From: Chang Bae <chang.bae@eecs.northwestern.edu>
Date: Wed, 20 Feb 2013 02:08:39 +0000 (-0600)
Subject: PMU Host Interface and initial implementation for Linux and AMD/Intel
X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?a=commitdiff_plain;h=17556749e79560e7254e5f40155926ce5cce5cab;p=palacios.releases.git

PMU Host Interface and initial implementation for Linux and AMD/Intel
---

diff --git a/linux_module/Makefile b/linux_module/Makefile
index 2236f81..3b8f699 100644
--- a/linux_module/Makefile
+++ b/linux_module/Makefile
@@ -33,6 +33,8 @@ v3vee-$(V3_CONFIG_HOST_DEVICE) += iface-host-dev.o
 v3vee-$(V3_CONFIG_GRAPHICS_CONSOLE) += iface-graphics-console.o
 v3vee-$(V3_CONFIG_EXT_MACH_CHECK) += mcheck.o
 
+v3vee-$(V3_CONFIG_HOST_PMU) += iface-pmu.o
+
 v3vee-$(V3_CONFIG_VNET) += 	palacios-vnet.o \
 				palacios-vnet-ctrl.o   \
 				palacios-vnet-brg.o
diff --git a/linux_module/iface-pmu-amd.h b/linux_module/iface-pmu-amd.h
new file mode 100644
index 0000000..c348c9c
--- /dev/null
+++ b/linux_module/iface-pmu-amd.h
@@ -0,0 +1,93 @@
+// Utility functions for AMD
+
+/*
+ * defines
+ */
+
+/*
+ * should be changed
+ *
+ *
+ */
+
+#define AMD_NUM_PMU_COUNTERS 4
+#define AMD_NUM_PMU_CONTROLS 4
+
+
+/*
+ * MSR OFFSETS FOR PMU RELATED:
+ */
+
+/*
+ * MSR_K7_EVNTSEL0-3 is in msr-index.h
+ *
+ * MSR_K7_PERFCTR0-3 is also in msr-index.h
+ */
+
+/*
+ * bit info according to AMD manual
+ performance monitoring counters: core performance event-select registers
+ *
+ */
+#define AMD_USR_BIT 16
+#define AMD_OS_BIT 17
+#define AMD_EDGE_BIT 18
+#define AMD_INT_BIT 20
+#define AMD_EN_BIT 22
+#define AMD_INV_BIT 23
+#define AMD_CMASK_BIT 24
+#define AMD_UMASK_BIT 8
+#define AMD_EVENT_BIT 0
+
+/*
+ * SOME MACROS
+ */
+
+#define AMD_CTR_READ(msrs, c) do {rdmsrl((MSR_K7_PERFCTR0 + (c)), (msrs).q);} while (0)
+#define AMD_CTR_WRITE(msrs, c) do {wrmsrl((MSR_K7_PERFCTR0 + (c)), (msrs).q);} while (0)
+
+#define AMD_CTRL_READ(msrs, c) do {rdmsrl((MSR_K7_EVNTSEL0 + (c)), (msrs).q);} while (0)
+#define AMD_CTRL_WRITE(msrs, c) \
+({ \
+	(msrs).q |= 0x1<<21; \
+	wrmsrl((MSR_K7_EVNTSEL0 + (c)), (msrs).q); \
+})
+
+// given even and mask, make it to track it on all ring levels
+#define AMD_CTRL_START(event, mask, i) \
+({  \
+	uint64_t tmp = 0x0; \
+	tmp |= (mask)<<AMD_UMASK_BIT; \
+	tmp |= (event)<<AMD_EVENT_BIT; \
+	tmp |= 0x3<<AMD_USR_BIT; \
+	tmp |= 0x1<<AMD_EN_BIT; \
+	wrmsrl((MSR_K7_EVNTSEL0 + (i)), tmp); \
+    	wrmsrl((MSR_K7_PERFCTR0 + (i)), 0x0); \
+})
+
+#define AMD_CTRL_STOP(i) do { wrmsrl((MSR_K7_EVNTSEL0 + (i)), 0x0); } while(0) \
+
+/*
+ * SELECTED PMU EVENTS AND UMASKS
+ * BIOS and Kernel Developer's Guid (BKDG) For AMD Family 11h Processors, July 2008
+ * 3.14 Performance Counter Events
+ *
+ */
+
+// CLK and INSTRUCTIONS events
+#define AMD_CLK_NOT_HALTED 0x76 // event
+#define AMD_RETIRED_INSTRUCTIONS 0xc0 // event
+
+// MEM INST events
+#define AMD_PREFETCH_INST_DISPATCHED 0x4B// event
+#define AMD_LOAD 0x1 // umask
+#define AMD_STORE 0x2 // umask
+
+// MEM LOAD events and umasks
+#define AMD_DATA_CACHE_ACCESSES 0x40 // event
+#define AMD_DATA_CACHE_MISSES 0x41 // event
+#define AMD_L1_DTLB_AND_L2_DTLB_MISS 0x46 // event
+
+// LLC MISSES events: per intel doc, it is advised to use this for perf measures
+//#define INTEL_LLC_MISSES 0x2E
+//#define INTEL_LLC_MISSES_UMASK 0x41
diff --git a/linux_module/iface-pmu-intel.h b/linux_module/iface-pmu-intel.h
new file mode 100644
index 0000000..2174d5c
--- /dev/null
+++ b/linux_module/iface-pmu-intel.h
@@ -0,0 +1,137 @@
+// Intel Utility Functions
+
+/*
+ * defines
+ */
+
+#define INTEL_IDX_INST_IN_FPMU 0
+#define INTEL_IDX_CLK_IN_FPMU 2
+
+/*
+ * REFERENCE CPU MODEL:
