cl349@4693: /******************************************************************************
cl349@4693:  * gnttab.c
cl349@4693:  * 
cl349@4693:  * Two sets of functionality:
cl349@4693:  * 1. Granting foreign access to our memory reservation.
cl349@4693:  * 2. Accessing others' memory reservations via grant references.
cl349@4693:  * (i.e., mechanisms for both sender and recipient of grant references)
cl349@4693:  * 
cl349@4693:  * Copyright (c) 2005, Christopher Clark
cl349@4693:  * Copyright (c) 2004, K A Fraser
cl349@4693:  */
cl349@4693: 
cl349@4693: #include <linux/config.h>
cl349@4693: #include <linux/module.h>
cl349@4693: #include <linux/sched.h>
cl349@4693: #include <asm/pgtable.h>
cl349@4693: #include <asm/fixmap.h>
cl349@4693: #include <asm/uaccess.h>
cl349@4693: #include <asm-xen/xen_proc.h>
cl349@4693: #include <asm-xen/linux-public/privcmd.h>
cl349@4693: #include <asm-xen/gnttab.h>
kaf24@6760: #include <asm/synch_bitops.h>
cl349@4693: 
cl349@4693: #if 1
cl349@4693: #define ASSERT(_p) \
cl349@4693:     if ( !(_p) ) { printk(KERN_ALERT"Assertion '%s': line %d, file %s\n", \
cl349@4693:     #_p , __LINE__, __FILE__); *(int*)0=0; }
cl349@4693: #else
cl349@4693: #define ASSERT(_p) ((void)0)
cl349@4693: #endif
cl349@4693: 
cl349@4693: #define WPRINTK(fmt, args...) \
cl349@4693:     printk(KERN_WARNING "xen_grant: " fmt, ##args)
cl349@4693: 
cl349@4693: 
cl349@4693: EXPORT_SYMBOL(gnttab_grant_foreign_access);
kaf24@6396: EXPORT_SYMBOL(gnttab_end_foreign_access_ref);
cl349@4693: EXPORT_SYMBOL(gnttab_end_foreign_access);
cl349@4693: EXPORT_SYMBOL(gnttab_query_foreign_access);
cl349@4693: EXPORT_SYMBOL(gnttab_grant_foreign_transfer);
kaf24@6396: EXPORT_SYMBOL(gnttab_end_foreign_transfer_ref);
cl349@4693: EXPORT_SYMBOL(gnttab_end_foreign_transfer);
cl349@4693: EXPORT_SYMBOL(gnttab_alloc_grant_references);
cl349@4693: EXPORT_SYMBOL(gnttab_free_grant_references);
cl349@6347: EXPORT_SYMBOL(gnttab_free_grant_reference);
cl349@4693: EXPORT_SYMBOL(gnttab_claim_grant_reference);
cl349@4693: EXPORT_SYMBOL(gnttab_release_grant_reference);
cl349@4693: EXPORT_SYMBOL(gnttab_grant_foreign_access_ref);
cl349@4693: EXPORT_SYMBOL(gnttab_grant_foreign_transfer_ref);
cl349@4693: 
cl349@6349: #define NR_GRANT_ENTRIES (NR_GRANT_FRAMES * PAGE_SIZE / sizeof(grant_entry_t))
cl349@6349: #define GNTTAB_LIST_END (NR_GRANT_ENTRIES + 1)
cl349@6349: 
cl349@6349: static grant_ref_t gnttab_list[NR_GRANT_ENTRIES];
cl349@6349: static int gnttab_free_count = NR_GRANT_ENTRIES;
cl349@4693: static grant_ref_t gnttab_free_head;
cl349@6349: static spinlock_t gnttab_list_lock = SPIN_LOCK_UNLOCKED;
cl349@4693: 
cl349@4693: static grant_entry_t *shared;
cl349@4693: 
cl349@6339: static struct gnttab_free_callback *gnttab_free_callback_list = NULL;
cl349@4693: 
cl349@6349: static int
cl349@6349: get_free_entries(int count)
cl349@4693: {
cl349@6349:     unsigned long flags;
cl349@6349:     int ref;
cl349@6349:     grant_ref_t head;
cl349@6349:     spin_lock_irqsave(&gnttab_list_lock, flags);
cl349@6349:     if (gnttab_free_count < count) {
cl349@6349: 	spin_unlock_irqrestore(&gnttab_list_lock, flags);
cl349@6349: 	return -1;
cl349@6349:     }
cl349@6349:     ref = head = gnttab_free_head;
cl349@6349:     gnttab_free_count -= count;
cl349@6349:     while (count-- > 1)
cl349@6349: 	head = gnttab_list[head];
cl349@6349:     gnttab_free_head = gnttab_list[head];
