| Message ID | 20210521102449.21505-13-ilstam@amazon.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: Implement nested TSC scaling | expand |
On Fri, 2021-05-21 at 11:24 +0100, Ilias Stamatis wrote: > Test that nested TSC scaling works as expected with both L1 and L2 > scaled. > > Signed-off-by: Ilias Stamatis <ilstam@amazon.com> > --- > tools/testing/selftests/kvm/.gitignore | 1 + > tools/testing/selftests/kvm/Makefile | 1 + > .../kvm/x86_64/vmx_nested_tsc_scaling_test.c | 242 ++++++++++++++++++ > 3 files changed, 244 insertions(+) > create mode 100644 tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c > > diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore > index bd83158e0e0b..cc02022f9951 100644 > --- a/tools/testing/selftests/kvm/.gitignore > +++ b/tools/testing/selftests/kvm/.gitignore > @@ -29,6 +29,7 @@ > /x86_64/vmx_preemption_timer_test > /x86_64/vmx_set_nested_state_test > /x86_64/vmx_tsc_adjust_test > +/x86_64/vmx_nested_tsc_scaling_test > /x86_64/xapic_ipi_test > /x86_64/xen_shinfo_test > /x86_64/xen_vmcall_test > diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile > index e439d027939d..1078240b1313 100644 > --- a/tools/testing/selftests/kvm/Makefile > +++ b/tools/testing/selftests/kvm/Makefile > @@ -60,6 +60,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/vmx_close_while_nested_test > TEST_GEN_PROGS_x86_64 += x86_64/vmx_dirty_log_test > TEST_GEN_PROGS_x86_64 += x86_64/vmx_set_nested_state_test > TEST_GEN_PROGS_x86_64 += x86_64/vmx_tsc_adjust_test > +TEST_GEN_PROGS_x86_64 += x86_64/vmx_nested_tsc_scaling_test > TEST_GEN_PROGS_x86_64 += x86_64/xapic_ipi_test > TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test > TEST_GEN_PROGS_x86_64 += x86_64/debug_regs > diff --git a/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c b/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c > new file mode 100644 > index 000000000000..2c130250fe3b > --- /dev/null > +++ b/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c > @@ -0,0 +1,242 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * vmx_nested_tsc_scaling_test > + * > + * Copyright (C) 2021 Amazon.com, Inc. or its affiliates. > + * > + * This test case verifies that nested TSC scaling behaves as expected when > + * both L1 and L2 are scaled using different ratios. For this test we scale > + * L1 down and scale L2 up. > + */ > + > +#include <time.h> > + > +#include "kvm_util.h" > +#include "vmx.h" > +#include "kselftest.h" > + > + > +#define VCPU_ID 0 > + > +/* L2 is scaled up (from L1's perspective) by this factor */ > +#define L2_SCALE_FACTOR 4ULL > + > +#define TSC_OFFSET_L2 ((uint64_t) -33125236320908) > +#define TSC_MULTIPLIER_L2 (L2_SCALE_FACTOR << 48) > + > +#define L2_GUEST_STACK_SIZE 64 > + > +enum { USLEEP, UCHECK_L1, UCHECK_L2 }; > +#define GUEST_SLEEP(sec) ucall(UCALL_SYNC, 2, USLEEP, sec) > +#define GUEST_CHECK(level, freq) ucall(UCALL_SYNC, 2, level, freq) > + > + > +/* > + * This function checks whether the "actual" TSC frequency of a guest matches > + * its expected frequency. In order to account for delays in taking the TSC > + * measurements, a difference of 1% between the actual and the expected value > + * is tolerated. > + */ > +static void compare_tsc_freq(uint64_t actual, uint64_t expected) > +{ > + uint64_t tolerance, thresh_low, thresh_high; > + > + tolerance = expected / 100; > + thresh_low = expected - tolerance; > + thresh_high = expected + tolerance; > + > + TEST_ASSERT(thresh_low < actual, > + "TSC freq is expected to be between %"PRIu64" and %"PRIu64 > + " but it actually is %"PRIu64, > + thresh_low, thresh_high, actual); > + TEST_ASSERT(thresh_high > actual, > + "TSC freq is expected to be between %"PRIu64" and %"PRIu64 > + " but it actually is %"PRIu64, > + thresh_low, thresh_high, actual); > +} > + > +static void check_tsc_freq(int level) > +{ > + uint64_t tsc_start, tsc_end, tsc_freq; > + > + /* > + * Reading the TSC twice with about a second's difference should give > + * us an approximation of the TSC frequency from the guest's > + * perspective. Now, this won't be completely accurate, but it should > + * be good enough for the purposes of this test. > + */ > + tsc_start = rdmsr(MSR_IA32_TSC); > + GUEST_SLEEP(1); > + tsc_end = rdmsr(MSR_IA32_TSC); > + > + tsc_freq = tsc_end - tsc_start; > + > + GUEST_CHECK(level, tsc_freq); > +} > + > +static void l2_guest_code(void) > +{ > + check_tsc_freq(UCHECK_L2); > + > + /* exit to L1 */ > + __asm__ __volatile__("vmcall"); > +} > + > +static void l1_guest_code(struct vmx_pages *vmx_pages) > +{ > + unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE]; > + uint32_t control; > + > + /* check that L1's frequency looks alright before launching L2 */ > + check_tsc_freq(UCHECK_L1); > + > + GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages)); > + GUEST_ASSERT(load_vmcs(vmx_pages)); > + > + /* prepare the VMCS for L2 execution */ > + prepare_vmcs(vmx_pages, l2_guest_code, &l2_guest_stack[L2_GUEST_STACK_SIZE]); > + > + /* enable TSC offsetting and TSC scaling for L2 */ > + control = vmreadz(CPU_BASED_VM_EXEC_CONTROL); > + control |= CPU_BASED_USE_MSR_BITMAPS | CPU_BASED_USE_TSC_OFFSETTING; > + vmwrite(CPU_BASED_VM_EXEC_CONTROL, control); > + > + control = vmreadz(SECONDARY_VM_EXEC_CONTROL); > + control |= SECONDARY_EXEC_TSC_SCALING; > + vmwrite(SECONDARY_VM_EXEC_CONTROL, control); > + > + vmwrite(TSC_OFFSET, TSC_OFFSET_L2); > + vmwrite(TSC_MULTIPLIER, TSC_MULTIPLIER_L2); > + vmwrite(TSC_MULTIPLIER_HIGH, TSC_MULTIPLIER_L2 >> 32); > + > + /* launch L2 */ > + GUEST_ASSERT(!vmlaunch()); > + GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL); > + > + /* check that L1's frequency still looks good */ > + check_tsc_freq(UCHECK_L1); > + > + GUEST_DONE(); > +} > + > +static void tsc_scaling_check_supported(void) > +{ > + if (!kvm_check_cap(KVM_CAP_TSC_CONTROL)) { > + print_skip("TSC scaling not supported by the HW"); > + exit(KSFT_SKIP); > + } > +} > + > +static void stable_tsc_check_supported(void) > +{ > + FILE *fp; > + char buf[4]; > + > + fp = fopen("/sys/devices/system/clocksource/clocksource0/current_clocksource", "r"); > + if (fp == NULL) > + goto skip_test; > + > + if (fgets(buf, sizeof(buf), fp) == NULL) > + goto skip_test; > + > + if (strncmp(buf, "tsc", sizeof(buf))) > + goto skip_test; > + > + return; > +skip_test: > + print_skip("TSC is not stable"); Tiny nitpick: I would print a message that expains the hack a bit better, something like "Kernel doesn't use TSC clocksource - assuming that host TSC is not stable - skipping test" > + exit(KSFT_SKIP); > +} > + > +int main(int argc, char *argv[]) > +{ > + struct kvm_vm *vm; > + vm_vaddr_t vmx_pages_gva; > + > + uint64_t tsc_start, tsc_end; > + uint64_t tsc_khz; > + uint64_t l1_scale_factor; > + uint64_t l0_tsc_freq = 0; > + uint64_t l1_tsc_freq = 0; > + uint64_t l2_tsc_freq = 0; > + > + nested_vmx_check_supported(); > + tsc_scaling_check_supported(); > + stable_tsc_check_supported(); > + > + /* > + * We