++++++++++---------
>> 5 files changed, 99 insertions(+), 119 deletions(-)
>>
>> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
>> index 48196efc9327..d7b6f4017254 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -578,9 +578,8 @@ struct iommu_ops {
>> int (*dev_enable_feat)(struct device *dev, enum iommu_dev_features f);
>> int (*dev_disable_feat)(struct device *dev, enum iommu_dev_features f);
>>
>> - int (*page_response)(struct device *dev,
>> - struct iopf_fault *evt,
>> - struct iommu_page_response *msg);
>> + void (*page_response)(struct device *dev, struct iopf_fault *evt,
>> + struct iommu_page_response *msg);
>>
>> int (*def_domain_type)(struct device *dev);
>> void (*remove_dev_pasid)(struct device *dev, ioasid_t pasid);
>> @@ -1551,8 +1550,8 @@ void iopf_queue_free(struct iopf_queue *queue);
>> int iopf_queue_discard_partial(struct iopf_queue *queue);
>> void iopf_free_group(struct iopf_group *group);
>> int iommu_report_device_fault(struct device *dev, struct iopf_fault *evt);
>> -int iopf_group_response(struct iopf_group *group,
>> - enum iommu_page_response_code status);
>> +void iopf_group_response(struct iopf_group *group,
>> + enum iommu_page_response_code status);
>> #else
>> static inline int
>> iopf_queue_add_device(struct iopf_queue *queue, struct device *dev)
>> @@ -1594,10 +1593,9 @@ iommu_report_device_fault(struct device *dev, struct iopf_fault *evt)
>> return -ENODEV;
>> }
>>
>> -static inline int iopf_group_response(struct iopf_group *group,
>> - enum iommu_page_response_code status)
>> +static inline void iopf_group_response(struct iopf_group *group,
>> + enum iommu_page_response_code status)
>> {
>> - return -ENODEV;
>> }
>> #endif /* CONFIG_IOMMU_IOPF */
>> #endif /* __LINUX_IOMMU_H */
>> diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
>> index 696d95293a69..cf9a28c7fab8 100644
>> --- a/drivers/iommu/intel/iommu.h
>> +++ b/drivers/iommu/intel/iommu.h
>> @@ -1079,8 +1079,8 @@ struct iommu_domain *intel_nested_domain_alloc(struct iommu_domain *parent,
>> void intel_svm_check(struct intel_iommu *iommu);
>> int intel_svm_enable_prq(struct intel_iommu *iommu);
>> int intel_svm_finish_prq(struct intel_iommu *iommu);
>> -int intel_svm_page_response(struct device *dev, struct iopf_fault *evt,
>> - struct iommu_page_response *msg);
>> +void intel_svm_page_response(struct device *dev, struct iopf_fault *evt,
>> + struct iommu_page_response *msg);
>> struct iommu_domain *intel_svm_domain_alloc(void);
>> void intel_svm_remove_dev_pasid(struct device *dev, ioasid_t pasid);
>> void intel_drain_pasid_prq(struct device *dev, u32 pasid);
>> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> index 4e93e845458c..42eb59cb99f4 100644
>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> @@ -920,31 +920,29 @@ static int arm_smmu_cmdq_batch_submit(struct arm_smmu_device *smmu,
>> return arm_smmu_cmdq_issue_cmdlist(smmu, cmds->cmds, cmds->num, true);
>> }
>>
>> -static int arm_smmu_page_response(struct device *dev,
>> - struct iopf_fault *unused,
>> - struct iommu_page_response *resp)
