Import OS interfaces to Xen services.

MFC after:	2 weeks

1 files changed, 597 insertions, 0 deletions

diff --git a/sys/xen/gnttab.c b/sys/xen/gnttab.c
new file mode 100644
index 0000000..11072f1
--- /dev/null
+++ b/sys/xen/gnttab.c
@@ -0,0 +1,597 @@
+/******************************************************************************
+ * 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("$FreeBSD$");
+
+#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 <vm/vm.h>
+#include <vm/vm_extern.h>
+
+#include <vm/vm_page.h>
+#include <vm/vm_kern.h>
+
+
+
+#include <machine/xen/hypervisor.h>
+#include <machine/xen/synch_bitops.h>
+#include <xen/gnttab.h>
+
+#define cmpxchg(a, b, c) atomic_cmpset_int((volatile u_int *)(a),(b),(c))
+
+
+#if 1
+#define ASSERT(_p) \
+    if ( !(_p) ) { printk("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("xen_grant: " fmt, ##args)
+
+/* External tools reserve first few grant table entries. */
+#define NR_RESERVED_ENTRIES 8
+#define GNTTAB_LIST_END 0xffffffff
+#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 ref, rc;
+	grant_ref_t head;
+	
+	mtx_lock(&gnttab_list_lock);
+	if ((gnttab_free_count < count) &&
+	    ((rc = gnttab_expand(count - gnttab_free_count)) < 0)) {
+		mtx_unlock(&gnttab_list_lock);
+		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;
+	mtx_unlock(&gnttab_list_lock);	
+	return (ref);
+}
+
+#define get_free_entry() get_free_entries(1)
+
+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)
+{
+	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)
+{
+	uint16_t nflags;
+	
+	nflags = shared[ref].flags;
+	
+	return (nflags & (GTF_reading|GTF_writing));
+}
+
+int
+gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
+{
+	uint16_t flags, nflags;
+
+	nflags = shared[ref].flags;
+	do {
+		if ( (flags = nflags) & (GTF_reading|GTF_writing) ) {
+			printf("WARNING: g.e. still in use!\n");
+			return (0);
+		}
+	} while ((nflags = synch_cmpxchg(&shared[ref].flags, flags, 0)) !=
+	       flags);
+
+	return (1);
+}
+
+void
+gnttab_end_foreign_access(grant_ref_t ref, int readonly, void *page)
+{
+	if (gnttab_end_foreign_access_ref(ref, readonly)) {
+		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("WARNING: leaking g.e. and page still in use!\n");
+	}
+}
+
+int
+gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
+{
+	int ref;
+	
+	if (unlikely((ref = get_free_entry()) == -1))
+		return -ENOSPC;
+
+	gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
+	
+	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_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;
+	PANIC_IF(frame == 0);
+
+	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;
+	
+	mtx_lock(&gnttab_list_lock);
+	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();
+	mtx_unlock(&gnttab_list_lock);
+}
+
+int
+gnttab_alloc_grant_references(uint16_t count, grant_ref_t *head)
+{
+	int h = get_free_entries(count);
+
+	if (h == -1)
+		return -ENOSPC;
+
+	*head = h;
+
+	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 -ENOSPC;
+	*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
+
+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 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;
+	}
+	PANIC_IF(rc || setup.status);
+
+	if (shared == NULL) {
+		vm_offset_t area;
+		
+		area = kmem_alloc_nofault(kernel_map,
+		    PAGE_SIZE * max_nr_grant_frames());
+		PANIC_IF(area == 0);
+		shared = (grant_entry_t *)area;
+	}
+	for (i = 0; i < nr_gframes; i++)
+		PT_SET_MA(((caddr_t)shared) + i*PAGE_SIZE, 
+		    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, pages;
+
+	pages = (PAGE_SIZE*nr_grant_frames) >> PAGE_SHIFT;
+
+	for (i = 0; i < pages; i++)
+		PT_SET_MA(shared + (i*PAGE_SIZE), (vm_paddr_t)0);
+
+	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 > max_nr_grant_frames())
+		return -ENOSPC;
+
+	if ((rc = gnttab_map(cur, cur + extra - 1)) == 0)
+		rc = grow_gnttab_list(extra);
+
+	return rc;
+}
+
+static int 
+gnttab_init(void *unused)
+{
+	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() < 0)
+		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;
+
+	printk("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); 
+SYSINIT(gnttab, SI_SUB_PSEUDO, SI_ORDER_FIRST, gnttab_init, NULL);