Re: [PATCH 6/6] xen/gntalloc, gntdev: Add unmap notify ioctl

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

> diff --git a/include/xen/gntalloc.h b/include/xen/gntalloc.h
> index bc3b85e..257cc8d 100644
> --- a/include/xen/gntalloc.h
> +++ b/include/xen/gntalloc.h
> @@ -47,4 +47,32 @@ struct ioctl_gntalloc_dealloc_gref {
>  	/* Number of references to unmap */
>  	uint32_t count;
>  };
> +
> +/*
> + * Sets up an unmap notification within the page, so that the other side can do
> + * cleanup if this side crashes. Required to implement cross-domain robust
> + * mutexes or close notification on communication channels.
> + *
> + * Each mapped page only supports one notification; multiple calls referring to
> + * the same page overwrite the previous notification. You must clear the
> + * notification prior to the IOCTL_GNTALLOC_DEALLOC_GREF if you do not want it
> + * to occur.
> + */
> +#define IOCTL_GNTALLOC_SET_UNMAP_NOTIFY \
> +_IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntalloc_unmap_notify))
> +struct ioctl_gntalloc_unmap_notify {
> +	/* IN parameters */
> +	/* Index of a byte in the page */
> +	uint64_t index;

That isn't actually the whole truth. It is the index within the page
and also the "offset used on a subsequent call to mmap()" (ioctl_gntdev_map_grant_ref)

It might make sense to change the description to: "offset of the mmap region
and the index within the page" perhaps?

> +	/* Action(s) to take on unmap */
> +	uint32_t action;
> +	/* Event channel to notify */
> +	uint32_t event_channel_port;
> +};
> +
> +/* Clear (set to zero) the byte specified by index */
> +#define UNMAP_NOTIFY_CLEAR_BYTE 0x1
> +/* Send an interrupt on the indicated event channel */
> +#define UNMAP_NOTIFY_SEND_EVENT 0x2
> +
>  #endif /* __LINUX_PUBLIC_GNTALLOC_H__ */
> diff --git a/include/xen/gntdev.h b/include/xen/gntdev.h
> index eb23f41..5d9b9b4 100644
> --- a/include/xen/gntdev.h
> +++ b/include/xen/gntdev.h
> @@ -116,4 +116,31 @@ struct ioctl_gntdev_set_max_grants {
>  	uint32_t count;
>  };
>  
> +/*
> + * Sets up an unmap notification within the page, so that the other side can do
> + * cleanup if this side crashes. Required to implement cross-domain robust
> + * mutexes or close notification on communication channels.
> + *
> + * Each mapped page only supports one notification; multiple calls referring to
> + * the same page overwrite the previous notification. You must clear the
> + * notification prior to the IOCTL_GNTALLOC_DEALLOC_GREF if you do not want it
> + * to occur.
> + */
> +#define IOCTL_GNTDEV_SET_UNMAP_NOTIFY \
> +_IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntdev_unmap_notify))
> +struct ioctl_gntdev_unmap_notify {
> +	/* IN parameters */
> +	/* Index of a byte in the page */
> +	uint64_t index;

Ditto.
> +	/* Action(s) to take on unmap */
> +	uint32_t action;
> +	/* Event channel to notify */
> +	uint32_t event_channel_port;
> +};
> +
> +/* Clear (set to zero) the byte specified by index */
> +#define UNMAP_NOTIFY_CLEAR_BYTE 0x1
> +/* Send an interrupt on the indicated event channel */
> +#define UNMAP_NOTIFY_SEND_EVENT 0x2
> +
>  #endif /* __LINUX_PUBLIC_GNTDEV_H__ */
> -- 
> 1.7.3.4
> 
> 
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