--- /dev/null
+/******************************************************************************
+ * 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 <linux/config.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <asm/pgtable.h>
+#include <asm/fixmap.h>
+#include <asm/uaccess.h>
+#include <asm-xen/xen_proc.h>
+#include <asm-xen/linux-public/privcmd.h>
+#include <asm-xen/gnttab.h>
+
+#ifndef set_fixmap_ma
+#define set_fixmap_ma set_fixmap
+#endif
+
+#if 1
+#define ASSERT(_p) \
+ if ( !(_p) ) { printk(KERN_ALERT"Assertion '%s': line %d, file %s\n", \
+ #_p , __LINE__, __FILE__); *(int*)0=0; }
+#else
+#define ASSERT(_p) ((void)0)
+#endif
+
+#define WPRINTK(fmt, args...) \
+ printk(KERN_WARNING "xen_grant: " fmt, ##args)
+
+
+EXPORT_SYMBOL(gnttab_grant_foreign_access);
+EXPORT_SYMBOL(gnttab_end_foreign_access);
+EXPORT_SYMBOL(gnttab_query_foreign_access);
+EXPORT_SYMBOL(gnttab_grant_foreign_transfer);
+EXPORT_SYMBOL(gnttab_end_foreign_transfer);
+EXPORT_SYMBOL(gnttab_alloc_grant_references);
+EXPORT_SYMBOL(gnttab_free_grant_references);
+EXPORT_SYMBOL(gnttab_claim_grant_reference);
+EXPORT_SYMBOL(gnttab_release_grant_reference);
+EXPORT_SYMBOL(gnttab_grant_foreign_access_ref);
+EXPORT_SYMBOL(gnttab_grant_foreign_transfer_ref);
+
+static grant_ref_t gnttab_free_list[NR_GRANT_ENTRIES];
+static grant_ref_t gnttab_free_head;
+
+static grant_entry_t *shared;
+
+/*
+ * Lock-free grant-entry allocator
+ */
+
+static inline int
+get_free_entry(
+ void)
+{
+ grant_ref_t fh, nfh = gnttab_free_head;
+ do { if ( unlikely((fh = nfh) == NR_GRANT_ENTRIES) ) return -1; }
+ while ( unlikely((nfh = cmpxchg(&gnttab_free_head, fh,
+ gnttab_free_list[fh])) != fh) );
+ return fh;
+}
+
+static inline void
+put_free_entry(
+ grant_ref_t ref)
+{
+ grant_ref_t fh, nfh = gnttab_free_head;
+ do { gnttab_free_list[ref] = fh = nfh; wmb(); }
+ while ( unlikely((nfh = cmpxchg(&gnttab_free_head, fh, ref)) != fh) );
+}
+
+/*
+ * 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;
+}
+
+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 )
+{
+ u16 nflags;
+
+ nflags = shared[ref].flags;
+
+ return ( nflags & (GTF_reading|GTF_writing) );
+}
+
+void
+gnttab_end_foreign_access( 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");
+ }
+ while ( (nflags = cmpxchg(&shared[ref].flags, flags, 0)) != flags );
+
+ put_free_entry(ref);
+}
+
+int
+gnttab_grant_foreign_transfer(
+ domid_t domid, unsigned long pfn )
+{
+ int ref;
+
+ if ( unlikely((ref = get_free_entry()) == -1) )
+ return -ENOSPC;
+
+ shared[ref].frame = pfn;
+ shared[ref].domid = domid;
+ wmb();
+ shared[ref].flags = GTF_accept_transfer;
+
+ return ref;
+}
+
+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(
+ grant_ref_t ref)
+{
+ unsigned long frame = 0;
+ u16 flags;
+
+ flags = shared[ref].flags;
+ ASSERT(flags == (GTF_accept_transfer | GTF_transfer_committed));
+
+ /*
+ * If a transfer is committed then wait for the frame address to appear.
+ * Otherwise invalidate the grant entry against future use.
