diff options
Diffstat (limited to 'xen/common/grant_table.c')
| -rw-r--r-- | xen/common/grant_table.c | 134 |
1 files changed, 134 insertions, 0 deletions
diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c new file mode 100644 index 0000000000..f1a73cb36a --- /dev/null +++ b/xen/common/grant_table.c @@ -0,0 +1,134 @@ +/****************************************************************************** + * 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. */ +} |