ChangeSet 1.1392.1.2, 2005/04/28 21:50:48+01:00, cl349@xxxxxxxxxxxxxxxxxxxx
Merge xen-2.0-testing "sync w/ unstable" changes.
arch/xen/kernel/gnttab.c | 391 +++++++++++++++++++++++++++++++++++++++++++++++
include/asm-xen/gnttab.h | 72 ++++++++
2 files changed, 463 insertions(+)
diff -Nru a/linux-2.6.11-xen-sparse/arch/xen/kernel/gnttab.c
b/linux-2.6.11-xen-sparse/arch/xen/kernel/gnttab.c
--- /dev/null Wed Dec 31 16:00:00 196900
+++ b/linux-2.6.11-xen-sparse/arch/xen/kernel/gnttab.c 2005-04-28 18:03:45
-04:00
@@ -0,0 +1,391 @@
+/******************************************************************************
+ * 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
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