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

From: Joel Granados
Date: Thu Jan 25 2024 - 11:27:47 EST

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@xxxxxxxxxx>
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> ---
> 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?

> -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)
> {
> struct iommu_fault_param *fault_param = group->fault_param;
> struct iopf_fault *iopf = &group->last_fault;
> @@ -274,7 +287,6 @@ int iopf_group_response(struct iopf_group *group,
> .grpid = iopf->fault.prm.grpid,
> .code = status,
> };
> - int ret = -EINVAL;
>
> if ((iopf->fault.prm.flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID) &&
> (iopf->fault.prm.flags & IOMMU_FAULT_PAGE_RESPONSE_NEEDS_PASID))
> @@ -283,12 +295,10 @@ int iopf_group_response(struct iopf_group *group,
> /* Only send response if there is a fault report pending */
> mutex_lock(&fault_param->lock);
> if (!list_empty(&group->pending_node)) {
> - ret = ops->page_response(dev, &group->last_fault, &resp);
> + ops->page_response(dev, &group->last_fault, &resp);
> list_del_init(&group->pending_node);
> }
> mutex_unlock(&fault_param->lock);
> -
> - return ret;
> }
> EXPORT_SYMBOL_GPL(iopf_group_response);
>
> --
> 2.34.1
>

--

Joel Granados

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