xen: Add grant table support

obj-$(CONFIG_PNP)		+= pnp/

obj-$(CONFIG_ARM_AMBA)		+= amba/

obj-$(CONFIG_XEN)		+= xen/

# char/ comes before serial/ etc so that the VT console is the boot-time

# default.

obj-y				+= char/

obj-y	+= grant-table.o

/******************************************************************************

 * grant_table.c

 *

 * Granting foreign access to our memory reservation.

 *

 * Copyright (c) 2005-2006, 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/module.h>

#include <linux/sched.h>

#include <linux/mm.h>

#include <linux/vmalloc.h>

#include <linux/uaccess.h>

#include <xen/interface/xen.h>

#include <xen/page.h>

#include <xen/grant_table.h>

#include <asm/pgtable.h>

#include <asm/sync_bitops.h>

/* External tools reserve first few grant table entries. */

#define NR_RESERVED_ENTRIES 8

#define GNTTAB_LIST_END 0xffffffff

#define GREFS_PER_GRANT_FRAME (PAGE_SIZE / sizeof(struct grant_entry))

static grant_ref_t **gnttab_list;

static unsigned int nr_grant_frames;

static unsigned int boot_max_nr_grant_frames;

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 gnttab_expand(unsigned int req_entries);

#define RPP (PAGE_SIZE / sizeof(grant_ref_t))

static inline grant_ref_t *__gnttab_entry(grant_ref_t entry)

{

	return &gnttab_list[(entry) / RPP][(entry) % RPP];

}

/* This can be used as an l-value */

#define gnttab_entry(entry) (*__gnttab_entry(entry))

static int get_free_entries(unsigned count)

{

	unsigned long flags;

	int ref, rc;

	grant_ref_t head;

	spin_lock_irqsave(&gnttab_list_lock, flags);

	if ((gnttab_free_count < count) &&

	    ((rc = gnttab_expand(count - gnttab_free_count)) < 0)) {

		spin_unlock_irqrestore(&gnttab_list_lock, flags);

		return rc;

	}

	ref = head = gnttab_free_head;

	gnttab_free_count -= count;

	while (count-- > 1)

		head = gnttab_entry(head);

	gnttab_free_head = gnttab_entry(head);

	gnttab_entry(head) = GNTTAB_LIST_END;

	spin_unlock_irqrestore(&gnttab_list_lock, flags);

	return ref;

}

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_entry(ref) = gnttab_free_head;

	gnttab_free_head = ref;

	gnttab_free_count++;

	check_free_callbacks();

	spin_unlock_irqrestore(&gnttab_list_lock, flags);

}

static void update_grant_entry(grant_ref_t ref, domid_t domid,

			       unsigned long frame, unsigned flags)

{

	/*

	 * Introducing a valid entry into the grant table:

	 *  1. Write ent->domid.

	 *  2. Write ent->frame:

	 *      GTF_permit_access:   Frame to which access is permitted.

	 *      GTF_accept_transfer: Pseudo-phys frame slot being filled by new

	 *                           frame, or zero if none.

	 *  3. Write memory barrier (WMB).

	 *  4. Write ent->flags, inc. valid type.

	 */

	shared[ref].frame = frame;

	shared[ref].domid = domid;

	wmb();

	shared[ref].flags = flags;

}

/*

 * Public grant-issuing interface functions

 */

void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,

				     unsigned long frame, int readonly)

{

	update_grant_entry(ref, domid, frame,

			   GTF_permit_access | (readonly ? GTF_readonly : 0));

}

EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);

int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,

				int readonly)

{

	int ref;

	ref = get_free_entries(1);

	if (unlikely(ref < 0))

		return -ENOSPC;

	gnttab_grant_foreign_access_ref(ref, domid, frame, readonly);

	return ref;

}

EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);

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 {

		flags = nflags;

		if (flags & (GTF_reading|GTF_writing)) {

			printk(KERN_ALERT "WARNING: g.e. still in use!\n");

			return 0;

		}

	} while ((nflags = sync_cmpxchg(&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;

	ref = get_free_entries(1);

	if (unlikely(ref < 0))

		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)

{

	update_grant_entry(ref, domid, pfn, 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 (sync_cmpxchg(&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();