+ */
+ if ( likely(flags != GTF_accept_transfer) ||
+ (cmpxchg(&shared[ref].flags, flags, 0) != GTF_accept_transfer) )
+ while ( unlikely((frame = shared[ref].frame) == 0) )
+ cpu_relax();
+
+ put_free_entry(ref);
+
+ return frame;
+}
+
+void
+gnttab_free_grant_references( u16 count, grant_ref_t head )
+{
+ /* TODO: O(N)...? */
+ grant_ref_t to_die = 0, next = head;
+ int i;
+
+ for ( i = 0; i < count; i++ )
+ to_die = next;
+ next = gnttab_free_list[next];
+ put_free_entry( to_die );
+}
+
+int
+gnttab_alloc_grant_references( u16 count,
+ grant_ref_t *head,
+ grant_ref_t *terminal )
+{
+ int i;
+ grant_ref_t h = gnttab_free_head;
+
+ for ( i = 0; i < count; i++ )
+ if ( unlikely(get_free_entry() == -1) )
+ goto not_enough_refs;
+
+ *head = h;
+ *terminal = gnttab_free_head;
+
+ return 0;
+
+not_enough_refs:
+ gnttab_free_head = h;
+ return -ENOSPC;
+}
+
+int
+gnttab_claim_grant_reference( grant_ref_t *private_head,
+ grant_ref_t terminal )
+{
+ grant_ref_t g;
+ if ( unlikely((g = *private_head) == terminal) )
+ return -ENOSPC;
+ *private_head = gnttab_free_list[g];
+ return g;
+}
+
+void
+gnttab_release_grant_reference( grant_ref_t *private_head,
+ grant_ref_t release )
+{
+ gnttab_free_list[release] = *private_head;
+ *private_head = release;
+}
+
+/*
+ * ProcFS operations
+ */
+
+#ifdef CONFIG_PROC_FS
+
+static struct proc_dir_entry *grant_pde;
+
+static int grant_ioctl(struct inode *inode, struct file *file,
+ unsigned int cmd, unsigned long data)
+{
+ int ret;
+ privcmd_hypercall_t hypercall;
+
+ /* XXX Need safety checks here if using for anything other
+ * than debugging */
+ return -ENOSYS;
+
+ if ( cmd != IOCTL_PRIVCMD_HYPERCALL )
+ return -ENOSYS;
+
+ if ( copy_from_user(&hypercall, (void *)data, sizeof(hypercall)) )
+ return -EFAULT;
+
+ if ( hypercall.op != __HYPERVISOR_grant_table_op )
+ return -ENOSYS;
+
+ /* hypercall-invoking asm taken from privcmd.c */
+ __asm__ __volatile__ (
+ "pushl %%ebx; pushl %%ecx; pushl %%edx; pushl %%esi; pushl %%edi; "
+ "movl 4(%%eax),%%ebx ;"
+ "movl 8(%%eax),%%ecx ;"
+ "movl 12(%%eax),%%edx ;"
+ "movl 16(%%eax),%%esi ;"
+ "movl 20(%%eax),%%edi ;"
+ "movl (%%eax),%%eax ;"
+ TRAP_INSTR "; "
+ "popl %%edi; popl %%esi; popl %%edx; popl %%ecx; popl %%ebx"
+ : "=a" (ret) : "0" (&hypercall) : "memory" );
+
+ return ret;
+}
+
+static struct file_operations grant_file_ops = {
+ ioctl: grant_ioctl,
+};
+
+static int grant_read(char *page, char **start, off_t off,
+ int count, int *eof, void *data)
+{
+ int len;
+ unsigned int i;
+ grant_entry_t *gt;
+
+ gt = (grant_entry_t *)shared;
+ len = 0;
+
+ for ( i = 0; i < NR_GRANT_ENTRIES; i++ )
+ /* TODO: safety catch here until this can handle >PAGE_SIZE output */
+ if (len > (PAGE_SIZE - 200))
+ {
+ len += sprintf( page + len, "Truncated.\n");
+ break;
+ }
+
+ if ( gt[i].flags )
+ len += sprintf( page + len,
+ "Grant: ref (0x%x) flags (0x%hx) dom (0x%hx) frame (0x%x)\n",
