linux/drivers/xen/grant-table.c
Andres Lagar-Cavilla c571898ffc xen/gndev: Xen backend support for paged out grant targets V4.
Since Xen-4.2, hvm domains may have portions of their memory paged out. When a
foreign domain (such as dom0) attempts to map these frames, the map will
initially fail. The hypervisor returns a suitable errno, and kicks an
asynchronous page-in operation carried out by a helper. The foreign domain is
expected to retry the mapping operation until it eventually succeeds. The
foreign domain is not put to sleep because itself could be the one running the
pager assist (typical scenario for dom0).

This patch adds support for this mechanism for backend drivers using grant
mapping and copying operations. Specifically, this covers the blkback and
gntdev drivers (which map foreign grants), and the netback driver (which copies
foreign grants).

* Add a retry method for grants that fail with GNTST_eagain (i.e. because the
  target foreign frame is paged out).
* Insert hooks with appropriate wrappers in the aforementioned drivers.

The retry loop is only invoked if the grant operation status is GNTST_eagain.
It guarantees to leave a new status code different from GNTST_eagain. Any other
status code results in identical code execution as before.

The retry loop performs 256 attempts with increasing time intervals through a
32 second period. It uses msleep to yield while waiting for the next retry.

V2 after feedback from David Vrabel:
* Explicit MAX_DELAY instead of wrap-around delay into zero
* Abstract GNTST_eagain check into core grant table code for netback module.

V3 after feedback from Ian Campbell:
* Add placeholder in array of grant table error descriptions for unrelated
  error code we jump over.
* Eliminate single map and retry macro in favor of a generic batch flavor.
* Some renaming.
* Bury most implementation in grant_table.c, cleaner interface.

V4 rebased on top of sync of Xen grant table interface headers.

Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
[v5: Fixed whitespace issues]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-09-21 09:23:51 -04:00

