The test checks the relative precision of the reference TSC page
and the time reference counter.
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
x86/Makefile.x86_64 | 4 +-
x86/hyperv.h | 9 +++
x86/hyperv_clock.c | 209 ++++++++++++++++++++++++++++++++++++++++++++++++++++
x86/unittests.cfg | 5 ++
4 files changed, 226 insertions(+), 1 deletion(-)
create mode 100644 x86/hyperv_clock.c
diff --git a/x86/Makefile.x86_64 b/x86/Makefile.x86_64
index e166911..f82492b 100644
--- a/x86/Makefile.x86_64
+++ b/x86/Makefile.x86_64
@@ -10,11 +10,13 @@ tests = $(TEST_DIR)/access.flat $(TEST_DIR)/apic.flat \
$(TEST_DIR)/xsave.flat $(TEST_DIR)/rmap_chain.flat \
$(TEST_DIR)/pcid.flat $(TEST_DIR)/debug.flat \
$(TEST_DIR)/ioapic.flat $(TEST_DIR)/memory.flat \
- $(TEST_DIR)/pku.flat
+ $(TEST_DIR)/pku.flat $(TEST_DIR)/hyperv_clock.flat
tests += $(TEST_DIR)/svm.flat
tests += $(TEST_DIR)/vmx.flat
tests += $(TEST_DIR)/tscdeadline_latency.flat
include $(TEST_DIR)/Makefile.common
+$(TEST_DIR)/hyperv_clock.elf: $(TEST_DIR)/hyperv_clock.o
+
$(TEST_DIR)/vmx.elf: $(TEST_DIR)/vmx_tests.o
diff --git a/x86/hyperv.h b/x86/hyperv.h
index 434a933..bef0317 100644
--- a/x86/hyperv.h
+++ b/x86/hyperv.h
@@ -11,6 +11,7 @@
#define HV_X64_MSR_SYNTIMER_AVAILABLE (1 << 3)
#define HV_X64_MSR_TIME_REF_COUNT 0x40000020
+#define HV_X64_MSR_REFERENCE_TSC 0x40000021
/* Define synthetic interrupt controller model specific registers. */
#define HV_X64_MSR_SCONTROL 0x40000080
@@ -179,4 +180,12 @@ void synic_sint_create(int vcpu, int sint, int vec, bool auto_eoi);
void synic_sint_set(int vcpu, int sint);
void synic_sint_destroy(int vcpu, int sint);
+struct hv_reference_tsc_page {
+ uint32_t tsc_sequence;
+ uint32_t res1;
+ uint64_t tsc_scale;
+ int64_t tsc_offset;
+};
+
+
#endif
diff --git a/x86/hyperv_clock.c b/x86/hyperv_clock.c
new file mode 100644
index 0000000..8b1deba
--- /dev/null
+++ b/x86/hyperv_clock.c
@@ -0,0 +1,209 @@
+#include "libcflat.h"
+#include "smp.h"
+#include "atomic.h"
+#include "processor.h"
+#include "hyperv.h"
+#include "vm.h"
+
+#define MAX_CPU 4
+#define TICKS_PER_SEC (1000000000 / 100)
+
+struct hv_reference_tsc_page *hv_clock;
+
+/*
+ * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
+ * yielding a 64-bit result.
+ */
+static inline u64 scale_delta(u64 delta, u64 mul_frac)
+{
+ u64 product, unused;
+
+ __asm__ (
+ "mul %3"
+ : "=d" (product), "=a" (unused) : "1" (delta), "rm" ((u64)mul_frac) );
+
+ return product;
+}
+
+static u64 hvclock_tsc_to_ticks(struct hv_reference_tsc_page *shadow, uint64_t tsc)
+{
+ u64 delta = tsc;
+ return scale_delta(delta, shadow->tsc_scale) + shadow->tsc_offset;
+}
+
+/*
+ * Reads a consistent set of time-base values from hypervisor,
+ * into a shadow data area.
