--- /dev/null
+/******************************************************************************
+ * gnttab.c
+ *
+ * Granting foreign access to our memory reservation.
+ *
+ * Copyright (c) 2005, Christopher Clark
+ * Copyright (c) 2004-2005, 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 version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <xen/interface/xen.h>
+#include <xen/gnttab.h>
+#include <asm/pgtable.h>
+#include <asm/uaccess.h>
+#include <asm/synch_bitops.h>
+
+/* External tools reserve first few grant table entries. */
+#define NR_RESERVED_ENTRIES 8
+
+#define NR_GRANT_ENTRIES \
+ (NR_GRANT_FRAMES * PAGE_SIZE / sizeof(struct grant_entry))
+#define GNTTAB_LIST_END (NR_GRANT_ENTRIES + 1)
+
+static grant_ref_t gnttab_list[NR_GRANT_ENTRIES];
+static int gnttab_free_count;
+static grant_ref_t gnttab_free_head;
+static DEFINE_SPINLOCK(gnttab_list_lock);
+
+static struct grant_entry *shared;
+
+static struct gnttab_free_callback *gnttab_free_callback_list;
+
+static int get_free_entries(int count)
+{
+ unsigned long flags;
+ int ref;
+ grant_ref_t head;
+ spin_lock_irqsave(&gnttab_list_lock, flags);
+ if (gnttab_free_count < count) {
+ spin_unlock_irqrestore(&gnttab_list_lock, flags);
+ return -1;
+ }
+ ref = head = gnttab_free_head;
+ gnttab_free_count -= count;
+ while (count-- > 1)
+ head = gnttab_list[head];
+ gnttab_free_head = gnttab_list[head];
+ gnttab_list[head] = GNTTAB_LIST_END;
+ spin_unlock_irqrestore(&gnttab_list_lock, flags);
+ return ref;
+}
+
+#define get_free_entry() get_free_entries(1)
+
+static void do_free_callbacks(void)
+{
+ struct gnttab_free_callback *callback, *next;
+
+ callback = gnttab_free_callback_list;
+ gnttab_free_callback_list = NULL;
+
+ while (callback != NULL) {
+ next = callback->next;
+ if (gnttab_free_count >= callback->count) {
+ callback->next = NULL;
+ callback->fn(callback->arg);
+ } else {
+ callback->next = gnttab_free_callback_list;
+ gnttab_free_callback_list = callback;
+ }
+ callback = next;
+ }
+}
+
+static inline void check_free_callbacks(void)
+{
+ if (unlikely(gnttab_free_callback_list))
+ do_free_callbacks();
+}
+
+static void put_free_entry(grant_ref_t ref)
+{
+ unsigned long flags;
+ spin_lock_irqsave(&gnttab_list_lock, flags);
+ gnttab_list[ref] = gnttab_free_head;
+ gnttab_free_head = ref;
+ gnttab_free_count++;
+ check_free_callbacks();
+ spin_unlock_irqrestore(&gnttab_list_lock, flags);
+}
+
+/*
+ * Public grant-issuing interface functions
+ */
+
+int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
+ int readonly)
+{
+ int ref;
+
+ if (unlikely((ref = get_free_entry()) == -1))
+ return -ENOSPC;
+
+ shared[ref].frame = frame;
+ shared[ref].domid = domid;
+ wmb();
+ shared[ref].flags = GTF_permit_access | (readonly ? GTF_readonly : 0);
+
+ return ref;
+}
+EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
+
+void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
+ unsigned long frame, int readonly)
+{
+ shared[ref].frame = frame;
+ shared[ref].domid = domid;
+ wmb();
+ shared[ref].flags = GTF_permit_access | (readonly ? GTF_readonly : 0);
+}
+EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);
+
+
+int gnttab_query_foreign_access(grant_ref_t ref)
+{
+ u16 nflags;
+
+ nflags = shared[ref].flags;
+
+ return (nflags & (GTF_reading|GTF_writing));
+}
+EXPORT_SYMBOL_GPL(gnttab_query_foreign_access);