cl349@6349:     gnttab_list[head] = GNTTAB_LIST_END;
cl349@6349:     spin_unlock_irqrestore(&gnttab_list_lock, flags);
cl349@6349:     return ref;
cl349@4693: }
cl349@4693: 
cl349@6349: #define get_free_entry() get_free_entries(1)
cl349@6349: 
cl349@6349: static void
cl349@6349: do_free_callbacks(void)
cl349@6339: {
cl349@6346:     struct gnttab_free_callback *callback = gnttab_free_callback_list, *next;
cl349@6339:     gnttab_free_callback_list = NULL;
cl349@6339:     while (callback) {
cl349@6342: 	next = callback->next;
cl349@6349: 	if (gnttab_free_count >= callback->count) {
cl349@6349: 	    callback->next = NULL;
cl349@6349: 	    callback->fn(callback->arg);
cl349@6349: 	} else {
cl349@6349: 	    callback->next = gnttab_free_callback_list;
cl349@6349: 	    gnttab_free_callback_list = callback;
cl349@6349: 	}
cl349@6342: 	callback = next;
cl349@6339:     }
cl349@4693: }
cl349@4693: 
cl349@4693: static inline void
cl349@6349: check_free_callbacks(void)
cl349@4693: {
cl349@6349:     if (unlikely(gnttab_free_callback_list))
cl349@6349: 	do_free_callbacks();
cl349@6349: }
cl349@6349: 
cl349@6349: static void
cl349@6349: put_free_entry(grant_ref_t ref)
cl349@6349: {
cl349@6346:     unsigned long flags;
cl349@6349:     spin_lock_irqsave(&gnttab_list_lock, flags);
cl349@6349:     gnttab_list[ref] = gnttab_free_head;
cl349@6349:     gnttab_free_head = ref;
cl349@6349:     gnttab_free_count++;
cl349@6349:     check_free_callbacks();
cl349@6349:     spin_unlock_irqrestore(&gnttab_list_lock, flags);
cl349@4693: }
cl349@4693: 
cl349@4693: /*
cl349@4693:  * Public grant-issuing interface functions
cl349@4693:  */
cl349@4693: 
cl349@4693: int
cl349@6349: gnttab_grant_foreign_access(domid_t domid, unsigned long frame, int readonly)
cl349@4693: {
cl349@4693:     int ref;
cl349@4693:     
cl349@4693:     if ( unlikely((ref = get_free_entry()) == -1) )
cl349@4693:         return -ENOSPC;
cl349@4693: 
cl349@4693:     shared[ref].frame = frame;
cl349@4693:     shared[ref].domid = domid;
cl349@4693:     wmb();
cl349@4693:     shared[ref].flags = GTF_permit_access | (readonly ? GTF_readonly : 0);
cl349@4693: 
cl349@4693:     return ref;
cl349@4693: }
cl349@4693: 
cl349@4693: void
cl349@6349: gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
cl349@6349: 				unsigned long frame, int readonly)
cl349@4693: {
cl349@4693:     shared[ref].frame = frame;
cl349@4693:     shared[ref].domid = domid;
cl349@4693:     wmb();
cl349@4693:     shared[ref].flags = GTF_permit_access | (readonly ? GTF_readonly : 0);
cl349@4693: }
cl349@4693: 
cl349@4693: 
cl349@4693: int
cl349@6349: gnttab_query_foreign_access(grant_ref_t ref)
cl349@4693: {
cl349@4693:     u16 nflags;
cl349@4693: 
cl349@4693:     nflags = shared[ref].flags;
cl349@4693: 
cl349@4693:     return ( nflags & (GTF_reading|GTF_writing) );
cl349@4693: }
cl349@4693: 
cl349@4693: void
kaf24@6396: gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
cl349@4693: {
cl349@4693:     u16 flags, nflags;
cl349@4693: 
cl349@4693:     nflags = shared[ref].flags;
cl349@4693:     do {
cl349@4693:         if ( (flags = nflags) & (GTF_reading|GTF_writing) )
cl349@4693:             printk(KERN_ALERT "WARNING: g.e. still in use!\n");
cl349@4693:     }
sos22@5391:     while ( (nflags = synch_cmpxchg(&shared[ref].flags, flags, 0)) != flags );
kaf24@6396: }
cl349@4693: 
kaf24@6396: void