+ *   Intel Xeon E5620  (family_cpuid: 06_1CH)
+ *   Architectural Performance Monitoring Version: 3
+ *   Number of general-purpose performance counters: 4
+ *
+ */
+
+#define INTEL_NUM_PMU_COUNTERS 4
+#define INTEL_NUM_PMU_CONTROLS 4
+#define INTEL_NUM_FIXED_PMU_COUNTERS 3
+#define INTEL_NUM_PMU_GLOBAL 3
+
+/*
+ * NOTICE currently there are 7 counters in a total (IA32_PMC0-3 + IA32_FIXED_CTR0-2)
+ * but, only 4 of those are being used if you will
+ * since hard-programmed now for CPI and LLCache Miss Rate are only events that are requested
+ *
+ * define NUM_USED_COUNTERS 4 at vmm_pmu.h
+ */
+
+/*
+ * MSR OFFSETS FOR PMU RELATED:
+ */
+
+#define INTEL_IA32_PMC0 0xc1
+#define INTEL_IA32_PMC1 0xc2
+#define INTEL_IA32_PMC2 0xc3
+#define INTEL_IA32_PMC3 0xc4
+
+#define INTEL_IA32_PERFEVTSEL0 0x186
+#define INTEL_IA32_PERFEVTSEL1 0x187
+#define INTEL_IA32_PERFEVTSEL2 0x188
+#define INTEL_IA32_PERFEVTSEL3 0x189
+
+/*
+ * 0x309 INTEL_IA32_FIXED_CTR0: counts Instr_Retired.Any
+ * 0x30A INTEL_IA32_FIXED_CTR1: counts CPU_CLK_Unhalted.Core
+ * 0x30B INTEL_IA32_FIXED_CTR2: counts CPU_CLK_Unhalted.Ref
+ */
+#define INTEL_IA32_FIXED_CTR0 0x309
+#define INTEL_IA32_FIXED_CTR1 0x30a
+#define INTEL_IA32_FIXED_CTR2 0x30b
+
+#define INTEL_IA32_FIXED_CTR_CTRL 0x38d
+
+#define INTEL_IA32_PERF_GLOBAL_STATUS 0x38e
+#define INTEL_IA32_PERF_GLOBAL_CTRL 0x38f
+#define INTEL_IA32_PERF_GLOBAL_OVF_CTRL 0x390
+
+#define INTEL_IA32_PERF_GLOBAL_STATUS_ORDER 0
+#define INTEL_IA32_PERF_GLOBAL_CTRL_ORDER 1
+#define INTEL_IA32_PERF_GLOBAL_OVF_CTRL_ORDER 2
+
+// bit for relevant configs for PEREVTSEL (perf event selection)
+#define INTEL_USR_BIT 16
+#define INTEL_OS_BIT 17
+#define INTEL_EDGE_BIT 18
+#define INTEL_PIN_BIT 19
+#define INT_BIT 20
+#define INTEL_ANY_BIT 21
+#define INTEL_EN_BIT 22
+#define INTEL_INV_BIT 23
+#define INTEL_CMASK_BIT 24
+#define INTEL_UMASK_BIT 8
+#define INTEL_EVENT_BIT 0
+
+
+
+/*
+ * SOME MACROS
+ */
+
+#define INTEL_MSR_OFFSET_PERF(val) (val & 0x3)
+
+#define INTEL_CTR_READ(msrs, c) do {rdmsrl((INTEL_IA32_PMC0 + (c)), (msrs).q);} while (0)
+#define INTEL_CTR_WRITE(msrs, c) do {wrmsrl((INTEL_IA32_PMC0 + (c)), (msrs).q);} while (0)
+
+#define INTEL_FIXED_CTR_READ(msrs, c) do {rdmsrl((INTEL_IA32_FIXED_CTR0 + (c)), (msrs).q);} while (0)
+#define INTEL_FIXED_CTR_WRITE(msrs, c) do {wrmsrl((INTEL_IA32_FIXED_CTR0 + (c)), (msrs).q);} while (0)
+
+#define INTEL_CTRL_READ(msrs, c) do {rdmsrl((INTEL_IA32_PERFEVTSEL0 + (c)), (msrs).q);} while (0)
+#define INTEL_CTRL_WRITE(msrs, c) do {wrmsrl((INTEL_IA32_PERFEVTSEL0 + (c)), (msrs).q);} while (0)
+
+// given even and mask, make it to track it on all ring levels
+#define INTEL_CTRL_START(event, mask, i) \
+({  \
+	uint64_t tmp = 0x0; \
+	tmp |= (mask)<<INTEL_UMASK_BIT; \
+	tmp |= (event)<<INTEL_EVENT_BIT; \
+	tmp |= 0x3<<INTEL_USR_BIT; \
+	tmp |= 0x1<<INTEL_EN_BIT; \
+	wrmsrl((INTEL_IA32_PERFEVTSEL0 + (i)), tmp); \
+        wrmsrl((INTEL_IA32_PMC0 + (i)), 0x0); \
+})
+
+#define INTEL_CTRL_STOP(i) do { wrmsrl((INTEL_IA32_PERFEVTSEL0 + (i)), 0x0); } while(0) \
+
+#define INTEL_FIXED_CTRL_READ(msrs) do {rdmsrl(INTEL_IA32_FIXED_CTR_CTRL, (msrs).q);} while (0)
+#define INTEL_FIXED_CTRL_WRITE(msrs) do {wrmsrl(INTEL_IA32_FIXED_CTR_CTRL, (msrs).q);} while (0)
+
+/*
+ * SELECTED PMU EVENTS AND UMASKS
+ * Intel 64 and IA-32 Arthitectures Software Developer's Manual, Jan 2013
+ * Chap 19 Performance-Monitoring Events
+ */
+
+// CLK and INSTRUCTIONS events
+#define INTEL_CLK_NOT_HALTED 0x3C // event
+#define INTEL_RETIRED_INSTRUCTIONS 0xC0 // event
+
+// MEM INST events
+#define INTEL_MEM_INST_RETIRED 0x0B // event
+	#define INTEL_LOADS 0x1 // umask
+	#define INTEL_STORES 0x2 // umask
+
+// MEM LOAD events and umasks
