Since (non-pvops, 32-bit only up to 2.6.27) Linux would report "BAD"
unconditionally on all SiS chipset versions (it only looks for a PCI
device at 0000:00:00.0 with SiS as the vendor), we must not crash if
the report on a 64-bit hypervisor doesn't match the #define (which is
zero).

While we could honor the quirk indication even on 64-bit, it doesn't
seem worthwhile, as there's no evidence that newer SiS chipsets
(supporting 64-bit CPUs) are actually affected.

This should also address bug 1687 (mis-reported, however, afaict).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

--- 2010-11-09.orig/xen/arch/x86/platform_hypercall.c
+++ 2010-11-09/xen/arch/x86/platform_hypercall.c
@@ -199,7 +199,10 @@ ret_t do_platform_op(XEN_GUEST_HANDLE(xe
             dprintk(XENLOG_INFO, "Domain 0 says that IO-APIC REGSEL is %s\n",
                     sis_apic_bug ? "bad" : "good");
 #else
-            BUG_ON(sis_apic_bug != (quirk_id == QUIRK_IOAPIC_BAD_REGSEL));
+            if ( sis_apic_bug != (quirk_id == QUIRK_IOAPIC_BAD_REGSEL) )
+                dprintk(XENLOG_WARNING,
+                        "Domain 0 thinks that IO-APIC REGSEL is %s\n",
+                        sis_apic_bug ? "good" : "bad");
 #endif
             break;
         default: