1 /******************************************************************************
2 * include/asm-x86/mem_sharing.h
3 *
4 * Memory sharing support.
5 *
6 * Copyright (c) 2009 Citrix Systems, Inc. (Grzegorz Milos)
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; If not, see <http://www.gnu.org/licenses/>.
20 */
21 #ifndef __MEM_SHARING_H__
22 #define __MEM_SHARING_H__
23
24 #include <public/domctl.h>
25 #include <public/memory.h>
26
27 /* Auditing of memory sharing code? */
28 #define MEM_SHARING_AUDIT 1
29
30 typedef uint64_t shr_handle_t;
31
32 typedef struct rmap_hashtab {
33 struct list_head *bucket;
34 /* Overlaps with prev pointer of list_head in union below.
35 * Unlike the prev pointer, this can be NULL. */
36 void *flag;
37 } rmap_hashtab_t;
38
39 struct page_sharing_info
40 {
41 struct page_info *pg; /* Back pointer to the page. */
42 shr_handle_t handle; /* Globally unique version / handle. */
43 #if MEM_SHARING_AUDIT
44 struct list_head entry; /* List of all shared pages (entry). */
45 struct rcu_head rcu_head; /* List of all shared pages (entry). */
46 #endif
47 /* Reverse map of <domain,gfn> tuples for this shared frame. */
48 union {
49 struct list_head gfns;
50 rmap_hashtab_t hash_table;
51 };
52 };
53
54 #define sharing_supported(_d) \
55 (is_hvm_domain(_d) && paging_mode_hap(_d))
56
57 unsigned int mem_sharing_get_nr_saved_mfns(void);
58 unsigned int mem_sharing_get_nr_shared_mfns(void);
59
60 #define MEM_SHARING_DESTROY_GFN (1<<1)
61 /* Only fails with -ENOMEM. Enforce it with a BUG_ON wrapper. */
62 int __mem_sharing_unshare_page(struct domain *d,
63 unsigned long gfn,
64 uint16_t flags);
mem_sharing_unshare_page(struct domain * d,unsigned long gfn,uint16_t flags)65 static inline int mem_sharing_unshare_page(struct domain *d,
66 unsigned long gfn,
67 uint16_t flags)
68 {
69 int rc = __mem_sharing_unshare_page(d, gfn, flags);
70 BUG_ON( rc && (rc != -ENOMEM) );
71 return rc;
72 }
73
74 /* If called by a foreign domain, possible errors are
75 * -EBUSY -> ring full
76 * -ENOSYS -> no ring to begin with
77 * and the foreign mapper is responsible for retrying.
78 *
79 * If called by the guest vcpu itself and allow_sleep is set, may
80 * sleep on a wait queue, so the caller is responsible for not
81 * holding locks on entry. It may only fail with ENOSYS
82 *
83 * If called by the guest vcpu itself and allow_sleep is not set,
84 * then it's the same as a foreign domain.
85 */
86 int mem_sharing_notify_enomem(struct domain *d, unsigned long gfn,
87 bool_t allow_sleep);
88 int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg);
89 int mem_sharing_domctl(struct domain *d,
90 struct xen_domctl_mem_sharing_op *mec);
91 void mem_sharing_init(void);
92
93 /* Scans the p2m and relinquishes any shared pages, destroying
94 * those for which this domain holds the final reference.
95 * Preemptible.
96 */
97 int relinquish_shared_pages(struct domain *d);
98
99 #endif /* __MEM_SHARING_H__ */
100