1253 lines
33 KiB
C

/******************************************************************************
* 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/slab.h>
#include <linux/vmalloc.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/hardirq.h>
#include <xen/xen.h>
#include <xen/interface/xen.h>
#include <xen/page.h>
#include <xen/grant_table.h>
#include <xen/interface/memory.h>
#include <xen/hvc-console.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/interface.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 \
(grant_table_version == 1 ? \
(PAGE_SIZE / sizeof(struct grant_entry_v1)) : \
(PAGE_SIZE / sizeof(union grant_entry_v2)))
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);
unsigned long xen_hvm_resume_frames;
EXPORT_SYMBOL_GPL(xen_hvm_resume_frames);
static union {
struct grant_entry_v1 *v1;
union grant_entry_v2 *v2;
void *addr;
} gnttab_shared;
/*This is a structure of function pointers for grant table*/
struct gnttab_ops {
/*
* Mapping a list of frames for storing grant entries. Frames parameter
* is used to store grant table address when grant table being setup,
* nr_gframes is the number of frames to map grant table. Returning
* GNTST_okay means success and negative value means failure.
*/
int (*map_frames)(unsigned long *frames, unsigned int nr_gframes);
/*
* Release a list of frames which are mapped in map_frames for grant
* entry status.
*/
void (*unmap_frames)(void);
/*
* Introducing a valid entry into the grant table, granting the frame of
* this grant entry to domain for accessing or transfering. Ref
* parameter is reference of this introduced grant entry, domid is id of
* granted domain, frame is the page frame to be granted, and flags is
* status of the grant entry to be updated.
*/
void (*update_entry)(grant_ref_t ref, domid_t domid,
unsigned long frame, unsigned flags);
/*
* Stop granting a grant entry to domain for accessing. Ref parameter is
* reference of a grant entry whose grant access will be stopped,
* readonly is not in use in this function. If the grant entry is
* currently mapped for reading or writing, just return failure(==0)
* directly and don't tear down the grant access. Otherwise, stop grant
* access for this entry and return success(==1).
*/
int (*end_foreign_access_ref)(grant_ref_t ref, int readonly);
/*
* Stop granting a grant entry to domain for transfer. Ref parameter is
* reference of a grant entry whose grant transfer will be stopped. If
* tranfer has not started, just reclaim the grant entry and return
* failure(==0). Otherwise, wait for the transfer to complete and then
* return the frame.
*/
unsigned long (*end_foreign_transfer_ref)(grant_ref_t ref);
/*
* Query the status of a grant entry. Ref parameter is reference of
* queried grant entry, return value is the status of queried entry.
* Detailed status(writing/reading) can be gotten from the return value
* 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);
};
static 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 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)
{
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 = 0;
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);
}
/*
* 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:
* 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.
*/
static void gnttab_update_entry_v1(grant_ref_t ref, domid_t domid,
unsigned long frame, unsigned flags)
{
gnttab_shared.v1[ref].domid = domid;
gnttab_shared.v1[ref].frame = frame;
wmb();
gnttab_shared.v1[ref].flags = flags;
}
static void gnttab_update_entry_v2(grant_ref_t ref, domid_t domid,
unsigned long frame, unsigned flags)
{
gnttab_shared.v2[ref].hdr.domid = domid;
gnttab_shared.v2[ref].full_page.frame = frame;
wmb();
gnttab_shared.v2[ref].hdr.flags = GTF_permit_access | flags;
}
/*
* Public grant-issuing interface functions
*/
void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
unsigned long frame, int readonly)
{
gnttab_interface->update_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);
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);
}
EXPORT_SYMBOL_GPL(gnttab_query_foreign_access);
static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly)
{
u16 flags, nflags;
u16 *pflags;
pflags = &gnttab_shared.v1[ref].flags;
nflags = *pflags;
do {
flags = nflags;
if (flags & (GTF_reading|GTF_writing))
return 0;
} while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags);
return 1;
}
static int gnttab_end_foreign_access_ref_v2(grant_ref_t ref, int readonly)
{
gnttab_shared.v2[ref].hdr.flags = 0;
mb();
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);
}
int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
{
if (_gnttab_end_foreign_access_ref(ref, readonly))
return 1;
pr_warn("WARNING: g.e. %#x still in use!\n", ref);
return 0;
}
EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
struct deferred_entry {
struct list_head list;
grant_ref_t ref;
bool ro;
uint16_t warn_delay;
struct page *page;
};
static LIST_HEAD(deferred_list);
static void gnttab_handle_deferred(unsigned long);
