Re: [PATCH V4 3/6] mdev: introduce device specific ops
From: Jason Wang
Date: Fri Oct 18 2019 - 03:35:17 EST
On 2019/10/17 äå11:07, Cornelia Huck wrote:
On Thu, 17 Oct 2019 18:48:33 +0800
Jason Wang <jasowang@xxxxxxxxxx> wrote:
Currently, except for the create and remove, the rest of
mdev_parent_ops is designed for vfio-mdev driver only and may not help
for kernel mdev driver. With the help of class id, this patch
introduces device specific callbacks inside mdev_device
structure. This allows different set of callback to be used by
vfio-mdev and virtio-mdev.
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
.../driver-api/vfio-mediated-device.rst | 25 +++++----
MAINTAINERS | 1 +
drivers/gpu/drm/i915/gvt/kvmgt.c | 18 ++++---
drivers/s390/cio/vfio_ccw_ops.c | 18 ++++---
drivers/s390/crypto/vfio_ap_ops.c | 14 +++--
drivers/vfio/mdev/mdev_core.c | 18 +++++--
drivers/vfio/mdev/mdev_private.h | 1 +
drivers/vfio/mdev/vfio_mdev.c | 37 ++++++-------
include/linux/mdev.h | 45 ++++------------
include/linux/vfio_mdev.h | 52 +++++++++++++++++++
samples/vfio-mdev/mbochs.c | 20 ++++---
samples/vfio-mdev/mdpy.c | 20 ++++---
samples/vfio-mdev/mtty.c | 18 ++++---
13 files changed, 184 insertions(+), 103 deletions(-)
create mode 100644 include/linux/vfio_mdev.h
diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
index f9a78d75a67a..0cca84d19603 100644
--- a/Documentation/driver-api/vfio-mediated-device.rst
+++ b/Documentation/driver-api/vfio-mediated-device.rst
@@ -152,11 +152,22 @@ callbacks per mdev parent device, per mdev type, or any other categorization.
Vendor drivers are expected to be fully asynchronous in this respect or
provide their own internal resource protection.)
-The callbacks in the mdev_parent_ops structure are as follows:
-
-* open: open callback of mediated device
-* close: close callback of mediated device
-* ioctl: ioctl callback of mediated device
+As multiple types of mediated devices may be supported, the device
+must set up the class id and the device specific callbacks in create()
s/in create()/in the create()/
Will fix.
+callback. E.g for vfio-mdev device it needs to be done through:
"Each class provides a helper function to do so; e.g. for vfio-mdev
devices, the function to be called is:"
?
This looks better.
+
+ int mdev_set_vfio_ops(struct mdev_device *mdev,
+ const struct vfio_mdev_ops *vfio_ops);
+
+The class id (set to MDEV_CLASS_ID_VFIO) is used to match a device
"(set by this helper function to MDEV_CLASS_ID_VFIO)" ?
Yes.
+with an mdev driver via its id table. The device specific callbacks
+(specified in *ops) are obtainable via mdev_get_dev_ops() (for use by
"(specified in *vfio_ops by the caller)" ?
Yes.
+the mdev bus driver). A vfio-mdev device (class id MDEV_CLASS_ID_VFIO)
+uses the following device-specific ops:
+
+* open: open callback of vfio mediated device
+* close: close callback of vfio mediated device
+* ioctl: ioctl callback of vfio mediated device
* read : read emulation callback
* write: write emulation callback
* mmap: mmap emulation callback
@@ -167,10 +178,6 @@ register itself with the mdev core driver::
extern int mdev_register_device(struct device *dev,
const struct mdev_parent_ops *ops);
-It is also required to specify the class_id in create() callback through::
-
- int mdev_set_class(struct mdev_device *mdev, u16 id);
-
I'm wondering if this patch set should start out with introducing
helper functions already (i.e. don't introduce mdev_set_class(), but
start out with mdev_set_class_vfio() which will gain the *vfio_ops
argument in this patch.)
I think it doesn't harm to keep it as is since in patch 1 we introduce
class_id and bus match method based on that without device ops there.Â
But if you stick I can change.
Thanks
However, the mdev_parent_ops structure is not required in the function call
that a driver should use to unregister itself with the mdev core driver::
(...)
diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index 3a9c52d71b4e..d0f3113c8071 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -45,15 +45,23 @@ void mdev_set_drvdata(struct mdev_device *mdev, void *data)
}
EXPORT_SYMBOL(mdev_set_drvdata);
-/* Specify the class for the mdev device, this must be called during
- * create() callback.
+/* Specify the VFIO device ops for the mdev device, this
+ * must be called during create() callback for VFIO mdev device.
*/
/*
* Specify the mdev device to be a VFIO mdev device, and set the
* VFIO devices ops for it. This must be called from the create()
* callback for VFIO mdev devices.
*/
?
-void mdev_set_class(struct mdev_device *mdev, u16 id)
+void mdev_set_vfio_ops(struct mdev_device *mdev,
+ const struct vfio_mdev_device_ops *vfio_ops)
{
WARN_ON(mdev->class_id);
- mdev->class_id = id;
+ mdev->class_id = MDEV_CLASS_ID_VFIO;
+ mdev->device_ops = vfio_ops;
}
-EXPORT_SYMBOL(mdev_set_class);
+EXPORT_SYMBOL(mdev_set_vfio_ops);
+
+const void *mdev_get_dev_ops(struct mdev_device *mdev)
+{
+ return mdev->device_ops;
+}
+EXPORT_SYMBOL(mdev_get_dev_ops);
struct device *mdev_dev(struct mdev_device *mdev)
{
(...)
The code change looks good to me; I'm just wondering if we should
introduce mdev_set_class() at all (see above).