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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen stable-4.10] gnttab: don't blindly free status pages upon version change
commit 16edf98e95bf995864d375b9b67b4fc2cef928a5
Author: Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Feb 27 14:19:19 2018 +0100
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Feb 27 14:19:19 2018 +0100
gnttab: don't blindly free status pages upon version change
There may still be active mappings, which would trigger the respective
BUG_ON(). Split the loop into one dealing with the page attributes and
the second (when the first fully passed) freeing the pages. Return an
error if any pages still have pending references.
This is part of XSA-255.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
master commit: 38bfcc165dda5f4284d7c218b91df9e144ddd88d
master date: 2018-02-27 14:07:12 +0100
---
xen/common/grant_table.c | 67 ++++++++++++++++++++++++++++++++++++---
xen/include/asm-arm/grant_table.h | 5 +++
xen/include/asm-x86/grant_table.h | 10 ++++--
3 files changed, 75 insertions(+), 7 deletions(-)
diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index b41d816..b100a28 100644
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -1636,23 +1636,74 @@ status_alloc_failed:
return -ENOMEM;
}
-static void
+static int
gnttab_unpopulate_status_frames(struct domain *d, struct grant_table *gt)
{
- int i;
+ unsigned int i;
for ( i = 0; i < nr_status_frames(gt); i++ )
{
struct page_info *pg = virt_to_page(gt->status[i]);
+ gfn_t gfn = gnttab_get_frame_gfn(gt, true, i);
+
+ /*
+ * For translated domains, recovering from failure after partial
+ * changes were made is more complicated than it seems worth
+ * implementing at this time. Hence respective error paths below
+ * crash the domain in such a case.
+ */
+ if ( paging_mode_translate(d) )
+ {
+ int rc = gfn_eq(gfn, INVALID_GFN)
+ ? 0
+ : guest_physmap_remove_page(d, gfn,
+ _mfn(page_to_mfn(pg)), 0);
+
+ if ( rc )
+ {
+ gprintk(XENLOG_ERR,
+ "Could not remove status frame %u (GFN %#lx) from
P2M\n",
+ i, gfn_x(gfn));
+ domain_crash(d);
+ return rc;
+ }
+ gnttab_set_frame_gfn(gt, true, i, INVALID_GFN);
+ }
BUG_ON(page_get_owner(pg) != d);
if ( test_and_clear_bit(_PGC_allocated, &pg->count_info) )
put_page(pg);
- BUG_ON(pg->count_info & ~PGC_xen_heap);
+
+ if ( pg->count_info & ~PGC_xen_heap )
+ {
+ if ( paging_mode_translate(d) )
+ {
+ gprintk(XENLOG_ERR,
+ "Wrong page state %#lx of status frame %u (GFN
%#lx)\n",
+ pg->count_info, i, gfn_x(gfn));
+ domain_crash(d);
+ }
+ else
+ {
+ if ( get_page(pg, d) )
+ set_bit(_PGC_allocated, &pg->count_info);
+ while ( i-- )
+ gnttab_create_status_page(d, gt, i);
+ }
+ return -EBUSY;
+ }
+
+ page_set_owner(pg, NULL);
+ }
+
+ for ( i = 0; i < nr_status_frames(gt); i++ )
+ {
free_xenheap_page(gt->status[i]);
gt->status[i] = NULL;
}
gt->nr_status_frames = 0;
+
+ return 0;
}
/*
@@ -2962,8 +3013,9 @@
gnttab_set_version(XEN_GUEST_HANDLE_PARAM(gnttab_set_version_t) uop)
break;
}
- if ( op.version < 2 && gt->gt_version == 2 )
- gnttab_unpopulate_status_frames(currd, gt);
+ if ( op.version < 2 && gt->gt_version == 2 &&
+ (res = gnttab_unpopulate_status_frames(currd, gt)) != 0 )
+ goto out_unlock;
/* Make sure there's no crud left over from the old version. */
for ( i = 0; i < nr_grant_frames(gt); i++ )
@@ -3803,6 +3855,11 @@ int gnttab_map_frame(struct domain *d, unsigned long
idx, gfn_t gfn,
rc = -EINVAL;
}
+ if ( !rc && paging_mode_translate(d) &&
+ !gfn_eq(gnttab_get_frame_gfn(gt, status, idx), INVALID_GFN) )
+ rc = guest_physmap_remove_page(d, gnttab_get_frame_gfn(gt, status,
idx),
+ *mfn, 0);
+
if ( !rc )
gnttab_set_frame_gfn(gt, status, idx, gfn);
diff --git a/xen/include/asm-arm/grant_table.h
b/xen/include/asm-arm/grant_table.h
index f5361c7..5b8994c 100644
--- a/xen/include/asm-arm/grant_table.h
+++ b/xen/include/asm-arm/grant_table.h
@@ -73,6 +73,11 @@ static inline unsigned int gnttab_dom0_max(void)
(gfn); \
} while ( 0 )
+#define gnttab_get_frame_gfn(gt, st, idx) ({ \
+ _gfn((st) ? gnttab_status_gmfn(NULL, gt, idx) \
+ : gnttab_shared_gmfn(NULL, gt, idx)); \
+})
+
#define gnttab_create_shared_page(d, t, i) \
do { \
share_xen_page_with_guest( \
diff --git a/xen/include/asm-x86/grant_table.h
b/xen/include/asm-x86/grant_table.h
index 3177d82..66e9742 100644
--- a/xen/include/asm-x86/grant_table.h
+++ b/xen/include/asm-x86/grant_table.h
@@ -47,6 +47,12 @@ static inline unsigned int gnttab_dom0_max(void)
#define gnttab_init_arch(gt) 0
#define gnttab_destroy_arch(gt) do {} while ( 0 )
#define gnttab_set_frame_gfn(gt, st, idx, gfn) do {} while ( 0 )
+#define gnttab_get_frame_gfn(gt, st, idx) ({ \
+ unsigned long mfn_ = (st) ? gnttab_status_mfn(gt, idx) \
+ : gnttab_shared_mfn(gt, idx); \
+ unsigned long gpfn_ = get_gpfn_from_mfn(mfn_); \
+ VALID_M2P(gpfn_) ? _gfn(gpfn_) : INVALID_GFN; \
+})
#define gnttab_create_shared_page(d, t, i) \
do { \
@@ -63,11 +69,11 @@ static inline unsigned int gnttab_dom0_max(void)
} while ( 0 )
-#define gnttab_shared_mfn(d, t, i) \
+#define gnttab_shared_mfn(t, i) \
((virt_to_maddr((t)->shared_raw[i]) >> PAGE_SHIFT))
#define gnttab_shared_gmfn(d, t, i) \
- (mfn_to_gmfn(d, gnttab_shared_mfn(d, t, i)))
+ (mfn_to_gmfn(d, gnttab_shared_mfn(t, i)))
#define gnttab_status_mfn(t, i) \
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.10
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