static DEFINE_TIMER(deferred_timer, gnttab_handle_deferred, 0, 0);
static void gnttab_handle_deferred(unsigned long unused)
{
unsigned int nr = 10;
struct deferred_entry *first = NULL;
unsigned long flags;
spin_lock_irqsave(&gnttab_list_lock, flags);
while (nr--) {
struct deferred_entry *entry
= list_first_entry(&deferred_list,
struct deferred_entry, list);
if (entry == first)
break;
list_del(&entry->list);
spin_unlock_irqrestore(&gnttab_list_lock, flags);
if (_gnttab_end_foreign_access_ref(entry->ref, entry->ro)) {
put_free_entry(entry->ref);
if (entry->page) {
pr_debug("freeing g.e. %#x (pfn %#lx)\n",
entry->ref, page_to_pfn(entry->page));
__free_page(entry->page);
} else
pr_info("freeing g.e. %#x\n", entry->ref);
kfree(entry);
entry = NULL;
} else {
if (!--entry->warn_delay)
pr_info("g.e. %#x still pending\n",
entry->ref);
if (!first)
first = entry;
}
spin_lock_irqsave(&gnttab_list_lock, flags);
if (entry)
list_add_tail(&entry->list, &deferred_list);
else if (list_empty(&deferred_list))
break;
}
if (!list_empty(&deferred_list) && !timer_pending(&deferred_timer)) {
deferred_timer.expires = jiffies + HZ;
add_timer(&deferred_timer);
}
spin_unlock_irqrestore(&gnttab_list_lock, flags);
}
static void gnttab_add_deferred(grant_ref_t ref, bool readonly,
struct page *page)
{
struct deferred_entry *entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
const char *what = KERN_WARNING "leaking";
if (entry) {
unsigned long flags;
entry->ref = ref;
entry->ro = readonly;
entry->page = page;
entry->warn_delay = 60;
spin_lock_irqsave(&gnttab_list_lock, flags);
list_add_tail(&entry->list, &deferred_list);
if (!timer_pending(&deferred_timer)) {
deferred_timer.expires = jiffies + HZ;
add_timer(&deferred_timer);
}
spin_unlock_irqrestore(&gnttab_list_lock, flags);
what = KERN_DEBUG "deferring";
}
printk("%s g.e. %#x (pfn %#lx)\n",
what, ref, page ? page_to_pfn(page) : -1);
}
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
gnttab_add_deferred(ref, readonly,
page ? virt_to_page(page) : NULL);
}
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)
{
gnttab_interface->update_entry(ref, domid, pfn, GTF_accept_transfer);
}
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref)
{
unsigned long frame;
u16 flags;
u16 *pflags;
pflags = &gnttab_shared.v1[ref].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.v1[ref].frame;
BUG_ON(frame == 0);
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_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;
unsigned int nr_glist_frames, new_nr_glist_frames;
new_nr_grant_frames = nr_grant_frames + more_frames;
extra_entries = more_frames * GREFS_PER_GRANT_FRAME;
nr_glist_frames = (nr_grant_frames * GREFS_PER_GRANT_FRAME + RPP - 1) / RPP;
new_nr_glist_frames =
(new_nr_grant_frames * GREFS_PER_GRANT_FRAME + RPP - 1) / RPP;
for (i = nr_glist_frames; i < new_nr_glist_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_glist_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;
}
unsigned int gnttab_max_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;
}
EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
/* Handling of paged out grant targets (GNTST_eagain) */
#define MAX_DELAY 256
static inline void
gnttab_retry_eagain_gop(unsigned int cmd, void *gop, int16_t *status,
const char *func)
{
unsigned delay = 1;
do {
BUG_ON(HYPERVISOR_grant_table_op(cmd, gop, 1));
if (*status == GNTST_eagain)
msleep(delay++);
} while ((*status == GNTST_eagain) && (delay < MAX_DELAY));
if (delay >= MAX_DELAY) {
printk(KERN_ERR "%s: %s eagain grant\n", func, current->comm);
*status = GNTST_bad_page;
}
}
void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count)
{
struct gnttab_map_grant_ref *op;
if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, batch, count))
BUG();
for (op = batch; op < batch + count; op++)
if (op->status == GNTST_eagain)
gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, op,
&op->status, __func__);
}
EXPORT_SYMBOL_GPL(gnttab_batch_map);
void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count)
{
struct gnttab_copy *op;
if (HYPERVISOR_grant_table_op(GNTTABOP_copy, batch, count))
BUG();
for (op = batch; op < batch + count; op++)
if (op->status == GNTST_eagain)
gnttab_retry_eagain_gop(GNTTABOP_copy, op,
&op->status, __func__);
}
EXPORT_SYMBOL_GPL(gnttab_batch_copy);
int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
struct gnttab_map_grant_ref *kmap_ops,
struct page **pages, unsigned int count)
{
int i, ret;
bool lazy = false;
pte_t *pte;
unsigned long mfn;
ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
if (ret)
return ret;
/* Retry eagain maps */
for (i = 0; i < count; i++)
if (map_ops[i].status == GNTST_eagain)
gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
&map_ops[i].status, __func__);
if (xen_feature(XENFEAT_auto_translated_physmap))
return ret;
if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
arch_enter_lazy_mmu_mode();
lazy = true;
}
for (i = 0; i < count; i++) {
/* Do not add to override if the map failed. */
if (map_ops[i].status)
continue;