+ i,
+ gt[i].flags,
+ gt[i].domid,
+ gt[i].frame );
+
+ *eof = 1;
+ return len;
+}
+
+static int grant_write(struct file *file, const char __user *buffer,
+ unsigned long count, void *data)
+{
+ /* TODO: implement this */
+ return -ENOSYS;
+}
+
+#endif /* CONFIG_PROC_FS */
+
+int gnttab_resume(void)
+{
+ gnttab_setup_table_t setup;
+ unsigned long frames[NR_GRANT_FRAMES];
+ int i;
+
+ setup.dom = DOMID_SELF;
+ setup.nr_frames = NR_GRANT_FRAMES;
+ setup.frame_list = frames;
+
+ BUG_ON(HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1) != 0);
+ BUG_ON(setup.status != 0);
+
+ for ( i = 0; i < NR_GRANT_FRAMES; i++ )
+ set_fixmap_ma(FIX_GNTTAB_END - i, frames[i] << PAGE_SHIFT);
+
+ return 0;
+}
+
+int gnttab_suspend(void)
+{
+ int i;
+
+ for ( i = 0; i < NR_GRANT_FRAMES; i++ )
+ clear_fixmap(FIX_GNTTAB_END - i);
+
+ return 0;
+}
+
+static int __init gnttab_init(void)
+{
+ int i;
+
+ BUG_ON(gnttab_resume());
+
+ shared = (grant_entry_t *)fix_to_virt(FIX_GNTTAB_END);
+
+ for ( i = 0; i < NR_GRANT_ENTRIES; i++ )
+ gnttab_free_list[i] = i + 1;
+
+#ifdef CONFIG_PROC_FS
+ /*
+ * /proc/xen/grant : used by libxc to access grant tables
+ */
+ if ( (grant_pde = create_xen_proc_entry("grant", 0600)) == NULL )
+ {
+ WPRINTK("Unable to create grant xen proc entry\n");
+ return -1;
+ }
+
+ grant_file_ops.read = grant_pde->proc_fops->read;
+ grant_file_ops.write = grant_pde->proc_fops->write;
+
+ grant_pde->proc_fops = &grant_file_ops;
+
+ grant_pde->read_proc = &grant_read;
+ grant_pde->write_proc = &grant_write;
+#endif
+
+ printk("Grant table initialized\n");
+ return 0;
+}
+
+__initcall(gnttab_init);
--- /dev/null
+/******************************************************************************
+ * gnttab.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, K A Fraser
+ * Copyright (c) 2005, Christopher Clark
+ */
+
+#ifndef __ASM_GNTTAB_H__
+#define __ASM_GNTTAB_H__
+
+#include <linux/config.h>
+#include <asm-xen/hypervisor.h>
+#include <asm-xen/xen-public/grant_table.h>
+
+/* NR_GRANT_FRAMES must be less than or equal to that configured in Xen */
+#define NR_GRANT_FRAMES 4
+#define NR_GRANT_ENTRIES (NR_GRANT_FRAMES * PAGE_SIZE / sizeof(grant_entry_t))
+
+int
+gnttab_grant_foreign_access(
+ domid_t domid, unsigned long frame, int readonly);
+
+void
+gnttab_end_foreign_access(
+ grant_ref_t ref, int readonly);
+
+int
+gnttab_grant_foreign_transfer(
+ domid_t domid, unsigned long pfn);
+
+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, grant_ref_t *private_terminal );
+
+void
+gnttab_free_grant_references(
+ u16 count, grant_ref_t private_head );
+
+int
+gnttab_claim_grant_reference( grant_ref_t *pprivate_head, grant_ref_t terminal
+);
+
+void
+gnttab_release_grant_reference(
+ grant_ref_t *private_head, grant_ref_t release );
+
+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);
+
+
+#endif /* __ASM_GNTTAB_H__ */
projects / xen.git / commitdiff