+#define INTEL_MEM_LOAD_RETIRED 0xCB // event
+	#define INTEL_L1D_HIT 0x1 // umask
+	#define INTEL_L2_HIT 0x2 // umask
+	#define INTEL_L3_UNSHARED_HIT 0x4 // umask
+	#define INTEL_OTHER_CORE_L2_HIT_HITM 0x8 // umask
+	#define INTEL_L3_MISS 0x10 // umask
+	#define INTEL_HIT_LFB 0x40 // umask
+	#define INTEL_DTLB_MISS 0x80 // umask
+
+
+
diff --git a/linux_module/iface-pmu.c b/linux_module/iface-pmu.c
new file mode 100644
index 0000000..b85ed3f
--- /dev/null
+++ b/linux_module/iface-pmu.c
@@ -0,0 +1,658 @@
+/*
+ * PMU
+ * (c) Chang S. Bae, 2013
+ */
+
+#include <linux/cdev.h>
+#include <linux/errno.h>
+#include <asm/msr.h>
+#include <asm/msr-index.h>
+
+#include <palacios/vmm_types.h>
+#include <palacios/vmm_util.h>
+#include <interfaces/vmm_pmu.h>
+
+#include "vm.h"
+#include "palacios.h"
+#include "iface-pmu-intel.h"
+#include "iface-pmu-amd.h"
+#include "util-queue.h"
+#include "linux-exts.h"
+
+
+// Number of inits/deinits we have seen (inc on init, dec on deinit)
+// This is per CPU - init/deinit mean init/deinit PMU
+// tracking ON THE CURRENT CORE
+static DEFINE_PER_CPU(u32, pmu_refcount) = 0;
+
+
+/*
+ * some macros may be commonly used
+ */
+#define MSR_READ(msrs, c) do {rdmsrl((c), (msrs).q);} while (0)
+#define MSR_WRITE(msrs, c) do {wrmsrl((c), (msrs).q);} while (0)
+#define SET_BIT(val, i) ((val) |= (1 << i))
+#define CLEAR_BIT(val, u, i) ((val) &= ~((u&1) << i))
+#define SET_BYTE(val, u, i) ((val) |= ((u&255) << i))
+#define CHECK_BIT(val, i) ((val) & (1U << i))
+
+
+static inline void cpuid_string(u32 id, u32 dest[4]) {
+  asm volatile("cpuid"
+	       :"=a"(dest),"=b"(*(dest+1)),"=c"(*(dest+2)),"=d"(*(dest+3))
+	       :"a"(id));
+}
+
+
+static int get_cpu_vendor(char name[13])
+{
+  u32 dest[4];
+  u32 maxid;
+
+  cpuid_string(0,dest);
+  maxid=dest[0];
+  ((u32*)name)[0]=dest[1];
+  ((u32*)name)[1]=dest[3];
+  ((u32*)name)[2]=dest[2];
+  name[12]=0;
+   
+  return maxid;
+}
+
+static int is_intel(void)
+{
+  char name[13];
+  get_cpu_vendor(name);
+  return !strcmp(name,"GenuineIntel");
+}
+
+static int is_amd(void)
+{
+  char name[13];
+  get_cpu_vendor(name);
+  return !strcmp(name,"AuthenticAMD");
+}
+
+
+
+/*
+ * AMD and Intel implementations are distinguished by prefix: INTEL or AMD
+ */
+
+/*
+ * name: *_get_slot
+ * description: check available slots in pmu
+ * return: -1 if none, else returns index: 0 ... 3
+ */
+
+static int intel_get_slot(void) {
+
+  int i, slot;
+  struct msr control;
+
+  slot = -1;
+  control.q = 0x0;
+
+  for (i=0; i<INTEL_NUM_PMU_CONTROLS; i++) {
+    INTEL_CTRL_READ(control, i);
+    if(control.q & (0x1<<INTEL_EN_BIT)) {
+      continue;
+    } else {
+      slot = i;
+      break;
+    }
+  }
+
+  return slot;
+}
+
+static int amd_get_slot(void) {
+  int i, slot;
+  struct msr control;
+
+  slot = -1;
+  control.q = 0x0;
+
+  for (i=0; i<AMD_NUM_PMU_CONTROLS; i++) {
+    AMD_CTRL_READ(control, i);
+    if(control.q & (0x1<<AMD_EN_BIT)) {
+      continue;
+    } else {
+      slot = i;
+      break;
+    }
+  }
+
+  return slot;
+  return -1;
+}
+
+/*
+ * name: *_find_idx
+ * description: find index of pmu register that is available
+ */
+static int intel_find_idx(uint8_t event, uint8_t mask) {
+  int i;
+
+  struct msr control;
+
+  control.q = 0x0;
+
+  for (i=0; i<INTEL_NUM_PMU_COUNTERS; i++) {
+    INTEL_CTRL_READ(control, i);
+    if((((control.l>>INTEL_EVENT_BIT) & 0xff) == event) &&
+       (((control.l>>INTEL_UMASK_BIT) & 0xff) == mask)) {
+      return i;
+    }
+  }
+
+  return -1;
+}
+
+
+/*
+ * following implementations : init, deinit, start_tracking, stop_track and get_value
+ * specifically fit into the pmu interface
+ */
+
