From 0623f56d0b04d4319c1be1972cf53918f92fa843 Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@suse.com>
Date: Fri, 8 May 2015 14:12:20 +0200
Subject: [PATCH] Revert "x86: add the RTC io space to the blocked access list"

This reverts commit 3b22924062b2648b3df83e9ebda6da52a28c1316, as it
breaks Dom0 access to CMOS/RTC.
---
 xen/arch/x86/domain_build.c | 3 ---
 xen/arch/x86/traps.c        | 4 ++++
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/domain_build.c b/xen/arch/x86/domain_build.c
index 2a23746a82..03e4bfeb84 100644
--- a/xen/arch/x86/domain_build.c
+++ b/xen/arch/x86/domain_build.c
@@ -37,7 +37,6 @@
 #include <asm/io_apic.h>
 #include <asm/hap.h>
 #include <asm/hpet.h>
-#include <asm/mc146818rtc.h>
 
 #include <public/version.h>
 
@@ -1549,8 +1548,6 @@ int __init construct_dom0(
         rc |= ioports_deny_access(d, pmtmr_ioport, pmtmr_ioport + 3);
     /* PCI configuration space (NB. 0xcf8 has special treatment). */
     rc |= ioports_deny_access(d, 0xcfc, 0xcff);
-    /* Never permit direct access to the RTC/CMOS registers. */
-    rc |= ioports_deny_access(d, RTC_PORT(0), RTC_PORT(1));
     /* Command-line I/O ranges. */
     process_dom0_ioports_disable(d);
 
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 0b0c5e96de..22cdfc48ae 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -1765,6 +1765,10 @@ static int admin_io_okay(
     if ( (port == 0xcf8) && (bytes == 4) )
         return 0;
 
+    /* We also never permit direct access to the RTC/CMOS registers. */
+    if ( ((port & ~1) == RTC_PORT(0)) )
+        return 0;
+
     return ioports_access_permitted(v->domain, port, port + bytes - 1);
 }
 
-- 
2.30.2