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/******************************************************************************
* include/asm-x86/mem_sharing.h
*
* Memory sharing support.
*
* Copyright (c) 2009 Citrix Systems, Inc. (Grzegorz Milos)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef __MEM_SHARING_H__
#define __MEM_SHARING_H__
#include <public/domctl.h>
#include <public/memory.h>
/* Auditing of memory sharing code? */
#define MEM_SHARING_AUDIT 1
typedef uint64_t shr_handle_t;
typedef struct rmap_hashtab {
struct list_head *bucket;
/* Overlaps with prev pointer of list_head in union below.
* Unlike the prev pointer, this can be NULL. */
void *flag;
} rmap_hashtab_t;
struct page_sharing_info
{
struct page_info *pg; /* Back pointer to the page. */
shr_handle_t handle; /* Globally unique version / handle. */
#if MEM_SHARING_AUDIT
struct list_head entry; /* List of all shared pages (entry). */
struct rcu_head rcu_head; /* List of all shared pages (entry). */
#endif
/* Reverse map of <domain,gfn> tuples for this shared frame. */
union {
struct list_head gfns;
rmap_hashtab_t hash_table;
};
};
#define sharing_supported(_d) \
(is_hvm_domain(_d) && paging_mode_hap(_d))
unsigned int mem_sharing_get_nr_saved_mfns(void);
unsigned int mem_sharing_get_nr_shared_mfns(void);
int mem_sharing_nominate_page(struct domain *d,
unsigned long gfn,
int expected_refcnt,
shr_handle_t *phandle);
#define MEM_SHARING_DESTROY_GFN (1<<1)
/* Only fails with -ENOMEM. Enforce it with a BUG_ON wrapper. */
int __mem_sharing_unshare_page(struct domain *d,
unsigned long gfn,
uint16_t flags);
static inline int mem_sharing_unshare_page(struct domain *d,
unsigned long gfn,
uint16_t flags)
{
int rc = __mem_sharing_unshare_page(d, gfn, flags);
BUG_ON( rc && (rc != -ENOMEM) );
return rc;
}
/* If called by a foreign domain, possible errors are
* -EBUSY -> ring full
* -ENOSYS -> no ring to begin with
* and the foreign mapper is responsible for retrying.
*
* If called by the guest vcpu itself and allow_sleep is set, may
* sleep on a wait queue, so the caller is responsible for not
* holding locks on entry. It may only fail with ENOSYS
*
* If called by the guest vcpu itself and allow_sleep is not set,
* then it's the same as a foreign domain.
*/
int mem_sharing_notify_enomem(struct domain *d, unsigned long gfn,
bool_t allow_sleep);
int mem_sharing_sharing_resume(struct domain *d);
int mem_sharing_memop(struct domain *d,
xen_mem_sharing_op_t *mec);
int mem_sharing_domctl(struct domain *d,
xen_domctl_mem_sharing_op_t *mec);
int mem_sharing_audit(void);
void mem_sharing_init(void);
/* Scans the p2m and relinquishes any shared pages, destroying
* those for which this domain holds the final reference.
* Preemptible.
*/
int relinquish_shared_pages(struct domain *d);
#endif /* __MEM_SHARING_H__ */
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