For the int80 slow path to jump to handle_exception_saved, %r14 needs to
be set up suitably for XPTI purposes. This is because of the difference
in nature between the int80 path (which is synchronous WRT guest
actions) and the exception path which is potentially asynchronous.
This is XSA-259.
Reported-by: Andrew Cooper <[hidden email]>
Signed-off-by: Jan Beulich <[hidden email]>
Reviewed-by: Andrew Cooper <[hidden email]>
master commit: 5a5c368faf45ced8a8c6235f4fbf5cdb38ec939f
master date: 2018-04-25 14:39:41 +0200
xen/arch/x86/x86_64/entry.S | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index b0bd5fab17..fd6c5d04e2 100644
@@ -398,6 +398,12 @@ int80_slow_path:
/* A GPF wouldn't have incremented the instruction pointer. */
+ * While we've cleared xen_cr3 above already, normal exception handling
+ * code has logic to restore the original value from %r15. Therefore we
+ * need to set up %r14 here, while %r15 is required to still be zero.
/* create_bounce_frame & helpers don't need to be in .text.entry */
generated by git-patchbot for /home/xen/git/xen.git#stable-4.9