+static uint64_t intel_get_value(v3_pmon_ctr_t ctr) {
+  /*
+   * local variables
+   */
+  int ctr_idx;
+  struct msr count;
+
+  count.q = 0x0;
+
+  switch(ctr) {
+  case V3_PMON_CLOCK_COUNT:
+    INTEL_FIXED_CTR_READ(count, INTEL_IDX_CLK_IN_FPMU);
+    break;
+  case V3_PMON_RETIRED_INST_COUNT:
+    INTEL_FIXED_CTR_READ(count, INTEL_IDX_INST_IN_FPMU);
+    break;
+  case V3_PMON_MEM_LOAD_COUNT:
+    if((ctr_idx = intel_find_idx(INTEL_MEM_INST_RETIRED, INTEL_LOADS)) >= 0) {
+      INTEL_CTR_READ(count, ctr_idx);
+    } else {
+      goto INTEL_READ_FAILED;
+    }
+    break;
+  case V3_PMON_MEM_STORE_COUNT:
+    if((ctr_idx = intel_find_idx(INTEL_MEM_INST_RETIRED, INTEL_STORES)) >= 0) {
+      INTEL_CTR_READ(count, ctr_idx);
+    } else {
+      goto INTEL_READ_FAILED;
+    }
+    break;
+  case V3_PMON_CACHE_MISS_COUNT:
+    if((ctr_idx = intel_find_idx(INTEL_MEM_LOAD_RETIRED, INTEL_L3_MISS)) >= 0) {
+      INTEL_CTR_READ(count, ctr_idx);
+    } else {
+      goto INTEL_READ_FAILED;
+    }
+    break;
+  case V3_PMON_TLB_MISS_COUNT:
+    if((ctr_idx = intel_find_idx(INTEL_MEM_LOAD_RETIRED, INTEL_DTLB_MISS)) >= 0) {
+      INTEL_CTR_READ(count, ctr_idx);
+    } else {
+      goto INTEL_READ_FAILED;
+    }
+    break;
+  }
+
+  return (uint64_t)count.q;
+
+ INTEL_READ_FAILED:
+  return 0;
+}
+
+
+static int intel_start_tracking(v3_pmon_ctr_t ctr) {
+  /*
+   * local variables
+   */
+  int ctr_idx;
+  struct msr msrs;
+
+  /*
+   * check if available slot in PMU, except for fixed counters (Intel specific)
+   */
+
+  switch(ctr) {
+  case V3_PMON_CLOCK_COUNT:
+    INTEL_FIXED_CTRL_READ(msrs);
+    msrs.l |= 0x3<<8;
+    INTEL_FIXED_CTRL_WRITE(msrs);
+    break;
+  case V3_PMON_RETIRED_INST_COUNT:
+    INTEL_FIXED_CTRL_READ(msrs);
+    msrs.l |= 0x3;
+    INTEL_FIXED_CTRL_WRITE(msrs);
+    break;
+  case V3_PMON_MEM_LOAD_COUNT:
+    if((ctr_idx = intel_get_slot()) >= 0) {
+      INTEL_CTRL_START(INTEL_MEM_INST_RETIRED, INTEL_LOADS, ctr_idx);
+    } else {
+      goto INTEL_START_FAILED;
+    }
+    break;
+  case V3_PMON_MEM_STORE_COUNT:
+    if((ctr_idx = intel_get_slot()) >= 0) {
+      INTEL_CTRL_START(INTEL_MEM_INST_RETIRED, INTEL_STORES, ctr_idx);
+    } else {
+      goto INTEL_START_FAILED;
+    }
+    break;
+  case V3_PMON_CACHE_MISS_COUNT:
+    if((ctr_idx = intel_get_slot()) >= 0) {
+      INTEL_CTRL_START(INTEL_MEM_LOAD_RETIRED, INTEL_L3_MISS, ctr_idx);
+    } else {
+      goto INTEL_START_FAILED;
+    }
+    break;
+  case V3_PMON_TLB_MISS_COUNT:
+    if((ctr_idx = intel_get_slot()) >= 0) {
+      INTEL_CTRL_START(INTEL_MEM_LOAD_RETIRED, INTEL_DTLB_MISS, ctr_idx);
+    } else {
+      goto INTEL_START_FAILED;
+    }
+    break;
+  }
+
+  return 0;
+
+ INTEL_START_FAILED:
+  ERROR("ERROR: no more slot remains for pmon events\n");
+  return -1;
+}
+
+/*
+ * descript: disabling pmu event counts
+ */
+
+static int intel_stop_tracking(v3_pmon_ctr_t ctr) {
+  /*
+   * local variables
+   */
+  int ctr_idx = -1;
+  struct msr msrs;
+
+  /*
+   * check if available slot in PMU, except
+   */
+
+  switch(ctr) {
+  case V3_PMON_CLOCK_COUNT:
+    INTEL_FIXED_CTRL_READ(msrs);
+    msrs.l &= ~(0xf<<8);
+    INTEL_FIXED_CTRL_WRITE(msrs);
+    break;
+  case V3_PMON_RETIRED_INST_COUNT:
+    INTEL_FIXED_CTRL_READ(msrs);
+    msrs.l &= ~(0xf);
+    INTEL_FIXED_CTRL_WRITE(msrs);
+    break;
+  case V3_PMON_MEM_LOAD_COUNT:
+    if((ctr_idx = intel_find_idx(INTEL_MEM_INST_RETIRED, INTEL_LOADS)) >= 0) {
+      INTEL_CTRL_STOP(ctr_idx);
+    } else {
+      goto INTEL_STOP_FAILED;
+    }
+    break;
+  case V3_PMON_MEM_STORE_COUNT:
+    if((ctr_idx = intel_find_idx(INTEL_MEM_INST_RETIRED, INTEL_STORES)) >= 0) {
+      INTEL_CTRL_STOP(ctr_idx);
