VFIO-AER: Vfio-pci driver changes for supporting AER

- New VFIO_SET_IRQ ioctl option to pass the eventfd that is signaled when
  an error occurs in the vfio_pci_device

- Register pci_error_handler for the vfio_pci driver

- When the device encounters an error, the error handler registered by
  the vfio_pci driver gets invoked by the AER infrastructure

- In the error handler, signal the eventfd registered for the device.

- This results in the qemu eventfd handler getting invoked and
  appropriate action taken for the guest.

Signed-off-by: Vijay Mohan Pandarathil <vijaymohan.pandarathil@hp.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

3 files changed, 108 insertions, 1 deletions

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 8189cb6a86af..acfcb1ae77bc 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -201,7 +201,9 @@ static int vfio_pci_get_irq_count(struct vfio_pci_device *vdev, int irq_type)
 
                         return (flags & PCI_MSIX_FLAGS_QSIZE) + 1;
                 }
-        }
+        } else if (irq_type == VFIO_PCI_ERR_IRQ_INDEX)
+                if (pci_is_pcie(vdev->pdev))
+                        return 1;
 
         return 0;
 }
@@ -317,6 +319,17 @@ static long vfio_pci_ioctl(void *device_data,
                 if (info.argsz < minsz || info.index >= VFIO_PCI_NUM_IRQS)
                         return -EINVAL;
 
+                switch (info.index) {
+                case VFIO_PCI_INTX_IRQ_INDEX ... VFIO_PCI_MSIX_IRQ_INDEX:
+                        break;
+                case VFIO_PCI_ERR_IRQ_INDEX:
+                        if (pci_is_pcie(vdev->pdev))
+                                break;
+                /* pass thru to return error */
+                default:
+                        return -EINVAL;
+                }
+
                 info.flags = VFIO_IRQ_INFO_EVENTFD;
 
                 info.count = vfio_pci_get_irq_count(vdev, info.index);
@@ -551,11 +564,40 @@ static void vfio_pci_remove(struct pci_dev *pdev)
         kfree(vdev);
 }
 
+static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
+                                                  pci_channel_state_t state)
+{
+        struct vfio_pci_device *vdev;
+        struct vfio_device *device;
+
+        device = vfio_device_get_from_dev(&pdev->dev);
+        if (device == NULL)
+                return PCI_ERS_RESULT_DISCONNECT;
+
+        vdev = vfio_device_data(device);
+        if (vdev == NULL) {
+                vfio_device_put(device);
+                return PCI_ERS_RESULT_DISCONNECT;
+        }
+
+        if (vdev->err_trigger)
+                eventfd_signal(vdev->err_trigger, 1);
+
+        vfio_device_put(device);
+
+        return PCI_ERS_RESULT_CAN_RECOVER;
+}
+
+static struct pci_error_handlers vfio_err_handlers = {
+        .error_detected = vfio_pci_aer_err_detected,
+};
+
 static struct pci_driver vfio_pci_driver = {
         .name           = "vfio-pci",
         .id_table       = NULL, /* only dynamic ids */
         .probe          = vfio_pci_probe,
         .remove         = vfio_pci_remove,
+        .err_handler    = &vfio_err_handlers,
 };
 
 static void __exit vfio_pci_cleanup(void)
diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index 3639371fa697..b84bf2210a91 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -745,6 +745,63 @@ static int vfio_pci_set_msi_trigger(struct vfio_pci_device *vdev,
         return 0;
 }
 
+static int vfio_pci_set_err_trigger(struct vfio_pci_device *vdev,
+                                    unsigned index, unsigned start,
+                                    unsigned count, uint32_t flags, void *data)
+{
+        int32_t fd = *(int32_t *)data;
+        struct pci_dev *pdev = vdev->pdev;
+
+        if ((index != VFIO_PCI_ERR_IRQ_INDEX) ||
+            !(flags & VFIO_IRQ_SET_DATA_TYPE_MASK))
+                return -EINVAL;
+
+        /*
+         * device_lock synchronizes setting and checking of
+         * err_trigger. The vfio_pci_aer_err_detected() is also
+         * called with device_lock held.
+         */
+
+        /* DATA_NONE/DATA_BOOL enables loopback testing */
+
+        if (flags & VFIO_IRQ_SET_DATA_NONE) {
+                device_lock(&pdev->dev);
+                if (vdev->err_trigger)
+                        eventfd_signal(vdev->err_trigger, 1);
+                device_unlock(&pdev->dev);
+                return 0;
+        } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
+                uint8_t trigger = *(uint8_t *)data;
+                device_lock(&pdev->dev);
+                if (trigger && vdev->err_trigger)
+                        eventfd_signal(vdev->err_trigger, 1);
+                device_unlock(&pdev->dev);
+                return 0;
+        }
+
+        /* Handle SET_DATA_EVENTFD */
+
+        if (fd == -1) {
+                device_lock(&pdev->dev);
+                if (vdev->err_trigger)
+                        eventfd_ctx_put(vdev->err_trigger);
+                vdev->err_trigger = NULL;
+                device_unlock(&pdev->dev);
+                return 0;
+        } else if (fd >= 0) {
+                struct eventfd_ctx *efdctx;
+                efdctx = eventfd_ctx_fdget(fd);
+                if (IS_ERR(efdctx))
+                        return PTR_ERR(efdctx);
+                device_lock(&pdev->dev);
+                if (vdev->err_trigger)
+                        eventfd_ctx_put(vdev->err_trigger);
+                vdev->err_trigger = efdctx;
+                device_unlock(&pdev->dev);
+                return 0;
+        } else
+                return -EINVAL;
+}
 int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev, uint32_t flags,
                             unsigned index, unsigned start, unsigned count,
                             void *data)
@@ -779,6 +836,13 @@ int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev, uint32_t flags,
                         break;
                 }
                 break;
+        case VFIO_PCI_ERR_IRQ_INDEX:
+                switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) {
+                case VFIO_IRQ_SET_ACTION_TRIGGER:
+                        if (pci_is_pcie(vdev->pdev))
+                                func = vfio_pci_set_err_trigger;
+                        break;
+                }
         }
 
         if (!func)
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index d7e55d03f49e..9c6d5d0f3b02 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -56,6 +56,7 @@ struct vfio_pci_device {
         bool                    has_vga;
         struct pci_saved_state  *pci_saved_state;
         atomic_t                refcnt;
+        struct eventfd_ctx      *err_trigger;
 };
 
 #define is_intx(vdev) (vdev->irq_type == VFIO_PCI_INTX_IRQ_INDEX)