[RFC v8 17/28] vfio/pci: Register handler for iommu fault

[Eric Auger]

We use the new extended IRQ VFIO_IRQ_TYPE_NESTED type and
VFIO_IRQ_SUBTYPE_DMA_FAULT subtype to set/unset
a notifier for physical DMA faults. The associated eventfd is
triggered, in nested mode, whenever a fault is detected at IOMMU
physical level.

The actual handler will be implemented in subsequent patches.

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---

v4 -> v5:
- index_to_str now returns the index name, ie. DMA_FAULT
- use the extended IRQ

v3 -> v4:
- check VFIO_PCI_DMA_FAULT_IRQ_INDEX is supported at kernel level
  before attempting to set signaling for it.
---
 hw/vfio/pci.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 hw/vfio/pci.h |  7 +++++
 2 files changed, 87 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 573c74b466..dfce777556 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2850,6 +2850,76 @@ static PCIPASIDOps vfio_pci_pasid_ops = {
     .set_pasid_table = vfio_iommu_set_pasid_table,
 };
 
+static void vfio_dma_fault_notifier_handler(void *opaque)
+{
+    VFIOPCIExtIRQ *ext_irq = opaque;
+
+    if (!event_notifier_test_and_clear(&ext_irq->notifier)) {
+        return;
+    }
+}
+
+static int vfio_register_ext_irq_handler(VFIOPCIDevice *vdev,
+                                         uint32_t type, uint32_t subtype,
+                                         IOHandler *handler)
+{
+    int32_t fd, ext_irq_index, index;
+    struct vfio_irq_info *irq_info;
+    Error *err = NULL;
+    EventNotifier *n;
+    int ret;
+
+    ret = vfio_get_dev_irq_info(&vdev->vbasedev, type, subtype, &irq_info);
+    if (ret) {
+        return ret;
+    }
+    index = irq_info->index;
+    ext_irq_index = irq_info->index - VFIO_PCI_NUM_IRQS;
+    g_free(irq_info);
+
+    vdev->ext_irqs[ext_irq_index].vdev = vdev;
+    vdev->ext_irqs[ext_irq_index].index = index;
+    n = &vdev->ext_irqs[ext_irq_index].notifier;
+
+    ret = event_notifier_init(n, 0);
+    if (ret) {
+        error_report("vfio: Unable to init event notifier for ext irq %d(%d)",
+                     ext_irq_index, ret);
+        return ret;
+    }
+
+    fd = event_notifier_get_fd(n);
+    qemu_set_fd_handler(fd, vfio_dma_fault_notifier_handler, NULL,
+                        &vdev->ext_irqs[ext_irq_index]);
+
+    ret = vfio_set_irq_signaling(&vdev->vbasedev, index, 0,
+                                 VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err);
+    if (ret) {
+        error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name);
+        qemu_set_fd_handler(fd, NULL, NULL, vdev);
+        event_notifier_cleanup(n);
+    }
+    return ret;
+}
+
+static void vfio_unregister_ext_irq_notifiers(VFIOPCIDevice *vdev)
+{
+    VFIODevice *vbasedev = &vdev->vbasedev;
+    Error *err = NULL;
+    int i;
+
+    for (i = 0; i < vbasedev->num_irqs - VFIO_PCI_NUM_IRQS; i++) {
+        if (vfio_set_irq_signaling(vbasedev, i + VFIO_PCI_NUM_IRQS , 0,
+                                   VFIO_IRQ_SET_ACTION_TRIGGER, -1, &err)) {
+            error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name);
+        }
+        qemu_set_fd_handler(event_notifier_get_fd(&vdev->ext_irqs[i].notifier),
+                            NULL, NULL, vdev);
+        event_notifier_cleanup(&vdev->ext_irqs[i].notifier);
+    }
+    g_free(vdev->ext_irqs);
+}
+
 static void vfio_realize(PCIDevice *pdev, Error **errp)
 {
     VFIOPCIDevice *vdev = VFIO_PCI(pdev);
@@ -2860,7 +2930,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     ssize_t len;
     struct stat st;
     int groupid;
-    int i, ret;
+    int i, ret, nb_ext_irqs;
     bool is_mdev;
 
     if (!vdev->vbasedev.sysfsdev) {
@@ -2948,6 +3018,11 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
         goto error;
     }
 
+    nb_ext_irqs = vdev->vbasedev.num_irqs - VFIO_PCI_NUM_IRQS;
+    if (nb_ext_irqs > 0) {
+        vdev->ext_irqs = g_new0(VFIOPCIExtIRQ, nb_ext_irqs);
+    }
+
     vfio_populate_device(vdev, &err);
     if (err) {
         error_propagate(errp, err);
@@ -3159,6 +3234,9 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
 
     vfio_register_err_notifier(vdev);
     vfio_register_req_notifier(vdev);
+    vfio_register_ext_irq_handler(vdev, VFIO_IRQ_TYPE_NESTED,
+                                  VFIO_IRQ_SUBTYPE_DMA_FAULT,
+                                  vfio_dma_fault_notifier_handler);
     vfio_setup_resetfn_quirk(vdev);
 
     pci_setup_pasid_ops(pdev, &vfio_pci_pasid_ops);
@@ -3201,6 +3279,7 @@ static void vfio_exitfn(PCIDevice *pdev)
 
     vfio_unregister_req_notifier(vdev);
     vfio_unregister_err_notifier(vdev);
+    vfio_unregister_ext_irq_notifiers(vdev);
     pci_device_set_intx_routing_notifier(&vdev->pdev, NULL);
     if (vdev->irqchip_change_notifier.notify) {
         kvm_irqchip_remove_change_notifier(&vdev->irqchip_change_notifier);
diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
index 1574ef983f..c5f06f4ae4 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -114,6 +114,12 @@ typedef struct VFIOMSIXInfo {
     unsigned long *pending;
 } VFIOMSIXInfo;
 
+typedef struct VFIOPCIExtIRQ {
+    struct VFIOPCIDevice *vdev;
+    EventNotifier notifier;
+    uint32_t index;
+} VFIOPCIExtIRQ;
+
 #define TYPE_VFIO_PCI "vfio-pci"
 OBJECT_DECLARE_SIMPLE_TYPE(VFIOPCIDevice, VFIO_PCI)
 
@@ -138,6 +144,7 @@ struct VFIOPCIDevice {
     PCIHostDeviceAddress host;
     EventNotifier err_notifier;
     EventNotifier req_notifier;
+    VFIOPCIExtIRQ *ext_irqs;
     int (*resetfn)(struct VFIOPCIDevice *);
     uint32_t vendor_id;
     uint32_t device_id;
-- 
2.26.2