>> +static void arm_smmu_page_response(struct device *dev, struct iopf_fault *unused,
>> + struct iommu_page_response *resp)
>> {
>> struct arm_smmu_cmdq_ent cmd = {0};
>> struct arm_smmu_master *master = dev_iommu_priv_get(dev);
>> int sid = master->streams[0].id;
>>
>> - if (master->stall_enabled) {
>> - cmd.opcode = CMDQ_OP_RESUME;
>> - cmd.resume.sid = sid;
>> - cmd.resume.stag = resp->grpid;
>> - switch (resp->code) {
>> - case IOMMU_PAGE_RESP_INVALID:
>> - case IOMMU_PAGE_RESP_FAILURE:
>> - cmd.resume.resp = CMDQ_RESUME_0_RESP_ABORT;
>> - break;
>> - case IOMMU_PAGE_RESP_SUCCESS:
>> - cmd.resume.resp = CMDQ_RESUME_0_RESP_RETRY;
>> - break;
>> - default:
>> - return -EINVAL;
>> - }
>> - } else {
>> - return -ENODEV;
>> + if (WARN_ON(!master->stall_enabled))
>> + return;
>> +
>> + cmd.opcode = CMDQ_OP_RESUME;
>> + cmd.resume.sid = sid;
>> + cmd.resume.stag = resp->grpid;
>> + switch (resp->code) {
>> + case IOMMU_PAGE_RESP_INVALID:
>> + case IOMMU_PAGE_RESP_FAILURE:
>> + cmd.resume.resp = CMDQ_RESUME_0_RESP_ABORT;
>> + break;
>> + case IOMMU_PAGE_RESP_SUCCESS:
>> + cmd.resume.resp = CMDQ_RESUME_0_RESP_RETRY;
>> + break;
>> + default:
>> + break;
>> }
>>
>> arm_smmu_cmdq_issue_cmd(master->smmu, &cmd);
>> @@ -954,8 +952,6 @@ static int arm_smmu_page_response(struct device *dev,
>> * terminated... at some point in the future. PRI_RESP is fire and
>> * forget.
>> */
>> -
>> - return 0;
>> }
>>
>> /* Context descriptor manipulation functions */
>> @@ -1516,16 +1512,6 @@ static int arm_smmu_handle_evt(struct arm_smmu_device *smmu, u64 *evt)
>> }
>>
>> ret = iommu_report_device_fault(master->dev, &fault_evt);
>> - if (ret && flt->type == IOMMU_FAULT_PAGE_REQ) {
>> - /* Nobody cared, abort the access */
>> - struct iommu_page_response resp = {
>> - .pasid = flt->prm.pasid,
>> - .grpid = flt->prm.grpid,
>> - .code = IOMMU_PAGE_RESP_FAILURE,
>> - };
>> - arm_smmu_page_response(master->dev, &fault_evt, &resp);
>> - }
>> -
>> out_unlock:
>> mutex_unlock(&smmu->streams_mutex);
>> return ret;
>> diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
>> index e1cbcb9515f0..2f8716636dbb 100644
>> --- a/drivers/iommu/intel/svm.c
>> +++ b/drivers/iommu/intel/svm.c
>> @@ -740,9 +740,8 @@ static irqreturn_t prq_event_thread(int irq, void *d)
>> return IRQ_RETVAL(handled);
>> }
>>
>> -int intel_svm_page_response(struct device *dev,
>> - struct iopf_fault *evt,
>> - struct iommu_page_response *msg)
>> +void intel_svm_page_response(struct device *dev, struct iopf_fault *evt,
>> + struct iommu_page_response *msg)
>> {
>> struct device_domain_info *info = dev_iommu_priv_get(dev);
>> struct intel_iommu *iommu = info->iommu;
>> @@ -751,7 +750,6 @@ int intel_svm_page_response(struct device *dev,
>> bool private_present;
>> bool pasid_present;
>> bool last_page;
>> - int ret = 0;
>> u16 sid;
>>
>> prm = &evt->fault.prm;
>> @@ -760,16 +758,6 @@ int intel_svm_page_response(struct device *dev,
>> private_present = prm->flags & IOMMU_FAULT_PAGE_REQUEST_PRIV_DATA;
>> last_page = prm->flags & IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE;