set L1's scale factor to be a random number from 2 to 10. > + * Ideally we would do the same for L2's factor but that one is > + * referenced by both main() and l1_guest_code() and using a global > + * variable does not work. > + */ > + srand(time(NULL)); > + l1_scale_factor = (rand() % 9) + 2; > + printf("L1's scale down factor is: %"PRIu64"\n", l1_scale_factor); > + printf("L2's scale up factor is: %llu\n", L2_SCALE_FACTOR); > + > + tsc_start = rdtsc(); > + sleep(1); > + tsc_end = rdtsc(); > + > + l0_tsc_freq = tsc_end - tsc_start; > + printf("real TSC frequency is around: %"PRIu64"\n", l0_tsc_freq); > + > + vm = vm_create_default(VCPU_ID, 0, (void *) l1_guest_code); > + vcpu_alloc_vmx(vm, &vmx_pages_gva); > + vcpu_args_set(vm, VCPU_ID, 1, vmx_pages_gva); > + > + tsc_khz = _vcpu_ioctl(vm, VCPU_ID, KVM_GET_TSC_KHZ, NULL); > + TEST_ASSERT(tsc_khz != -1, "vcpu ioctl KVM_GET_TSC_KHZ failed"); > + > + /* scale down L1's TSC frequency */ > + vcpu_ioctl(vm, VCPU_ID, KVM_SET_TSC_KHZ, > + (void *) (tsc_khz / l1_scale_factor)); > + > + for (;;) { > + volatile struct kvm_run *run = vcpu_state(vm, VCPU_ID); > + struct ucall uc; > + > + vcpu_run(vm, VCPU_ID); > + TEST_ASSERT(run->exit_reason == KVM_EXIT_IO, > + "Got exit_reason other than KVM_EXIT_IO: %u (%s)\n", > + run->exit_reason, > + exit_reason_str(run->exit_reason)); > + > + switch (get_ucall(vm, VCPU_ID, &uc)) { > + case UCALL_ABORT: > + TEST_FAIL("%s", (const char *) uc.args[0]); > + case UCALL_SYNC: > + switch (uc.args[0]) { > + case USLEEP: > + sleep(uc.args[1]); > + break; > + case UCHECK_L1: > + l1_tsc_freq = uc.args[1]; > + printf("L1's TSC frequency is around: %"PRIu64 > + "\n", l1_tsc_freq); > + > + compare_tsc_freq(l1_tsc_freq, > + l0_tsc_freq / l1_scale_factor); > + break; > + case UCHECK_L2: > + l2_tsc_freq = uc.args[1]; > + printf("L2's TSC frequency is around: %"PRIu64 > + "\n", l2_tsc_freq); > + > + compare_tsc_freq(l2_tsc_freq, > + l1_tsc_freq * L2_SCALE_FACTOR); > + break; > + } > + break; > + case UCALL_DONE: > + goto done; > + default: > + TEST_FAIL("Unknown ucall %lu", uc.cmd); > + } > + } > + > +done: > + kvm_vm_free(vm); > + return 0; > +} Overall looks good to me. Thanks! Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Best regards, Maxim Levitsky
diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore index bd83158e0e0b..cc02022f9951 100644 --- a/tools/testing/selftests/kvm/.gitignore +++ b/tools/testing/selftests/kvm/.gitignore @@ -29,6 +29,7 @@ /x86_64/vmx_preemption_timer_test /x86_64/vmx_set_nested_state_test /x86_64/vmx_tsc_adjust_test +/x86_64/vmx_nested_tsc_scaling_test /x86_64/xapic_ipi_test /x86_64/xen_shinfo_test /x86_64/xen_vmcall_test diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index e439d027939d..1078240b1313 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -60,6 +60,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/vmx_close_while_nested_test TEST_GEN_PROGS_x86_64 += x86_64/vmx_dirty_log_test TEST_GEN_PROGS_x86_64 += x86_64/vmx_set_nested_state_test TEST_GEN_PROGS_x86_64 += x86_64/vmx_tsc_adjust_test +TEST_GEN_PROGS_x86_64 += x86_64/vmx_nested_tsc_scaling_test TEST_GEN_PROGS_x86_64 += x86_64/xapic_ipi_test TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test TEST_GEN_PROGS_x86_64 += x86_64/debug_regs diff --git a/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c b/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c new file mode 