Introduce a new selftest for Hyper-V clocksources (MSR-based reference TSC
and TSC page). As a starting point, test the following:
1) Reference TSC is 1Ghz clock.
2) Reference TSC and TSC page give the same reading.
3) TSC page gets updated upon KVM_SET_CLOCK call.
4) TSC page does not get updated when guest opted for reenlightenment.
5) Disabled TSC page doesn't get updated.
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
tools/testing/selftests/kvm/.gitignore | 1 +
tools/testing/selftests/kvm/Makefile | 1 +
.../selftests/kvm/x86_64/hyperv_clock.c | 233 ++++++++++++++++++
3 files changed, 235 insertions(+)
create mode 100644 tools/testing/selftests/kvm/x86_64/hyperv_clock.c
diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 32b87cc77c8e..22be05c55f13 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -9,6 +9,7 @@
/x86_64/evmcs_test
/x86_64/get_cpuid_test
/x86_64/kvm_pv_test
+/x86_64/hyperv_clock
/x86_64/hyperv_cpuid
/x86_64/mmio_warning_test
/x86_64/platform_info_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index a6d61f451f88..c3672e9087d3 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -41,6 +41,7 @@ LIBKVM_s390x = lib/s390x/processor.c lib/s390x/ucall.c lib/s390x/diag318_test_ha
TEST_GEN_PROGS_x86_64 = x86_64/cr4_cpuid_sync_test
TEST_GEN_PROGS_x86_64 += x86_64/evmcs_test
TEST_GEN_PROGS_x86_64 += x86_64/get_cpuid_test
+TEST_GEN_PROGS_x86_64 += x86_64/hyperv_clock
TEST_GEN_PROGS_x86_64 += x86_64/hyperv_cpuid
TEST_GEN_PROGS_x86_64 += x86_64/kvm_pv_test
TEST_GEN_PROGS_x86_64 += x86_64/mmio_warning_test
diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_clock.c b/tools/testing/selftests/kvm/x86_64/hyperv_clock.c
new file mode 100644
index 000000000000..39d6491d8458
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_clock.c
@@ -0,0 +1,233 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2021, Red Hat, Inc.
+ *
+ * Tests for Hyper-V clocksources
+ */
+#include "test_util.h"
+#include "kvm_util.h"
+#include "processor.h"
+
+struct ms_hyperv_tsc_page {
+ volatile u32 tsc_sequence;
+ u32 reserved1;
+ volatile u64 tsc_scale;
+ volatile s64 tsc_offset;
+} __packed;
+
+#define HV_X64_MSR_GUEST_OS_ID 0x40000000
+#define HV_X64_MSR_TIME_REF_COUNT 0x40000020
+#define HV_X64_MSR_REFERENCE_TSC 0x40000021
+#define HV_X64_MSR_TSC_FREQUENCY 0x40000022
+#define HV_X64_MSR_REENLIGHTENMENT_CONTROL 0x40000106
+#define HV_X64_MSR_TSC_EMULATION_CONTROL 0x40000107
+
+/* Simplified mul_u64_u64_shr() */
+static inline u64 mul_u64_u64_shr64(u64 a, u64 b)
+{
+ union {
+ u64 ll;
+ struct {
+ u32 low, high;
+ } l;
+ } rm, rn, rh, a0, b0;
+ u64 c;
+
+ a0.ll = a;
+ b0.ll = b;
+
+ rm.ll = (u64)a0.l.low * b0.l.high;
+ rn.ll = (u64)a0.l.high * b0.l.low;
+ rh.ll = (u64)a0.l.high * b0.l.high;
+
+ rh.l.low = c = rm.l.high + rn.l.high + rh.l.low;
+ rh.l.high = (c >> 32) + rh.l.high;
+
+ return rh.ll;
+}
+
+static inline void nop_loop(void)
+{
+ int i;
+
+ for (i = 0; i < 1000000; i++)
+ asm volatile("nop");
+}
+
+static inline void check_tsc_msr_rdtsc(void)
+{
+ u64 tsc_freq, r1, r2, t1, t2;
+ s64 delta_ns;
+
+ tsc_freq = rdmsr(HV_X64_MSR_TSC_FREQUENCY);
+ GUEST_ASSERT(tsc_freq > 0);
+
+ /* First, check MSR-based clocksource */
+ r1 = rdtsc();
+ t1 = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
+ nop_loop();
+ r2 = rdtsc();
+ t2 = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
+
+ GUEST_ASSERT(t2 > t1);
+
+ /* HV_X64_MSR_TIME_REF_COUNT is in 100ns */
+ delta_ns = ((t2 - t1) * 100) - ((r2 - r1) * 1000000000 / tsc_freq);
+ if (delta_ns < 0)
+ delta_ns = -delta_ns;
+
+ /* 1% tolerance */
+ GUEST_ASSERT(delta_ns * 100 < (t2 - t1) * 100);
+}
+
+static inline void check_tsc_msr_tsc_page(struct ms_hyperv_tsc_page *tsc_page)
+{
+ u64 r1, r2, t1, t2;
+ s64 delta_ns;
+
+ /* Compare TSC page clocksource with HV_X64_MSR_TIME_REF_COUNT */
+ t1 = mul_u64_u64_shr64(rdtsc(), tsc_page->tsc_scale) + tsc_page->tsc_offset;
