[PATCH v3 14/21] KVM: selftests: Explicitly pass TSC frequencies to guts of TSC scaling test

[Sean Christopherson <seanjc@google.com>]

Explicitly pass the L1 and L2 TSC frequencies, along with the L2 multiplier,
to the main test routine in the nested TSC scaling test.  This will allow
testing both "scale up" and "scale down" scenarios, and that KVM saturates
L2's frequency if it's scale up/down beyond what hardware can support, in
which case the expected frequency will not exactly match the L2 multiplier.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 .../kvm/x86/nested_tsc_scaling_test.c         | 42 ++++++++-----------
 1 file changed, 17 insertions(+), 25 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86/nested_tsc_scaling_test.c b/tools/testing/selftests/kvm/x86/nested_tsc_scaling_test.c
index a78585af0ffd..a8f9307ed2a4 100644
--- a/tools/testing/selftests/kvm/x86/nested_tsc_scaling_test.c
+++ b/tools/testing/selftests/kvm/x86/nested_tsc_scaling_test.c
@@ -8,7 +8,7 @@
  * both L1 and L2 are scaled using different ratios. For this test we scale
  * L1 down and scale L2 up.
  */
-
+#include <linux/math64.h>
 #include <time.h>
 
 #include "kvm_util.h"
@@ -135,21 +135,19 @@ static void l1_guest_code(void *data)
 		l1_svm_code(data);
 }
 
-static void test_tsc_scaling(u64 l0_tsc_freq, u64 l1_scale_factor, u64 l2_scale_factor)
+static void test_tsc_scaling(u64 l0_tsc_freq, u64 l1_tsc_freq, u64 l2_tsc_freq,
+			     u64 __l2_multiplier)
 {
-	u64 l1_tsc_freq, l2_tsc_freq;
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
 	gva_t guest_gva;
-	u8 frac_bits;
 
-	printf("L1's scale down factor is: %lu\n", l1_scale_factor);
-	printf("L2's scale up factor is: %lu\n", l2_scale_factor);
-
-	frac_bits = kvm_cpu_has(X86_FEATURE_VMX) ? 48 : 32;
-	l2_multiplier = l2_scale_factor << frac_bits;
+	printf("Testing L0 freq = %lu, L1 freq = %lu, L2 freq = %lu, L2 mult = 0x%lx\n",
+	       l0_tsc_freq, l1_tsc_freq, l2_tsc_freq, __l2_multiplier);
 
 	vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code);
+
+	l2_multiplier = __l2_multiplier;
 	sync_global_to_guest(vm, l2_multiplier);
 
 	if (kvm_cpu_has(X86_FEATURE_VMX))
@@ -159,11 +157,7 @@ static void test_tsc_scaling(u64 l0_tsc_freq, u64 l1_scale_factor, u64 l2_scale_
 
 	vcpu_args_set(vcpu, 1, guest_gva);
 
-	/* scale down L1's TSC frequency */
-	vcpu_ioctl(vcpu, KVM_SET_TSC_KHZ, (void *) (l0_tsc_freq / l1_scale_factor));
-
-	/* L1 will communicate its frequency before the L2 check.*/
-	l1_tsc_freq = 0;
+	vcpu_ioctl(vcpu, KVM_SET_TSC_KHZ, (void *)(l1_tsc_freq / 1000));
 
 	for (;;) {
 		struct ucall uc;
@@ -180,18 +174,12 @@ static void test_tsc_scaling(u64 l0_tsc_freq, u64 l1_scale_factor, u64 l2_scale_
 				sleep(uc.args[1]);
 				break;
 			case UCHECK_L1:
-				l1_tsc_freq = uc.args[1];
-				printf("L1's TSC frequency is around: %lu\n", l1_tsc_freq);
-
-				host_check_tsc_freq(1, l1_tsc_freq,
-						 l0_tsc_freq / l1_scale_factor);
+				printf("L1's observed TSC frequency: %lu\n", uc.args[1]);
+				host_check_tsc_freq(1, uc.args[1], l1_tsc_freq);
 				break;
 			case UCHECK_L2:
-				l2_tsc_freq = uc.args[1];
-				printf("L2's TSC frequency is around: %lu\n", l2_tsc_freq);
-
-				host_check_tsc_freq(2, l2_tsc_freq,
-						 l1_tsc_freq * l2_scale_factor);
+				printf("L2's observed TSC frequency: %lu\n", uc.args[1]);
+				host_check_tsc_freq(2, uc.args[1], l2_tsc_freq);
 				break;
 			}
 			break;
@@ -209,6 +197,7 @@ static void test_tsc_scaling(u64 l0_tsc_freq, u64 l1_scale_factor, u64 l2_scale_
 int main(int argc, char *argv[])
 {
 	u64 l0_tsc_freq, tsc_start, tsc_end, l1_scale, l2_scale;
+	u8 frac_bits = kvm_cpu_has(X86_FEATURE_VMX) ? 48 : 32;
 	struct kvm_vm *vm;
 
 	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX) ||
@@ -237,7 +226,10 @@ int main(int argc, char *argv[])
 	/* Scale L1 "down" and L2 "up" at a random factor from 2 to 10. */
 	l1_scale = (kvm_random_u32(&kvm_rng) % 9) + 2;
 	l2_scale = (kvm_random_u32(&kvm_rng) % 9) + 2;
-	test_tsc_scaling(l0_tsc_freq, l1_scale, l2_scale);
+
+	test_tsc_scaling(l0_tsc_freq, l0_tsc_freq / l1_scale,
+			 mul_u64_u64_div64(l0_tsc_freq, l2_scale, l1_scale),
+			 (l2_scale << frac_bits));
 
 	return 0;
 }
-- 
2.56.0.rc1.315.gc6ed9934b7-goog