KVM: selftests: x86: Add vmx_nested_tsc_scaling_test
Test that nested TSC scaling works as expected with both L1 and L2 scaled. Signed-off-by: Ilias Stamatis <ilstam@amazon.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210526184418.28881-12-ilstam@amazon.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Ilias Stamatis
Paolo Bonzini
Родитель
d041b5ea93
Коммит
efe585493f
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@ -29,6 +29,7 @@
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/x86_64/vmx_preemption_timer_test
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/x86_64/vmx_set_nested_state_test
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/x86_64/vmx_tsc_adjust_test
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/x86_64/vmx_nested_tsc_scaling_test
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/x86_64/xapic_ipi_test
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/x86_64/xen_shinfo_test
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/x86_64/xen_vmcall_test
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@ -60,6 +60,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/vmx_close_while_nested_test
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TEST_GEN_PROGS_x86_64 += x86_64/vmx_dirty_log_test
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TEST_GEN_PROGS_x86_64 += x86_64/vmx_set_nested_state_test
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TEST_GEN_PROGS_x86_64 += x86_64/vmx_tsc_adjust_test
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TEST_GEN_PROGS_x86_64 += x86_64/vmx_nested_tsc_scaling_test
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TEST_GEN_PROGS_x86_64 += x86_64/xapic_ipi_test
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TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test
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TEST_GEN_PROGS_x86_64 += x86_64/debug_regs
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@ -0,0 +1,242 @@
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* vmx_nested_tsc_scaling_test
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*
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* Copyright 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* This test case verifies that nested TSC scaling behaves as expected when
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* both L1 and L2 are scaled using different ratios. For this test we scale
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* L1 down and scale L2 up.
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*/
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#include <time.h>
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#include "kvm_util.h"
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#include "vmx.h"
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#include "kselftest.h"
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#define VCPU_ID 0
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/* L2 is scaled up (from L1's perspective) by this factor */
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#define L2_SCALE_FACTOR 4ULL
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#define TSC_OFFSET_L2 ((uint64_t) -33125236320908)
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#define TSC_MULTIPLIER_L2 (L2_SCALE_FACTOR << 48)
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#define L2_GUEST_STACK_SIZE 64
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enum { USLEEP, UCHECK_L1, UCHECK_L2 };
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#define GUEST_SLEEP(sec) ucall(UCALL_SYNC, 2, USLEEP, sec)
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#define GUEST_CHECK(level, freq) ucall(UCALL_SYNC, 2, level, freq)
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/*
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* This function checks whether the "actual" TSC frequency of a guest matches
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* its expected frequency. In order to account for delays in taking the TSC
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* measurements, a difference of 1% between the actual and the expected value
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* is tolerated.
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*/
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static void compare_tsc_freq(uint64_t actual, uint64_t expected)
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{
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uint64_t tolerance, thresh_low, thresh_high;
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tolerance = expected / 100;
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thresh_low = expected - tolerance;
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thresh_high = expected + tolerance;
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TEST_ASSERT(thresh_low < actual,
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"TSC freq is expected to be between %"PRIu64" and %"PRIu64
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" but it actually is %"PRIu64,
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thresh_low, thresh_high, actual);
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TEST_ASSERT(thresh_high > actual,
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"TSC freq is expected to be between %"PRIu64" and %"PRIu64
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" but it actually is %"PRIu64,
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thresh_low, thresh_high, actual);
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}
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static void check_tsc_freq(int level)
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{
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uint64_t tsc_start, tsc_end, tsc_freq;
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/*
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* Reading the TSC twice with about a second's difference should give
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* us an approximation of the TSC frequency from the guest's
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* perspective. Now, this won't be completely accurate, but it should
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* be good enough for the purposes of this test.
