# HG changeset patch
# User Keir Fraser <keir@xxxxxxxxxxxxx>
# Date 1193761220 0
# Node ID 3ce0fb37cf590c9fc185d701691203ebd4feb296
# Parent f983730bfc809f768506fbbb27b0c5a5ec3ea626
x86, hvm: Flush local TLB after any change to linear pagetable
mapping.
This was not needed when vmenter/vmexit always had the side effect of
flushing host TLBs.
But, with SVM ASIDs, it is possible to:
(1) Update CR3 update,
(2) vmenter the guest, and
(3) and vmexit due to a page fault
all without an intervening host TLB flush.
Then the page fault code could use the linear pagetable
to read a top-level shadow page table entry.
But, without this change, it would fetch the wrong value
due to a stale TLB.
Signed-off-by: Robert Phillips <rphillips@xxxxxxxxxxxxxxx>
Signed-off-by: Ben Guthro <bguthro@xxxxxxxxxxxxxxx>
xen-unstable changeset: 16275:9379c83e14b5b0a9ab2fe627ed786a8abded0d38
xen-unstable date: Tue Oct 30 16:15:17 2007 +0000
---
xen/arch/x86/mm/shadow/multi.c | 15 +++++++++++++++
1 files changed, 15 insertions(+)
diff -r f983730bfc80 -r 3ce0fb37cf59 xen/arch/x86/mm/shadow/multi.c
--- a/xen/arch/x86/mm/shadow/multi.c Thu Oct 25 09:46:36 2007 +0100
+++ b/xen/arch/x86/mm/shadow/multi.c Tue Oct 30 16:20:20 2007 +0000
@@ -3351,6 +3351,21 @@ sh_update_linear_entries(struct vcpu *v)
#else
#error this should not happen
#endif
+
+ if ( shadow_mode_external(d) )
+ {
+ /*
+ * Having modified the linear pagetable mapping, flush local host TLBs.
+ * This was not needed when vmenter/vmexit always had the side effect
+ * of flushing host TLBs but, with ASIDs, it is possible to finish
+ * this CR3 update, vmenter the guest, vmexit due to a page fault,
+ * without an intervening host TLB flush. Then the page fault code
+ * could use the linear pagetable to read a top-level shadow page
+ * table entry. But, without this change, it would fetch the wrong
+ * value due to a stale TLB.
+ */
+ local_flush_tlb();
+ }
}
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