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From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: x86: Disable the use of auto-translated PV guests
This is a minimal backport of c/s 92942fd3d469 "x86/mm: drop
guest_{map,get_eff}_l1e() hooks" from Xen 4.7, which stated:
Disallow the unmaintained and presumed broken translated-but-not-external
paging mode combination ...
It turns out that this mode is insecure to run with, as opposed to just simply
broken.
This is part of XSA-243.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
diff --git a/xen/arch/x86/mm/paging.c b/xen/arch/x86/mm/paging.c
index dcff4fb..945bb61 100644
--- a/xen/arch/x86/mm/paging.c
+++ b/xen/arch/x86/mm/paging.c
@@ -835,6 +835,15 @@ void paging_final_teardown(struct domain *d)
* creation. */
int paging_enable(struct domain *d, u32 mode)
{
+ switch ( mode & (PG_external | PG_translate) )
+ {
+ case 0:
+ case PG_external | PG_translate:
+ break;
+ default:
+ return -EINVAL;
+ }
+
if ( hap_enabled(d) )
return hap_enable(d, mode | PG_HAP_enable);
else
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