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FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
| Current File : //sys/xen/gnttab.c |
/******************************************************************************
* gnttab.c
*
* 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) 2005, Christopher Clark
* Copyright (c) 2004, K A Fraser
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/sys/xen/gnttab.c 214077 2010-10-19 20:53:30Z gibbs $");
#include "opt_global.h"
#include "opt_pmap.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/module.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <machine/xen/xen-os.h>
#include <xen/hypervisor.h>
#include <machine/xen/synch_bitops.h>
#include <xen/hypervisor.h>
#include <xen/gnttab.h>
#include <vm/vm.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
#include <vm/pmap.h>
#define cmpxchg(a, b, c) atomic_cmpset_int((volatile u_int *)(a),(b),(c))
/* External tools reserve first few grant table entries. */
#define NR_RESERVED_ENTRIES 8
#define GREFS_PER_GRANT_FRAME (PAGE_SIZE / sizeof(grant_entry_t))
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 struct mtx gnttab_list_lock;
static grant_entry_t *shared;
static struct gnttab_free_callback *gnttab_free_callback_list = NULL;
static int gnttab_expand(unsigned int req_entries);
#define RPP (PAGE_SIZE / sizeof(grant_ref_t))
#define gnttab_entry(entry) (gnttab_list[(entry) / RPP][(entry) % RPP])
static int
get_free_entries(int count, int *entries)
{
int ref, error;
grant_ref_t head;
mtx_lock(&gnttab_list_lock);
if ((gnttab_free_count < count) &&
((error = gnttab_expand(count - gnttab_free_count)) != 0)) {
mtx_unlock(&gnttab_list_lock);
return (error);
}
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;
mtx_unlock(&gnttab_list_lock);
*entries = ref;
return (0);
}
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 != NULL))
do_free_callbacks();
}
static void
put_free_entry(grant_ref_t ref)
{
mtx_lock(&gnttab_list_lock);
gnttab_entry(ref) = gnttab_free_head;
gnttab_free_head = ref;
gnttab_free_count++;
check_free_callbacks();
mtx_unlock(&gnttab_list_lock);
}
/*
* Public grant-issuing interface functions
*/
int
gnttab_grant_foreign_access(domid_t domid, unsigned long frame, int readonly,
grant_ref_t *result)
{
int error, ref;
error = get_free_entries(1, &ref);
if (unlikely(error))
return (error);
shared[ref].frame = frame;
shared[ref].domid = domid;
wmb();
shared[ref].flags = GTF_permit_access | (readonly ? GTF_readonly : 0);
if (result)
*result = ref;
return (0);
}
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);
}
int
gnttab_query_foreign_access(grant_ref_t ref)
{
uint16_t nflags;
nflags = shared[ref].flags;
return (nflags & (GTF_reading|GTF_writing));
}
int
gnttab_end_foreign_access_ref(grant_ref_t ref)
{
uint16_t flags, nflags;
nflags = shared[ref].flags;
do {
if ( (flags = nflags) & (GTF_reading|GTF_writing) ) {
printf("%s: WARNING: g.e. still in use!\n", __func__);
return (0);
}
} while ((nflags = synch_cmpxchg(&shared[ref].flags, flags, 0)) !=
flags);
return (1);
}
void
gnttab_end_foreign_access(grant_ref_t ref, void *page)
{
if (gnttab_end_foreign_access_ref(ref)) {
put_free_entry(ref);
if (page != NULL) {
free(page, M_DEVBUF);
}
}
else {
/* XXX This needs to be fixed so that the ref and page are
placed on a list to be freed up later. */
printf("%s: WARNING: leaking g.e. and page still in use!\n",
__func__);
}
}
void
gnttab_end_foreign_access_references(u_int count, grant_ref_t *refs)
{
grant_ref_t *last_ref;
grant_ref_t head;
grant_ref_t tail;
head = GNTTAB_LIST_END;
tail = *refs;
last_ref = refs + count;
while (refs != last_ref) {
if (gnttab_end_foreign_access_ref(*refs)) {
gnttab_entry(*refs) = head;
head = *refs;
} else {
/*
* XXX This needs to be fixed so that the ref
* is placed on a list to be freed up later.