	}

	rmb();	/* Read the frame number /after/ reading completion status. */

	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_entry(ref) != GNTTAB_LIST_END) {

		ref = gnttab_entry(ref);

		count++;

	}

	gnttab_entry(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 < 0)

		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_entry(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_entry(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);

static int grow_gnttab_list(unsigned int more_frames)

{

	unsigned int new_nr_grant_frames, extra_entries, i;

	new_nr_grant_frames = nr_grant_frames + more_frames;

	extra_entries       = more_frames * GREFS_PER_GRANT_FRAME;

	for (i = nr_grant_frames; i < new_nr_grant_frames; i++) {

		gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC);

		if (!gnttab_list[i])

			goto grow_nomem;

	}

	for (i = GREFS_PER_GRANT_FRAME * nr_grant_frames;

	     i < GREFS_PER_GRANT_FRAME * new_nr_grant_frames - 1; i++)

		gnttab_entry(i) = i + 1;

	gnttab_entry(i) = gnttab_free_head;

	gnttab_free_head = GREFS_PER_GRANT_FRAME * nr_grant_frames;

	gnttab_free_count += extra_entries;

	nr_grant_frames = new_nr_grant_frames;

	check_free_callbacks();

	return 0;

grow_nomem:

	for ( ; i >= nr_grant_frames; i--)

		free_page((unsigned long) gnttab_list[i]);

	return -ENOMEM;

}

static unsigned int __max_nr_grant_frames(void)

{

	struct gnttab_query_size query;

	int rc;

	query.dom = DOMID_SELF;

	rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1);

	if ((rc < 0) || (query.status != GNTST_okay))

		return 4; /* Legacy max supported number of frames */

	return query.max_nr_frames;

}

static inline unsigned int max_nr_grant_frames(void)

{

	unsigned int xen_max = __max_nr_grant_frames();

	if (xen_max > boot_max_nr_grant_frames)

		return boot_max_nr_grant_frames;

	return xen_max;

}

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, mfn_pte((*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;

}

static int gnttab_map(unsigned int start_idx, unsigned int end_idx)

{

	struct gnttab_setup_table setup;

	unsigned long *frames;

	unsigned int nr_gframes = end_idx + 1;

	int rc;

	frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);

	if (!frames)

		return -ENOMEM;

	setup.dom        = DOMID_SELF;

	setup.nr_frames  = nr_gframes;

	setup.frame_list = frames;

	rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);

	if (rc == -ENOSYS) {

		kfree(frames);

		return -ENOSYS;

	}

	BUG_ON(rc || setup.status);

	if (shared == NULL) {

		struct vm_struct *area;

		area = alloc_vm_area(PAGE_SIZE * max_nr_grant_frames());

		BUG_ON(area == NULL);

		shared = area->addr;

	}

	rc = apply_to_page_range(&init_mm, (unsigned long)shared,

				 PAGE_SIZE * nr_gframes,

				 map_pte_fn, &frames);

	BUG_ON(rc);

	frames -= nr_gframes; /* adjust after map_pte_fn() */

	kfree(frames);

	return 0;

}

static int gnttab_resume(void)

{

	if (max_nr_grant_frames() < nr_grant_frames)

		return -ENOSYS;

	return gnttab_map(0, nr_grant_frames - 1);

}

static int gnttab_suspend(void)

{

	apply_to_page_range(&init_mm, (unsigned long)shared,

			    PAGE_SIZE * nr_grant_frames,

			    unmap_pte_fn, NULL);

	return 0;

}

static int gnttab_expand(unsigned int req_entries)

{

	int rc;

	unsigned int cur, extra;

	cur = nr_grant_frames;

	extra = ((req_entries + (GREFS_PER_GRANT_FRAME-1)) /

		 GREFS_PER_GRANT_FRAME);

	if (cur + extra > max_nr_grant_frames())

		return -ENOSPC;

	rc = gnttab_map(cur, cur + extra - 1);

	if (rc == 0)

		rc = grow_gnttab_list(extra);

	return rc;

}

static int __devinit gnttab_init(void)

{

	int i;

	unsigned int max_nr_glist_frames;

	unsigned int nr_init_grefs;

	if (!is_running_on_xen())

		return -ENODEV;

	nr_grant_frames = 1;

	boot_max_nr_grant_frames = __max_nr_grant_frames();

	/* Determine the maximum number of frames required for the

	 * grant reference free list on the current hypervisor.

