iommu/vt-d: Remove unnecessary SVA data accesses in page fault path

The existing I/O page fault handling code accesses the per-PASID SVA data
structures. This is unnecessary and makes the fault handling code only
suitable for SVA scenarios. This removes the SVA data accesses from the
I/O page fault reporting and responding code, so that the fault handling
code could be generic.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20220914011821.400986-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index 74b0e19..b5fb770 100644 (file)
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -586,6 +586,7 @@ struct intel_iommu {
 #ifdef CONFIG_INTEL_IOMMU_SVM
        struct page_req_dsc *prq;
        unsigned char prq_name[16];    /* Name for PRQ interrupt */
+       unsigned long prq_seq_number;
        struct completion prq_complete;
        struct ioasid_allocator_ops pasid_allocator; /* Custom allocator for PASIDs */
 #endif
@@ -761,7 +762,6 @@ struct intel_svm_dev {
        struct device *dev;
        struct intel_iommu *iommu;
        struct iommu_sva sva;
-       unsigned long prq_seq_number;
        u32 pasid;
        int users;
        u16 did;

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index 8bcfb93..d1cab93 100644 (file)
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -49,23 +49,6 @@ static void *pasid_private_find(ioasid_t pasid)
 }
 
 static struct intel_svm_dev *
-svm_lookup_device_by_sid(struct intel_svm *svm, u16 sid)
-{
-       struct intel_svm_dev *sdev = NULL, *t;
-
-       rcu_read_lock();
-       list_for_each_entry_rcu(t, &svm->devs, list) {
-               if (t->sid == sid) {
-                       sdev = t;
-                       break;
-               }
-       }
-       rcu_read_unlock();
-
-       return sdev;
-}
-
-static struct intel_svm_dev *
 svm_lookup_device_by_dev(struct intel_svm *svm, struct device *dev)
 {
        struct intel_svm_dev *sdev = NULL, *t;
@@ -706,11 +689,10 @@ static void handle_bad_prq_event(struct intel_iommu *iommu,
 
 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;
        struct page_req_dsc *req;
        int head, tail, handled;
+       struct pci_dev *pdev;
        u64 address;
 
        /*
@@ -730,8 +712,6 @@ static irqreturn_t prq_event_thread(int irq, void *d)
                        pr_err("IOMMU: %s: Page request without PASID\n",
                               iommu->name);
 bad_req:
-                       svm = NULL;
-                       sdev = NULL;
                        handle_bad_prq_event(iommu, req, QI_RESP_INVALID);
                        goto prq_advance;
                }
@@ -758,34 +738,19 @@ bad_req:
                if (unlikely(req->lpig && !req->rd_req && !req->wr_req))
                        goto prq_advance;
 
-               if (!svm || svm->pasid != req->pasid) {
-                       /*
-                        * It can't go away, because the driver is not permitted
-                        * to unbind the mm while any page faults are outstanding.
-                        */
-                       svm = pasid_private_find(req->pasid);
-                       if (IS_ERR_OR_NULL(svm) || (svm->flags & SVM_FLAG_SUPERVISOR_MODE))
-                               goto bad_req;
-               }
-
-               if (!sdev || sdev->sid != req->rid) {
-                       sdev = svm_lookup_device_by_sid(svm, req->rid);
-                       if (!sdev)
-                               goto bad_req;
-               }
-
-               sdev->prq_seq_number++;
-
+               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 (intel_svm_prq_report(iommu, sdev->dev, req))
+               if (!pdev || intel_svm_prq_report(iommu, &pdev->dev, req))
                        handle_bad_prq_event(iommu, req, QI_RESP_INVALID);
 
-               trace_prq_report(iommu, sdev->dev, req->qw_0, req->qw_1,
+               trace_prq_report(iommu, &pdev->dev, req->qw_0, req->qw_1,
                                 req->priv_data[0], req->priv_data[1],
-                                sdev->prq_seq_number);
+                                iommu->prq_seq_number++);
 prq_advance:
                head = (head + sizeof(*req)) & PRQ_RING_MASK;
        }
@@ -881,8 +846,6 @@ int intel_svm_page_response(struct device *dev,
                            struct iommu_page_response *msg)
 {
        struct iommu_fault_page_request *prm;
-       struct intel_svm_dev *sdev = NULL;
-       struct intel_svm *svm = NULL;
        struct intel_iommu *iommu;
        bool private_present;
        bool pasid_present;
@@ -901,8 +864,6 @@ int intel_svm_page_response(struct device *dev,
        if (!msg || !evt)
                return -EINVAL;
 
-       mutex_lock(&pasid_mutex);
-
        prm = &evt->fault.prm;
        sid = PCI_DEVID(bus, devfn);
        pasid_present = prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID;
@@ -919,12 +880,6 @@ int intel_svm_page_response(struct device *dev,
                goto out;
        }
 
-       ret = pasid_to_svm_sdev(dev, prm->pasid, &svm, &sdev);
-       if (ret || !sdev) {
-               ret = -ENODEV;
-               goto out;
-       }
-
        /*
         * Per VT-d spec. v3.0 ch7.7, system software must respond
         * with page group response if private data is present (PDP)
@@ -954,6 +909,5 @@ int intel_svm_page_response(struct device *dev,
                qi_submit_sync(iommu, &desc, 1, 0);
        }
 out:
-       mutex_unlock(&pasid_mutex);
        return ret;
 }