+
+int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
+{
+ u16 flags, nflags;
+
+ nflags = shared[ref].flags;
+ do {
+ if ((flags = nflags) & (GTF_reading|GTF_writing)) {
+ printk(KERN_ALERT "WARNING: g.e. still in use!\n");
+ return 0;
+ }
+ } while ((nflags = synch_cmpxchg_subword(&shared[ref].flags, flags, 0)) !=
+ flags);
+
+ return 1;
+}
+EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
+
+void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
+ unsigned long page)
+{
+ if (gnttab_end_foreign_access_ref(ref, readonly)) {
+ put_free_entry(ref);
+ if (page != 0)
+ free_page(page);
+ } else {
+ /* XXX This needs to be fixed so that the ref and page are
+ placed on a list to be freed up later. */
+ printk(KERN_WARNING
+ "WARNING: leaking g.e. and page still in use!\n");
+ }
+}
+EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
+
+int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
+{
+ int ref;
+
+ if (unlikely((ref = get_free_entry()) == -1))
+ return -ENOSPC;
+ gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
+
+ return ref;
+}
+EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);
+
+void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
+ unsigned long pfn)
+{
+ shared[ref].frame = pfn;
+ shared[ref].domid = domid;
+ wmb();
+ shared[ref].flags = GTF_accept_transfer;
+}
+EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
+
+unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
+{
+ unsigned long frame;
+ u16 flags;
+
+ /*
+ * If a transfer is not even yet started, try to reclaim the grant
+ * reference and return failure (== 0).
+ */
+ while (!((flags = shared[ref].flags) & GTF_transfer_committed)) {
+ if (synch_cmpxchg_subword(&shared[ref].flags, 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 = shared[ref].flags;
+ cpu_relax();
+ }
+
+ /* Read the frame number /after/ reading completion status. */
+ rmb();
+ frame = shared[ref].frame;
+ BUG_ON(frame == 0);
+
+ return frame;
+}
+EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);
+
+unsigned long gnttab_end_foreign_transfer(grant_ref_t ref)
+{
+ unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
+ put_free_entry(ref);
+ return frame;
+}
+EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);
+
+void gnttab_free_grant_reference(grant_ref_t ref)
+{
+ put_free_entry(ref);
+}
+EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
+
+void gnttab_free_grant_references(grant_ref_t head)
+{
+ grant_ref_t ref;
+ unsigned long flags;
+ int count = 1;
+ if (head == GNTTAB_LIST_END)
+ return;
+ spin_lock_irqsave(&gnttab_list_lock, flags);
+ ref = head;
+ while (gnttab_list[ref] != GNTTAB_LIST_END) {
+ ref = gnttab_list[ref];
+ count++;
+ }
+ gnttab_list[ref] = gnttab_free_head;
+ gnttab_free_head = head;
+ gnttab_free_count += count;
+ check_free_callbacks();
+ spin_unlock_irqrestore(&gnttab_list_lock, flags);
+}
+EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
+
+int gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
+{
+ int h = get_free_entries(count);
+
+ if (h == -1)
+ return -ENOSPC;
+
+ *head = h;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
+
+int gnttab_empty_grant_references(const grant_ref_t *private_head)
+{
+ return (*private_head == GNTTAB_LIST_END);
+}
+EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
+
