hvm: Do not crash guest if it does an unaligned access to an HPET

register. Some CrashMe test apaprently does this and we don't want
that to crash the domain it runs in.
From: Dexuan Cui <dexuan.cui@intel.com>
Signed-off-by: Keir Fraser <keir.fraser@eu.citrix.com>

diff --git a/xen/arch/x86/hvm/hpet.c b/xen/arch/x86/hvm/hpet.c
index 595495580991ed9d73304e21b5eea1778c97673d..ee7d91f652dd68514fdd7db2c05cb0c1aeda0c2e 100644 (file)
--- a/xen/arch/x86/hvm/hpet.c
+++ b/xen/arch/x86/hvm/hpet.c
@@ -127,9 +127,13 @@ static inline int hpet_check_access_length(
 {
     if ( (addr & (len - 1)) || (len > 8) )
     {
-        gdprintk(XENLOG_ERR, "HPET: access across register boundary: "
+        /*
+         * According to ICH9 specification, unaligned accesses may result
+         * in unexpected behaviour or master abort, but should not crash/hang.
+         * Hence we read all-ones, drop writes, and log a warning.
+         */
+        gdprintk(XENLOG_WARNING, "HPET: access across register boundary: "
                  "%lx %lx\n", addr, len);
-        domain_crash(current->domain);
         return -EINVAL;
     }