kaf24@6396: gnttab_end_foreign_access(grant_ref_t ref, int readonly)
kaf24@6396: {
kaf24@6396:     gnttab_end_foreign_access_ref(ref, readonly);
cl349@4693:     put_free_entry(ref);
cl349@4693: }
cl349@4693: 
cl349@4693: int
cl349@6349: gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
cl349@4693: {
cl349@4693:     int ref;
cl349@4693: 
cl349@4693:     if ( unlikely((ref = get_free_entry()) == -1) )
cl349@4693:         return -ENOSPC;
cl349@4693: 
cl349@4693:     shared[ref].frame = pfn;
cl349@4693:     shared[ref].domid = domid;
cl349@4693:     wmb();
cl349@4693:     shared[ref].flags = GTF_accept_transfer;
cl349@4693: 
cl349@4693:     return ref;
cl349@4693: }
cl349@4693: 
cl349@4693: void
cl349@6349: gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
cl349@6349: 				  unsigned long pfn)
cl349@4693: {
cl349@4693:     shared[ref].frame = pfn;
cl349@4693:     shared[ref].domid = domid;
cl349@4693:     wmb();
cl349@4693:     shared[ref].flags = GTF_accept_transfer;
cl349@4693: }
cl349@4693: 
cl349@4693: unsigned long
kaf24@6396: gnttab_end_foreign_transfer_ref(grant_ref_t ref)
cl349@4693: {
cl349@4693:     unsigned long frame = 0;
cl349@4693:     u16           flags;
cl349@4693: 
cl349@4693:     flags = shared[ref].flags;
kaf24@6396: 
cl349@4693:     /*
cl349@4693:      * If a transfer is committed then wait for the frame address to appear.
cl349@4693:      * Otherwise invalidate the grant entry against future use.
cl349@4693:      */
cl349@4693:     if ( likely(flags != GTF_accept_transfer) ||
sos22@5391:          (synch_cmpxchg(&shared[ref].flags, flags, 0) != GTF_accept_transfer) )
cl349@4693:         while ( unlikely((frame = shared[ref].frame) == 0) )
cl349@4693:             cpu_relax();
cl349@4693: 
kaf24@6396:     return frame;
kaf24@6396: }
kaf24@6396: 
kaf24@6396: unsigned long
kaf24@6396: gnttab_end_foreign_transfer(grant_ref_t ref)
kaf24@6396: {
kaf24@6396:     unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
cl349@4693:     put_free_entry(ref);
cl349@4693:     return frame;
cl349@4693: }
cl349@4693: 
cl349@4693: void
cl349@6349: gnttab_free_grant_reference(grant_ref_t ref)
cl349@4693: {
cl349@6339: 
cl349@6339:     put_free_entry(ref);
cl349@6339: }
cl349@4693: 
cl349@6339: void
cl349@6349: gnttab_free_grant_references(grant_ref_t head)
cl349@4693: {
cl349@6339:     grant_ref_t ref;
cl349@6349:     unsigned long flags;
cl349@6349:     int count = 1;
cl349@6349:     if (head == GNTTAB_LIST_END)
cl349@6349: 	return;
cl349@6349:     spin_lock_irqsave(&gnttab_list_lock, flags);
cl349@6349:     ref = head;
cl349@6349:     while (gnttab_list[ref] != GNTTAB_LIST_END) {
cl349@6349: 	ref = gnttab_list[ref];
cl349@6349: 	count++;
vh249@5272:     }
cl349@6349:     gnttab_list[ref] = gnttab_free_head;
cl349@6349:     gnttab_free_head = head;
cl349@6349:     gnttab_free_count += count;
cl349@6349:     check_free_callbacks();
cl349@6349:     spin_unlock_irqrestore(&gnttab_list_lock, flags);
cl349@4693: }
cl349@4693: 
cl349@4693: int
cl349@6349: gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
cl349@4693: {
cl349@6349:     int h = get_free_entries(count);
cl349@4693: 
cl349@6349:     if (h == -1)
cl349@6349: 	return -ENOSPC;
cl349@4693: 
cl349@4693:     *head = h;
cl349@4693: 
cl349@4693:     return 0;
cl349@4693: }
cl349@4693: 
cl349@4693: int
cl349@6349: gnttab_claim_grant_reference(grant_ref_t *private_head)
