diff options
Diffstat (limited to 'drivers/xen')
| -rw-r--r-- | drivers/xen/grant-table.c | 312 |
1 files changed, 306 insertions, 6 deletions
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c index 2c6a9114d332..65c4bdb0b463 100644 --- a/drivers/xen/grant-table.c +++ b/drivers/xen/grant-table.c @@ -71,6 +71,7 @@ struct grant_frames xen_auto_xlat_grant_frames; static union { struct grant_entry_v1 *v1; + union grant_entry_v2 *v2; void *addr; } gnttab_shared; @@ -121,6 +122,29 @@ struct gnttab_ops { * by bit operations. */ int (*query_foreign_access)(grant_ref_t ref); + /* + * Grant a domain to access a range of bytes within the page referred by + * an available grant entry. Ref parameter is reference of a grant entry + * which will be sub-page accessed, domid is id of grantee domain, frame + * is frame address of subpage grant, flags is grant type and flag + * information, page_off is offset of the range of bytes, and length is + * length of bytes to be accessed. + */ + void (*update_subpage_entry)(grant_ref_t ref, domid_t domid, + unsigned long frame, int flags, + unsigned page_off, unsigned length); + /* + * Redirect an available grant entry on domain A to another grant + * reference of domain B, then allow domain C to use grant reference + * of domain B transitively. Ref parameter is an available grant entry + * reference on domain A, domid is id of domain C which accesses grant + * entry transitively, flags is grant type and flag information, + * trans_domid is id of domain B whose grant entry is finally accessed + * transitively, trans_gref is grant entry transitive reference of + * domain B. + */ + void (*update_trans_entry)(grant_ref_t ref, domid_t domid, int flags, + domid_t trans_domid, grant_ref_t trans_gref); }; struct unmap_refs_callback_data { @@ -130,6 +154,9 @@ struct unmap_refs_callback_data { static const struct gnttab_ops *gnttab_interface; +/* This reflects status of grant entries, so act as a global value. */ +static grant_status_t *grstatus; + static int grant_table_version; static int grefs_per_grant_frame; @@ -138,6 +165,7 @@ static struct gnttab_free_callback *gnttab_free_callback_list; static int gnttab_expand(unsigned int req_entries); #define RPP (PAGE_SIZE / sizeof(grant_ref_t)) +#define SPP (PAGE_SIZE / sizeof(grant_status_t)) static inline grant_ref_t *__gnttab_entry(grant_ref_t entry) { @@ -210,7 +238,7 @@ static void put_free_entry(grant_ref_t ref) } /* - * Following applies to gnttab_update_entry_v1. + * Following applies to gnttab_update_entry_v1 and gnttab_update_entry_v2. * Introducing a valid entry into the grant table: * 1. Write ent->domid. * 2. Write ent->frame: @@ -229,6 +257,15 @@ static void gnttab_update_entry_v1(grant_ref_t ref, domid_t domid, gnttab_shared.v1[ref].flags = flags; } +static void gnttab_update_entry_v2(grant_ref_t ref, domid_t domid, + unsigned long frame, unsigned int flags) +{ + gnttab_shared.v2[ref].hdr.domid = domid; + gnttab_shared.v2[ref].full_page.frame = frame; + wmb(); /* Hypervisor concurrent accesses. */ + gnttab_shared.v2[ref].hdr.flags = GTF_permit_access | flags; +} + /* * Public grant-issuing interface functions */ @@ -255,11 +292,132 @@ int gnttab_grant_foreign_access(domid_t domid, unsigned long frame, } EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access); +static void gnttab_update_subpage_entry_v2(grant_ref_t ref, domid_t domid, + unsigned long frame, int flags, + unsigned page_off, unsigned length) +{ + gnttab_shared.v2[ref].sub_page.frame = frame; + gnttab_shared.v2[ref].sub_page.page_off = page_off; + gnttab_shared.v2[ref].sub_page.length = length; + gnttab_shared.v2[ref].hdr.domid = domid; + wmb(); + gnttab_shared.v2[ref].hdr.flags = + GTF_permit_access | GTF_sub_page | flags; +} + +int gnttab_grant_foreign_access_subpage_ref(grant_ref_t ref, domid_t domid, + unsigned long frame, int flags, + unsigned page_off, + unsigned length) +{ + if (flags & (GTF_accept_transfer | GTF_reading | + GTF_writing | GTF_transitive)) + return -EPERM; + + if (gnttab_interface->update_subpage_entry == NULL) + return -ENOSYS; + + gnttab_interface->update_subpage_entry(ref, domid, frame, flags, + page_off, length); + + return 0; +} +EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_subpage_ref); + +int gnttab_grant_foreign_access_subpage(domid_t domid, unsigned long frame, + int flags, unsigned page_off, + unsigned length) +{ + int ref, rc; + + ref = get_free_entries(1); + if (unlikely(ref < 0)) + return -ENOSPC; + + rc = gnttab_grant_foreign_access_subpage_ref(ref, domid, frame, flags, + page_off, length); + if (rc < 0) { + put_free_entry(ref); + return rc; + } + + return ref; +} +EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_subpage); + +bool gnttab_subpage_grants_available(void) +{ + return gnttab_interface->update_subpage_entry != NULL; +} +EXPORT_SYMBOL_GPL(gnttab_subpage_grants_available); + +static void gnttab_update_trans_entry_v2(grant_ref_t ref, domid_t domid, + int flags, domid_t trans_domid, + grant_ref_t trans_gref) +{ + gnttab_shared.v2[ref].transitive.trans_domid = trans_domid; + gnttab_shared.v2[ref].transitive.gref = trans_gref; + gnttab_shared.v2[ref].hdr.domid = domid; + wmb(); + gnttab_shared.v2[ref].hdr.flags = + GTF_permit_access | GTF_transitive | flags; +} + +int gnttab_grant_foreign_access_trans_ref(grant_ref_t ref, domid_t domid, + int flags, domid_t trans_domid, + grant_ref_t trans_gref) +{ + if (flags & (GTF_accept_transfer | GTF_reading | + GTF_writing | GTF_sub_page)) + return -EPERM; + + if (gnttab_interface->update_trans_entry == NULL) + return -ENOSYS; + + gnttab_interface->update_trans_entry(ref, domid, flags, trans_domid, + trans_gref); + + return 0; +} +EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_trans_ref); + +int gnttab_grant_foreign_access_trans(domid_t domid, int flags, + domid_t trans_domid, + grant_ref_t trans_gref) +{ + int ref, rc; + + ref = get_free_entries(1); + if (unlikely(ref < 0)) + return -ENOSPC; + + rc = gnttab_grant_foreign_access_trans_ref(ref, domid, flags, + trans_domid, trans_gref); + if (rc < 0) { + put_free_entry(ref); + return rc; + } + + return ref; +} +EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_trans); + +bool gnttab_trans_grants_available(void) +{ + return gnttab_interface->update_trans_entry != NULL; +} +EXPORT_SYMBOL_GPL(gnttab_trans_grants_available); + static int gnttab_query_foreign_access_v1(grant_ref_t ref) { return gnttab_shared.v1[ref].flags & (GTF_reading|GTF_writing); } +static int gnttab_query_foreign_access_v2(grant_ref_t ref) +{ + return grstatus[ref] & (GTF_reading|GTF_writing); +} + int gnttab_query_foreign_access(grant_ref_t ref) { return gnttab_interface->query_foreign_access(ref); @@ -282,6 +440,29 @@ static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly) return 1; } +static int gnttab_end_foreign_access_ref_v2(grant_ref_t ref, int readonly) +{ + gnttab_shared.v2[ref].hdr.flags = 0; + mb(); /* Concurrent access by hypervisor. */ + if (grstatus[ref] & (GTF_reading|GTF_writing)) { + return 0; + } else { + /* + * The read of grstatus needs to have acquire semantics. + * On x86, reads already have that, and we just need to + * protect against compiler reorderings. + * On other architectures we may need a full barrier. + */ +#ifdef CONFIG_X86 + barrier(); +#else + mb(); +#endif + } + + return 1; +} + static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly) { return gnttab_interface->end_foreign_access_ref(ref, readonly); @@ -442,6 +623,37 @@ static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref) return frame; } +static unsigned long gnttab_end_foreign_transfer_ref_v2(grant_ref_t ref) +{ + unsigned long frame; + u16 flags; + u16 *pflags; + + pflags = &gnttab_shared.v2[ref].hdr.flags; + + /* + * If a transfer is not even yet started, try to reclaim the grant + * reference and return failure (== 0). + */ + while (!((flags = *pflags) & GTF_transfer_committed)) { + if (sync_cmpxchg(pflags, flags, 0) == flags) + return 0; + cpu_relax(); + } + + /* If a transfer is in progress then wait until it is completed. */ + while (!