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

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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: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20240220065939.121116-3-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Lu Baolu 2024-02-27 10:14:41 +08:00 committed by Joerg Roedel
parent 1a75cc710b
commit def054b01a
4 changed files with 15 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/iommu/intel/dmar.c
View File

@ -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);

3
drivers/iommu/intel/iommu.c
View File

@ -4362,8 +4362,11 @@ free:
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);

2
drivers/iommu/intel/iommu.h
View File

@ -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.*/

17
drivers/iommu/intel/svm.c
View File

@ -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 @@ bad_req:
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;
}