+ */
+static void hvclock_get_time_values(struct hv_reference_tsc_page *shadow,
+ struct hv_reference_tsc_page *page)
+{
+ int seq;
+ do {
+ seq = page->tsc_sequence;
+ rmb(); /* fetch version before data */
+ *shadow = *page;
+ rmb(); /* test version after fetching data */
+ } while (shadow->tsc_sequence != seq);
+}
+
+uint64_t hv_clock_read(void)
+{
+ struct hv_reference_tsc_page shadow;
+
+ hvclock_get_time_values(&shadow, hv_clock);
+ return hvclock_tsc_to_ticks(&shadow, rdtsc());
+}
+
+atomic_t cpus_left;
+bool ok[MAX_CPU];
+uint64_t loops[MAX_CPU];
+
+#define iabs(x) ((x) < 0 ? -(x) : (x))
+
+static void hv_clock_test(void *data)
+{
+ int i = smp_id();
+ uint64_t t = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
+ uint64_t end = t + 3 * TICKS_PER_SEC;
+ uint64_t msr_sample = t + TICKS_PER_SEC;
+ int min_delta = 123456, max_delta = -123456;
+ bool got_drift = false;
+ bool got_warp = false;
+
+ ok[i] = true;
+ do {
+ uint64_t now = hv_clock_read();
+ int delta = rdmsr(HV_X64_MSR_TIME_REF_COUNT) - now;
+
+ min_delta = delta < min_delta ? delta : min_delta;
+ if (t < msr_sample) {
+ max_delta = delta > max_delta ? delta: max_delta;
+ } else if (delta < 0 || delta > max_delta * 3 / 2) {
+ printf("suspecting drift on CPU %d? delta = %d, acceptable [0, %d)\n", smp_id(),
+ delta, max_delta);
+ ok[i] = false;
+ got_drift = true;
+ max_delta *= 2;
+ }
+
+ if (now < t && !got_warp) {
+ printf("warp on CPU %d!\n", smp_id());
+ ok[i] = false;
+ got_warp = true;
+ break;
+ }
+ t = now;
+ } while(t < end);
+
+ if (!got_drift)
+ printf("delta on CPU %d was %d...%d\n", smp_id(), min_delta, max_delta);
+ barrier();
+ atomic_dec(&cpus_left);
+}
+
+static void check_test(int ncpus)
+{
+ int i;
+ bool pass;
+
+ atomic_set(&cpus_left, ncpus);
+ for (i = ncpus - 1; i >= 0; i--)
+ on_cpu_async(i, hv_clock_test, NULL);
+
+ /* Wait for the end of other vcpu */
+ while(atomic_read(&cpus_left))
+ ;
+
+ pass = true;
+ for (i = ncpus - 1; i >= 0; i--)
+ pass &= ok[i];
+
+ report("TSC reference precision test", pass);
+}
+
+static void hv_perf_test(void *data)
+{
+ uint64_t t = hv_clock_read();
+ uint64_t end = t + 1000000000 / 100;
+ uint64_t local_loops = 0;
+
+ do {
+ t = hv_clock_read();
+ local_loops++;
+ } while(t < end);
+
+ loops[smp_id()] = local_loops;
+ atomic_dec(&cpus_left);
+}
+
+static void perf_test(int ncpus)
+{
+ int i;
+ uint64_t total_loops;
+
+ atomic_set(&cpus_left, ncpus);
+ for (i = ncpus - 1; i >= 0; i--)
+ on_cpu_async(i, hv_perf_test, NULL);
+
+ /* Wait for the end of other vcpu */
+ while(atomic_read(&cpus_left))
+ ;
+
+ total_loops = 0;
+ for (i = ncpus - 1; i >= 0; i--)
+ total_loops += loops[i];
+ printf("iterations/sec: %" PRId64"\n", total_loops / ncpus);
+}
+
+int main(int ac, char **av)
+{
+ int nerr = 0;
+ int ncpus;
+ struct hv_reference_tsc_page shadow;
+ uint64_t tsc1, t1, tsc2, t2;
+ uint64_t ref1, ref2;
+
+ setup_vm();
+ smp_init();
+
+ hv_clock = alloc_page();
+ wrmsr(HV_X64_MSR_REFERENCE_TSC, (u64)(uintptr_t)hv_clock | 1);
+ report("MSR value after enabling",
+ rdmsr(HV_X64_MSR_REFERENCE_TSC) == ((u64)(uintptr_t)hv_clock | 1));
+
+ hvclock_get_time_values(&shadow, hv_clock);
+ if (shadow.tsc_sequence == 0 || shadow.tsc_sequence == 0xFFFFFFFF) {
+ printf("Reference TSC page not available\n");
+ exit(1);
+ }
+
+ printf("scale: %" PRIx64" offset: %" PRId64"\n", shadow.tsc_scale, shadow.tsc_offset);
+ ref1 = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
+ tsc1 = rdtsc();
+ t1 = hvclock_tsc_to_ticks(&shadow, tsc1);
+ printf("refcnt %" PRId64", TSC %" PRIx64", TSC reference %" PRId64"\n",
+ ref1, tsc1, t1);
+
+ do
+ ref2 = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
+ while (ref2 < ref1 + 2 * TICKS_PER_SEC);
+
+ tsc2 = rdtsc();
+ t2 = hvclock_tsc_to_ticks(&shadow, tsc2);
+ printf("refcnt %" PRId64" (delta %" PRId64"), TSC %" PRIx64", "
+ "TSC reference %" PRId64" (delta %" PRId64")\n",
+ ref2, ref2 - ref1, tsc2, t2, t2 - t1);
+
+ ncpus = cpu_count();
+ if (ncpus > MAX_CPU)
+ ncpus = MAX_CPU;
+
+ check_test(ncpus);
+ perf_test(ncpus);
+
+ wrmsr(HV_X64_MSR_REFERENCE_TSC, 0LL);
+ report("MSR value after disabling", rdmsr(HV_X64_MSR_REFERENCE_TSC) == 0);
+
+ return nerr > 0 ? 1 : 0;
+}
diff --git a/x86/unittests.cfg b/x86/unittests.cfg
index f76f0d4..c932f11 100644
--- a/x86/unittests.cfg
+++ b/x86/unittests.cfg
@@ -201,3 +201,8 @@ extra_params = -cpu kvm64,hv_synic -device hyperv-testdev
file = hyperv_stimer.flat
smp = 2
extra_params = -cpu kvm64,hv_time,hv_synic,hv_stimer -device hyperv-testdev
+
+[hyperv_clock]
+file = hyperv_clock.flat
+smp = 2
+extra_params = -cpu kvm64,hv_time
--
1.8.3.1
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
