From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: Re: [PATCH V4 3/6] mdev: introduce device specific ops Date: Thu, 17 Oct 2019 11:53:10 -0600 Message-ID: <20191017115310.0481cc52__17361.7245441832$1571334817$gmane$org@x1.home> References: <20191017104836.32464-1-jasowang@redhat.com> <20191017104836.32464-4-jasowang@redhat.com> <20191017170755.15506ada.cohuck@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20191017170755.15506ada.cohuck@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Cornelia Huck Cc: stefanha@redhat.com, christophe.de.dinechin@gmail.com, kvm@vger.kernel.org, mst@redhat.com, airlied@linux.ie, joonas.lahtinen@linux.intel.com, heiko.carstens@de.ibm.com, dri-devel@lists.freedesktop.org, virtualization@lists.linux-foundation.org, kwankhede@nvidia.com, rob.miller@broadcom.com, linux-s390@vger.kernel.org, sebott@linux.ibm.com, lulu@redhat.com, eperezma@redhat.com, pasic@linux.ibm.com, borntraeger@de.ibm.com, haotian.wang@sifive.com, intel-gfx@lists.freedesktop.org, zhi.a.wang@intel.com, farman@linux.ibm.com, idos@mellanox.com, gor@linux.ibm.com, jani.nikula@linux.intel.com, rodrigo.vivi@intel.com, xiao.w.wang@intel.com, freude@linux.ibm.com, zhenyuw@linux.intel.com, parav@mellanox.com, zhihong.wang@intel.com, intel-gvt-dev@lists.freedesktop.org, akrowiak@linux.ibm.com, oberpar@linux.ibm.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, maxime.co List-Id: virtualization@lists.linuxfoundation.org On Thu, 17 Oct 2019 17:07:55 +0200 Cornelia Huck wrote: > On Thu, 17 Oct 2019 18:48:33 +0800 > Jason Wang 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 > > --- > > .../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()/ > > > +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:" > > ? > > > + > > + 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)" ? > > > +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)" ? > > > +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.) Yes, it would be cleaner, but is it really worth the churn? Correct me if I'm wrong, but I think we get to the same point after this patch and aside from the function name itself, the difference is really just that the class_id is briefly exposed to the parent driver, right? Thanks, Alex > > 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).