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Message-ID: <3-v2-940e479ceba9+3821-fwctl_jgg@nvidia.com>
Date: Mon, 24 Jun 2024 19:47:27 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Jonathan Corbet <corbet@....net>,
Itay Avraham <itayavr@...dia.com>,
Jakub Kicinski <kuba@...nel.org>,
Leon Romanovsky <leon@...nel.org>,
linux-doc@...r.kernel.org,
linux-rdma@...r.kernel.org,
netdev@...r.kernel.org,
Paolo Abeni <pabeni@...hat.com>,
Saeed Mahameed <saeedm@...dia.com>,
Tariq Toukan <tariqt@...dia.com>
Cc: Andy Gospodarek <andrew.gospodarek@...adcom.com>,
Aron Silverton <aron.silverton@...cle.com>,
Dan Williams <dan.j.williams@...el.com>,
David Ahern <dsahern@...nel.org>,
Christoph Hellwig <hch@...radead.org>,
Jiri Pirko <jiri@...dia.com>,
Leonid Bloch <lbloch@...dia.com>,
Leon Romanovsky <leonro@...dia.com>,
linux-cxl@...r.kernel.org,
patches@...ts.linux.dev
Subject: [PATCH v2 3/8] fwctl: FWCTL_INFO to return basic information about the device
Userspace will need to know some details about the fwctl interface being
used to locate the correct userspace code to communicate with the
kernel. Provide a simple device_type enum indicating what the kernel
driver is.
Allow the device to provide a device specific info struct that contains
any additional information that the driver may need to provide to
userspace.
Signed-off-by: Jason Gunthorpe <jgg@...dia.com>
---
drivers/fwctl/main.c | 53 ++++++++++++++++++++++++++++++++++++++
include/linux/fwctl.h | 8 ++++++
include/uapi/fwctl/fwctl.h | 29 +++++++++++++++++++++
3 files changed, 90 insertions(+)
diff --git a/drivers/fwctl/main.c b/drivers/fwctl/main.c
index 6872c01d5c62e8..f1dec0b590aee4 100644
--- a/drivers/fwctl/main.c
+++ b/drivers/fwctl/main.c
@@ -17,6 +17,8 @@ enum {
static dev_t fwctl_dev;
static DEFINE_IDA(fwctl_ida);
+DEFINE_FREE(kfree_errptr, void *, if (!IS_ERR_OR_NULL(_T)) kfree(_T));
+
struct fwctl_ucmd {
struct fwctl_uctx *uctx;
void __user *ubuffer;
@@ -24,8 +26,58 @@ struct fwctl_ucmd {
u32 user_size;
};
+static int ucmd_respond(struct fwctl_ucmd *ucmd, size_t cmd_len)
+{
+ if (copy_to_user(ucmd->ubuffer, ucmd->cmd,
+ min_t(size_t, ucmd->user_size, cmd_len)))
+ return -EFAULT;
+ return 0;
+}
+
+static int copy_to_user_zero_pad(void __user *to, const void *from,
+ size_t from_len, size_t user_len)
+{
+ size_t copy_len;
+
+ copy_len = min(from_len, user_len);
+ if (copy_to_user(to, from, copy_len))
+ return -EFAULT;
+ if (copy_len < user_len) {
+ if (clear_user(to + copy_len, user_len - copy_len))
+ return -EFAULT;
+ }
+ return 0;
+}
+
+static int fwctl_cmd_info(struct fwctl_ucmd *ucmd)
+{
+ struct fwctl_device *fwctl = ucmd->uctx->fwctl;
+ struct fwctl_info *cmd = ucmd->cmd;
+ size_t driver_info_len = 0;
+
+ if (cmd->flags)
+ return -EOPNOTSUPP;
+
+ if (cmd->device_data_len) {
+ void *driver_info __free(kfree_errptr) =
+ fwctl->ops->info(ucmd->uctx, &driver_info_len);
+ if (IS_ERR(driver_info))
+ return PTR_ERR(driver_info);
+
+ if (copy_to_user_zero_pad(u64_to_user_ptr(cmd->out_device_data),
+ driver_info, driver_info_len,
+ cmd->device_data_len))