+    } else {
+      goto INTEL_STOP_FAILED;
+    }
+    break;
+  case V3_PMON_CACHE_MISS_COUNT:
+    if((ctr_idx = intel_find_idx(INTEL_MEM_LOAD_RETIRED, INTEL_L3_MISS)) >= 0) {
+      INTEL_CTRL_STOP(ctr_idx);
+    } else {
+      goto INTEL_STOP_FAILED;
+    }
+    break;
+  case V3_PMON_TLB_MISS_COUNT:
+    if((ctr_idx = intel_find_idx(INTEL_MEM_LOAD_RETIRED, INTEL_DTLB_MISS)) >= 0) {
+      INTEL_CTRL_STOP(ctr_idx);
+    } else {
+      goto INTEL_STOP_FAILED;
+    }
+    break;
+  }
+
+  return 0;
+
+ INTEL_STOP_FAILED:
+  ERROR("ERROR: no more slot remains for pmon events\n");
+  return -1;
+}
+
+static void intel_pmu_init(void) {
+  int i;
+  struct msr control;
+
+  if ((get_cpu_var(pmu_refcount)++) > 1) {
+    put_cpu_var(pmu_refcount);
+    // only the first init clears the pmu
+    return;
+  }
+  put_cpu_var(pmu_refcount);
+    
+
+  control.q=0x0;
+
+  /*
+   * per Intel PMU architecture,
+   * there are two class of counters
+   * fixed ones (3 counters) and programmable ones (4 counters)
+   * events for fixed coutners are determined, so enabling or not is the option
+   * whereas, programmable ones are litterally programmable.
+   */
+
+  /*
+   * enable fixed counters in global
+   */
+  MSR_READ(control, INTEL_IA32_PERF_GLOBAL_CTRL);
+  control.q |= 0x70000000f; // enable fix counters (3 for the intel model)
+  MSR_WRITE(control, INTEL_IA32_PERF_GLOBAL_CTRL);
+
+  /*
+   * disable in fixed counters control
+   */
+
+  INTEL_FIXED_CTRL_WRITE(control);
+
+  /*
+   * clean up programmable counter control
+   */
+  for (i=0; i<INTEL_NUM_PMU_CONTROLS; i++) {
+    INTEL_CTRL_WRITE(control, i);
+  }
+}
+
+static void intel_pmu_deinit(void) {
+  if ((get_cpu_var(pmu_refcount)--)==0) {
+    put_cpu_var(pmu_refcount);
+    // actually deinit
+  }
+  put_cpu_var(pmu_refcount);
+}
+
+
+
+
+
+static int amd_find_idx(uint8_t event, uint8_t mask) {
+  int i;
+
+  struct msr control;
+
+  control.q = 0x0;
+
+  for (i=0; i<AMD_NUM_PMU_COUNTERS; i++) {
+    AMD_CTRL_READ(control, i);
+    if((((control.l>>AMD_EVENT_BIT) & 0xff) == event) &&
+       (((control.l>>AMD_UMASK_BIT) & 0xff) == mask)) {
+      return i;
+    }
+  }
+
+  return -1;
+}
+
+
+static uint64_t amd_get_value(v3_pmon_ctr_t ctr) {
+  int ctr_idx;
+  struct msr count;
+
+  count.q = 0x0;
+
+  switch(ctr) {
+  case V3_PMON_CLOCK_COUNT:
+    if((ctr_idx = amd_find_idx(AMD_CLK_NOT_HALTED, 0x0)) >= 0) {
+      AMD_CTR_READ(count, ctr_idx);
+    } else {
+      goto AMD_READ_FAILED;
+    }
+    break;
+  case V3_PMON_RETIRED_INST_COUNT:
+    if((ctr_idx = amd_find_idx(AMD_RETIRED_INSTRUCTIONS, 0x0)) >= 0) {
+      AMD_CTR_READ(count, ctr_idx);
+    } else {
+      goto AMD_READ_FAILED;
+    }
+    break;
+  case V3_PMON_MEM_LOAD_COUNT:
+    if((ctr_idx = amd_find_idx(AMD_PREFETCH_INST_DISPATCHED, AMD_LOAD)) >= 0) {
+      AMD_CTR_READ(count, ctr_idx);
+    } else {
+      goto AMD_READ_FAILED;
+    }
+    break;
+  case V3_PMON_MEM_STORE_COUNT:
+    if((ctr_idx = amd_find_idx(AMD_PREFETCH_INST_DISPATCHED, AMD_STORE)) >= 0) {
+      AMD_CTR_READ(count, ctr_idx);
+    } else {
+      goto AMD_READ_FAILED;
+    }
+    break;
+  case V3_PMON_CACHE_MISS_COUNT:
+    if((ctr_idx = amd_find_idx(AMD_DATA_CACHE_MISSES, 0x0)) >= 0) {
+      AMD_CTR_READ(count, ctr_idx);
+    } else {
+      goto AMD_READ_FAILED;
+    }
+    break;
+  case V3_PMON_TLB_MISS_COUNT:
+    if((ctr_idx = amd_find_idx(AMD_L1_DTLB_AND_L2_DTLB_MISS, 0x0)) >= 0) {
+      AMD_CTR_READ(count, ctr_idx);
+    } else {
+      goto AMD_READ_FAILED;
+    }
+    break;
+  }
+
+  return (uint64_t)count.q;
+
+ AMD_READ_FAILED:
+  return 0;
+}
+
+static int amd_start_tracking(v3_pmon_ctr_t ctr) {
+