>>
>> - if (!pasid_present) {
>> - ret = -EINVAL;
>> - goto out;
>> - }
>> -
>> - if (prm->pasid == 0 || prm->pasid >= PASID_MAX) {
>> - ret = -EINVAL;
>> - goto out;
>> - }
>> -
>> /*
>> * Per VT-d spec. v3.0 ch7.7, system software must respond
>> * with page group response if private data is present (PDP)
>> @@ -798,8 +786,6 @@ int intel_svm_page_response(struct device *dev,
>>
>> qi_submit_sync(iommu, &desc, 1, 0);
>> }
>> -out:
>> - return ret;
>> }
>>
>> static int intel_svm_set_dev_pasid(struct iommu_domain *domain,
>> diff --git a/drivers/iommu/io-pgfault.c b/drivers/iommu/io-pgfault.c
>> index c22e13df84c2..6e63e5a02884 100644
>> --- a/drivers/iommu/io-pgfault.c
>> +++ b/drivers/iommu/io-pgfault.c
>> @@ -39,7 +39,7 @@ static void iopf_put_dev_fault_param(struct iommu_fault_param *fault_param)
>> kfree_rcu(fault_param, rcu);
>> }
>>
>> -void iopf_free_group(struct iopf_group *group)
>> +static void __iopf_free_group(struct iopf_group *group)
>> {
>> struct iopf_fault *iopf, *next;
>>
>> @@ -50,6 +50,11 @@ void iopf_free_group(struct iopf_group *group)
>>
>> /* Pair with iommu_report_device_fault(). */
>> iopf_put_dev_fault_param(group->fault_param);
>> +}
>> +
>> +void iopf_free_group(struct iopf_group *group)
>> +{
>> + __iopf_free_group(group);
>> kfree(group);
>> }
>> EXPORT_SYMBOL_GPL(iopf_free_group);
>> @@ -97,14 +102,49 @@ static int report_partial_fault(struct iommu_fault_param *fault_param,
>> return 0;
>> }
>>
>> +static struct iopf_group *iopf_group_alloc(struct iommu_fault_param *iopf_param,
>> + struct iopf_fault *evt,
>> + struct iopf_group *abort_group)
>> +{
>> + struct iopf_fault *iopf, *next;
>> + struct iopf_group *group;
>> +
>> + group = kzalloc(sizeof(*group), GFP_KERNEL);
>> + if (!group) {
>> + /*
>> + * We always need to construct the group as we need it to abort
>> + * the request at the driver if it cfan't be handled.
>> + */
>> + group = abort_group;
>> + }
>> +
>> + group->fault_param = iopf_param;
>> + group->last_fault.fault = evt->fault;
>> + INIT_LIST_HEAD(&group->faults);
>> + INIT_LIST_HEAD(&group->pending_node);
>> + list_add(&group->last_fault.list, &group->faults);
>> +
>> + /* See if we have partial faults for this group */
>> + mutex_lock(&iopf_param->lock);
>> + list_for_each_entry_safe(iopf, next, &iopf_param->partial, list) {
>> + if (iopf->fault.prm.grpid == evt->fault.prm.grpid)
>> + /* Insert*before* the last fault */
>> + list_move(&iopf->list, &group->faults);
>> + }
>> + list_add(&group->pending_node, &iopf_param->faults);
>> + mutex_unlock(&iopf_param->lock);
>> +
>> + return group;
>> +}
>> +
>> /**
>> * iommu_report_device_fault() - Report fault event to device driver
>> * @dev: the device
>> * @evt: fault event data
>> *
>> * Called by IOMMU drivers when a fault is detected, typically in a threaded IRQ
>> - * handler. When this function fails and the fault is recoverable, it is the
>> - * caller's responsibility to complete the fault.
>> + * handler. If this function fails then ops->page_response() was called to
>> + * complete evt if required.