*/
printf("%s: WARNING: leaking g.e. still in use!\n",
__func__);
count--;
}
refs++;
}
if (count != 0) {
mtx_lock(&gnttab_list_lock);
gnttab_free_count += count;
gnttab_entry(tail) = gnttab_free_head;
gnttab_free_head = head;
mtx_unlock(&gnttab_list_lock);
}
}
int
gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn,
grant_ref_t *result)
{
int error, ref;
error = get_free_entries(1, &ref);
if (unlikely(error))
return (error);
gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
*result = ref;
return (0);
}
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;
}
unsigned long
gnttab_end_foreign_transfer_ref(grant_ref_t ref)
{
unsigned long frame;
uint16_t 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(&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;
KASSERT(frame != 0, ("grant table inconsistent"));
return (frame);
}
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);
}
void
gnttab_free_grant_reference(grant_ref_t ref)
{
put_free_entry(ref);
}
void
gnttab_free_grant_references(grant_ref_t head)
{
grant_ref_t ref;
int count = 1;
if (head == GNTTAB_LIST_END)
return;
ref = head;
while (gnttab_entry(ref) != GNTTAB_LIST_END) {
ref = gnttab_entry(ref);
count++;
}
mtx_lock(&gnttab_list_lock);
gnttab_entry(ref) = gnttab_free_head;
gnttab_free_head = head;
gnttab_free_count += count;
check_free_callbacks();
mtx_unlock(&gnttab_list_lock);
}
int
gnttab_alloc_grant_references(uint16_t count, grant_ref_t *head)
{
int ref, error;
error = get_free_entries(count, &ref);
if (unlikely(error))
return (error);
*head = ref;
return (0);
}
int
gnttab_empty_grant_references(const grant_ref_t *private_head)
{
return (*private_head == GNTTAB_LIST_END);
}
int
gnttab_claim_grant_reference(grant_ref_t *private_head)
{
grant_ref_t g = *private_head;
if (unlikely(g == GNTTAB_LIST_END))
return (g);
*private_head = gnttab_entry(g);
return (g);
}
void
gnttab_release_grant_reference(grant_ref_t *private_head, grant_ref_t release)
{
gnttab_entry(release) = *private_head;
*private_head = release;
}
void
gnttab_request_free_callback(struct gnttab_free_callback *callback,
void (*fn)(void *), void *arg, uint16_t count)
{
mtx_lock(&gnttab_list_lock);
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:
mtx_unlock(&gnttab_list_lock);
}
void
gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
{
struct gnttab_free_callback **pcb;
mtx_lock(&gnttab_list_lock);
for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
if (*pcb == callback) {
*pcb = callback->next;
break;
}
}
mtx_unlock(&gnttab_list_lock);
}
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 *)
malloc(PAGE_SIZE, M_DEVBUF, M_NOWAIT);
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(gnttab_list[i], M_DEVBUF);
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);
}
#ifdef notyet
/*
* XXX needed for backend support
*
*/
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
#ifndef XENHVM
static int
gnttab_map(unsigned int start_idx, unsigned int end_idx)
{
struct gnttab_setup_table setup;
u_long *frames;
unsigned int nr_gframes = end_idx + 1;
int i, rc;
frames = malloc(nr_gframes * sizeof(unsigned long), M_DEVBUF, M_NOWAIT);
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) {
free(frames, M_DEVBUF);
return (ENOSYS);
}
KASSERT(!(rc || setup.status),
("unexpected result from grant_table_op"));
if (shared == NULL) {
vm_offset_t area;
area = kmem_alloc_nofault(kernel_map,
PAGE_SIZE * max_nr_grant_frames());
KASSERT(area, ("can't allocate VM space for grant table"));
shared = (grant_entry_t *)area;
}
for (i = 0; i < nr_gframes; i++)
PT_SET_MA(((caddr_t)shared) + i*PAGE_SIZE,
((vm_paddr_t)frames[i]) << PAGE_SHIFT | PG_RW | PG_V);
free(frames, M_DEVBUF);
return (0);
}
int
gnttab_resume(void)
{
if (max_nr_grant_frames() < nr_grant_frames)
return (ENOSYS);
return (gnttab_map(0, nr_grant_frames - 1));
}
int
gnttab_suspend(void)
{
int i;
for (i = 0; i < nr_grant_frames; i++)
pmap_kremove((vm_offset_t) shared + i * PAGE_SIZE);
return (0);
}
#else /* XENHVM */
#include <dev/xen/xenpci/xenpcivar.h>
static vm_paddr_t resume_frames;
static int
gnttab_map(unsigned int start_idx, unsigned int end_idx)
{
struct xen_add_to_physmap xatp;
unsigned int i = end_idx;
/*
* 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 = (resume_frames >> PAGE_SHIFT) + i;
if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp))
panic("HYPERVISOR_memory_op failed to map gnttab");
} while (i-- > start_idx);
if (shared == NULL) {
vm_offset_t area;
area = kmem_alloc_nofault(kernel_map,
PAGE_SIZE * max_nr_grant_frames());
KASSERT(area, ("can't allocate VM space for grant table"));
shared = (grant_entry_t *)area;
}
for (i = start_idx; i <= end_idx; i++) {
pmap_kenter((vm_offset_t) shared + i * PAGE_SIZE,
resume_frames + i * PAGE_SIZE);
}
return (0);
}
int
gnttab_resume(void)
{
int error;
unsigned int max_nr_gframes, nr_gframes;
nr_gframes = nr_grant_frames;
max_nr_gframes = max_nr_grant_frames();
if (max_nr_gframes < nr_gframes)
return (ENOSYS);
if (!resume_frames) {
error = xenpci_alloc_space(PAGE_SIZE * max_nr_gframes,
&resume_frames);
if (error) {
printf("error mapping gnttab share frames\n");
return (error);
}
}
return (gnttab_map(0, nr_gframes - 1));
}
#endif
static int
gnttab_expand(unsigned int req_entries)
{
int error;
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);
error = gnttab_map(cur, cur + extra - 1);
if (!error)
error = grow_gnttab_list(extra);
return (error);
}
int
gnttab_init()
{
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 = malloc(max_nr_glist_frames * sizeof(grant_ref_t *),
M_DEVBUF, M_NOWAIT);
if (gnttab_list == NULL)
return (ENOMEM);
for (i = 0; i < nr_grant_frames; i++) {
gnttab_list[i] = (grant_ref_t *)
malloc(PAGE_SIZE, M_DEVBUF, M_NOWAIT);
if (gnttab_list[i] == NULL)
goto ini_nomem;
}
if (gnttab_resume())
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;
if (bootverbose)
printf("Grant table initialized\n");
return (0);
ini_nomem:
for (i--; i >= 0; i--)
free(gnttab_list[i], M_DEVBUF);
free(gnttab_list, M_DEVBUF);
return (ENOMEM);
}
MTX_SYSINIT(gnttab, &gnttab_list_lock, "GNTTAB LOCK", MTX_DEF);