Don't fail on wrmsr(GS_BASE)

src/const.js

@@ -271,6 +271,9 @@ var MSR_SMI_COUNT = 0x34;
 /** @const */
 var IA32_MCG_CAP = 0x179;
 
+/** @const */
+var IA32_KERNEL_GS_BASE = 0xC0000101 | 0;
+
 /** @const */
 var MSR_PKG_C2_RESIDENCY = 0x60D;
 

src/instructions.js

@@ -2119,6 +2119,11 @@ t[0x30] = cpu => {
             // netbsd
             break;
 
+        case IA32_KERNEL_GS_BASE:
+            // Only used in 64 bit mode (by SWAPGS), but set by kvm-unit-test
+            dbg_log("GS Base written", LOG_CPU);
+            break;
+
         default:
             dbg_assert(false, "Unknown msr: " + h(index >>> 0, 8));
     }