Commit def054b0 authored by Lu Baolu's avatar Lu Baolu Committed by Joerg Roedel
Browse files

iommu/vt-d: Use device rbtree in iopf reporting path 



The existing I/O page fault handler currently locates the PCI device by
calling pci_get_domain_bus_and_slot(). This function searches the list
of all PCI devices until the desired device is found. To improve lookup
efficiency, replace it with device_rbtree_find() to search the device
within the probed device rbtree.

The I/O page fault is initiated by the device, which does not have any
synchronization mechanism with the software to ensure that the device
stays in the probed device tree. Theoretically, a device could be released
by the IOMMU subsystem after device_rbtree_find() and before
iopf_get_dev_fault_param(), which would cause a use-after-free problem.

Add a mutex to synchronize the I/O page fault reporting path and the IOMMU
release device path. This lock doesn't introduce any performance overhead,
as the conflict between I/O page fault reporting and device releasing is
very rare.

Signed-off-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20240220065939.121116-3-baolu.lu@linux.intel.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 1a75cc71

drivers/iommu/intel/dmar.c

+1 −0
Original line number Diff line number Diff line
@@ -1097,6 +1097,7 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd) 
	iommu->segment = drhd->segment;

	iommu->device_rbtree = RB_ROOT;

	spin_lock_init(&iommu->device_rbtree_lock);

	mutex_init(&iommu->iopf_lock);

	iommu->node = NUMA_NO_NODE;



	ver = readl(iommu->reg + DMAR_VER_REG);

drivers/iommu/intel/iommu.c

+3 −0
Original line number Diff line number Diff line
@@ -4362,8 +4362,11 @@ static struct iommu_device *intel_iommu_probe_device(struct device *dev) 
static void intel_iommu_release_device(struct device *dev)

{

	struct device_domain_info *info = dev_iommu_priv_get(dev);

	struct intel_iommu *iommu = info->iommu;



	mutex_lock(&iommu->iopf_lock);

	device_rbtree_remove(info);

	mutex_unlock(&iommu->iopf_lock);

	dmar_remove_one_dev_info(dev);

	intel_pasid_free_table(dev);

	intel_iommu_debugfs_remove_dev(info);

drivers/iommu/intel/iommu.h

+2 −0
Original line number Diff line number Diff line
@@ -713,6 +713,8 @@ struct intel_iommu { 
#endif

	struct iopf_queue *iopf_queue;

	unsigned char iopfq_name[16];

	/* Synchronization between fault report and iommu device release. */

	struct mutex iopf_lock;

	struct q_inval  *qi;            /* Queued invalidation info */

	u32 iommu_state[MAX_SR_DMAR_REGS]; /* Store iommu states between suspend and resume.*/

drivers/iommu/intel/svm.c

+9 −8
Original line number Diff line number Diff line
@@ -643,7 +643,7 @@ static irqreturn_t prq_event_thread(int irq, void *d) 
	struct intel_iommu *iommu = d;

	struct page_req_dsc *req;

	int head, tail, handled;

	struct pci_dev *pdev;

	struct device *dev;

	u64 address;



	/*
@@ -689,23 +689,24 @@ static irqreturn_t prq_event_thread(int irq, void *d) 
		if (unlikely(req->lpig && !req->rd_req && !req->wr_req))

			goto prq_advance;



		pdev = pci_get_domain_bus_and_slot(iommu->segment,

						   PCI_BUS_NUM(req->rid),

						   req->rid & 0xff);

		/*

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

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

		 */

		if (!pdev)

		mutex_lock(&iommu->iopf_lock);

		dev = device_rbtree_find(iommu, req->rid);

		if (!dev) {

			mutex_unlock(&iommu->iopf_lock);

			goto bad_req;

		}



		if (intel_svm_prq_report(iommu, &pdev->dev, req))

		if (intel_svm_prq_report(iommu, dev, req))

			handle_bad_prq_event(iommu, req, QI_RESP_INVALID);

		else

			trace_prq_report(iommu, &pdev->dev, req->qw_0, req->qw_1,

			trace_prq_report(iommu, dev, req->qw_0, req->qw_1,

					 req->priv_data[0], req->priv_data[1],

					 iommu->prq_seq_number++);

		pci_dev_put(pdev);

		mutex_unlock(&iommu->iopf_lock);

prq_advance:

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

	}