+ return -EFAULT;
+ }
+
+ cmd->out_device_type = fwctl->ops->device_type;
+ cmd->device_data_len = driver_info_len;
+ return ucmd_respond(ucmd, sizeof(*cmd));
+}
+
/* On stack memory for the ioctl structs */
union ucmd_buffer {
+ struct fwctl_info info;
};
struct fwctl_ioctl_op {
@@ -45,6 +97,7 @@ struct fwctl_ioctl_op {
.execute = _fn, \
}
static const struct fwctl_ioctl_op fwctl_ioctl_ops[] = {
+ IOCTL_OP(FWCTL_INFO, fwctl_cmd_info, struct fwctl_info, out_device_data),
};
static long fwctl_fops_ioctl(struct file *filp, unsigned int cmd,
diff --git a/include/linux/fwctl.h b/include/linux/fwctl.h
index 1d9651de92fc19..9a906b861acf3a 100644
--- a/include/linux/fwctl.h
+++ b/include/linux/fwctl.h
@@ -7,12 +7,14 @@
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/cleanup.h>
+#include <uapi/fwctl/fwctl.h>
struct fwctl_device;
struct fwctl_uctx;
/**
* struct fwctl_ops - Driver provided operations
+ * @device_type: The drivers assigned device_type number. This is uABI
* @uctx_size: The size of the fwctl_uctx struct to allocate. The first
* bytes of this memory will be a fwctl_uctx. The driver can use the
* remaining bytes as its private memory.
@@ -20,11 +22,17 @@ struct fwctl_uctx;
* used.
* @close_uctx: Called when the uctx is destroyed, usually when the FD is
* closed.
+ * @info: Implement FWCTL_INFO. Return a kmalloc() memory that is copied to
+ * out_device_data. On input length indicates the size of the user buffer
+ * on output it indicates the size of the memory. The driver can ignore
+ * length on input, the core code will handle everything.
*/
struct fwctl_ops {
+ enum fwctl_device_type device_type;
size_t uctx_size;
int (*open_uctx)(struct fwctl_uctx *uctx);
void (*close_uctx)(struct fwctl_uctx *uctx);
+ void *(*info)(struct fwctl_uctx *uctx, size_t *length);
};
/**
diff --git a/include/uapi/fwctl/fwctl.h b/include/uapi/fwctl/fwctl.h
index 0bdce95b6d69d9..39db9f09f8068e 100644
--- a/include/uapi/fwctl/fwctl.h
+++ b/include/uapi/fwctl/fwctl.h
@@ -36,6 +36,35 @@
*/
enum {
FWCTL_CMD_BASE = 0,
+ FWCTL_CMD_INFO = 0,
+ FWCTL_CMD_RPC = 1,
};
+enum fwctl_device_type {
+ FWCTL_DEVICE_TYPE_ERROR = 0,
+};
+
+/**
+ * struct fwctl_info - ioctl(FWCTL_INFO)
+ * @size: sizeof(struct fwctl_info)
+ * @flags: Must be 0
+ * @out_device_type: Returns the type of the device from enum fwctl_device_type
+ * @device_data_len: On input the length of the out_device_data memory. On
+ * output the size of the kernel's device_data which may be larger or
+ * smaller than the input. Maybe 0 on input.
+ * @out_device_data: Pointer to a memory of device_data_len bytes. Kernel will
+ * fill the entire memory, zeroing as required.
+ *
+ * Returns basic information about this fwctl instance, particularly what driver
+ * is being used to define the device_data format.
+ */
+struct fwctl_info {
+ __u32 size;
+ __u32 flags;
+ __u32 out_device_type;
+ __u32 device_data_len;
+ __aligned_u64 out_device_data;
+};
+#define FWCTL_INFO _IO(FWCTL_TYPE, FWCTL_CMD_INFO)
+
#endif
--
2.45.2
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