[PATCH kvm-unit-tests v2 8/8] Add tests for kvm-clock

[Jason Wang <jasowang@redhat.com>]

This patch implements three tests for kvmclock. First one check whether
the date of time returned by kvmclock matches the value got from
host. Second one check whether the cycle of kvmclock grows
monotonically in smp guest and the count of warps and stalls are also
recorded. The last test is a performance test to measure the guest
cycles cost when trying to read cycle of kvmclock.

Three parameters were accepted by the test: test loops, seconds
since 1970-01-01 00:00:00 UTC which could be easily get through date
+%s and the max accepted offset value between the tod of guest and
host.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 config-x86-common.mak |    6 +-
 x86/README            |    1 
 x86/kvmclock_test.c   |  166 +++++++++++++++++++++++++++++++++++++++++++++++++
 x86/unittests.cfg     |    5 +
 4 files changed, 177 insertions(+), 1 deletions(-)
 create mode 100644 x86/kvmclock_test.c

diff --git a/config-x86-common.mak b/config-x86-common.mak
index b8ca859..b541c1c 100644
--- a/config-x86-common.mak
+++ b/config-x86-common.mak
@@ -26,7 +26,8 @@ FLATLIBS = lib/libcflat.a $(libgcc)
 tests-common = $(TEST_DIR)/vmexit.flat $(TEST_DIR)/tsc.flat \
                $(TEST_DIR)/smptest.flat  $(TEST_DIR)/port80.flat \
                $(TEST_DIR)/realmode.flat $(TEST_DIR)/msr.flat \
-               $(TEST_DIR)/hypercall.flat $(TEST_DIR)/sieve.flat
+               $(TEST_DIR)/hypercall.flat $(TEST_DIR)/sieve.flat \
+               $(TEST_DIR)/kvmclock_test.flat
 
 tests_and_config = $(TEST_DIR)/*.flat $(TEST_DIR)/unittests.cfg
 
@@ -70,6 +71,9 @@ $(TEST_DIR)/rmap_chain.flat: $(cstart.o) $(TEST_DIR)/rmap_chain.o \
 
