On 2020/1/21 下午4:40, Tian, Kevin wrote:
From: Jason Wang <jasowang@xxxxxxxxxx>
Sent: Friday, January 17, 2020 11:03 AM
On 2020/1/16 下午11:22, Jason Gunthorpe wrote:
On Thu, Jan 16, 2020 at 08:42:29PM +0800, Jason Wang wrote:
vDPA device is a device that uses a datapath which complies with the
virtio specifications with vendor specific control path. vDPA devices
can be both physically located on the hardware or emulated by
software. vDPA hardware devices are usually implemented through PCIE
with the following types:
- PF (Physical Function) - A single Physical Function
- VF (Virtual Function) - Device that supports single root I/O
virtualization (SR-IOV). Its Virtual Function (VF) represents a
virtualized instance of the device that can be assigned to different
partitions
- VDEV (Virtual Device) - With technologies such as Intel Scalable
IOV, a virtual device composed by host OS utilizing one or more
ADIs.
the concept of VDEV includes both software bits and ADIs. If you
only take about hardware types, using ADI is more accurate.
Ok.
- SF (Sub function) - Vendor specific interface to slice the Physical
Function to multiple sub functions that can be assigned to different
partitions as virtual devices.
I really hope we don't end up with two different ways to spell this
same thing.
I think you meant ADI vs SF. It looks to me that ADI is limited to the
scope of scalable IOV but SF not.
ADI is just a term for minimally assignable resource in Scalable IOV.
'assignable' implies several things, e.g. the resource can be independently
mapped to/accessed by user space or guest, DMAs between two
ADIs are isolated, operating one ADI doesn't affecting another ADI,
etc. I'm not clear about other vendor specific interfaces, but supposing
they need match the similar requirements. Then do we really want to
differentiate ADI vs. SF? What about merging them with ADI as just
one example of finer-grained slicing?
I think so. That what Jason G want as well.
Thanks
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_VDPA) += vdpa.o
diff --git a/drivers/virtio/vdpa/vdpa.c b/drivers/virtio/vdpa/vdpa.c
new file mode 100644
index 000000000000..2b0e4a9f105d
+++ b/drivers/virtio/vdpa/vdpa.c
@@ -0,0 +1,141 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * vDPA bus.
+ *
+ * Copyright (c) 2019, Red Hat. All rights reserved.
+ * Author: Jason Wang <jasowang@xxxxxxxxxx>
2020 tests days
Will fix.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/idr.h>
+#include <linux/vdpa.h>
+
+#define MOD_VERSION "0.1"
I think module versions are discouraged these days
Will remove.
+#define MOD_DESC "vDPA bus"
+#define MOD_AUTHOR "Jason Wang <jasowang@xxxxxxxxxx>"
+#define MOD_LICENSE "GPL v2"
+
+static DEFINE_IDA(vdpa_index_ida);
+
+struct device *vdpa_get_parent(struct vdpa_device *vdpa)
+{
+ return vdpa->dev.parent;
+}
+EXPORT_SYMBOL(vdpa_get_parent);
+
+void vdpa_set_parent(struct vdpa_device *vdpa, struct device *parent)
+{
+ vdpa->dev.parent = parent;
+}
+EXPORT_SYMBOL(vdpa_set_parent);
+
+struct vdpa_device *dev_to_vdpa(struct device *_dev)
+{
+ return container_of(_dev, struct vdpa_device, dev);
+}
+EXPORT_SYMBOL_GPL(dev_to_vdpa);
+
+struct device *vdpa_to_dev(struct vdpa_device *vdpa)
+{
+ return &vdpa->dev;
+}
+EXPORT_SYMBOL_GPL(vdpa_to_dev);
Why these trivial assessors? Seems unnecessary, or should at least be
static inlines in a header
Will fix.
+int register_vdpa_device(struct vdpa_device *vdpa)
+{
Usually we want to see symbols consistently prefixed with vdpa_*, is
there a reason why register/unregister are swapped?
I follow the name from virtio. I will switch to vdpa_*.
+ int err;
+
+ if (!vdpa_get_parent(vdpa))
+ return -EINVAL;
+
+ if (!vdpa->config)
+ return -EINVAL;
+
+ err = ida_simple_get(&vdpa_index_ida, 0, 0, GFP_KERNEL);
+ if (err < 0)
+ return -EFAULT;
+
+ vdpa->dev.bus = &vdpa_bus;
+ device_initialize(&vdpa->dev);
IMHO device_initialize should not be called inside something called
register, toooften we find out that the caller drivers need the device
to be initialized earlier, ie to use the kref, or something.
I find the best flow is to have some init function that does the
device_initialize and sets the device_name that the driver can call
early.
Ok, will do.
Shouldn't there be a device/driver matching process of some kind?
The question is what do we want do match here.
1) "virtio" vs "vhost", I implemented matching method for this in mdev
series, but it looks unnecessary for vDPA device driver to know about
this. Anyway we can use sysfs driver bind/unbind to switch drivers
2) virtio device id and vendor id. I'm not sure we need this consider
the two drivers so far (virtio/vhost) are all bus drivers.
Thanks
Jason