if (map_ops[i].flags & GNTMAP_contains_pte) {
pte = (pte_t *) (mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
(map_ops[i].host_addr & ~PAGE_MASK));
mfn = pte_mfn(*pte);
} else {
mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
}
ret = m2p_add_override(mfn, pages[i], kmap_ops ?
&kmap_ops[i] : NULL);
if (ret)
return ret;
}
if (lazy)
arch_leave_lazy_mmu_mode();
return ret;
}
EXPORT_SYMBOL_GPL(gnttab_map_refs);
int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
struct page **pages, unsigned int count, bool clear_pte)
{
int i, ret;
bool lazy = false;
ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
if (ret)
return ret;
if (xen_feature(XENFEAT_auto_translated_physmap))
return ret;
if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
arch_enter_lazy_mmu_mode();
lazy = true;
}
for (i = 0; i < count; i++) {
ret = m2p_remove_override(pages[i], clear_pte);
if (ret)
return ret;
}
if (lazy)
arch_leave_lazy_mmu_mode();
return ret;
}
EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
static unsigned nr_status_frames(unsigned nr_grant_frames)
{
return (nr_grant_frames * GREFS_PER_GRANT_FRAME + SPP - 1) / SPP;
}
static int gnttab_map_frames_v1(unsigned long *frames, unsigned int nr_gframes)
{
int rc;
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_v1(void)
{
arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
}
static int gnttab_map_frames_v2(unsigned long *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(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;
unsigned long *frames;
unsigned int nr_gframes = end_idx + 1;
int rc;
if (xen_hvm_domain()) {
struct xen_add_to_physmap xatp;
unsigned int i = end_idx;
rc = 0;
/*
* Loop backwards, so that the first hypercall has the largest
* index, ensuring that the table will grow only once.
*/
do {
xatp.domid = DOMID_SELF;
xatp.idx = i;
xatp.space = XENMAPSPACE_grant_table;
xatp.gpfn = (xen_hvm_resume_frames >> PAGE_SHIFT) + i;
rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
if (rc != 0) {
printk(KERN_WARNING
"grant table add_to_physmap failed, err=%d\n", rc);
break;
}
} while (i-- > start_idx);
return rc;
}
/* No need for kzalloc as it is initialized in following hypercall
* GNTTABOP_setup_table.
*/
frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
if (!frames)
return -ENOMEM;
setup.dom = DOMID_SELF;
setup.nr_frames = nr_gframes;
set_xen_guest_handle(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);
rc = gnttab_interface->map_frames(frames, nr_gframes);
kfree(frames);
return rc;
}
static struct gnttab_ops gnttab_v1_ops = {
.map_frames = gnttab_map_frames_v1,
.unmap_frames = gnttab_unmap_frames_v1,
.update_entry = gnttab_update_entry_v1,
.end_foreign_access_ref = gnttab_end_foreign_access_ref_v1,
.end_foreign_transfer_ref = gnttab_end_foreign_transfer_ref_v1,
.query_foreign_access = gnttab_query_foreign_access_v1,
};
static 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)
{
int rc;
struct gnttab_set_version gsv;
if (xen_hvm_domain())
gsv.version = 1;
else
gsv.version = 2;
rc = HYPERVISOR_grant_table_op(GNTTABOP_set_version, &gsv, 1);
if (rc == 0 && gsv.version == 2) {
grant_table_version = 2;
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;
gnttab_interface = &gnttab_v1_ops;
}
printk(KERN_INFO "Grant tables using version %d layout.\n",
grant_table_version);
}
int gnttab_resume(void)
{
unsigned int max_nr_gframes;
gnttab_request_version();
max_nr_gframes = gnttab_max_grant_frames();
if (max_nr_gframes < nr_grant_frames)
return -ENOSYS;
if (xen_pv_domain())
return gnttab_map(0, nr_grant_frames - 1);
if (gnttab_shared.addr == NULL) {
gnttab_shared.addr = ioremap(xen_hvm_resume_frames,
PAGE_SIZE * max_nr_gframes);
if (gnttab_shared.addr == NULL) {
printk(KERN_WARNING
"Failed to ioremap gnttab share frames!");
return -ENOMEM;
}
}
gnttab_map(0, nr_grant_frames - 1);
return 0;
}
int gnttab_suspend(void)
{
gnttab_interface->unmap_frames();
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 > gnttab_max_grant_frames())
return -ENOSPC;
rc = gnttab_map(cur, cur + extra - 1);
if (rc == 0)
rc = grow_gnttab_list(extra);
return rc;
}
int gnttab_init(void)
{
int i;
unsigned int max_nr_glist_frames, nr_glist_frames;
unsigned int nr_init_grefs;
int ret;
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 / RPP);
gnttab_list = kmalloc(max_nr_glist_frames * sizeof(grant_ref_t *),
GFP_KERNEL);
if (gnttab_list == NULL)
return -ENOMEM;
nr_glist_frames = (nr_grant_frames * GREFS_PER_GRANT_FRAME + RPP - 1) / RPP;
for (i = 0; i < nr_glist_frames; i++) {
gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL);
if (gnttab_list[i] == NULL) {
ret = -ENOMEM;
goto ini_nomem;
}
}
if (gnttab_resume() < 0) {
ret = -ENODEV;
goto ini_nomem;
}
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 ret;
}
EXPORT_SYMBOL_GPL(gnttab_init);
static int __devinit __gnttab_init(void)
{
/* Delay grant-table initialization in the PV on HVM case */
if (xen_hvm_domain())
return 0;
if (!xen_pv_domain())
return -ENODEV;
return gnttab_init();
}
core_initcall(__gnttab_init);