[PATCH 2/3] test: Add kvmclock driver

[Jason Wang <jasowang@redhat.com>]

This patch add a kvmclock driver for unittest. A special bit:
PV_CLOCK_CYCLE_RAW_TEST_BIT is used to notify the driver to return
just the raw cycle supplied by the hypervisor.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 kvm/test/x86/kvmclock.c |  206 +++++++++++++++++++++++++++++++++++++++++++++++
 kvm/test/x86/kvmclock.h |   51 ++++++++++++
 2 files changed, 257 insertions(+), 0 deletions(-)
 create mode 100644 kvm/test/x86/kvmclock.c
 create mode 100644 kvm/test/x86/kvmclock.h

diff --git a/kvm/test/x86/kvmclock.c b/kvm/test/x86/kvmclock.c
new file mode 100644
index 0000000..1520ea4
--- /dev/null
+++ b/kvm/test/x86/kvmclock.c
@@ -0,0 +1,206 @@
+#include "libcflat.h"
+#include "smp.h"
+#include "kvmclock.h"
+
+#define barrier() asm volatile("":::"memory")
+#define rmb() asm volatile("lfence":::"memory")
+
+struct pvclock_vcpu_time_info hv_clock[MAX_CPU];
+struct pvclock_wall_clock wall_clock;
+static unsigned char valid_flags = 0;
+static u64 __attribute__((aligned(8))) last_value = 0;
+
+#ifdef __i386__
+static inline u64 atomic64_read(const u64 *v)
+{
+    u64 res;
+
+    asm volatile("mov %%ebx, %%eax;"
+		 "mov %%ecx, %%edx;"
+		 "lock cmpxchg8b %1;"
+		 : "=&A" (res)
+		 : "m" (*v)
+		 );
+
+    return res;
+}
+
+static u64 atomic64_cmpxchg(u64 *v, u64 old, u64 new)
+{
+    u32 low = new;
+    u32 high = new >> 32;
+
+    asm volatile("lock cmpxchg8b %1\n"
+		 : "+A" (old), "+m" (*v)
+		 : "b" (low), "c" (high)
+		 );
+
+    return old;
+}
+#elif defined(__x86_64__)
+static inline u64 atomic64_read(const u64 *v)
+{
+    return (*(volatile long *)v);
+}
+
+static u64 atomic64_cmpxchg(u64 *v, u64 old, u64 new)
+{
+    u64 ret;
+    u64 _old = old;
+    u64 _new = new;
+
+    asm volatile("lock cmpxchgq %1,%2"
+		 : "=a" (ret)
+		 : "r" (_new), "m" (*(volatile long *)v), "0" (_old)
+		 : "memory"
+		 );
+    return ret;
+}
+#endif
+
+static void wrmsr(unsigned index, u64 value)
+{
+    unsigned a = value, d = value >> 32;
+    
+    asm volatile("wrmsr" : : "a"(a), "d"(d), "c"(index));
+}
+
+static u64 native_read_tsc(void)
+{
+    unsigned a, d;
+    
+    asm volatile("rdtsc" : "=a"(a), "=d"(d));
+    return a | (u64)d << 32;
+}
+
+static inline u64 scale_delta(u64 delta, u32 mul_frac, int shift)
+{
+    u64 product;
+#ifdef __i386__
+    u32 tmp1, tmp2;
+#endif
+    
+    if (shift < 0)
+	delta >>= -shift;
+    else
+	delta <<= shift;
+    
+#ifdef __i386__
+    __asm__ (
+	     "mul  %5       ; "
+	     "mov  %4,%%eax ; "
+	     "mov  %%edx,%4 ; "
+	     "mul  %5       ; "
+	     "xor  %5,%5    ; "
+	     "add  %4,%%eax ; "
+	     "adc  %5,%%edx ; "
+	     : "=A" (product), "=r" (tmp1), "=r" (tmp2)
+	     : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
+#elif defined(__x86_64__)
+    __asm__ (
+	     "mul %%rdx ; shrd $32,%%rdx,%%rax"
+	     : "=a" (product) : "0" (delta), "d" ((u64)mul_frac) );
+#else
+#error implement me!
+#endif
+    
+    return product;
+}
+
+static unsigned pvclock_get_time_values(struct pvclock_shadow_time *dst,
+					struct pvclock_vcpu_time_info *src)
+{
+    do {
+	dst->version = src->version;
+	rmb();		/* fetch version before data */
+	dst->tsc_timestamp     = src->tsc_timestamp;
+	dst->system_timestamp  = src->system_time;
+	dst->tsc_to_nsec_mul   = src->tsc_to_system_mul;
+	dst->tsc_shift         = src->tsc_shift;
+	dst->flags             = src->flags;
