[RFC PATCH 10/10] vhost/vdpa: return configuration bytes read and written to user space

From: Stefano Garzarella
Date: Tue Feb 16 2021 - 04:51:27 EST


vdpa_get_config() and vdpa_set_config() now return the amount
of bytes read and written, so let's return them to the user space.

We also modify vhost_vdpa_config_validate() to return 0 (bytes read
or written) instead of an error, when the buffer length is 0.

Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
---
drivers/vhost/vdpa.c | 26 +++++++++++++++-----------
1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 21eea2be5afa..b754c53171a7 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -191,9 +191,6 @@ static ssize_t vhost_vdpa_config_validate(struct vhost_vdpa *v,
struct vdpa_device *vdpa = v->vdpa;
u32 size = vdpa->config->get_config_size(vdpa);

- if (c->len == 0)
- return -EINVAL;
-
return min(c->len, size);
}

@@ -204,6 +201,7 @@ static long vhost_vdpa_get_config(struct vhost_vdpa *v,
struct vhost_vdpa_config config;
unsigned long size = offsetof(struct vhost_vdpa_config, buf);
ssize_t config_size;
+ long ret;
u8 *buf;

if (copy_from_user(&config, c, size))
@@ -217,15 +215,18 @@ static long vhost_vdpa_get_config(struct vhost_vdpa *v,
if (!buf)
return -ENOMEM;

- vdpa_get_config(vdpa, config.off, buf, config_size);
-
- if (copy_to_user(c->buf, buf, config_size)) {
- kvfree(buf);
- return -EFAULT;
+ ret = vdpa_get_config(vdpa, config.off, buf, config_size);
+ if (ret < 0) {
+ ret = -EFAULT;
+ goto out;
}

+ if (copy_to_user(c->buf, buf, config_size))
+ ret = -EFAULT;
+
+out:
kvfree(buf);
- return 0;
+ return ret;
}

static long vhost_vdpa_set_config(struct vhost_vdpa *v,
@@ -235,6 +236,7 @@ static long vhost_vdpa_set_config(struct vhost_vdpa *v,
struct vhost_vdpa_config config;
unsigned long size = offsetof(struct vhost_vdpa_config, buf);
ssize_t config_size;
+ long ret;
u8 *buf;

if (copy_from_user(&config, c, size))
@@ -248,10 +250,12 @@ static long vhost_vdpa_set_config(struct vhost_vdpa *v,
if (IS_ERR(buf))
return PTR_ERR(buf);

- vdpa_set_config(vdpa, config.off, buf, config_size);
+ ret = vdpa_set_config(vdpa, config.off, buf, config_size);
+ if (ret < 0)
+ ret = -EFAULT;

kvfree(buf);
- return 0;
+ return ret;
}

static long vhost_vdpa_get_features(struct vhost_vdpa *v, u64 __user *featurep)
--
2.29.2