[XTF PATCH v1 10/15] x86: introduce simple time management

[dmukhin@xxxxxxxx]

From: Denis Mukhin <dmukhin@xxxxxxxx>

Some tests needs some estimation on certain operations longevity.

On x86 systems Xen conveniently exposes TSC frequency via
CPUID[ECX] 0x40000003.

Add TSC-based primitives into XTF to allow time measurements, including
TSC to time conversion routines.

Add common xtf_init_time() so that it can be called on demand if
the test needs time management.

Signed-off-by: Denis Mukhin <dmukhin@xxxxxxxx>
---
 arch/x86/include/arch/time.h | 48 ++++++++++++++++++++++++++++++++++++
 arch/x86/tsc.c               | 32 ++++++++++++++++++++++++
 build/files.mk               |  2 ++
 common/time.c                |  6 +++++
 include/xen/arch-x86/cpuid.h | 26 +++++++++++++++++++
 include/xtf/time.h           |  8 ++++++
 6 files changed, 122 insertions(+)
 create mode 100644 arch/x86/include/arch/time.h
 create mode 100644 arch/x86/tsc.c
 create mode 100644 common/time.c
 create mode 100644 include/xtf/time.h

diff --git a/arch/x86/include/arch/time.h b/arch/x86/include/arch/time.h
new file mode 100644
index 000000000000..3a244a2a6eda
--- /dev/null
+++ b/arch/x86/include/arch/time.h
@@ -0,0 +1,48 @@
+#ifndef __X86_TIME_H_
+#define __X86_TIME_H_
+
+#include <stdint.h>
+
+extern uint32_t tsc_khz;
+
+void arch_init_time(void);
+
+static inline uint64_t rdtsc_ordered(void)
+{
+    uint32_t lo, hi;
+
+    asm volatile (
+        "lfence;"
+        "rdtsc;"
+        : "=a" (lo), "=d" (hi)
+        :
+        : "memory"
+    );
+
+    return ((uint64_t)hi << 32) | lo;
+}
+
+static inline uint64_t cycles_to_time_units(uint64_t cycles, uint64_t mult)
+{
+    if ( !tsc_khz )
+        return 0;
+
+    return cycles * mult / tsc_khz;
+}
+
+static inline uint64_t cycles_to_ns(uint64_t cycles)
+{
+    return cycles_to_time_units(cycles, 1000000ULL);
+}
+
+static inline uint64_t cycles_to_us(uint64_t cycles)
+{
+    return cycles_to_time_units(cycles, 1000ULL);
+}
+
+static inline uint64_t cycles_to_ms(uint64_t cycles)
+{
+    return cycles_to_time_units(cycles, 1ULL);
+}
+
+#endif /* __X86_TIME_H_ */
diff --git a/arch/x86/tsc.c b/arch/x86/tsc.c
new file mode 100644
index 000000000000..93c4de197984
--- /dev/null
+++ b/arch/x86/tsc.c
@@ -0,0 +1,32 @@
+#include <arch/cpuid.h>
+#include <arch/time.h>
+
+#include <xtf.h>
+
+uint32_t tsc_khz;
+
+void arch_init_time(void)
+{
+    uint32_t eax, ebx, ecx, edx;
+    bool emulated, reliable;
+
+    cpuid_count(XEN_CPUID_LEAF(3), 0, &eax, &ebx, &ecx, &edx);
+
+    tsc_khz = ecx;
+    emulated = !!(eax & XEN_CPUID_TSC_EMULATED);
+    reliable = !!(eax & XEN_CPUID_HOST_TSC_RELIABLE);
+
+    printk("Xen TSC: emulated=%u reliable=%u mode=%u "
+           "guest=%u kHz incarnation=%u\n",
+           emulated, reliable,
+           ebx, ecx, edx);
+
+    cpuid_count(XEN_CPUID_LEAF(3), 2,
+                &eax, &ebx, &ecx, &edx);
+
+    printk("Xen TSC: host=%u kHz\n", eax);
+
+    if ( emulated || !reliable )
+        xtf_warning("Xen TSC: time measurements are not reliable\n");
+}
+
diff --git a/build/files.mk b/build/files.mk
index 8a7d6f8d588f..ad39c00751b7 100644
--- a/build/files.mk
+++ b/build/files.mk
@@ -14,6 +14,7 @@ obj-perbits += $(ROOT)/common/libc/string.o
 obj-perbits += $(ROOT)/common/libc/vsnprintf.o
 obj-perbits += $(ROOT)/common/report.o
 obj-perbits += $(ROOT)/common/setup.o
+obj-perbits += $(ROOT)/common/time.o
 obj-perbits += $(ROOT)/common/xenbus.o
 obj-perbits += $(ROOT)/common/weak-defaults.o
 