+  int ctr_idx;
+
+  switch(ctr) {
+  case V3_PMON_CLOCK_COUNT:
+    if((ctr_idx = amd_get_slot()) >= 0) {
+      AMD_CTRL_START(AMD_CLK_NOT_HALTED, 0x0, ctr_idx);
+    } else {
+      goto AMD_START_FAILED;
+    }
+    break;
+  case V3_PMON_RETIRED_INST_COUNT:
+    if((ctr_idx = amd_get_slot()) >= 0) {
+      AMD_CTRL_START(AMD_RETIRED_INSTRUCTIONS, 0x0, ctr_idx);
+    } else {
+      goto AMD_START_FAILED;
+    }
+    break;
+  case V3_PMON_MEM_LOAD_COUNT:
+    if((ctr_idx = amd_get_slot()) >= 0) {
+      AMD_CTRL_START(AMD_PREFETCH_INST_DISPATCHED, AMD_LOAD, ctr_idx);
+    } else {
+      goto AMD_START_FAILED;
+    }
+    break;
+  case V3_PMON_MEM_STORE_COUNT:
+    if((ctr_idx = amd_get_slot()) >= 0) {
+      AMD_CTRL_START(AMD_PREFETCH_INST_DISPATCHED, AMD_STORE, ctr_idx);
+    } else {
+      goto AMD_START_FAILED;
+    }
+    break;
+  case V3_PMON_CACHE_MISS_COUNT:
+    if((ctr_idx = amd_get_slot()) >= 0) {
+      AMD_CTRL_START(AMD_DATA_CACHE_MISSES, 0x0, ctr_idx);
+    } else {
+      goto AMD_START_FAILED;
+    }
+    break;
+  case V3_PMON_TLB_MISS_COUNT:
+    if((ctr_idx = amd_get_slot()) >= 0) {
+      AMD_CTRL_START(AMD_L1_DTLB_AND_L2_DTLB_MISS, 0x0, ctr_idx);
+    } else {
+      goto AMD_START_FAILED;
+    }
+    break;
+  }
+
+  return 0;
+
+ AMD_START_FAILED:
+  ERROR("ERROR: no more slot remains for pmon events\n");
+  return -1;
+}
+
+
+static int amd_stop_tracking(v3_pmon_ctr_t ctr) {
+
+  int ctr_idx = -1;
+
+
+  switch(ctr) {
+  case V3_PMON_CLOCK_COUNT:
+    if((ctr_idx = amd_find_idx(AMD_CLK_NOT_HALTED, 0x0)) >= 0) {
+      AMD_CTRL_STOP(ctr_idx);
+    } else {
+      goto AMD_STOP_FAILED;
+    }
+    break;
+  case V3_PMON_RETIRED_INST_COUNT:
+    if((ctr_idx = amd_find_idx(AMD_RETIRED_INSTRUCTIONS, 0x0)) >= 0) {
+      AMD_CTRL_STOP(ctr_idx);
+    } else {
+      goto AMD_STOP_FAILED;
+    }
+    break;
+  case V3_PMON_MEM_LOAD_COUNT:
+    if((ctr_idx = amd_find_idx(AMD_PREFETCH_INST_DISPATCHED, AMD_LOAD)) >= 0) {
+      AMD_CTRL_STOP(ctr_idx);
+    } else {
+      goto AMD_STOP_FAILED;
+    }
+    break;
+  case V3_PMON_MEM_STORE_COUNT:
+    if((ctr_idx = amd_find_idx(AMD_PREFETCH_INST_DISPATCHED, AMD_STORE)) >= 0) {
+      AMD_CTRL_STOP(ctr_idx);
+    } else {
+      goto AMD_STOP_FAILED;
+    }
+    break;
+  case V3_PMON_CACHE_MISS_COUNT:
+    if((ctr_idx = amd_find_idx(AMD_DATA_CACHE_MISSES, 0x0)) >= 0) {
+      AMD_CTRL_STOP(ctr_idx);
+    } else {
+      goto AMD_STOP_FAILED;
+    }
+    break;
+  case V3_PMON_TLB_MISS_COUNT:
+    if((ctr_idx = amd_find_idx(AMD_L1_DTLB_AND_L2_DTLB_MISS, 0x0)) >= 0) {
+      AMD_CTRL_STOP(ctr_idx);
+    } else {
+      goto AMD_STOP_FAILED;
+    }
+    break;
+  }
+
+  return 0;
+
+ AMD_STOP_FAILED:
+  ERROR("ERROR: no more slot remains for pmon events\n");
+  return -1;
+}
+
+
+static void amd_pmu_init(void) {
+
+  int i;
+  struct msr control;
+
+  
+  if ((get_cpu_var(pmu_refcount)++) > 1) {
+    put_cpu_var(pmu_refcount);
+    // only the first init clears the pmu
+    return;
+  }
+  put_cpu_var(pmu_refcount);
+  
+  
+
+  // initialize variables
+  control.q=0x0;
+
+  /*
+   * clean up programmable counter control
+   */
+  for (i=0; i<AMD_NUM_PMU_CONTROLS; i++) {
+    AMD_CTRL_WRITE(control, i);
+  }
+}
+
+static void amd_pmu_deinit(void) {
+  if ((get_cpu_var(pmu_refcount)--)==0) {
+    put_cpu_var(pmu_refcount);
+    // actually deinit
+  }
+  put_cpu_var(pmu_refcount);
+}
+
+
+static struct v3_pmu_iface palacios_pmu_intel = {
+  .init = intel_pmu_init,
+  .deinit = intel_pmu_deinit,
+  .start_tracking = intel_start_tracking,
+  .stop_tracking = intel_stop_tracking,
+  .get_value = intel_get_value
+};
+
+static struct v3_pmu_iface palacios_pmu_amd = {
