virtio_pci_modern: introduce helper to map vq notify area

This patch factors out the logic of vq notify area mapping. Following
patches will switch to use this common helpers for both virtio_pci
library and virtio-pci vDPA driver.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210415073147.19331-2-jasowang@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>

diff --git a/drivers/virtio/virtio_pci_modern_dev.c b/drivers/virtio/virtio_pci_modern_dev.c
index cbd6674..28cb584 100644 (file)
--- a/drivers/virtio/virtio_pci_modern_dev.c
+++ b/drivers/virtio/virtio_pci_modern_dev.c
@@ -593,6 +593,41 @@ u16 vp_modern_get_queue_notify_off(struct virtio_pci_modern_device *mdev,
 }
 EXPORT_SYMBOL_GPL(vp_modern_get_queue_notify_off);
 
+/*
+ * vp_modern_map_vq_notify - map notification area for a
+ * specific virtqueue
+ * @mdev: the modern virtio-pci device
+ * @index: the queue index
+ *
+ * Returns the address of the notification area
+ */
+void *vp_modern_map_vq_notify(struct virtio_pci_modern_device *mdev,
+                             u16 index)
+{
+       u16 off = vp_modern_get_queue_notify_off(mdev, index);
+
+       if (mdev->notify_base) {
+               /* offset should not wrap */
+               if ((u64)off * mdev->notify_offset_multiplier + 2
+                       > mdev->notify_len) {
+                       dev_warn(&mdev->pci_dev->dev,
+                                "bad notification offset %u (x %u) "
+                                "for queue %u > %zd",
+                                off, mdev->notify_offset_multiplier,
+                                index, mdev->notify_len);
+                       return NULL;
+               }
+               return (void __force *)mdev->notify_base +
+                       off * mdev->notify_offset_multiplier;
+       } else {
+               return (void __force *)vp_modern_map_capability(mdev,
+                                      mdev->notify_map_cap, 2, 2,
+                                      off * mdev->notify_offset_multiplier, 2,
+                                      NULL);
+       }
+}
+EXPORT_SYMBOL_GPL(vp_modern_map_vq_notify);
+
 MODULE_VERSION("0.1");
 MODULE_DESCRIPTION("Modern Virtio PCI Device");
 MODULE_AUTHOR("Jason Wang <jasowang@redhat.com>");

diff --git a/include/linux/virtio_pci_modern.h b/include/linux/virtio_pci_modern.h
index f26acbe..1b95d39 100644 (file)
--- a/include/linux/virtio_pci_modern.h
+++ b/include/linux/virtio_pci_modern.h
@@ -106,6 +106,8 @@ void __iomem *vp_modern_map_capability(struct virtio_pci_modern_device *mdev, in
                                       u32 align,
                                       u32 start, u32 size,
                                       size_t *len);
+void *vp_modern_map_vq_notify(struct virtio_pci_modern_device *mdev,
+                              u16 index);
 int vp_modern_probe(struct virtio_pci_modern_device *mdev);
 void vp_modern_remove(struct virtio_pci_modern_device *mdev);
 #endif