>> *
>> * This module doesn't handle PCI PASID Stop Marker; IOMMU drivers must discard
>> * them before reporting faults. A PASID Stop Marker (LRW = 0b100) doesn't
>> @@ -143,22 +183,18 @@ int iommu_report_device_fault(struct device *dev, struct iopf_fault *evt)
>> {
>> struct iommu_fault *fault = &evt->fault;
>> struct iommu_fault_param *iopf_param;
>> - struct iopf_fault *iopf, *next;
>> - struct iommu_domain *domain;
>> + struct iopf_group abort_group = {};
>> struct iopf_group *group;
>> int ret;
>>
>> - if (fault->type != IOMMU_FAULT_PAGE_REQ)
>> - return -EOPNOTSUPP;
>> -
>> iopf_param = iopf_get_dev_fault_param(dev);
>> - if (!iopf_param)
>> + if (WARN_ON(!iopf_param))
>> return -ENODEV;
>>
>> if (!(fault->prm.flags & IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE)) {
>> ret = report_partial_fault(iopf_param, fault);
>> iopf_put_dev_fault_param(iopf_param);
>> -
>> + /* A request that is not the last does not need to be ack'd */
>> return ret;
>> }
>>
>> @@ -170,56 +206,33 @@ int iommu_report_device_fault(struct device *dev, struct iopf_fault *evt)
>> * will send a response to the hardware. We need to clean up before
>> * leaving, otherwise partial faults will be stuck.
>> */
>> - domain = get_domain_for_iopf(dev, fault);
>> - if (!domain) {
>> + group = iopf_group_alloc(iopf_param, evt, &abort_group);
>> + if (group == &abort_group) {
>> + ret = -ENOMEM;
>> + goto err_abort;
>> + }
>> +
>> + group->domain = get_domain_for_iopf(dev, fault);
>> + if (!group->domain) {
>> ret = -EINVAL;
>> - goto cleanup_partial;
>> + goto err_abort;
>> }
>>
>> - group = kzalloc(sizeof(*group), GFP_KERNEL);
>> - if (!group) {
>> - ret = -ENOMEM;
>> - goto cleanup_partial;
>> - }
>> -
>> - group->fault_param = iopf_param;
>> - group->last_fault.fault = *fault;
>> - INIT_LIST_HEAD(&group->faults);
>> - INIT_LIST_HEAD(&group->pending_node);
>> - group->domain = domain;
>> - list_add(&group->last_fault.list, &group->faults);
>> -
>> - /* See if we have partial faults for this group */
>> - mutex_lock(&iopf_param->lock);
>> - list_for_each_entry_safe(iopf, next, &iopf_param->partial, list) {
>> - if (iopf->fault.prm.grpid == fault->prm.grpid)
>> - /* Insert*before* the last fault */
>> - list_move(&iopf->list, &group->faults);
>> - }
>> - list_add(&group->pending_node, &iopf_param->faults);
>> - mutex_unlock(&iopf_param->lock);
>> + /*
>> + * On success iopf_handler must call iopf_group_response() and
>> + * iopf_free_group()
>> + */
>> + ret = group->domain->iopf_handler(group);
>> + if (ret)
>> + goto err_abort;
>> + return 0;
>>
>> - ret = domain->iopf_handler(group);
>> - if (ret) {
>> - mutex_lock(&iopf_param->lock);
>> - list_del_init(&group->pending_node);
>> - mutex_unlock(&iopf_param->lock);
>> +err_abort:
>> + iopf_group_response(group, IOMMU_PAGE_RESP_FAILURE);
>> + if (group == &abort_group)
>> + __iopf_free_group(group);
>> + else
>> iopf_free_group(group);
>> - }
>> -
>> - return ret;
>> -
>> -cleanup_partial:
>> - mutex_lock(&iopf_param->lock);
>> - list_for_each_entry_safe(iopf, next, &iopf_param->partial, list) {
>> - if (iopf->fault.prm.grpid == fault->prm.grpid) {
>> - list_del(&iopf->list);
>> - kfree(iopf);
>> - }
>> - }
>> - mutex_unlock(&iopf_param->lock);
>> - iopf_put_dev_fault_param(iopf_param);
>> -
>> return ret;
>> }
>> EXPORT_SYMBOL_GPL(iommu_report_device_fault);
>> @@ -262,8 +275,8 @@ EXPORT_SYMBOL_GPL(iopf_queue_flush_dev);
>> *
>> * Return 0 on success and <0 on error.
>> */
> Should you adjust the docs as well?

Yes. Will do.

Best regards,
baolu