+	rmb();		/* test version after fetching data */
+    } while ((src->version & 1) || (dst->version != src->version));
+    
+    return dst->version;
+}
+
+static u64 pvclock_get_nsec_offset(struct pvclock_shadow_time *shadow)
+{
+    u64 delta = native_read_tsc() - shadow->tsc_timestamp;
+    return scale_delta(delta, shadow->tsc_to_nsec_mul, shadow->tsc_shift);
+}
+
+static cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src)
+{
+    struct pvclock_shadow_time shadow;
+    unsigned version;
+    cycle_t ret, offset;
+    u64 last;
+    
+    do {
+	version = pvclock_get_time_values(&shadow, src);
+	barrier();
+	offset = pvclock_get_nsec_offset(&shadow);
+	ret = shadow.system_timestamp + offset;
+	barrier();
+    } while (version != src->version);
+
+    if ((valid_flags & PVCLOCK_CYCLE_RAW_TEST_BIT) ||
+	((valid_flags & PVCLOCK_TSC_STABLE_BIT) &&
+	 (shadow.flags & PVCLOCK_TSC_STABLE_BIT)))
+	return ret;
+
+    last = atomic64_read(&last_value);
+    do {
+	if (ret < last)
+	    return last;
+	last = atomic64_cmpxchg(&last_value, last, ret);
+    } while (last != ret);
+    
+    return ret;
+}
+
+cycle_t kvm_clock_read()
+{
+    struct pvclock_vcpu_time_info *src;
+    cycle_t ret;
+    int index = smp_id();
+    
+    src = &hv_clock[index];
+    ret = pvclock_clocksource_read(src);
+    return ret;
+}
+
+void kvm_clock_init(void *data)
+{
+    int index = smp_id();
+    struct pvclock_vcpu_time_info *hvc = &hv_clock[index];
+
+    printf("kvm-clock: cpu %d, msr 0x:%lx \n", index, hvc);
+    wrmsr(MSR_KVM_SYSTEM_TIME, (unsigned long)hvc | 1);
+}
+
+void kvm_clock_clear(void *data)
+{
+    wrmsr(MSR_KVM_SYSTEM_TIME, 0LL);
+}
+
+void kvm_get_wallclock(struct timespec *ts)
+{
+    u32 version;
+    wrmsr(MSR_KVM_WALL_CLOCK, (u64)&wall_clock);
+
+    do {
+	version = wall_clock.version;
+	rmb();		/* fetch version before time */
+	ts->sec = wall_clock.sec;
+	ts->nsec = wall_clock.nsec;
+	rmb();		/* fetch time before checking version */
+    } while ((wall_clock.version & 1) || (version != wall_clock.version));	
+
+}
+
+void pvclock_set_flags(unsigned char flags)
+{
+    valid_flags = flags;
+}
diff --git a/kvm/test/x86/kvmclock.h b/kvm/test/x86/kvmclock.h
new file mode 100644
index 0000000..6cc545e
--- /dev/null
+++ b/kvm/test/x86/kvmclock.h
@@ -0,0 +1,51 @@
+#ifndef KVMCLOCK_H
+#define KVMCLOCK_H
+
+#define MSR_KVM_WALL_CLOCK  0x11
+#define MSR_KVM_SYSTEM_TIME 0x12
+
+#define MAX_CPU 4
+
+#define PVCLOCK_TSC_STABLE_BIT (1 << 0)
+#define PVCLOCK_CYCLE_RAW_TEST_BIT (1 << 1) /* Get raw cycle */
+
+typedef u64 cycle_t;
+
+struct pvclock_vcpu_time_info {
+    u32   version;
+    u32   pad0;
+    u64   tsc_timestamp;
+    u64   system_time;
+    u32   tsc_to_system_mul;
+    signed char    tsc_shift;
+    u8    flags;
+    u8    pad[2];
+} __attribute__((__packed__)); /* 32 bytes */
+
+struct pvclock_shadow_time {
+    u64 tsc_timestamp;     /* TSC at last update of time vals.  */
+    u64 system_timestamp;  /* Time, in nanosecs, since boot.    */
+    u32 tsc_to_nsec_mul;
+    int tsc_shift;
+    u32 version;
+    u8  flags;
+};
+
+struct pvclock_wall_clock {
+    u32   version;
+    u32   sec;
+    u32   nsec;
+} __attribute__((__packed__));
+
+struct timespec {
+    u32   sec;
+    u32   nsec;
+};
+
+void pvclock_set_flags(unsigned char flags);
+cycle_t kvm_clock_read();
+void kvm_get_wallclock(struct timespec *ts);
+void kvm_clock_init(void *data);
+void kvm_clock_clear(void *data);
+
+#endif