	 */

	max_nr_glist_frames = (boot_max_nr_grant_frames *

			       GREFS_PER_GRANT_FRAME /

			       (PAGE_SIZE / sizeof(grant_ref_t)));

	gnttab_list = kmalloc(max_nr_glist_frames * sizeof(grant_ref_t *),

			      GFP_KERNEL);

	if (gnttab_list == NULL)

		return -ENOMEM;

	for (i = 0; i < nr_grant_frames; i++) {

		gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL);

		if (gnttab_list[i] == NULL)

			goto ini_nomem;

	}

	if (gnttab_resume() < 0)

		return -ENODEV;

	nr_init_grefs = nr_grant_frames * GREFS_PER_GRANT_FRAME;

	for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++)

		gnttab_entry(i) = i + 1;

	gnttab_entry(nr_init_grefs - 1) = GNTTAB_LIST_END;

	gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES;

	gnttab_free_head  = NR_RESERVED_ENTRIES;

	printk("Grant table initialized\n");

	return 0;

 ini_nomem:

	for (i--; i >= 0; i--)

		free_page((unsigned long)gnttab_list[i]);

	kfree(gnttab_list);

	return -ENOMEM;

}

core_initcall(gnttab_init);

/******************************************************************************

 * grant_table.h

 *

 * Two sets of functionality:

 * 1. Granting foreign access to our memory reservation.

 * 2. Accessing others' memory reservations via grant references.

 * (i.e., mechanisms for both sender and recipient of grant references)

 *

 * Copyright (c) 2004-2005, K A Fraser

 * Copyright (c) 2005, Christopher Clark

 *

 * 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.

 */

#ifndef __ASM_GNTTAB_H__

#define __ASM_GNTTAB_H__

#include <asm/xen/hypervisor.h>

#include <xen/interface/grant_table.h>

/* NR_GRANT_FRAMES must be less than or equal to that configured in Xen */

#define NR_GRANT_FRAMES 4

struct gnttab_free_callback {

	struct gnttab_free_callback *next;

	void (*fn)(void *);

	void *arg;

	u16 count;

};

int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,

				int readonly);

/*

 * End access through the given grant reference, iff the grant entry is no

 * longer in use.  Return 1 if the grant entry was freed, 0 if it is still in

 * use.

 */

int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly);

/*

 * Eventually end access through the given grant reference, and once that

 * access has been ended, free the given page too.  Access will be ended

 * immediately iff the grant entry is not in use, otherwise it will happen

 * some time later.  page may be 0, in which case no freeing will occur.

 */

void gnttab_end_foreign_access(grant_ref_t ref, int readonly,

			       unsigned long page);

int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn);

unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref);

unsigned long gnttab_end_foreign_transfer(grant_ref_t ref);

int gnttab_query_foreign_access(grant_ref_t ref);

/*

 * operations on reserved batches of grant references

 */

int gnttab_alloc_grant_references(u16 count, grant_ref_t *pprivate_head);

void gnttab_free_grant_reference(grant_ref_t ref);

void gnttab_free_grant_references(grant_ref_t head);

int gnttab_empty_grant_references(const grant_ref_t *pprivate_head);

int gnttab_claim_grant_reference(grant_ref_t *pprivate_head);

void gnttab_release_grant_reference(grant_ref_t *private_head,

				    grant_ref_t release);

void gnttab_request_free_callback(struct gnttab_free_callback *callback,

				  void (*fn)(void *), void *arg, u16 count);

void gnttab_cancel_free_callback(struct gnttab_free_callback *callback);

void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,

				     unsigned long frame, int readonly);

void gnttab_grant_foreign_transfer_ref(grant_ref_t, domid_t domid,

				       unsigned long pfn);

#define gnttab_map_vaddr(map) ((void *)(map.host_virt_addr))

#endif /* __ASM_GNTTAB_H__ */