Commit eb8d93ea authored by Lu Baolu's avatar Lu Baolu Committed by Joerg Roedel
Browse files

iommu/vt-d: Report page request faults for guest SVA 



A pasid might be bound to a page table from a VM guest via the iommu
ops.sva_bind_gpasid. In this case, when a DMA page fault is detected
on the physical IOMMU, we need to inject the page fault request into
the guest. After the guest completes handling the page fault, a page
response need to be sent back via the iommu ops.page_response().

This adds support to report a page request fault. Any external module
which is interested in handling this fault should regiester a notifier
with iommu_register_device_fault_handler().

Co-developed-by: default avatarJacob Pan <jacob.jun.pan@linux.intel.com>
Co-developed-by: default avatarLiu Yi L <yi.l.liu@intel.com>
Signed-off-by: default avatarJacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: default avatarLiu Yi L <yi.l.liu@intel.com>
Signed-off-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20200724014925.15523-11-baolu.lu@linux.intel.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 19abcf70

drivers/iommu/intel/svm.c

+85 −18
Original line number Diff line number Diff line
@@ -811,8 +811,63 @@ qi_retry: 
	}

}



static int prq_to_iommu_prot(struct page_req_dsc *req)

{

	int prot = 0;



	if (req->rd_req)

		prot |= IOMMU_FAULT_PERM_READ;

	if (req->wr_req)

		prot |= IOMMU_FAULT_PERM_WRITE;

	if (req->exe_req)

		prot |= IOMMU_FAULT_PERM_EXEC;

	if (req->pm_req)

		prot |= IOMMU_FAULT_PERM_PRIV;



	return prot;

}



static int

intel_svm_prq_report(struct device *dev, struct page_req_dsc *desc)

{

	struct iommu_fault_event event;



	if (!dev || !dev_is_pci(dev))

		return -ENODEV;



	/* Fill in event data for device specific processing */

	memset(&event, 0, sizeof(struct iommu_fault_event));

	event.fault.type = IOMMU_FAULT_PAGE_REQ;

	event.fault.prm.addr = desc->addr;

	event.fault.prm.pasid = desc->pasid;

	event.fault.prm.grpid = desc->prg_index;

	event.fault.prm.perm = prq_to_iommu_prot(desc);



	if (desc->lpig)

		event.fault.prm.flags |= IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE;

	if (desc->pasid_present) {

		event.fault.prm.flags |= IOMMU_FAULT_PAGE_REQUEST_PASID_VALID;

		event.fault.prm.flags |= IOMMU_FAULT_PAGE_RESPONSE_NEEDS_PASID;

	}

	if (desc->priv_data_present) {

		/*

		 * Set last page in group bit if private data is present,

		 * page response is required as it does for LPIG.

		 * iommu_report_device_fault() doesn't understand this vendor

		 * specific requirement thus we set last_page as a workaround.

		 */

		event.fault.prm.flags |= IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE;

		event.fault.prm.flags |= IOMMU_FAULT_PAGE_REQUEST_PRIV_DATA;

		memcpy(event.fault.prm.private_data, desc->priv_data,

		       sizeof(desc->priv_data));

	}



	return iommu_report_device_fault(dev, &event);

}



static irqreturn_t prq_event_thread(int irq, void *d)

{

	struct intel_svm_dev *sdev = NULL;

	struct intel_iommu *iommu = d;

	struct intel_svm *svm = NULL;

	int head, tail, handled = 0;
@@ -824,7 +879,6 @@ static irqreturn_t prq_event_thread(int irq, void *d) 
	tail = dmar_readq(iommu->reg + DMAR_PQT_REG) & PRQ_RING_MASK;

	head = dmar_readq(iommu->reg + DMAR_PQH_REG) & PRQ_RING_MASK;

	while (head != tail) {

		struct intel_svm_dev *sdev;

		struct vm_area_struct *vma;

		struct page_req_dsc *req;

		struct qi_desc resp;
@@ -860,6 +914,20 @@ static irqreturn_t prq_event_thread(int irq, void *d) 
			}

		}



		if (!sdev || sdev->sid != req->rid) {

			struct intel_svm_dev *t;



			sdev = NULL;

			rcu_read_lock();

			list_for_each_entry_rcu(t, &svm->devs, list) {

				if (t->sid == req->rid) {

					sdev = t;

					break;

				}

			}

			rcu_read_unlock();

		}



		result = QI_RESP_INVALID;

		/* Since we're using init_mm.pgd directly, we should never take

		 * any faults on kernel addresses. */
@@ -870,6 +938,17 @@ static irqreturn_t prq_event_thread(int irq, void *d) 
		if (!is_canonical_address(address))

			goto bad_req;



		/*

		 * If prq is to be handled outside iommu driver via receiver of

		 * the fault notifiers, we skip the page response here.

		 */

		if (svm->flags & SVM_FLAG_GUEST_MODE) {

			if (sdev && !intel_svm_prq_report(sdev->dev, req))

				goto prq_advance;

			else

				goto bad_req;

		}



		/* If the mm is already defunct, don't handle faults. */

		if (!mmget_not_zero(svm->mm))

			goto bad_req;
@@ -892,20 +971,7 @@ static irqreturn_t prq_event_thread(int irq, void *d) 
		mmap_read_unlock(svm->mm);

		mmput(svm->mm);

bad_req:

		/* Accounting for major/minor faults? */

		rcu_read_lock();

		list_for_each_entry_rcu(sdev, &svm->devs, list) {

			if (sdev->sid == req->rid)

				break;

		}

		/* Other devices can go away, but the drivers are not permitted

		 * to unbind while any page faults might be in flight. So it's

		 * OK to drop the 'lock' here now we have it. */

		rcu_read_unlock();



		if (WARN_ON(&sdev->list == &svm->devs))

			sdev = NULL;



		WARN_ON(!sdev);

		if (sdev && sdev->ops && sdev->ops->fault_cb) {

			int rwxp = (req->rd_req << 3) | (req->wr_req << 2) |

				(req->exe_req << 1) | (req->pm_req);
@@ -941,6 +1007,7 @@ static irqreturn_t prq_event_thread(int irq, void *d) 
			resp.qw3 = 0;

			qi_submit_sync(iommu, &resp, 1, 0);

		}

prq_advance:

		head = (head + sizeof(*req)) & PRQ_RING_MASK;

	}

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