cl349@4693: {
cl349@6349:     grant_ref_t g = *private_head;
cl349@6349:     if (unlikely(g == GNTTAB_LIST_END))
cl349@4693:         return -ENOSPC;
cl349@6349:     *private_head = gnttab_list[g];
cl349@4693:     return g;
cl349@4693: }
cl349@4693: 
cl349@4693: void
cl349@6349: gnttab_release_grant_reference(grant_ref_t *private_head, grant_ref_t  release)
cl349@4693: {
cl349@6349:     gnttab_list[release] = *private_head;
cl349@4693:     *private_head = release;
cl349@4693: }
cl349@4693: 
cl349@6339: void
cl349@6339: gnttab_request_free_callback(struct gnttab_free_callback *callback,
cl349@6349: 			     void (*fn)(void *), void *arg, u16 count)
cl349@4693: {
cl349@6346:     unsigned long flags;
cl349@6349:     spin_lock_irqsave(&gnttab_list_lock, flags);
cl349@6342:     if (callback->next)
cl349@6349: 	goto out;
cl349@6342:     callback->fn = fn;
cl349@6342:     callback->arg = arg;
cl349@6349:     callback->count = count;
cl349@6339:     callback->next = gnttab_free_callback_list;
cl349@6339:     gnttab_free_callback_list = callback;
cl349@6349:     check_free_callbacks();
cl349@6349:  out:
cl349@6349:     spin_unlock_irqrestore(&gnttab_list_lock, flags);
cl349@4693: }
cl349@4693: 
cl349@4693: /*
cl349@4693:  * ProcFS operations
cl349@4693:  */
cl349@4693: 
cl349@4693: #ifdef CONFIG_PROC_FS
cl349@4693: 
cl349@4693: static struct proc_dir_entry *grant_pde;
cl349@4693: 
cl349@6349: static int
cl349@6349: grant_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
cl349@6349: 	    unsigned long data)
cl349@4693: {
cl349@4693:     int                     ret;
cl349@4693:     privcmd_hypercall_t     hypercall;
cl349@4693: 
cl349@4693:     /* XXX Need safety checks here if using for anything other
cl349@4693:      *     than debugging */
cl349@4693:     return -ENOSYS;
cl349@4693: 
cl349@4693:     if ( cmd != IOCTL_PRIVCMD_HYPERCALL )
cl349@4693:         return -ENOSYS;
cl349@4693: 
cl349@4693:     if ( copy_from_user(&hypercall, (void *)data, sizeof(hypercall)) )
cl349@4693:         return -EFAULT;
cl349@4693: 
cl349@4693:     if ( hypercall.op != __HYPERVISOR_grant_table_op )
cl349@4693:         return -ENOSYS;
cl349@4693: 
cl349@4693:     /* hypercall-invoking asm taken from privcmd.c */
cl349@4693:     __asm__ __volatile__ (
cl349@4693:         "pushl %%ebx; pushl %%ecx; pushl %%edx; pushl %%esi; pushl %%edi; "
cl349@4693:         "movl  4(%%eax),%%ebx ;"
cl349@4693:         "movl  8(%%eax),%%ecx ;"
cl349@4693:         "movl 12(%%eax),%%edx ;"
cl349@4693:         "movl 16(%%eax),%%esi ;"
cl349@4693:         "movl 20(%%eax),%%edi ;"
cl349@4693:         "movl   (%%eax),%%eax ;"
cl349@4693:         TRAP_INSTR "; "
cl349@4693:         "popl %%edi; popl %%esi; popl %%edx; popl %%ecx; popl %%ebx"
cl349@4693:         : "=a" (ret) : "0" (&hypercall) : "memory" );
cl349@4693: 
cl349@4693:     return ret;
cl349@4693: }
cl349@4693: 
cl349@4693: static struct file_operations grant_file_ops = {
cl349@4693:     ioctl:  grant_ioctl,
cl349@4693: };
cl349@4693: 
cl349@6349: static int
cl349@6349: grant_read(char *page, char **start, off_t off, int count, int *eof,
cl349@6349: 	   void *data)
cl349@4693: {
cl349@4693:     int             len;
cl349@4693:     unsigned int    i;
cl349@4693:     grant_entry_t  *gt;
cl349@4693: 
cl349@4693:     gt = (grant_entry_t *)shared;
cl349@4693:     len = 0;