+  .init = amd_pmu_init,
+  .deinit = amd_pmu_deinit,
+  .start_tracking = amd_start_tracking,
+  .stop_tracking = amd_stop_tracking,
+  .get_value = amd_get_value
+};
+
+static int pmu_init( void ) {
+  if (is_intel()) {
+    INFO("Intel PMU featureset detected\n");
+    V3_Init_PMU(&palacios_pmu_intel);
+  } else if (is_amd()) { 
+    INFO("AMD PMU featureset detected\n");
+    V3_Init_PMU(&palacios_pmu_amd);
+  } else {
+    ERROR("This is neither an Intel nor AMD machine - No PMU functionality configured\n");
+    return -1;
+  }
+
+  return 0;
+}
+
+
+static struct linux_ext pmu_ext = {
+  .name = "PMU",
+  .init = pmu_init,
+  .deinit = NULL,
+  .guest_init = NULL,
+  .guest_deinit = NULL
+};
+
+register_extension(&pmu_ext);
+
+
+
+
diff --git a/palacios/include/interfaces/vmm_pmu.h b/palacios/include/interfaces/vmm_pmu.h
new file mode 100644
index 0000000..74beb5a
--- /dev/null
+++ b/palacios/include/interfaces/vmm_pmu.h
@@ -0,0 +1,89 @@
+/*
+ * This file is part of the Palacios Virtual Machine Monitor developed
+ * by the V3VEE Project with funding from the United States National
+ * Science Foundation and the Department of Energy.
+ *
+ * The V3VEE Project is a joint project between Northwestern University
+ * and the University of New Mexico.  You can find out more at
+ * http://www.v3vee.org
+ *
+ * Copyright (c) 2013, The V3VEE Project <http://www.v3vee.org>
+ * All rights reserved.
+ *
+ * Author: Chang S. Bae <chang.bae@eecs.northwestern.edu>
+ *
+ * This is free software.  You are permitted to use,
+ * redistribute, and modify it as specified in the file "V3VEE_LICENSE".
+ */
+
+#ifndef __VMM_PMU
+#define __VMM_PMU
+
+#include <palacios/vmm_types.h>
+
+/*
+ * defines
+ */
+
+/*
+ * The following is the set of performance
+ * counters available in Palacios.  The implementation
+ * of the interface translates these names to
+ * the underlying counters needed on the specific platform
+ */
+typedef enum {
+  V3_PMON_RETIRED_INST_COUNT=0,
+  V3_PMON_CLOCK_COUNT,
+  V3_PMON_MEM_LOAD_COUNT,
+  V3_PMON_MEM_STORE_COUNT,
+  V3_PMON_CACHE_MISS_COUNT,
+  V3_PMON_TLB_MISS_COUNT
+
+  //V3_PMON_TLB_INVALIDATION_COUNT
+  /* you can add more here, but then need to implement them
+     in the interface */
+
+} v3_pmon_ctr_t;
+
+
+struct v3_pmu_iface {
+    /* init/deinit pmu data on the core on which it is called */
+
+
+    void  (*init)(void);
+    void  (*deinit)(void);
+
+    // Request tracking of a counter, returns -1 if it is not possible
+    int (*start_tracking)(v3_pmon_ctr_t ctr);
+    // Get the counter value, provided it being tracked
+    uint64_t (*get_value)(v3_pmon_ctr_t ctr);
+    // Stop tracking a counter
+    int (*stop_tracking)(v3_pmon_ctr_t ctr);
+
+};
+
+
+/*
+ *  function prototypes
+ */
+
+extern void V3_Init_PMU(struct v3_pmu_iface * palacios_pmu);
+
+#ifdef __V3VEE__
+
+/* This is a PER PHYSICAL CORE init/deinit */
+void v3_pmu_init(void);
+
+// Call these after an init
+int v3_pmu_start_tracking(v3_pmon_ctr_t ctr);
+int v3_pmu_stop_tracking(v3_pmon_ctr_t ctr);
+uint64_t v3_pmu_get_value(v3_pmon_ctr_t ctr);
+
+// Call this after you are done with the PMU
+void v3_pmu_deinit(void);
+
+
+
+#endif
+
+#endif
diff --git a/palacios/src/interfaces/Kconfig b/palacios/src/interfaces/Kconfig
index 5f86790..7535376 100644
--- a/palacios/src/interfaces/Kconfig
+++ b/palacios/src/interfaces/Kconfig
@@ -1,7 +1,7 @@
 menu "Host Interfaces"
 
 config FILE
-        bool "Host Support for file operations"
+        bool "Host support for file operations"
         default n
         help
           Select this if your host OS supports file operatoins and you want Palacios to be able to use them.
