Index: sys/x86/x86/tsc.c
===================================================================
--- sys/x86/x86/tsc.c	(revision 221188)
+++ sys/x86/x86/tsc.c	(working copy)
@@ -32,6 +32,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/param.h>
 #include <sys/bus.h>
 #include <sys/cpu.h>
+#include <sys/limits.h>
 #include <sys/malloc.h>
 #include <sys/systm.h>
 #include <sys/sysctl.h>
@@ -90,6 +91,77 @@ static struct timecounter tsc_timecounter = {
 	800,			/* quality (adjusted in code) */
 };
 
+#define	VMW_HVMAGIC		0x564d5868
+#define	VMW_HVPORT		0x5658
+#define	VMW_HVCMD_GETVERSION	10
+#define	VMW_HVCMD_GETHZ		45
+
+static __inline void
+vmware_hvcall(u_int cmd, u_int *p)
+{
+
+	__asm __volatile("inl (%%dx)"
+	: "=a" (p[0]), "=b" (p[1]), "=c" (p[2]), "=d" (p[3])
+	: "0" (VMW_HVMAGIC), "1" (UINT_MAX), "2" (cmd), "3" (VMW_HVPORT)
+	: "memory");
+}
+
+static int
+tsc_freq_vmware(void)
+{
+	char hv_sig[13];
+	u_int regs[4];
+	char *p;
+	u_int hv_high;
+	int i;
+
+	/*
+	 * [RFC] CPUID usage for interaction between Hypervisors and Linux.
+	 * http://lkml.org/lkml/2008/10/1/246
+	 *
+	 * KB1009458: Mechanisms to determine if software is running in
+	 * a VMware virtual machine
+	 * http://kb.vmware.com/kb/1009458
+	 */
+	hv_high = 0;
+	if ((cpu_feature2 & CPUID2_HV) != 0) {
+		do_cpuid(0x40000000, regs);
+		hv_high = regs[0];
+		for (i = 1, p = hv_sig; i < 4; i++, p += sizeof(regs) / 4)
+			memcpy(p, &regs[i], sizeof(regs[i]));
+		*p = '\0';
+		if (bootverbose)
+			printf("Hypervisor detected (\"%s\")\n", hv_sig);
+		if (strncmp(hv_sig, "VMwareVMware", sizeof(hv_sig) - 1) != 0)
+			return (0);
+	} else {
+		p = getenv("smbios.system.serial");
+		if (p == NULL)
+			return (0);
+		if (strncmp(p, "VMware-", 7) != 0) {
+			freeenv(p);
+			return (0);
+		}
+		freeenv(p);
+		vmware_hvcall(VMW_HVCMD_GETVERSION, regs);
+		if (regs[1] != VMW_HVMAGIC)
+			return (0);
+	}
+	if (hv_high >= 0x40000010) {
+		do_cpuid(0x40000010, regs);
+		tsc_freq = regs[0] * 1000;
+	} else {
+		vmware_hvcall(VMW_HVCMD_GETHZ, regs);
+		if (regs[1] != UINT_MAX)
+			tsc_freq = regs[0] | ((uint64_t)regs[1] << 32);
+	}
+	tsc_is_invariant = 1;
+#ifdef SMP
+	smp_tsc = 1;
+#endif
+	return (1);
+}
+
 static void
 tsc_freq_intel(void)
 {
@@ -102,7 +174,6 @@ tsc_freq_intel(void)
 	/*
 	 * Intel Processor Identification and the CPUID Instruction
 	 * Application Note 485.
-	 *
 	 * http://www.intel.com/assets/pdf/appnote/241618.pdf
 	 */
 	if (cpu_exthigh >= 0x80000004) {
@@ -156,6 +227,25 @@ probe_tsc_freq(void)
 	u_int regs[4];
 	uint64_t tsc1, tsc2;
 
+	if (cpu_high >= 6) {
+		do_cpuid(6, regs);
+		if ((regs[2] & CPUID_PERF_STAT) != 0) {
+			/*
+			 * XXX Some emulators expose host CPUID without actual
+			 * support for these MSRs.  We must test whether they
+			 * really work.
+			 */
+			wrmsr(MSR_MPERF, 0);
+			wrmsr(MSR_APERF, 0);
+			DELAY(10);
+			if (rdmsr(MSR_MPERF) > 0 && rdmsr(MSR_APERF) > 0)
+				tsc_perf_stat = 1;
+		}
+	}
+
+	if (tsc_freq_vmware())
+		return;
+
 	switch (cpu_vendor_id) {
 	case CPU_VENDOR_AMD:
 		if ((amd_pminfo & AMDPM_TSC_INVARIANT) != 0 ||
@@ -181,22 +271,6 @@ probe_tsc_freq(void)
 		break;
 	}
 
-	if (cpu_high >= 6) {
-		do_cpuid(6, regs);
-		if ((regs[2] & CPUID_PERF_STAT) != 0) {
-			/*
-			 * XXX Some emulators expose host CPUID without actual
-			 * support for these MSRs.  We must test whether they
-			 * really work.
-			 */
-			wrmsr(MSR_MPERF, 0);
-			wrmsr(MSR_APERF, 0);
-			DELAY(10);
-			if (rdmsr(MSR_MPERF) > 0 && rdmsr(MSR_APERF) > 0)
-				tsc_perf_stat = 1;
-		}
-	}
-
 	if (tsc_skip_calibration) {
 		if (cpu_vendor_id == CPU_VENDOR_INTEL)
 			tsc_freq_intel();