100644 index 000000000000..2c130250fe3b --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c @@ -0,0 +1,242 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * vmx_nested_tsc_scaling_test + * + * Copyright (C) 2021 Amazon.com, Inc. or its affiliates. + * + * This test case verifies that nested TSC scaling behaves as expected when + * both L1 and L2 are scaled using different ratios. For this test we scale + * L1 down and scale L2 up. + */ + +#include <time.h> + +#include "kvm_util.h" +#include "vmx.h" +#include "kselftest.h" + + +#define VCPU_ID 0 + +/* L2 is scaled up (from L1's perspective) by this factor */ +#define L2_SCALE_FACTOR 4ULL + +#define TSC_OFFSET_L2 ((uint64_t) -33125236320908) +#define TSC_MULTIPLIER_L2 (L2_SCALE_FACTOR << 48) + +#define L2_GUEST_STACK_SIZE 64 + +enum { USLEEP, UCHECK_L1, UCHECK_L2 }; +#define GUEST_SLEEP(sec) ucall(UCALL_SYNC, 2, USLEEP, sec) +#define GUEST_CHECK(level, freq) ucall(UCALL_SYNC, 2, level, freq) + + +/* + * This function checks whether the "actual" TSC frequency of a guest matches + * its expected frequency. In order to account for delays in taking the TSC + * measurements, a difference of 1% between the actual and the expected value + * is tolerated. + */ +static void compare_tsc_freq(uint64_t actual, uint64_t expected) +{ + uint64_t tolerance, thresh_low, thresh_high; + + tolerance = expected / 100; + thresh_low = expected - tolerance; + thresh_high = expected + tolerance; + + TEST_ASSERT(thresh_low < actual, + "TSC freq is expected to be between %"PRIu64" and %"PRIu64 + " but it actually is %"PRIu64, + thresh_low, thresh_high, actual); + TEST_ASSERT(thresh_high > actual, + "TSC freq is expected to be between %"PRIu64" and %"PRIu64 + " but it actually is %"PRIu64, + thresh_low, thresh_high, actual); +} + +static void check_tsc_freq(int level) +{ + uint64_t tsc_start, tsc_end, tsc_freq; + + /* + * Reading the TSC twice with about a second's difference should give + * us an approximation of the TSC frequency from the guest's + * perspective. Now, this won't be completely accurate, but it should + * be good enough for the purposes of this test. + */ + tsc_start = rdmsr(MSR_IA32_TSC); + GUEST_SLEEP(1); + tsc_end = rdmsr(MSR_IA32_TSC); + + tsc_freq = tsc_end - tsc_start; + + GUEST_CHECK(level, tsc_freq); +} + +static void l2_guest_code(void) +{ + check_tsc_freq(UCHECK_L2); + + /* exit to L1 */ + __asm__ __volatile__("vmcall"); +} + +static void l1_guest_code(struct vmx_pages *vmx_pages) +{ + unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE]; + uint32_t control; + + /* check that L1's frequency looks alright before launching L2 */ + check_tsc_freq(UCHECK_L1); + + GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages)); + GUEST_ASSERT(load_vmcs(vmx_pages)); + + /* prepare the VMCS for L2 execution */ + prepare_vmcs(vmx_pages, l2_guest_code, &l2_guest_stack[L2_GUEST_STACK_SIZE]); + + /* enable TSC offsetting and TSC scaling for L2 */ + control = vmreadz(CPU_BASED_VM_EXEC_CONTROL); + control |= CPU_BASED_USE_MSR_BITMAPS | CPU_BASED_USE_TSC_OFFSETTING; + vmwrite(CPU_BASED_VM_EXEC_CONTROL, control); + + control = vmreadz(SECONDARY_VM_EXEC_CONTROL); + control |= SECONDARY_EXEC_TSC_SCALING; + vmwrite(SECONDARY_VM_EXEC_CONTROL, control); + + vmwrite(TSC_OFFSET, TSC_OFFSET_L2); + vmwrite(TSC_MULTIPLIER, TSC_MULTIPLIER_L2); + vmwrite(TSC_MULTIPLIER_HIGH, TSC_MULTIPLIER_L2 >> 32); + + /* launch L2 */ + GUEST_ASSERT(!vmlaunch()); + GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL); + + /* check that L1's frequency still looks good */ + check_tsc_freq(UCHECK_L1); + + GUEST_DONE(); +} + +static void tsc_scaling_check_supported(void) +{ + if (!kvm_check_cap(KVM_CAP_TSC_CONTROL)) { + print_skip("TSC scaling not supported by the HW"); + exit(KSFT_SKIP); + } +} + +static void stable_tsc_check_supported(void) +{ + FILE *fp; + char buf[4]; + + fp = fopen("/sys/devices/system/clocksource/clocksource0/current_clocksource", "r"); + if (fp == NULL) + goto skip_test; + + if (fgets(buf, sizeof(buf), fp) == NULL) + goto skip_test; + + if (strncmp(buf, "tsc", sizeof(buf))) + goto skip_test; + + return; +skip_test: + print_skip("TSC is not stable"); + exit(KSFT_SKIP); +} + +int main(int argc, char *argv[]) +{ + struct kvm_vm *vm; + vm_vaddr_t vmx_pages_gva; + + uint64_t tsc_start, tsc_end; + uint64_t tsc_khz; + uint64_t l1_scale_factor; + uint64_t l0_tsc_freq = 0; + uint64_t l1_tsc_freq = 0; + uint64_t l2_tsc_freq = 0; + + nested_vmx_check_supported(); + tsc_scaling_check_supported(); + stable_tsc_check_supported(); + + /* + * We set L1's scale factor to be a random number from 2 to 10. + * Ideally we would do the same for L2's factor but that one is + * referenced by both main() and l1_guest_code() and using a global + * variable does not work. + */ + srand(time(NULL)); + l1_scale_factor = (rand() % 9) + 2; + printf("L1's scale down factor is: %"PRIu64"\n", l1_scale_factor); + printf("L2's scale up factor is: %llu\n", L2_SCALE_FACTOR); + + tsc_start = rdtsc(); + sleep(1); + tsc_end = rdtsc(); + + l0_tsc_freq = tsc_end - tsc_start; + printf("real TSC frequency is around: %"PRIu64"\n", l0_tsc_freq); + + vm = vm_create_default(VCPU_ID, 0, (void *) l1_guest_code); + vcpu_alloc_vmx(vm, &vmx_pages_gva); + vcpu_args_set(vm, VCPU_ID, 1, vmx_pages_gva); + + tsc_khz = _vcpu_ioctl(vm, VCPU_ID, KVM_GET_TSC_KHZ, NULL); + TEST_ASSERT(tsc_khz != -1, "vcpu ioctl KVM_GET_TSC_KHZ failed"); + + /* scale down L1's TSC frequency */ + vcpu_ioctl(vm, VCPU_ID, KVM_SET_TSC_KHZ, + (void *) (tsc_khz / l1_scale_factor)); + + for (;;) { + volatile struct kvm_run *run = vcpu_state(vm, VCPU_ID); + struct ucall uc; + + vcpu_run(vm, VCPU_ID); + TEST_ASSERT(run->exit_reason == KVM_EXIT_IO, + "Got exit_reason other than KVM_EXIT_IO: %u (%s)\n", + run->exit_reason, + exit_reason_str(run->exit_reason)); + + switch (get_ucall(vm, VCPU_ID, &uc)) { + case UCALL_ABORT: + TEST_FAIL("%s", (const char *) uc.args[0]); + case UCALL_SYNC: + switch (uc.args[0]) { + case USLEEP: + sleep(uc.args[1]); + break; + case UCHECK_L1: + l1_tsc_freq = uc.args[1]; + printf("L1's TSC frequency is around: %"PRIu64 + "\n", l1_tsc_freq); + + compare_tsc_freq(l1_tsc_freq, + l0_tsc_freq / l1_scale_factor); + break; + case UCHECK_L2: + l2_tsc_freq = uc.args[1]; + printf("L2's TSC frequency is around: %"PRIu64 + "\n", l2_tsc_freq); + + compare_tsc_freq(l2_tsc_freq, + l1_tsc_freq * L2_SCALE_FACTOR); + break; + } + break; + case UCALL_DONE: + goto done; + default: + TEST_FAIL("Unknown ucall %lu", uc.cmd); + } + } + +done: + kvm_vm_free(vm); + return 0; +}
Test that nested TSC scaling works as expected with both L1 and L2 scaled. Signed-off-by: Ilias Stamatis <ilstam@amazon.com> --- tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile | 1 + .../kvm/x86_64/vmx_nested_tsc_scaling_test.c | 242 ++++++++++++++++++ 3 files changed, 244 insertions(+) create mode 100644 tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c