Re: [PATCH 7/7] [v2] drivers/misc: introduce Freescale hypervisor management driver

From: Arnd Bergmann
Date: Wed Jun 01 2011 - 17:41:00 EST


On Wednesday 01 June 2011, Timur Tabi wrote:
> The Freescale hypervisor management driver provides several services to
> drivers and applications related to the Freescale hypervisor:
>
> 1. An ioctl interface for querying and managing partitions
>
> 2. A file interface to reading incoming doorbells
>
> 3. An interrupt handler for shutting down the partition upon receiving the
> shutdown doorbell from a manager partition
>
> 4. An interface for receiving callbacks when a managed partition shuts down.
>
> Signed-off-by: Timur Tabi <timur@xxxxxxxxxxxxx>
> ---
> drivers/misc/Kconfig | 7 +
> drivers/misc/Makefile | 1 +
> drivers/misc/fsl_hypervisor.c | 941 ++++++++++++++++++++++++++++++++++++++++
> include/linux/Kbuild | 1 +
> include/linux/fsl_hypervisor.h | 203 +++++++++
> 5 files changed, 1153 insertions(+), 0 deletions(-)
> create mode 100644 drivers/misc/fsl_hypervisor.c
> create mode 100644 include/linux/fsl_hypervisor.h

I think drivers/misc is not the right place for this, but I'm not completely
sure what is. drivers/firmware would be better at least, but virt/fsl might
also be ok.

> +static long ioctl_dtprop(struct fsl_hv_ioctl_prop __user *p, int set)
> +{
> + struct fsl_hv_ioctl_prop param;
> + char __user *upath, *upropname;
> + void __user *upropval;
> + char *path = NULL, *propname = NULL;
> + void *propval = NULL;
> + int ret = 0;
> +

I'm not convinced that an ioctl interface is the right way to work with
device tree properties. A more natural way would be to export it as
a file system, or maybe as a flattened device tree blob (the latter option
would require changing the hypervisor interface, which might not be
possible).

> +/**
> + * fsl_hv_ioctl: ioctl main entry point
> + */
> +static long fsl_hv_ioctl(struct file *file, unsigned int cmd,
> + unsigned long argaddr)
> +{
> + union fsl_hv_ioctl_param __user *arg =
> + (union fsl_hv_ioctl_param __user *)argaddr;
> + long ret;
> +

For an ioctl, please follow the normal pattern of defining a separate
structure for each case, no union.

You can use a void __user * in the common ioctl function, and pass that
to the typed argument list in the specific functions.

Arnd
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