> From: Jacob Pan [mailto:jacob.jun....@linux.intel.com] > Sent: Thursday, May 17, 2018 11:59 PM > On Thu, 17 May 2018 11:41:56 +0000 > "Liu, Yi L" <yi.l....@intel.com> wrote: > > > > +int iommu_report_device_fault(struct device *dev, struct > > > +iommu_fault_event *evt) { > > > + int ret = 0; > > > + struct iommu_fault_event *evt_pending; > > > + struct iommu_fault_param *fparam; > > > + > > > + /* iommu_param is allocated when device is added to group > > > */ > > > + if (!dev->iommu_param | !evt) > > > + return -EINVAL; > > > + /* we only report device fault if there is a handler > > > registered */ > > > + mutex_lock(&dev->iommu_param->lock); > > > + if (!dev->iommu_param->fault_param || > > > + !dev->iommu_param->fault_param->handler) { > > > + ret = -EINVAL; > > > + goto done_unlock; > > > + } > > > + fparam = dev->iommu_param->fault_param; > > > + if (evt->type == IOMMU_FAULT_PAGE_REQ && evt->last_req) { > > > + evt_pending = kmemdup(evt, sizeof(struct > > > iommu_fault_event), > > > + GFP_KERNEL); > > > + if (!evt_pending) { > > > + ret = -ENOMEM; > > > + goto done_unlock; > > > + } > > > + mutex_lock(&fparam->lock); > > > + list_add_tail(&evt_pending->list, > > > &fparam->faults); > > > > I may missed it. Here only see list add, how about removing? Who would > > remove entry from the fault list? > > > deletion of the pending event is in page response function (int > iommu_page_response), once iommu driver finds a matching response for the > pending request, it will delete the pending event. > > if the response never came, right now we don't delete it, just gives warning.
Got it. > > > > + mutex_unlock(&fparam->lock); > > > + } > > > + ret = fparam->handler(evt, fparam->data); > > > > I remember you mentioned there will be a queue to store the faults. > > Is it in the fparam->faults list? Or there is no such queue? > There are two use cases: > case A: guest SVA, PRQ events are reported outside IOMMU subsystem, > e.g. vfio > case B: in-kernel > > The io page fault queuing is Jean's patchset, mostly for case B (in-kernel IO > page > fault handling). I will convert intel-svm to Jean's io page fault mechanism > so that we > can also have parallel and out of order queuing of PRQ. I still need some > time to > evaluate intel specific needs such as streaming page request/response. > > For case A, there is no queuing in host IOMMU driver. My understanding of the > flow > is as the following: > 1. host IOMMU receives PRQ > 2. host IOMMU driver reports PRQ fault event to registered called, i.e. > vfio > 3. VFIO reports fault event to QEMU > 4. QEMU injects PRQ to guest > 5. Guest IOMMU driver receives PRQ in IRQ 6. Guest IOMMU driver queue PRQ by > groups, PASID. Correct. > So as long as in-kernel PRQ handling can do queuing, there is no need for > queuing in > the host reporting path. Will it affect current interface? Here the handler only get an "evt" per a PRQ IRQ. And I suppose vfio needs not rely on host iommu queuing? Thanks, Yi Liu