static union {
struct grant_entry_v1 *v1;
+ union grant_entry_v2 *v2;
void *addr;
} gnttab_shared;
* 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 {
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;
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)
{
}
/*
- * 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:
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
*/
}
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);
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);
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);
}
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;
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;
.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);
}
}
}
- 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;
projects / users / willy / pagecache.git / commitdiff