Re: [RFC PATCH v4 3/3] vfio: platform: return device properties as arrays of unsigned integers

[Baptiste Reynal <b.reynal@xxxxxxxxxxxxxxxxxxxxxx>]

On Wed, Sep 9, 2015 at 10:48 PM, Alex Williamson <alex.williamson@xxxxxxxxxx> wrote:

On Wed, 2015-09-09 at 11:17 +0200, Baptiste Reynal wrote:
> From: Antonios Motakis <a.motakis@xxxxxxxxxxxxxxxxxxxxxx>
>
> Certain properties of a device are accessible as an array of unsigned
> integers, either u64, u32, u16, or u8. Let the VFIO user query this
> type of device properties.
>
> Signed-off-by: Antonios Motakis <a.motakis@xxxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Baptiste Reynal <b.reynal@xxxxxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/vfio/platform/properties.c | 62 +++++++++++++++++++++++++++++++++++++-
>  1 file changed, 61 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vfio/platform/properties.c b/drivers/vfio/platform/properties.c
> index 8bf9c8f..625e2d3 100644
> --- a/drivers/vfio/platform/properties.c
> +++ b/drivers/vfio/platform/properties.c
> @@ -70,7 +70,67 @@ 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 ret, n;
> +     u8 *out;
> +     size_t sz;
> +     int (*func)(const struct device *, const char *, void *, size_t)
> +             = NULL;
> +
> +     switch (type) {
> +     case VFIO_DEV_PROPERTY_TYPE_U64:
> +             sz = sizeof(u64);
> +             func = (int (*)(const struct device *,
> +                             const char *, void *, size_t))
> +                     device_property_read_u64_array;
> +             break;
> +     case VFIO_DEV_PROPERTY_TYPE_U32:
> +             sz = sizeof(u32);
> +             func = (int (*)(const struct device *,
> +                             const char *, void *, size_t))
> +                     device_property_read_u32_array;
> +             break;
> +     case VFIO_DEV_PROPERTY_TYPE_U16:
> +             sz = sizeof(u16);
> +             func = (int (*)(const struct device *,
> +                             const char *, void *, size_t))
> +                     device_property_read_u16_array;
> +             break;
> +     case VFIO_DEV_PROPERTY_TYPE_U8:
> +             sz = sizeof(u8);
> +             func = (int (*)(const struct device *,
> +                             const char *, void *, size_t))
> +                     device_property_read_u8_array;
> +             break;
> +
> +     default:
> +             return -EINVAL;
> +     }
> +
> +     /* get size of array */
> +     n = func(dev, name, NULL, 0);
> +     if (n < 0)
> +             return n;
> +
> +     if (lenp)
> +             *lenp = n * sz;

Why is this conditional?

Same paranoia as before. If lenp is not allocated, the function behaviour is the same.

 

> +
> +     if (n * sz > datasz)
> +             return -EOVERFLOW;

Ugh, this isn't E2BIG or ENOSPC...

Ok, will be changed to ENOSPC.
 

> +
> +     out = kcalloc(n, sz, GFP_KERNEL);
> +     if (!out)
> +             return -ENOMEM;
> +
> +     ret = func(dev, name, out, n);
> +     if (ret)
> +             goto out;
> +
> +     if (copy_to_user(datap, out, n * sz))
> +             ret = -EFAULT;
> +
> +out:
> +     kfree(out);
> +     return ret;
>  }
>
>  int vfio_platform_dev_properties(struct device *dev, uint32_t *flags,

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