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/******************************************************************************
* common/grant_table.c
*
* Mechanism for granting foreign access to page frames, and receiving
* page-ownership transfers.
*
* Copyright (c) 2004 K A Fraser
*
* 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
*/
#define __GRANT_TABLE_IMPLEMENTATION__
typedef struct grant_table grant_table_t;
#include <xen/config.h>
#include <xen/sched.h>
#include <hypervisor-ifs/grant_table.h>
/* Active grant entry - used for shadowing GTF_permit_access grants. */
typedef struct {
u32 counts; /* Reference count information. */
u16 next; /* Mapping hash chain. */
domid_t domid; /* Domain being granted access. */
unsigned long frame; /* Frame being granted. */
} active_grant_entry_t;
/* Bitfields in active_grant_entry_t:counts. */
/* Grant is pinned by 'domid' for read mappings and I/O. */
#define _GNTCNT_read_pinned (0)
#define GNTCNT_read_pinned (1<<_GNTCNT_read_pinned)
/* Grant is pinned by 'domid' for write mappings and I/O. */
#define _GNTCNT_write_pinned (1)
#define GNTCNT_write_pinned (1<<_GNTCNT_write_pinned)
/* Grant is pinned in IOMMU (read-only unless GNTCNT_write_pinned). */
#define _GNTCNT_io_pinned (2)
#define GNTCNT_io_pinned (1<<_GNTCNT_io_pinned)
/* Grant is mappable (read-only unless GNTCNT_write_pinned). */
#define _GNTCNT_mappable (3)
#define GNTCNT_mappable (1<<_GNTCNT_mappable)
/* Count of writable page mappings. (!GNTCNT_write_pinned => count==0). */
#define GNTCNT_wmap_shift (4)
#define GNTCNT_wmap_mask (0x3FFFU << GNTCNT_wmap_shift)
/* Count of read-only page mappings. */
#define GNTCNT_rmap_shift (18)
#define GNTCNT_rmap_mask (0x3FFFU << GNTCNT_rmap_shift)
#define MAPHASH_SZ (256)
#define MAPHASH(_k) ((_k) & (MAPHASH_SZ-1))
#define MAPHASH_INVALID (0xFFFFU)
#define NR_GRANT_ENTRIES (PAGE_SIZE / sizeof(grant_entry_t))
/* Per-domain grant information. */
struct grant_table {
/* Shared grant table (see include/hypervisor-ifs/grant_table.h). */
grant_entry_t *shared;
/* Active grant table. */
active_grant_entry_t *active;
/* Lock protecting updates to maphash and shared grant table. */
spinlock_t lock;
/* Hash table: frame -> active grant entry. */
u16 maphash[MAPHASH_SZ];
};
int grant_table_create(struct domain *d)
{
grant_table_t *t;
int i;
if ( (t = xmalloc(sizeof(grant_table_t))) == NULL )
goto no_mem;
/* Simple stuff. */
t->shared = NULL;
t->active = NULL;
spin_lock_init(&t->lock);
for ( i = 0; i < MAPHASH_SZ; i++ )
t->maphash[i] = MAPHASH_INVALID;
/* Active grant-table page. */
if ( (t->active = xmalloc(sizeof(active_grant_entry_t) *
NR_GRANT_ENTRIES)) == NULL )
goto no_mem;
/* Set up shared grant-table page. */
if ( (t->shared = (void *)alloc_xenheap_page()) == NULL )
goto no_mem;
memset(t->shared, 0, PAGE_SIZE);
SHARE_PFN_WITH_DOMAIN(virt_to_page(t->shared), d);
/* Okay, install the structure. */
d->grant_table = t;
return 0;
no_mem:
if ( t != NULL )
{
if ( t->active != NULL )
xfree(t->active);
xfree(t);
}
return -ENOMEM;
}
void grant_table_destroy(struct domain *d)
{
grant_table_t *t;
if ( (t = d->grant_table) != NULL )
{
/* Free memory relating to this grant table. */
d->grant_table = NULL;
free_xenheap_page((unsigned long)t->shared);
xfree(t->active);
xfree(t);
}
}
void grant_table_init(void)
{
/* Nothing. */
}
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