Merge pull request #311 from rn/up

vmm: Hide host cpuid 0x15 TSC/Crystal ratio/freq info from guest

Author: djs55

src/include/xhyve/vmm/x86.h

@@ -40,6 +40,7 @@
 #define	CPUID_0000_000A	(0xA)
 #define	CPUID_0000_000B	(0xB)
 #define	CPUID_0000_000D	(0xD)
+#define CPUID_0000_0015 (0x15)
 #define CPUID_8000_0000	(0x80000000)
 #define CPUID_8000_0001	(0x80000001)
 #define CPUID_8000_0002	(0x80000002)

src/lib/vmm/x86.c

@@ -439,6 +439,18 @@ x86_emulate_cpuid(struct vm *vm, int vcpu_id,
 			}
 			break;
 
+		case CPUID_0000_0015:
+			/*
+			 * Don't report CPU TSC/Crystal ratio and clock
+			 * values since guests may use these to derive the
+			 * local APIC frequency..
+			 */
+			regs[0] = 0;
+			regs[1] = 0;
+			regs[2] = 0;
+			regs[3] = 0;
+			break;
+
 		case 0x40000000:
 			regs[0] = CPUID_VM_HIGH;
 			bcopy(bhyve_id, &regs[1], 4);