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Subject[RFC PATCH v4 1/3] vfio: platform: add device properties skeleton and user API
Date
From: Antonios Motakis <a.motakis@virtualopensystems.com>

This patch introduces an API that allows to return device properties (OF
or ACPI) of a device bound to the vfio-platform/vfio-amba driver and the
skeleton of the implementation for VFIO_PLATFORM. Information about any
device node bound by VFIO_PLATFORM should be queried via the introduced
ioctl VFIO_DEVICE_GET_DEV_PROPERTY.

The user needs to know the name and the data type of the property he is
accessing.

Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
Signed-off-by: Baptiste Reynal <b.reynal@virtualopensystems.com>

---
v3 -> v4:
- added flags placeholder in vfio_dev_properties
- ioctl returns -E2BIG if the buffer is too small
- details VFIO_DEVICE_GET_DEV_PROPERTY documentation
---
drivers/vfio/platform/Makefile | 3 +-
drivers/vfio/platform/properties.c | 77 +++++++++++++++++++++++++++
drivers/vfio/platform/vfio_platform_common.c | 35 ++++++++++++
drivers/vfio/platform/vfio_platform_private.h | 7 +++
include/uapi/linux/vfio.h | 31 +++++++++++
5 files changed, 152 insertions(+), 1 deletion(-)
create mode 100644 drivers/vfio/platform/properties.c

diff --git a/drivers/vfio/platform/Makefile b/drivers/vfio/platform/Makefile
index 9ce8afe..37cf5ed 100644
--- a/drivers/vfio/platform/Makefile
+++ b/drivers/vfio/platform/Makefile
@@ -1,5 +1,6 @@

-vfio-platform-y := vfio_platform.o vfio_platform_common.o vfio_platform_irq.o
+vfio-platform-y := vfio_platform.o vfio_platform_common.o vfio_platform_irq.o \
+ properties.o

obj-$(CONFIG_VFIO_PLATFORM) += vfio-platform.o
obj-$(CONFIG_VFIO_PLATFORM) += reset/
diff --git a/drivers/vfio/platform/properties.c b/drivers/vfio/platform/properties.c
new file mode 100644
index 0000000..98754c2
--- /dev/null
+++ b/drivers/vfio/platform/properties.c
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2015 - Virtual Open Systems
+ * Authors: Antonios Motakis <a.motakis@virtualopensystems.com>
+ * Baptiste Reynal <b.reynal@virtualopensystems.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/slab.h>
+#include <linux/vfio.h>
+#include <linux/property.h>
+#include "vfio_platform_private.h"
+
+static int dev_property_get_strings(struct device *dev, uint32_t *flags,
+ char *name, unsigned *lenp,
+ void __user *datap, unsigned long datasz)
+{
+ return -EINVAL;
+}
+
+static int dev_property_get_uint(struct device *dev, uint32_t *flags,
+ char *name, uint32_t type, unsigned *lenp,
+ void __user *datap, unsigned long datasz)
+{
+ return -EINVAL;
+}
+
+int vfio_platform_dev_properties(struct device *dev, uint32_t *flags,
+ uint32_t type, unsigned *lenp,
+ void __user *datap, unsigned long datasz)
+{
+ char *name;
+ long namesz;
+ int ret;
+
+ namesz = strnlen_user(datap, datasz);
+ if (!namesz)
+ return -EFAULT;
+ if (namesz > datasz)
+ return -EINVAL;
+
+ name = kzalloc(namesz, GFP_KERNEL);
+ if (!name)
+ return -ENOMEM;
+ if (strncpy_from_user(name, datap, namesz) <= 0) {
+ kfree(name);
+ return -EFAULT;
+ }
+
+ switch (type) {
+ case VFIO_DEV_PROPERTY_TYPE_STRINGS:
+ ret = dev_property_get_strings(dev, flags, name, lenp,
+ datap, datasz);
+ break;
+
+ case VFIO_DEV_PROPERTY_TYPE_U64:
+ case VFIO_DEV_PROPERTY_TYPE_U32:
+ case VFIO_DEV_PROPERTY_TYPE_U16:
+ case VFIO_DEV_PROPERTY_TYPE_U8:
+ ret = dev_property_get_uint(dev, flags, name, type, lenp,
+ datap, datasz);
+ break;
+
+ default:
+ ret = -EINVAL;
+ }
+
+ kfree(name);
+ return ret;
+}
diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index e43efb5..44ba22c 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -20,6 +20,7 @@
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/vfio.h>
+#include <linux/property.h>

#include "vfio_platform_private.h"

@@ -302,6 +303,34 @@ static long vfio_platform_ioctl(void *device_data,
return vdev->reset(vdev);
else
return -EINVAL;
+ } else if (cmd == VFIO_DEVICE_GET_DEV_PROPERTY) {
+ struct vfio_dev_property info;
+ void __user *datap;
+ unsigned long datasz;
+ int ret;
+
+ if (!vdev->dev)
+ return -EINVAL;
+
+ minsz = offsetofend(struct vfio_dev_property, length);
+
+ if (copy_from_user(&info, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (info.argsz < minsz)
+ return -EINVAL;
+
+ datap = (void __user *) arg + minsz;
+ datasz = info.argsz - minsz;
+
+ ret = vfio_platform_dev_properties(vdev->dev, &info.flags,
+ info.type, &info.length, datap, datasz);
+
+ if (copy_to_user((void __user *)arg, &info, minsz))
+ ret = -EFAULT;
+
+ return ret;
+
}

return -ENOTTY;
@@ -553,6 +582,12 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,

vfio_platform_get_reset(vdev, dev);

+ /* add device properties flag */
+ if (device_property_present(dev, "name")) {
+ vdev->dev = dev;
+ vdev->flags |= VFIO_DEVICE_FLAGS_DEV_PROPERTIES;
+ }
+
mutex_init(&vdev->igate);

return 0;
diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
index 1c9b3d5..c75b089 100644
--- a/drivers/vfio/platform/vfio_platform_private.h
+++ b/drivers/vfio/platform/vfio_platform_private.h
@@ -56,6 +56,7 @@ struct vfio_platform_device {
u32 num_irqs;
int refcnt;
struct mutex igate;
+ struct device *dev;

/*
* These fields should be filled by the bus specific binder
@@ -89,4 +90,10 @@ extern int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
unsigned start, unsigned count,
void *data);

+/* device properties support in properties.c */
+extern int vfio_platform_dev_properties(struct device *dev, uint32_t *flags,
+ uint32_t type, unsigned *lenp,
+ void __user *datap,
+ unsigned long datasz);
+
#endif /* VFIO_PLATFORM_PRIVATE_H */
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 9fd7b5d..a1a0eaa 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -164,12 +164,43 @@ struct vfio_device_info {
#define VFIO_DEVICE_FLAGS_PCI (1 << 1) /* vfio-pci device */
#define VFIO_DEVICE_FLAGS_PLATFORM (1 << 2) /* vfio-platform device */
#define VFIO_DEVICE_FLAGS_AMBA (1 << 3) /* vfio-amba device */
+#define VFIO_DEVICE_FLAGS_DEV_PROPERTIES (1 << 4) /* Device properties */
__u32 num_regions; /* Max region index + 1 */
__u32 num_irqs; /* Max IRQ index + 1 */
};
#define VFIO_DEVICE_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 7)

/**
+ * VFIO_DEVICE_GET_DEV_PROPERTY - _IOR(VFIO_TYPE, VFIO_BASE + 17,
+ * struct vfio_devtree_info)
+ *
+ * Retrieve a device property, e.g. from a HW description (device tree or ACPI)
+ * if available.
+ * Caller will initialize data[] with a single string with the requested
+ * devicetree property name, and type depending on whether an array of strings
+ * or an array of u32 values is expected. On success, data[] will be filled
+ * with the requested information, either as an array of u32, or with a list
+ * of strings separated by the NULL terminating character.
+ * Return: 0 on success, -errno on failure.
+ * Errors:
+ * E2BIG: the property is too big to fit in the data[] buffer (the required
+ * size is then written into the length field).
+ */
+struct vfio_dev_property {
+ __u32 argsz;
+ __u32 flags; /* Placeholder for future extension */
+ __u32 type;
+#define VFIO_DEV_PROPERTY_TYPE_STRINGS 0
+#define VFIO_DEV_PROPERTY_TYPE_U8 1
+#define VFIO_DEV_PROPERTY_TYPE_U16 2
+#define VFIO_DEV_PROPERTY_TYPE_U32 3
+#define VFIO_DEV_PROPERTY_TYPE_U64 4
+ __u32 length; /* Size of data[] */
+ __u8 data[];
+};
+#define VFIO_DEVICE_GET_DEV_PROPERTY _IO(VFIO_TYPE, VFIO_BASE + 17)
+
+/**
* VFIO_DEVICE_GET_REGION_INFO - _IOWR(VFIO_TYPE, VFIO_BASE + 8,
* struct vfio_region_info)
*
--
2.5.1


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