[kvm-unit-tests PATCH] x86: add HPET counter read micro benchmark and enable/disable torture tests

[Igor Mammedov <imammedo@redhat.com>]

test is to be used for benchmarking/validating HPET main counter read

how to run:
   QEMU=/foo/qemu-system-x86_64 x86/run x86/hpet_read_test.flat -smp X
where X is max number of logical CPUs on host

it will 1st execute concurrent read benchmark
and after that it will run torture test enabling/disabling HPET counter,
while running readers in parallel. Goal is to verify counter that always
goes up.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
this also will be used for testing upcomming HPET fain-grained
locking QEMU series  

---
 x86/Makefile.common  |  2 ++
 x86/hpet_read_test.c | 66 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)
 create mode 100644 x86/hpet_read_test.c

diff --git a/x86/Makefile.common b/x86/Makefile.common
index 5663a65d..ef0e09a6 100644
--- a/x86/Makefile.common
+++ b/x86/Makefile.common
@@ -101,6 +101,8 @@ tests-common += $(TEST_DIR)/realmode.$(exe) \
 realmode_bits := $(if $(call cc-option,-m16,""),16,32)
 endif
 
+tests-common += $(TEST_DIR)/hpet_read_test.$(exe)
+
 test_cases: $(tests-common) $(tests)
 
 $(TEST_DIR)/%.o: CFLAGS += -std=gnu99 -ffreestanding -I $(SRCDIR)/lib -I $(SRCDIR)/lib/x86 -I lib
diff --git a/x86/hpet_read_test.c b/x86/hpet_read_test.c
new file mode 100644
index 00000000..2f56ab6b
--- /dev/null
+++ b/x86/hpet_read_test.c
@@ -0,0 +1,66 @@
+#include "libcflat.h"
+#include "smp.h"
+
+#define HPET_ADDR         0xFED00000L
+#define HPET_COUNTER_ADDR ((uint8_t *)HPET_ADDR + 0xF0UL)
+#define HPET_CONFIG_ADDR  ((uint8_t *)HPET_ADDR + 0x10UL)
+#define HPET_ENABLE_BIT   0x01UL
+#define HPET_CLK_PERIOD   10
+
+static int fail = 0;
+static void hpet_reader(void *data)
+{
+    long cycles = (long)data;
+
+    while (cycles--) {
+        uint64_t old_counter = 0, new_counter;
+        new_counter = *(volatile uint64_t *)HPET_COUNTER_ADDR;
+        if (new_counter < old_counter) {
+            fail = 1;
+            report_abort("HPET counter jumped back");
+        }
+    }
+}
+
+
+static void hpet_writer(void *data)
+{
+    int i;
+    long cycles = (long)data;
+
+    for (i = 0; i < cycles; ++i)
+        if (i % 2)
+            *(volatile uint64_t *)HPET_CONFIG_ADDR |= HPET_ENABLE_BIT;
+        else
+            *(volatile uint64_t *)HPET_CONFIG_ADDR &= ~HPET_ENABLE_BIT;
+}
+
+int main(void)
+{
+    long cycles = 100000;
+    int i;
+    int ncpus;
+    uint64_t start, end, time_ns;
+
+    ncpus = cpu_count();
+    do {
+        printf("starting concurrent read bench on %d cpus\n", ncpus);
+        *(volatile uint64_t *)HPET_CONFIG_ADDR |= HPET_ENABLE_BIT;
+        start = *(volatile uint64_t *)HPET_COUNTER_ADDR;
+        on_cpus(hpet_reader, (void *)cycles);
+        end = (*(volatile uint64_t *)HPET_COUNTER_ADDR);
+        time_ns = (end - start) * HPET_CLK_PERIOD;
+        report(time_ns, "read test took %lu ms\n", time_ns/1000000);
+    } while (0);
+
+    do {
+        printf("starting enable/disable with concurent readers torture\n");
+        for (i = 2; i < ncpus; i++)
+            on_cpu_async(i, hpet_reader, (void *)cycles);
+
+        on_cpu(1, hpet_writer, (void *)cycles);
+    } while (0);
+
+    report(!fail, "passed torture test\n");
+    return report_summary();
+}
-- 
2.47.1