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Tamas K Lengyel
0002467f12
Disable it by default as it is only an experimental subsystem. Signed-off-by: Tamas K Lengyel <tamas@tklengyel.com> Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov> Acked-by: Razvan Cojocaru <rcojocaru@bitdefender.com> Acked-by: Jan Beulich <jbeulich@suse.com>
131 lines
4.1 KiB
C
131 lines
4.1 KiB
C
/******************************************************************************
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* include/asm-x86/mem_sharing.h
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*
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* Memory sharing support.
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*
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* Copyright (c) 2009 Citrix Systems, Inc. (Grzegorz Milos)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __MEM_SHARING_H__
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#define __MEM_SHARING_H__
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#include <public/domctl.h>
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#include <public/memory.h>
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#ifdef CONFIG_MEM_SHARING
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/* Auditing of memory sharing code? */
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#ifndef NDEBUG
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#define MEM_SHARING_AUDIT 1
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#else
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#define MEM_SHARING_AUDIT 0
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#endif
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typedef uint64_t shr_handle_t;
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typedef struct rmap_hashtab {
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struct list_head *bucket;
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/* Overlaps with prev pointer of list_head in union below.
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* Unlike the prev pointer, this can be NULL. */
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void *flag;
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} rmap_hashtab_t;
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struct page_sharing_info
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{
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struct page_info *pg; /* Back pointer to the page. */
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shr_handle_t handle; /* Globally unique version / handle. */
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#if MEM_SHARING_AUDIT
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struct list_head entry; /* List of all shared pages (entry). */
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struct rcu_head rcu_head; /* List of all shared pages (entry). */
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#endif
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/* Reverse map of <domain,gfn> tuples for this shared frame. */
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union {
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struct list_head gfns;
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rmap_hashtab_t hash_table;
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};
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};
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#define sharing_supported(_d) \
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(is_hvm_domain(_d) && paging_mode_hap(_d))
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unsigned int mem_sharing_get_nr_saved_mfns(void);
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unsigned int mem_sharing_get_nr_shared_mfns(void);
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#define MEM_SHARING_DESTROY_GFN (1<<1)
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/* Only fails with -ENOMEM. Enforce it with a BUG_ON wrapper. */
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int __mem_sharing_unshare_page(struct domain *d,
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unsigned long gfn,
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uint16_t flags);
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static inline int mem_sharing_unshare_page(struct domain *d,
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unsigned long gfn,
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uint16_t flags)
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{
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int rc = __mem_sharing_unshare_page(d, gfn, flags);
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BUG_ON( rc && (rc != -ENOMEM) );
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return rc;
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}
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/* If called by a foreign domain, possible errors are
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* -EBUSY -> ring full
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* -ENOSYS -> no ring to begin with
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* and the foreign mapper is responsible for retrying.
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*
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* If called by the guest vcpu itself and allow_sleep is set, may
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* sleep on a wait queue, so the caller is responsible for not
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* holding locks on entry. It may only fail with ENOSYS
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*
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* If called by the guest vcpu itself and allow_sleep is not set,
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* then it's the same as a foreign domain.
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*/
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int mem_sharing_notify_enomem(struct domain *d, unsigned long gfn,
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bool allow_sleep);
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int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg);
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int mem_sharing_domctl(struct domain *d,
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struct xen_domctl_mem_sharing_op *mec);
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/* Scans the p2m and relinquishes any shared pages, destroying
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* those for which this domain holds the final reference.
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* Preemptible.
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*/
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int relinquish_shared_pages(struct domain *d);
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#else
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static inline unsigned int mem_sharing_get_nr_saved_mfns(void)
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{
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return 0;
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}
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static inline unsigned int mem_sharing_get_nr_shared_mfns(void)
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{
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return 0;
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}
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static inline int mem_sharing_unshare_page(struct domain *d,
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unsigned long gfn,
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uint16_t flags)
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{
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ASSERT_UNREACHABLE();
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return -EOPNOTSUPP;
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}
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static inline int mem_sharing_notify_enomem(struct domain *d, unsigned long gfn,
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bool allow_sleep)
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{
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ASSERT_UNREACHABLE();
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return -EOPNOTSUPP;
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}
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#endif
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#endif /* __MEM_SHARING_H__ */
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