[PATCH] x86/IST: Fix comment about stack layout

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

This was an oversight in c/s 5d37af364dc "x86/traps: Use an Interrupt Stack
Table for #DB" which introduced the #DB IST to begin with.

Reported-by: Jan Beulich <JBeulich@xxxxxxxx>
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/include/asm-x86/current.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/include/asm-x86/current.h b/xen/include/asm-x86/current.h
index 0b47485337..39c2c6cbf8 100644
--- a/xen/include/asm-x86/current.h
+++ b/xen/include/asm-x86/current.h
@@ -18,7 +18,7 @@
  * 6 - Primary stack
  * 5 - Optionally not present (MEMORY_GUARD)
  * 4 - Unused; optionally not present (MEMORY_GUARD)
- * 3 - Unused; optionally not present (MEMORY_GUARD)
+ * 3 -  DB IST stack
  * 2 - MCE IST stack
  * 1 - NMI IST stack
  * 0 - Double Fault IST stack
-- 
2.11.0