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*/
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tsc_start = rdmsr(MSR_IA32_TSC);
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GUEST_SLEEP(1);
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tsc_end = rdmsr(MSR_IA32_TSC);
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tsc_freq = tsc_end - tsc_start;
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GUEST_CHECK(level, tsc_freq);
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}
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static void l2_guest_code(void)
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{
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check_tsc_freq(UCHECK_L2);
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/* exit to L1 */
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__asm__ __volatile__("vmcall");
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}
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static void l1_guest_code(struct vmx_pages *vmx_pages)
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{
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unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
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uint32_t control;
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/* check that L1's frequency looks alright before launching L2 */
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check_tsc_freq(UCHECK_L1);
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GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
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GUEST_ASSERT(load_vmcs(vmx_pages));
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/* prepare the VMCS for L2 execution */
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prepare_vmcs(vmx_pages, l2_guest_code, &l2_guest_stack[L2_GUEST_STACK_SIZE]);
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/* enable TSC offsetting and TSC scaling for L2 */
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control = vmreadz(CPU_BASED_VM_EXEC_CONTROL);
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control |= CPU_BASED_USE_MSR_BITMAPS | CPU_BASED_USE_TSC_OFFSETTING;
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vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);
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control = vmreadz(SECONDARY_VM_EXEC_CONTROL);
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control |= SECONDARY_EXEC_TSC_SCALING;
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vmwrite(SECONDARY_VM_EXEC_CONTROL, control);
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vmwrite(TSC_OFFSET, TSC_OFFSET_L2);
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vmwrite(TSC_MULTIPLIER, TSC_MULTIPLIER_L2);
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vmwrite(TSC_MULTIPLIER_HIGH, TSC_MULTIPLIER_L2 >> 32);
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/* launch L2 */
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GUEST_ASSERT(!vmlaunch());
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GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
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/* check that L1's frequency still looks good */
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check_tsc_freq(UCHECK_L1);
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GUEST_DONE();
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}
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static void tsc_scaling_check_supported(void)
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{
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if (!kvm_check_cap(KVM_CAP_TSC_CONTROL)) {
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print_skip("TSC scaling not supported by the HW");
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exit(KSFT_SKIP);
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}
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}
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static void stable_tsc_check_supported(void)
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{
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FILE *fp;
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char buf[4];
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fp = fopen("/sys/devices/system/clocksource/clocksource0/current_clocksource", "r");
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if (fp == NULL)
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goto skip_test;
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if (fgets(buf, sizeof(buf), fp) == NULL)
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goto skip_test;
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if (strncmp(buf, "tsc", sizeof(buf)))
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goto skip_test;
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return;
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skip_test:
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print_skip("Kernel does not use TSC clocksource - assuming that host TSC is not stable");
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exit(KSFT_SKIP);
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}
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int main(int argc, char *argv[])
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{
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struct kvm_vm *vm;
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vm_vaddr_t vmx_pages_gva;
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uint64_t tsc_start, tsc_end;
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uint64_t tsc_khz;
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uint64_t l1_scale_factor;
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uint64_t l0_tsc_freq = 0;
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uint64_t l1_tsc_freq = 0;
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uint64_t l2_tsc_freq = 0;
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nested_vmx_check_supported();
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tsc_scaling_check_supported();
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stable_tsc_check_supported();
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/*
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* We set L1's scale factor to be a random number from 2 to 10.
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* Ideally we would do the same for L2's factor but that one is
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* referenced by both main() and l1_guest_code() and using a global
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* variable does not work.
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*/
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srand(time(NULL));
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l1_scale_factor = (rand() % 9) + 2;
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printf("L1's scale down factor is: %"PRIu64"\n", l1_scale_factor);
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printf("L2's scale up factor is: %llu\n", L2_SCALE_FACTOR);
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tsc_start = rdtsc();
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sleep(1);
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tsc_end = rdtsc();
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l0_tsc_freq = tsc_end - tsc_start;
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printf("real TSC frequency is around: %"PRIu64"\n", l0_tsc_freq);
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vm = vm_create_default(VCPU_ID, 0, (void *) l1_guest_code);
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vcpu_alloc_vmx(vm, &vmx_pages_gva);
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vcpu_args_set(vm, VCPU_ID, 1, vmx_pages_gva);
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tsc_khz = _vcpu_ioctl(vm, VCPU_ID, KVM_GET_TSC_KHZ, NULL);
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TEST_ASSERT(tsc_khz != -1, "vcpu ioctl KVM_GET_TSC_KHZ failed");
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/* scale down L1's TSC frequency */
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vcpu_ioctl(vm, VCPU_ID, KVM_SET_TSC_KHZ,
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(void *) (tsc_khz / l1_scale_factor));
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for (;;) {
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volatile struct kvm_run *run = vcpu_state(vm, VCPU_ID);
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struct ucall uc;
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vcpu_run(vm, VCPU_ID);
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TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
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"Got exit_reason other than KVM_EXIT_IO: %u (%s)\n",
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run->exit_reason,
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exit_reason_str(run->exit_reason));
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switch (get_ucall(vm, VCPU_ID, &uc)) {
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case UCALL_ABORT:
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TEST_FAIL("%s", (const char *) uc.args[0]);
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case UCALL_SYNC:
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switch (uc.args[0]) {
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case USLEEP:
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sleep(uc.args[1]);
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break;
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case UCHECK_L1:
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l1_tsc_freq = uc.args[1];
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printf("L1's TSC frequency is around: %"PRIu64
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"\n", l1_tsc_freq);
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compare_tsc_freq(l1_tsc_freq,
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l0_tsc_freq / l1_scale_factor);
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break;
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case UCHECK_L2:
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l2_tsc_freq = uc.args[1];
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printf("L2's TSC frequency is around: %"PRIu64
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"\n", l2_tsc_freq);
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compare_tsc_freq(l2_tsc_freq,
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l1_tsc_freq * L2_SCALE_FACTOR);
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break;
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}
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break;
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case UCALL_DONE:
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goto done;
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default:
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TEST_FAIL("Unknown ucall %lu", uc.cmd);
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}
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}
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done:
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kvm_vm_free(vm);
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return 0;
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}
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