(flags & GTF_transfer_completed)) { + flags = *pflags; + cpu_relax(); + } + + rmb(); /* Read the frame number /after/ reading completion status. */ + frame = gnttab_shared.v2[ref].full_page.frame; + BUG_ON(frame == 0); + + return frame; +} + unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref) { return gnttab_interface->end_foreign_transfer_ref(ref); @@ -938,6 +1150,12 @@ int gnttab_unmap_refs_sync(struct gntab_unmap_queue_data *item) } EXPORT_SYMBOL_GPL(gnttab_unmap_refs_sync); +static unsigned int nr_status_frames(unsigned int nr_grant_frames) +{ + BUG_ON(grefs_per_grant_frame == 0); + return (nr_grant_frames * grefs_per_grant_frame + SPP - 1) / SPP; +} + static int gnttab_map_frames_v1(xen_pfn_t *frames, unsigned int nr_gframes) { int rc; @@ -955,6 +1173,55 @@ static void gnttab_unmap_frames_v1(void) arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames); } +static int gnttab_map_frames_v2(xen_pfn_t *frames, unsigned int nr_gframes) +{ + uint64_t *sframes; + unsigned int nr_sframes; + struct gnttab_get_status_frames getframes; + int rc; + + nr_sframes = nr_status_frames(nr_gframes); + + /* No need for kzalloc as it is initialized in following hypercall + * GNTTABOP_get_status_frames. + */ + sframes = kmalloc_array(nr_sframes, sizeof(uint64_t), GFP_ATOMIC); + if (!sframes) + return -ENOMEM; + + getframes.dom = DOMID_SELF; + getframes.nr_frames = nr_sframes; + set_xen_guest_handle(getframes.frame_list, sframes); + + rc = HYPERVISOR_grant_table_op(GNTTABOP_get_status_frames, + &getframes, 1); + if (rc == -ENOSYS) { + kfree(sframes); + return -ENOSYS; + } + + BUG_ON(rc || getframes.status); + + rc = arch_gnttab_map_status(sframes, nr_sframes, + nr_status_frames(gnttab_max_grant_frames()), + &grstatus); + BUG_ON(rc); + kfree(sframes); + + rc = arch_gnttab_map_shared(frames, nr_gframes, + gnttab_max_grant_frames(), + &gnttab_shared.addr); + BUG_ON(rc); + + return 0; +} + +static void gnttab_unmap_frames_v2(void) +{ + arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames); + arch_gnttab_unmap(grstatus, nr_status_frames(nr_grant_frames)); +} + static int gnttab_map(unsigned int start_idx, unsigned int end_idx) { struct gnttab_setup_table setup; @@ -1022,13 +1289,45 @@ static const struct gnttab_ops gnttab_v1_ops = { .query_foreign_access = gnttab_query_foreign_access_v1, }; +static const struct gnttab_ops gnttab_v2_ops = { + .map_frames = gnttab_map_frames_v2, + .unmap_frames = gnttab_unmap_frames_v2, + .update_entry = gnttab_update_entry_v2, + .end_foreign_access_ref = gnttab_end_foreign_access_ref_v2, + .end_foreign_transfer_ref = gnttab_end_foreign_transfer_ref_v2, + .query_foreign_access = gnttab_query_foreign_access_v2, + .update_subpage_entry = gnttab_update_subpage_entry_v2, + .update_trans_entry = gnttab_update_trans_entry_v2, +}; + static void gnttab_request_version(void) { - /* Only version 1 is used, which will always be available. */ - grant_table_version = 1; - grefs_per_grant_frame = XEN_PAGE_SIZE / sizeof(struct grant_entry_v1); - gnttab_interface = &gnttab_v1_ops; + int rc; + struct gnttab_set_version gsv; + gsv.version = 1; + + rc = HYPERVISOR_grant_table_op(GNTTABOP_set_version, &gsv, 1); + if (rc == 0 && gsv.version == 2) { + grant_table_version = 2; + grefs_per_grant_frame = XEN_PAGE_SIZE / + sizeof(union grant_entry_v2); + gnttab_interface = &gnttab_v2_ops; + } else if (grant_table_version == 2) { + /* + * If we've already used version 2 features, + * but then suddenly discover that they're not + * available (e.g. migrating to an older + * version of Xen), almost unbounded badness + * can happen. + */ + panic("we need grant tables version 2, but only version 1 is available"); + } else { + grant_table_version = 1; + grefs_per_grant_frame = XEN_PAGE_SIZE / + sizeof(struct grant_entry_v1); + gnttab_interface = &gnttab_v1_ops; + } pr_info("Grant tables using version %d layout\n", grant_table_version); } @@ -1122,7 +1421,8 @@ int gnttab_init(void) } } - ret = arch_gnttab_init(max_nr_grant_frames); + ret = arch_gnttab_init(max_nr_grant_frames, + nr_status_frames(max_nr_grant_frames)); if (ret < 0) goto ini_nomem; |