cl349@4693: 
cl349@4693:     for ( i = 0; i < NR_GRANT_ENTRIES; i++ )
cl349@4693:         /* TODO: safety catch here until this can handle >PAGE_SIZE output */
cl349@4693:         if (len > (PAGE_SIZE - 200))
cl349@4693:         {
cl349@4693:             len += sprintf( page + len, "Truncated.\n");
cl349@4693:             break;
cl349@4693:         }
cl349@4693: 
cl349@4693:         if ( gt[i].flags )
cl349@4693:             len += sprintf( page + len,
cl349@4693:                     "Grant: ref (0x%x) flags (0x%hx) dom (0x%hx) frame (0x%x)\n", 
cl349@4693:                     i,
cl349@4693:                     gt[i].flags,
cl349@4693:                     gt[i].domid,
cl349@4693:                     gt[i].frame );
cl349@4693: 
cl349@4693:     *eof = 1;
cl349@4693:     return len;
cl349@4693: }
cl349@4693: 
cl349@6349: static int
cl349@6349: grant_write(struct file *file, const char __user *buffer, unsigned long count,
cl349@6349: 	    void *data)
cl349@4693: {
cl349@4693:     /* TODO: implement this */
cl349@4693:     return -ENOSYS;
cl349@4693: }
cl349@4693: 
cl349@4693: #endif /* CONFIG_PROC_FS */
cl349@4693: 
cl349@6349: int
cl349@6349: gnttab_resume(void)
cl349@4693: {
cl349@4693:     gnttab_setup_table_t setup;
cl349@4693:     unsigned long        frames[NR_GRANT_FRAMES];
cl349@4693:     int                  i;
cl349@4693: 
cl349@4693:     setup.dom        = DOMID_SELF;
cl349@4693:     setup.nr_frames  = NR_GRANT_FRAMES;
cl349@4693:     setup.frame_list = frames;
cl349@4693: 
cl349@4693:     BUG_ON(HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1) != 0);
cl349@4693:     BUG_ON(setup.status != 0);
cl349@4693: 
cl349@4693:     for ( i = 0; i < NR_GRANT_FRAMES; i++ )
cl349@4777:         set_fixmap(FIX_GNTTAB_END - i, frames[i] << PAGE_SHIFT);
cl349@4693: 
cl349@4693:     return 0;
cl349@4693: }
cl349@4693: 
cl349@6349: int
cl349@6349: gnttab_suspend(void)
cl349@4693: {
cl349@4693:     int i;
cl349@4693: 
cl349@4693:     for ( i = 0; i < NR_GRANT_FRAMES; i++ )
cl349@4693: 	clear_fixmap(FIX_GNTTAB_END - i);
cl349@4693: 
cl349@4693:     return 0;
cl349@4693: }
cl349@4693: 
cl349@6349: static int __init
cl349@6349: gnttab_init(void)
cl349@4693: {
cl349@4693:     int i;
cl349@4693: 
cl349@4693:     BUG_ON(gnttab_resume());
cl349@4693: 
cl349@4693:     shared = (grant_entry_t *)fix_to_virt(FIX_GNTTAB_END);
cl349@4693: 
cl349@4693:     for ( i = 0; i < NR_GRANT_ENTRIES; i++ )
cl349@6349:         gnttab_list[i] = i + 1;
cl349@4693:     
cl349@4693: #ifdef CONFIG_PROC_FS
cl349@4693:     /*
cl349@4693:      *  /proc/xen/grant : used by libxc to access grant tables
cl349@4693:      */
cl349@4693:     if ( (grant_pde = create_xen_proc_entry("grant", 0600)) == NULL )
cl349@4693:     {
cl349@4693:         WPRINTK("Unable to create grant xen proc entry\n");
cl349@4693:         return -1;
cl349@4693:     }
cl349@4693: 
cl349@4693:     grant_file_ops.read   = grant_pde->proc_fops->read;
cl349@4693:     grant_file_ops.write  = grant_pde->proc_fops->write;
cl349@4693: 
cl349@4693:     grant_pde->proc_fops  = &grant_file_ops;
cl349@4693: 
cl349@4693:     grant_pde->read_proc  = &grant_read;
cl349@4693:     grant_pde->write_proc = &grant_write;
cl349@4693: #endif
cl349@4693: 
cl349@4693:     printk("Grant table initialized\n");
cl349@4693:     return 0;
cl349@4693: }
cl349@4693: 
cl349@4693: __initcall(gnttab_init);