Re: [PATCH 1/6 v2] xenbus: Support HVM backends

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

On Thu, Oct 20, 2011 at 12:48:04PM -0400, Daniel De Graaf wrote:
> Initial version lacked the list_del in xenbus_unmap_ring_vfree_hvm
> 
> -------------------------------------------------------->8
> 
> Add HVM implementations of xenbus_(map,unmap)_ring_v(alloc,free) so
> that ring mappings can be done without using GNTMAP_contains_pte which
> is not supported on HVM.
> 
> Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
> ---
>  drivers/xen/xenbus/xenbus_client.c |  155 +++++++++++++++++++++++++++++-------
>  1 files changed, 125 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
> index 52bc57f..4b2fbcc 100644
> --- a/drivers/xen/xenbus/xenbus_client.c
> +++ b/drivers/xen/xenbus/xenbus_client.c
> @@ -32,15 +32,26 @@
>  
>  #include <linux/slab.h>
>  #include <linux/types.h>
> +#include <linux/spinlock.h>
>  #include <linux/vmalloc.h>
>  #include <asm/xen/hypervisor.h>
>  #include <asm/xen/page.h>
>  #include <xen/interface/xen.h>
>  #include <xen/interface/event_channel.h>
> +#include <xen/balloon.h>
>  #include <xen/events.h>
>  #include <xen/grant_table.h>
>  #include <xen/xenbus.h>
>  
> +struct xenbus_map_node {
> +	struct list_head next;
> +	struct page *page;
> +	grant_handle_t handle;
> +};
> +
> +static DEFINE_SPINLOCK(xenbus_valloc_lock);
> +static LIST_HEAD(xenbus_valloc_pages);
> +
>  const char *xenbus_strstate(enum xenbus_state state)
>  {
>  	static const char *const name[] = {
> @@ -419,21 +430,8 @@ int xenbus_free_evtchn(struct xenbus_device *dev, int port)
>  EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
>  
>  
> -/**
> - * xenbus_map_ring_valloc
> - * @dev: xenbus device
> - * @gnt_ref: grant reference
> - * @vaddr: pointer to address to be filled out by mapping
> - *
> - * Based on Rusty Russell's skeleton driver's map_page.
> - * Map a page of memory into this domain from another domain's grant table.
> - * xenbus_map_ring_valloc allocates a page of virtual address space, maps the
> - * page to that address, and sets *vaddr to that address.
> - * Returns 0 on success, and GNTST_* (see xen/include/interface/grant_table.h)
> - * or -ENOMEM on error. If an error is returned, device will switch to
> - * XenbusStateClosing and the error message will be saved in XenStore.
> - */
> -int xenbus_map_ring_valloc(struct xenbus_device *dev, int gnt_ref, void **vaddr)
> +static int xenbus_map_ring_valloc_pv(struct xenbus_device *dev,
> +                                     int gnt_ref, void **vaddr)
>  {
>  	struct gnttab_map_grant_ref op = {
>  		.flags = GNTMAP_host_map | GNTMAP_contains_pte,
> @@ -468,6 +466,64 @@ int xenbus_map_ring_valloc(struct xenbus_device *dev, int gnt_ref, void **vaddr)
>  	*vaddr = area->addr;
>  	return 0;
>  }
> +
> +static int xenbus_map_ring_valloc_hvm(struct xenbus_device *dev,
> +                                     int gnt_ref, void **vaddr)
> +{
> +	struct xenbus_map_node *node;
> +	int err;
> +	void *addr;
> +
> +	*vaddr = NULL;
> +
> +	node = kzalloc(sizeof(*node), GFP_KERNEL);
> +	if (!node)
> +		return -ENOMEM;
> +
> +	err = alloc_xenballooned_pages(1, &node->page, false);

Add  /* lowmem */ on the 'false' parameter.