vfio-pci: Add device request interface

Userspace can opt to receive a device request notification,
indicating that the device should be released.  This is setup
the same way as the error IRQ and also supports eventfd signaling.
Future support may forcefully remove the device from the user if
the request is ignored.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

4 files changed, 38 insertions, 1 deletions

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 7cc0122a18ce..f8a186381ae8 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -239,9 +239,12 @@ 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)
+	} else if (irq_type == VFIO_PCI_ERR_IRQ_INDEX) {
 		if (pci_is_pcie(vdev->pdev))
 			return 1;
+	} else if (irq_type == VFIO_PCI_REQ_IRQ_INDEX) {
+		return 1;
+	}
 
 	return 0;
 }
@@ -464,6 +467,7 @@ static long vfio_pci_ioctl(void *device_data,
 
 		switch (info.index) {
 		case VFIO_PCI_INTX_IRQ_INDEX ... VFIO_PCI_MSIX_IRQ_INDEX:
+		case VFIO_PCI_REQ_IRQ_INDEX:
 			break;
 		case VFIO_PCI_ERR_IRQ_INDEX:
 			if (pci_is_pcie(vdev->pdev))
@@ -828,6 +832,20 @@ static int vfio_pci_mmap(void *device_data, struct vm_area_struct *vma)
 			       req_len, vma->vm_page_prot);
 }
 
+static void vfio_pci_request(void *device_data, unsigned int count)
+{
+	struct vfio_pci_device *vdev = device_data;
+
+	mutex_lock(&vdev->igate);
+
+	if (vdev->req_trigger) {
+		dev_dbg(&vdev->pdev->dev, "Requesting device from user\n");
+		eventfd_signal(vdev->req_trigger, 1);
+	}
+
+	mutex_unlock(&vdev->igate);
+}
+
 static const struct vfio_device_ops vfio_pci_ops = {
 	.name		= "vfio-pci",
 	.open		= vfio_pci_open,
@@ -836,6 +854,7 @@ static const struct vfio_device_ops vfio_pci_ops = {
 	.read		= vfio_pci_read,
 	.write		= vfio_pci_write,
 	.mmap		= vfio_pci_mmap,
+	.request	= vfio_pci_request,
 };
 
 static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index b134befbfd0e..f88bfdf5b6a0 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -817,6 +817,16 @@ static int vfio_pci_set_err_trigger(struct vfio_pci_device *vdev,
 	return vfio_pci_set_ctx_trigger_single(&vdev->err_trigger, flags, data);
 }
 
+static int vfio_pci_set_req_trigger(struct vfio_pci_device *vdev,
+				    unsigned index, unsigned start,
+				    unsigned count, uint32_t flags, void *data)
+{
+	if (index != VFIO_PCI_REQ_IRQ_INDEX || start != 0 || count != 1)
+		return -EINVAL;
+
+	return vfio_pci_set_ctx_trigger_single(&vdev->req_trigger, flags, data);
+}
+
 int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev, uint32_t flags,
 			    unsigned index, unsigned start, unsigned count,
 			    void *data)
@@ -858,6 +868,12 @@ int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev, uint32_t flags,
 				func = vfio_pci_set_err_trigger;
 			break;
 		}
+	case VFIO_PCI_REQ_IRQ_INDEX:
+		switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) {
+		case VFIO_IRQ_SET_ACTION_TRIGGER:
+			func = vfio_pci_set_req_trigger;
+			break;
+		}
 	}
 
 	if (!func)
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index 671c17a6e6d0..c9f9b323f152 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -58,6 +58,7 @@ struct vfio_pci_device {
 	struct pci_saved_state	*pci_saved_state;
 	int			refcnt;
 	struct eventfd_ctx	*err_trigger;
+	struct eventfd_ctx	*req_trigger;
 };
 
 #define is_intx(vdev) (vdev->irq_type == VFIO_PCI_INTX_IRQ_INDEX)
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 29715d27548f..82889c30f4f5 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -333,6 +333,7 @@ enum {
 	VFIO_PCI_MSI_IRQ_INDEX,
 	VFIO_PCI_MSIX_IRQ_INDEX,
 	VFIO_PCI_ERR_IRQ_INDEX,
+	VFIO_PCI_REQ_IRQ_INDEX,
 	VFIO_PCI_NUM_IRQS
 };