 $(TEST_DIR)/svm.flat: $(cstart.o) $(TEST_DIR)/vm.o
 
+$(TEST_DIR)/kvmclock_test.flat: $(cstart.o) $(TEST_DIR)/kvmclock.o \
+                                $(TEST_DIR)/kvmclock_test.o
+
 arch_clean:
 	$(RM) $(TEST_DIR)/*.o $(TEST_DIR)/*.flat \
 	$(TEST_DIR)/.*.d $(TEST_DIR)/lib/.*.d $(TEST_DIR)/lib/*.o
diff --git a/x86/README b/x86/README
index ab5a2ae..215fb2f 100644
--- a/x86/README
+++ b/x86/README
@@ -12,3 +12,4 @@ sieve: heavy memory access with no paging and with paging static and with paging
 smptest: run smp_id() on every cpu and compares return value to number
 tsc: write to tsc(0) and write to tsc(100000000000) and read it back
 vmexit: long loops for each: cpuid, vmcall, mov_from_cr8, mov_to_cr8, inl_pmtimer, ipi, ipi+halt
+kvmclock_test: test of wallclock, monotonic cycle and performance of kvmclock
diff --git a/x86/kvmclock_test.c b/x86/kvmclock_test.c
new file mode 100644
index 0000000..5b14ae2
--- /dev/null
+++ b/x86/kvmclock_test.c
@@ -0,0 +1,166 @@
+#include "libcflat.h"
+#include "smp.h"
+#include "atomic.h"
+#include "processor.h"
+#include "kvmclock.h"
+
+#define DEFAULT_TEST_LOOPS 100000000L
+#define DEFAULT_THRESHOLD  5L
+
+struct test_info {
+        struct spinlock lock;
+        long loops;               /* test loops */
+        u64 warps;                /* warp count */
+        u64 stalls;               /* stall count */
+        long long worst;          /* worst warp */
+        volatile cycle_t last;    /* last cycle seen by test */
+        atomic_t ncpus;           /* number of cpu in the test*/
+        int check;                /* check cycle ? */
+};
+
+struct test_info ti[4];
+
+static int wallclock_test(long sec, long threshold)
+{
+        long ksec, offset;
+        struct timespec ts;
+
+        printf("Wallclock test, threshold %ld\n", threshold);
+        kvm_get_wallclock(&ts);
+        ksec = ts.tv_sec;
+
+        offset = ksec - sec;
+        printf("Seconds get from host:     %ld\n", sec);
+        printf("Seconds get from kvmclock: %ld\n", ksec);
+        printf("Offset:                    %ld\n", offset);
+
+        if (offset > threshold || offset < -threshold) {
+                printf("offset too large!\n");
+                return 1;
+        }
+
+        return 0;
+}
+
+static void kvm_clock_test(void *data)
+{
+        struct test_info *hv_test_info = (struct test_info *)data;
+        long i, check = hv_test_info->check;
+
+        for (i = 0; i < hv_test_info->loops; i++){
+                cycle_t t0, t1;
+                long long delta;
+
+                if (check == 0) {
+                        kvm_clock_read();
+                        continue;
+                }
+
+                spin_lock(&hv_test_info->lock);
+                t1 = kvm_clock_read();
+                t0 = hv_test_info->last;
+                hv_test_info->last = kvm_clock_read();
+                spin_unlock(&hv_test_info->lock);
+
+                delta = t1 - t0;
+                if (delta < 0) {
+                        spin_lock(&hv_test_info->lock);
+                        ++hv_test_info->warps;
+                        if (delta < hv_test_info->worst){
+                                hv_test_info->worst = delta;
+                                printf("Worst warp %lld %\n", hv_test_info->worst);
+                        }
+                        spin_unlock(&hv_test_info->lock);
+                }
+                if (delta == 0)
+                        ++hv_test_info->stalls;
+
+                if (!((unsigned long)i & 31))
+                        asm volatile("rep; nop");
+        }
+
+        atomic_dec(&hv_test_info->ncpus);
+}
+
+static int cycle_test(int ncpus, long loops, int check, struct test_info *ti)
+{
+        int i;
+        unsigned long long begin, end;
+
+        begin = rdtsc();
+
+        atomic_set(&ti->ncpus, ncpus);
+        ti->loops = loops;
+        ti->check = check;
+        for (i = ncpus - 1; i >= 0; i--)
+                on_cpu_async(i, kvm_clock_test, (void *)ti);
+
+        /* Wait for the end of other vcpu */
+        while(atomic_read(&ti->ncpus))
+                ;
+
+        end = rdtsc();
+
+        printf("Total vcpus: %d\n", ncpus);
+        printf("Test  loops: %ld\n", ti->loops);
+        if (check == 1) {
+                printf("Total warps:  %lld\n", ti->warps);
+                printf("Total stalls: %lld\n", ti->stalls);
+                printf("Worst warp:   %lld\n", ti->worst);
+        } else
+                printf("TSC cycles:  %lld\n", end - begin);
+
+        return ti->warps ? 1 : 0;
+}
+
+int main(int ac, char **av)
+{
+        int ncpus = cpu_count();
+        int nerr = 0, i;
+        long loops = DEFAULT_TEST_LOOPS;
+        long sec = 0;
+        long threshold = DEFAULT_THRESHOLD;
+
+        if (ac > 1)
+                loops = atol(av[1]);
+        if (ac > 2)
+                sec = atol(av[2]);
+        if (ac > 3)
+                threshold = atol(av[3]);
+
+        smp_init();
+
+        if (ncpus > MAX_CPU)
+                ncpus = MAX_CPU;
+        for (i = 0; i < ncpus; ++i)
+                on_cpu(i, kvm_clock_init, (void *)0);
+
+        if (ac > 2)
+                nerr += wallclock_test(sec, threshold);
+
+        printf("Check the stability of raw cycle ...\n");
+        pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT
+                          | PVCLOCK_RAW_CYCLE_BIT);
+        if (cycle_test(ncpus, loops, 1, &ti[0]))
+                printf("Raw cycle is not stable\n");
+        else
+                printf("Raw cycle is stable\n");
+
+        pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
+        printf("Monotonic cycle test:\n");
+        nerr += cycle_test(ncpus, loops, 1, &ti[1]);
+
+        printf("Measure the performance of raw cycle ...\n");
+        pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT
+                          | PVCLOCK_RAW_CYCLE_BIT);
+        cycle_test(ncpus, loops, 0, &ti[2]);
+
+        printf("Measure the performance of adjusted cycle ...\n");
+        pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
+        cycle_test(ncpus, loops, 0, &ti[3]);
+
+        for (i = 0; i < ncpus; ++i)
+                on_cpu(i, kvm_clock_clear, (void *)0);
+
+        return nerr > 0 ? 1 : 0;
+}
diff --git a/x86/unittests.cfg b/x86/unittests.cfg
index 7796e41..228ac1d 100644
--- a/x86/unittests.cfg
+++ b/x86/unittests.cfg
@@ -63,3 +63,8 @@ extra_params = -enable-nesting -cpu qemu64,+svm
 file = svm.flat
 smp = 2
 extra_params = -cpu qemu64,-svm
+
+[kvmclock_test]
+file = kvmclock_test.flat
+smp = 2
+extra_params = --append "10000000 `date +%s`"