@@ -25,6 +26,7 @@ obj-perenv += $(ROOT)/arch/x86/hypercall_page.o
 obj-perenv += $(ROOT)/arch/x86/msr.o
 obj-perenv += $(ROOT)/arch/x86/setup.o
 obj-perenv += $(ROOT)/arch/x86/traps.o
+obj-perenv += $(ROOT)/arch/x86/tsc.o
 
 
 # HVM specific objects
diff --git a/common/time.c b/common/time.c
new file mode 100644
index 000000000000..c6e5136a1567
--- /dev/null
+++ b/common/time.c
@@ -0,0 +1,6 @@
+#include <xtf/time.h>
+
+void xtf_init_time(void)
+{
+    arch_init_time();
+}
diff --git a/include/xen/arch-x86/cpuid.h b/include/xen/arch-x86/cpuid.h
index 2fbc8eb656a0..9e1e7e6ac51b 100644
--- a/include/xen/arch-x86/cpuid.h
+++ b/include/xen/arch-x86/cpuid.h
@@ -15,6 +15,7 @@
  */
 
 #define XEN_CPUID_FIRST_LEAF 0x40000000
+#define XEN_CPUID_LEAF(i)    (XEN_CPUID_FIRST_LEAF + (i))
 
 /*
  * Leaf 1 (0x40000x00)
@@ -36,6 +37,31 @@
  * EDX: Features 2. Unused bits are set to zero.
  */
 
+/*
+ * Leaf 4 (0x40000x03)
+ * Sub-leaf 0: EAX: bit 0: emulated tsc
+ *                  bit 1: host tsc is known to be reliable
+ *                  bit 2: RDTSCP instruction available
+ *             EBX: tsc_mode: 0=default (emulate if necessary), 1=emulate,
+ *                            2=no emulation, 3=no emulation + TSC_AUX support
+ *             ECX: guest tsc frequency in kHz
+ *             EDX: guest tsc incarnation (migration count)
+ * Sub-leaf 1: EAX: tsc offset low part
+ *             EBX: tsc offset high part
+ *             ECX: multiplicator for tsc->ns conversion
+ *             EDX: shift amount for tsc->ns conversion
+ * Sub-leaf 2: EAX: host tsc frequency in kHz
+ */
+
+#define XEN_CPUID_TSC_EMULATED               (1u << 0)
+#define XEN_CPUID_HOST_TSC_RELIABLE          (1u << 1)
+#define XEN_CPUID_RDTSCP_INSTR_AVAIL         (1u << 2)
+
+#define XEN_CPUID_TSC_MODE_DEFAULT           (0)
+#define XEN_CPUID_TSC_MODE_ALWAYS_EMULATE    (1u)
+#define XEN_CPUID_TSC_MODE_NEVER_EMULATE     (2u)
+#define XEN_CPUID_TSC_MODE_PVRDTSCP          (3u)
+
 /*
  * Leaf 5 (0x40000x04)
  * HVM-specific features
diff --git a/include/xtf/time.h b/include/xtf/time.h
new file mode 100644
index 000000000000..1e5895122a34
--- /dev/null
+++ b/include/xtf/time.h
@@ -0,0 +1,8 @@
+#ifndef __XTF_TIME_H_
+#define __XTF_TIME_H_
+
+#include <arch/time.h>
+
+void xtf_init_time(void);
+
+#endif /* __XTF_TIME_H_ */
-- 
2.55.0