@@ -14,19 +14,21 @@ config KEYED_STREAMS
           Palacios Checkpoint/Restore and Migration depends on this feature
 
 config STREAM
-	bool "Stream support"
+	bool "Host support for streams"
 	default n
-
+    help
+        Select this if your host OS supports streams
+        Palacios serial ports and similar functions depend on this feature
           
 config CONSOLE
-	bool "Host Support for VM text-mode console"
+	bool "Host support for VM text-mode console"
         default n
         help
           Select this if you want to forward a guest console interface to some host OS service
           This is for a TEXT MODE console.   Select the framebuffer console for graphics and text
             
 config GRAPHICS_CONSOLE
-        bool "Host Support for VM graphics and text-mode console based on a frame buffer"
+        bool "Host support for VM graphics and text-mode console based on a frame buffer"
         default n
 	help
           Select this if you want to forward a guest graphics-mode (and text-mode) console
@@ -51,7 +53,7 @@ config PACKET
 
 
 config HOST_PCI
-	bool "Host PCI Support"
+	bool "Host PCI support"
 	depends on EXPERIMENTAL
 	default y
 	help 
@@ -73,4 +75,10 @@ config HOST_HYPERCALL
           to register host-based implementations of hypercalls,
           for example, implemented in Linux kernel modules
 
+config HOST_PMU
+       bool "Host PMU support"
+       default n
+       help
+          Select this if you would like to access performance
+          counters (the PMU) within Palacios
 endmenu
diff --git a/palacios/src/interfaces/Makefile b/palacios/src/interfaces/Makefile
index c04193f..d0c7aa2 100644
--- a/palacios/src/interfaces/Makefile
+++ b/palacios/src/interfaces/Makefile
@@ -8,6 +8,7 @@ obj-$(V3_CONFIG_KEYED_STREAMS) += vmm_keyed_stream.o
 obj-$(V3_CONFIG_HOST_DEVICE) += vmm_host_dev.o
 obj-$(V3_CONFIG_HOST_HYPERCALL) += vmm_host_hypercall.o
 obj-$(V3_CONFIG_HOST_PCI) += host_pci.o
+obj-$(V3_CONFIG_HOST_PMU) += vmm_pmu.o
 
 obj-y += null.o
 
diff --git a/palacios/src/interfaces/vmm_pmu.c b/palacios/src/interfaces/vmm_pmu.c
new file mode 100644
index 0000000..a9b2fe1
--- /dev/null
+++ b/palacios/src/interfaces/vmm_pmu.c
@@ -0,0 +1,102 @@
+/* 
+ * This file is part of the Palacios Virtual Machine Monitor developed
+ * by the V3VEE Project with funding from the United States National 
+ * Science Foundation and the Department of Energy.  
+ *
+ * The V3VEE Project is a joint project between Northwestern University
+ * and the University of New Mexico.  You can find out more at 
+ * http://www.v3vee.org
+ *
+ * Copyright (c) 2013, The V3VEE Project <http://www.v3vee.org> 
+ * All rights reserved.
+ *
+ * Author: Chang S. Bae  <chang.bae@eecs.northwestern.edu>
+ * 
+ * This is free software.  You are permitted to use,
+ * redistribute, and modify it as specified in the file "V3VEE_LICENSE".
+ */
+
+
+#include <palacios/vmm.h>
+#include <palacios/vmm_debug.h>
+#include <palacios/vmm_types.h>
+#include <palacios/vm_guest.h>
+#include <palacios/vmm_lowlevel.h>
+#include <interfaces/vmm_pmu.h>
+
+struct v3_pmu_iface * palacios_pmu = 0;
+
+/*
+ * functions
+ */
+
+/*
+ * description: init pmu through the interface on this core
+ */
+
+void v3_pmu_init(void) {
+
+    V3_ASSERT(VM_NONE, VCORE_NONE, palacios_pmu != NULL);
+    V3_ASSERT(VM_NONE, VCORE_NONE, palacios_pmu->init != NULL);
+
+    palacios_pmu->init();
+}
+
+/*
+ * description: actually stop pmu running through the interface
+ *              on this core
+ */
+void v3_pmu_deinit(void) {
+
+    V3_ASSERT(VM_NONE, VCORE_NONE, palacios_pmu != NULL);
+    V3_ASSERT(VM_NONE, VCORE_NONE, palacios_pmu->deinit != NULL);
+
+    palacios_pmu->deinit();
+}
+
+/*
+ * description: init pmu through the interface
+ */
+
+int v3_pmu_start_tracking(v3_pmon_ctr_t ctr) {
+
+    V3_ASSERT(VM_NONE, VCORE_NONE, palacios_pmu != NULL);
+    V3_ASSERT(VM_NONE, VCORE_NONE, palacios_pmu->start_tracking != NULL);
+
+    return palacios_pmu->start_tracking(ctr);
+}
+
+/*
+ * description: actually stop pmu running through the interface
+ */
+int v3_pmu_stop_tracking(v3_pmon_ctr_t ctr) {
+
+    V3_ASSERT(VM_NONE, VCORE_NONE, palacios_pmu != NULL);
+    V3_ASSERT(VM_NONE, VCORE_NONE, palacios_pmu->stop_tracking != NULL);
+
+    return palacios_pmu->stop_tracking(ctr);
+}
+
+/*
+ * description: actually stop pmu running through the interface
+ */
+uint64_t v3_pmu_get_value(v3_pmon_ctr_t ctr) {
+
+    V3_ASSERT(VM_NONE, VCORE_NONE, palacios_pmu != NULL);
+    V3_ASSERT(VM_NONE, VCORE_NONE, palacios_pmu->get_value != NULL);
+
+    return palacios_pmu->get_value(ctr);
+}
+
+
+/*
+ * description: init whole interface to pmu 
+ */
+
+void V3_Init_PMU(struct v3_pmu_iface * pmu_iface) {
+    palacios_pmu = pmu_iface;
+
+    return;
+}
+
+