+int gnttab_claim_grant_reference(grant_ref_t *private_head)
+{
+ grant_ref_t g = *private_head;
+ if (unlikely(g == GNTTAB_LIST_END))
+ return -ENOSPC;
+ *private_head = gnttab_list[g];
+ return g;
+}
+EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
+
+void gnttab_release_grant_reference(grant_ref_t *private_head,
+ grant_ref_t release)
+{
+ gnttab_list[release] = *private_head;
+ *private_head = release;
+}
+EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
+
+void gnttab_request_free_callback(struct gnttab_free_callback *callback,
+ void (*fn)(void *), void *arg, u16 count)
+{
+ unsigned long flags;
+ spin_lock_irqsave(&gnttab_list_lock, flags);
+ if (callback->next)
+ goto out;
+ callback->fn = fn;
+ callback->arg = arg;
+ callback->count = count;
+ callback->next = gnttab_free_callback_list;
+ gnttab_free_callback_list = callback;
+ check_free_callbacks();
+out:
+ spin_unlock_irqrestore(&gnttab_list_lock, flags);
+}
+EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
+
+void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
+{
+ struct gnttab_free_callback **pcb;
+ unsigned long flags;
+
+ spin_lock_irqsave(&gnttab_list_lock, flags);
+ for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
+ if (*pcb == callback) {
+ *pcb = callback->next;
+ break;
+ }
+ }
+ spin_unlock_irqrestore(&gnttab_list_lock, flags);
+}
+EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
+
+#ifndef __ia64__
+static int map_pte_fn(pte_t *pte, struct page *pmd_page,
+ unsigned long addr, void *data)
+{
+ unsigned long **frames = (unsigned long **)data;
+
+ set_pte_at(&init_mm, addr, pte, pfn_pte_ma((*frames)[0], PAGE_KERNEL));
+ (*frames)++;
+ return 0;
+}
+
+static int unmap_pte_fn(pte_t *pte, struct page *pmd_page,
+ unsigned long addr, void *data)
+{
+
+ set_pte_at(&init_mm, addr, pte, __pte(0));
+ return 0;
+}
+#endif
+
+int gnttab_resume(void)
+{
+ struct gnttab_setup_table setup;
+ unsigned long frames[NR_GRANT_FRAMES];
+ int rc;
+#ifndef __ia64__
+ void *pframes = frames;
+ struct vm_struct *area;
+#endif
+
+ setup.dom = DOMID_SELF;
+ setup.nr_frames = NR_GRANT_FRAMES;
+ set_xen_guest_handle(setup.frame_list, frames);
+
+ rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
+ if (rc == -ENOSYS)
+ return -ENOSYS;
+
+ BUG_ON(rc || setup.status);
+
+#ifndef __ia64__
+ if (shared == NULL) {
+ area = get_vm_area(PAGE_SIZE * NR_GRANT_FRAMES, VM_IOREMAP);
+ BUG_ON(area == NULL);
+ shared = area->addr;
+ }
+ rc = apply_to_page_range(&init_mm, (unsigned long)shared,
+ PAGE_SIZE * NR_GRANT_FRAMES,
+ map_pte_fn, &pframes);
+ BUG_ON(rc);
+#else
+ shared = __va(frames[0] << PAGE_SHIFT);
+ printk("grant table at %p\n", shared);
+#endif
+
+ return 0;
+}
+
+int gnttab_suspend(void)
+{
+
+#ifndef __ia64__
+ apply_to_page_range(&init_mm, (unsigned long)shared,
+ PAGE_SIZE * NR_GRANT_FRAMES,
+ unmap_pte_fn, NULL);
+#endif
+
+ return 0;
+}
+
+static int __init gnttab_init(void)
+{
+ int i;
+
+ if (!is_running_on_xen())
+ return -ENODEV;
+
+ if (gnttab_resume() < 0)
+ return -ENODEV;
+
+ for (i = NR_RESERVED_ENTRIES; i < NR_GRANT_ENTRIES; i++)
+ gnttab_list[i] = i + 1;
+ gnttab_free_count = NR_GRANT_ENTRIES - NR_RESERVED_ENTRIES;
+ gnttab_free_head = NR_RESERVED_ENTRIES;
+
+ printk("Grant table initialized\n");
+ return 0;
+}
+
+core_initcall(gnttab_init);
git://git.onelab.eu / linux-2.6.git / blobdiff