Module Name: src
Committed By: royger
Date: Wed Oct 24 13:07:46 UTC 2012
Modified Files:
src/sys/arch/xen/xen: xengnt.c
Log Message:
xen: don't use grants 0-8
Not all grants from the first frame can be used, grants from 0 to 8
(both included) are reserved for external tools. Using this grants
caused system crashes and fs corruption.
Closes PR port-xen/47057 and port-xen/47056
Reviewed by bouyer@
To generate a diff of this commit:
cvs rdiff -u -r1.24 -r1.25 src/sys/arch/xen/xen/xengnt.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/xen/xen/xengnt.c
diff -u src/sys/arch/xen/xen/xengnt.c:1.24 src/sys/arch/xen/xen/xengnt.c:1.25
--- src/sys/arch/xen/xen/xengnt.c:1.24 Sat Jun 30 23:36:20 2012
+++ src/sys/arch/xen/xen/xengnt.c Wed Oct 24 13:07:46 2012
@@ -1,4 +1,4 @@
-/* $NetBSD: xengnt.c,v 1.24 2012/06/30 23:36:20 jym Exp $ */
+/* $NetBSD: xengnt.c,v 1.25 2012/10/24 13:07:46 royger Exp $ */
/*
* Copyright (c) 2006 Manuel Bouyer.
@@ -26,7 +26,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: xengnt.c,v 1.24 2012/06/30 23:36:20 jym Exp $");
+__KERNEL_RCSID(0, "$NetBSD: xengnt.c,v 1.25 2012/10/24 13:07:46 royger Exp $");
#include <sys/types.h>
#include <sys/param.h>
@@ -51,6 +51,9 @@ __KERNEL_RCSID(0, "$NetBSD: xengnt.c,v 1
#define NR_GRANT_ENTRIES_PER_PAGE (PAGE_SIZE / sizeof(grant_entry_t))
+/* External tools reserve first few grant table entries. */
+#define NR_RESERVED_ENTRIES 8
+
/* Current number of frames making up the grant table */
int gnt_nr_grant_frames;
/* Maximum number of frames that can make up the grant table */
@@ -161,7 +164,7 @@ xengnt_more_entries(void)
gnttab_setup_table_t setup;
u_long *pages;
int nframes_new = gnt_nr_grant_frames + 1;
- int i;
+ int i, start_gnt;
KASSERT(mutex_owned(&grant_lock));
if (gnt_nr_grant_frames == gnt_max_grant_frames)
@@ -204,9 +207,14 @@ xengnt_more_entries(void)
/*
* add the grant entries associated to the last grant table frame
- * and mark them as free
+ * and mark them as free. Prevent using the first grants (from 0 to 8)
+ * since they are used by the tools.
*/
- for (i = gnt_nr_grant_frames * NR_GRANT_ENTRIES_PER_PAGE;
+ start_gnt = (gnt_nr_grant_frames * NR_GRANT_ENTRIES_PER_PAGE) <
+ (NR_RESERVED_ENTRIES + 1) ?
+ (NR_RESERVED_ENTRIES + 1) :
+ (gnt_nr_grant_frames * NR_GRANT_ENTRIES_PER_PAGE);
+ for (i = start_gnt;
i < nframes_new * NR_GRANT_ENTRIES_PER_PAGE;
i++) {
KASSERT(gnt_entries[last_gnt_entry] == XENGNT_NO_ENTRY);
@@ -240,7 +248,7 @@ xengnt_get_entry(void)
last_gnt_entry--;
entry = gnt_entries[last_gnt_entry];
gnt_entries[last_gnt_entry] = XENGNT_NO_ENTRY;
- KASSERT(entry != XENGNT_NO_ENTRY);
+ KASSERT(entry != XENGNT_NO_ENTRY && entry > NR_RESERVED_ENTRIES);
KASSERT(last_gnt_entry >= 0);
KASSERT(last_gnt_entry <= gnt_max_grant_frames * NR_GRANT_ENTRIES_PER_PAGE);
return entry;
@@ -253,6 +261,7 @@ static void
xengnt_free_entry(grant_ref_t entry)
{
mutex_enter(&grant_lock);
+ KASSERT(entry > NR_RESERVED_ENTRIES);
KASSERT(gnt_entries[last_gnt_entry] == XENGNT_NO_ENTRY);
KASSERT(last_gnt_entry >= 0);
KASSERT(last_gnt_entry <= gnt_max_grant_frames * NR_GRANT_ENTRIES_PER_PAGE);
