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

[Stefano Garzarella]

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 <sgarz...@redhat.com>
---
 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

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