+ r1 = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
+ nop_loop();
+ t2 = mul_u64_u64_shr64(rdtsc(), tsc_page->tsc_scale) + tsc_page->tsc_offset;
+ r2 = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
+
+ delta_ns = ((r2 - r1) - (t2 - t1)) * 100;
+ if (delta_ns < 0)
+ delta_ns = -delta_ns;
+
+ /* 1% tolerance */
+ GUEST_ASSERT(delta_ns * 100 < (t2 - t1) * 100);
+}
+
+static void guest_main(struct ms_hyperv_tsc_page *tsc_page, vm_paddr_t tsc_page_gpa)
+{
+ u64 tsc_scale, tsc_offset;
+
+ /* Set Guest OS id to enable Hyper-V emulation */
+ GUEST_SYNC(1);
+ wrmsr(HV_X64_MSR_GUEST_OS_ID, (u64)0x8100 << 48);
+ GUEST_SYNC(2);
+
+ check_tsc_msr_rdtsc();
+
+ GUEST_SYNC(3);
+
+ /* Set up TSC page is disabled state, check that it's clean */
+ wrmsr(HV_X64_MSR_REFERENCE_TSC, tsc_page_gpa);
+ GUEST_ASSERT(tsc_page->tsc_sequence == 0);
+ GUEST_ASSERT(tsc_page->tsc_scale == 0);
+ GUEST_ASSERT(tsc_page->tsc_offset == 0);
+
+ GUEST_SYNC(4);
+
+ /* Set up TSC page is enabled state */
+ wrmsr(HV_X64_MSR_REFERENCE_TSC, tsc_page_gpa | 0x1);
+ GUEST_ASSERT(tsc_page->tsc_sequence != 0);
+
+ GUEST_SYNC(5);
+
+ check_tsc_msr_tsc_page(tsc_page);
+
+ GUEST_SYNC(6);
+
+ tsc_offset = tsc_page->tsc_offset;
+ /* Call KVM_SET_CLOCK from userspace, check that TSC page was updated */
+ GUEST_SYNC(7);
+ GUEST_ASSERT(tsc_page->tsc_offset != tsc_offset);
+
+ nop_loop();
+
+ /*
+ * Enable Re-enlightenment and check that TSC page stays constant across
+ * KVM_SET_CLOCK.
+ */
+ wrmsr(HV_X64_MSR_REENLIGHTENMENT_CONTROL, 0x1 << 16 | 0xff);
+ wrmsr(HV_X64_MSR_TSC_EMULATION_CONTROL, 0x1);
+ tsc_offset = tsc_page->tsc_offset;
+ tsc_scale = tsc_page->tsc_scale;
+ GUEST_SYNC(8);
+ GUEST_ASSERT(tsc_page->tsc_offset == tsc_offset);
+ GUEST_ASSERT(tsc_page->tsc_scale == tsc_scale);
+
+ GUEST_SYNC(9);
+
+ check_tsc_msr_tsc_page(tsc_page);
+
+ /*
+ * Disable re-enlightenment and TSC page, check that KVM doesn't update
+ * it anymore.
+ */
+ wrmsr(HV_X64_MSR_REENLIGHTENMENT_CONTROL, 0);
+ wrmsr(HV_X64_MSR_TSC_EMULATION_CONTROL, 0);
+ wrmsr(HV_X64_MSR_REFERENCE_TSC, 0);
+ memset(tsc_page, 0, sizeof(*tsc_page));
+
+ GUEST_SYNC(10);
+ GUEST_ASSERT(tsc_page->tsc_sequence == 0);
+ GUEST_ASSERT(tsc_page->tsc_offset == 0);
+ GUEST_ASSERT(tsc_page->tsc_scale == 0);
+
+ GUEST_DONE();
+}
+
+#define VCPU_ID 0
+
+int main(void)
+{
+ struct kvm_vm *vm;
+ struct kvm_run *run;
+ struct ucall uc;
+ vm_vaddr_t tsc_page_gva;
+ int stage;
+
+ vm = vm_create_default(VCPU_ID, 0, guest_main);
+ run = vcpu_state(vm, VCPU_ID);
+
+ vcpu_set_hv_cpuid(vm, VCPU_ID);
+
+ tsc_page_gva = vm_vaddr_alloc(vm, getpagesize(), 0x10000, 0, 0);
+ memset(addr_gpa2hva(vm, tsc_page_gva), 0x0, getpagesize());
+ TEST_ASSERT((addr_gva2gpa(vm, tsc_page_gva) & (getpagesize() - 1)) == 0,
+ "TSC page has to be page aligned\n");
+ vcpu_args_set(vm, VCPU_ID, 2, tsc_page_gva, addr_gva2gpa(vm, tsc_page_gva));
+
+ for (stage = 1;; stage++) {
+ _vcpu_run(vm, VCPU_ID);
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+ "Stage %d: unexpected exit reason: %u (%s),\n",
+ stage, run->exit_reason,
+ exit_reason_str(run->exit_reason));
+
+ switch (get_ucall(vm, VCPU_ID, &uc)) {
+ case UCALL_ABORT:
+ TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0],
+ __FILE__, uc.args[1]);
+ /* NOT REACHED */
+ case UCALL_SYNC:
+ break;
+ case UCALL_DONE:
+ /* Keep in sync with guest_main() */
+ TEST_ASSERT(stage == 11, "Testing ended prematurely, stage %d\n",
+ stage);
+ goto out;
+ default:
+ TEST_FAIL("Unknown ucall %lu", uc.cmd);
+ }
+
+ TEST_ASSERT(!strcmp((const char *)uc.args[0], "hello") &&
+ uc.args[1] == stage,
+ "Stage %d: Unexpected register values vmexit, got %lx",
+ stage, (ulong)uc.args[1]);
+
+ /* Reset kvmclock triggering TSC page update */
+ if (stage == 7 || stage == 8 || stage == 10) {
+ struct kvm_clock_data clock = {0};
+
+ vm_ioctl(vm, KVM_SET_CLOCK, &clock);
+ }
+ }
+
+out:
+ kvm_vm_free(vm);
+}
--
2.30.2
