Add selftests for KVM cap KVM_CAP_X86_DISABLE_EXITS overriding flags in VM and vCPU scope both working as expected. Suggested-by: Chao Gao <chao.gao@xxxxxxxxx> Suggested-by: Shaoqin Huang <shaoqin.huang@xxxxxxxxx> Suggested-by: Zhi Wang <zhi.wang.linux@xxxxxxxxx> Signed-off-by: Kechen Lu <kechenl@xxxxxxxxxx> --- tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/x86_64/disable_exits_test.c | 363 ++++++++++++++++++ 2 files changed, 364 insertions(+) create mode 100644 tools/testing/selftests/kvm/x86_64/disable_exits_test.c diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index 1750f91dd936..eeeba35e2536 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -114,6 +114,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/sev_migrate_tests TEST_GEN_PROGS_x86_64 += x86_64/amx_test TEST_GEN_PROGS_x86_64 += x86_64/max_vcpuid_cap_test TEST_GEN_PROGS_x86_64 += x86_64/triple_fault_event_test +TEST_GEN_PROGS_x86_64 += x86_64/disable_exits_test TEST_GEN_PROGS_x86_64 += access_tracking_perf_test TEST_GEN_PROGS_x86_64 += demand_paging_test TEST_GEN_PROGS_x86_64 += dirty_log_test diff --git a/tools/testing/selftests/kvm/x86_64/disable_exits_test.c b/tools/testing/selftests/kvm/x86_64/disable_exits_test.c new file mode 100644 index 000000000000..74a2152b35dd --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/disable_exits_test.c @@ -0,0 +1,363 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Test per-VM and per-vCPU disable exits cap + * 1) Per-VM scope + * 2) Per-vCPU scope + * + */ + +#define _GNU_SOURCE /* for program_invocation_short_name */ +#include <pthread.h> +#include <inttypes.h> +#include <string.h> +#include <time.h> +#include <sys/ioctl.h> + +#include "test_util.h" +#include "kvm_util.h" +#include "svm_util.h" +#include "vmx.h" +#include "processor.h" +#include "asm/kvm.h" +#include "linux/kvm.h" + +/* Arbitrary chosen IPI vector value from sender to halter vCPU */ +#define IPI_VECTOR 0xa5 +/* Number of HLTs halter vCPU thread executes */ +#define LOOP_DURATION 3 + +struct guest_stats { + uint32_t halter_apic_id; + volatile uint64_t hlt_count; + volatile uint64_t wake_count; +}; + +static u64 read_vcpu_stats_halt_exits(struct kvm_vcpu *vcpu) +{ + int i; + struct kvm_stats_header header; + u64 *stats_data; + u64 ret = 0; + struct kvm_stats_desc *stats_desc; + struct kvm_stats_desc *pdesc; + int stats_fd = vcpu_get_stats_fd(vcpu); + + read_stats_header(stats_fd, &header); + if (header.num_desc == 0) { + fprintf(stderr, + "Cannot read halt exits since no KVM stats defined\n"); + return ret; + } + + stats_desc = read_stats_descriptors(stats_fd, &header); + for (i = 0; i < header.num_desc; ++i) { + pdesc = get_stats_descriptor(stats_desc, i, &header); + if (!strncmp(pdesc->name, "halt_exits", 10)) { + stats_data = malloc(pdesc->size * sizeof(*stats_data)); + read_stat_data(stats_fd, &header, pdesc, stats_data, + pdesc->size); + ret = *stats_data; + free(stats_data); + break; + } + } + free(stats_desc); + return ret; +} + +/* HLT multiple times in one vCPU */ +static void halter_guest_code(struct guest_stats *data) +{ + xapic_enable(); + data->halter_apic_id = GET_APIC_ID_FIELD(xapic_read_reg(APIC_ID)); + + for (;;) { + data->hlt_count++; + asm volatile("sti; hlt; cli"); + data->wake_count++; + } +} + +/* Runs on halter vCPU when IPI arrives */ +static void guest_ipi_handler(struct ex_regs *regs) +{ + xapic_write_reg(APIC_EOI, 11); +} + +/* Sender vCPU waits for ~1sec to assume HLT executed */ +static void sender_wait_loop(struct guest_stats *data, uint64_t old_hlt_count, + uint64_t old_wake_count) +{ + uint64_t tsc_start = rdtsc(); + + while (rdtsc() - tsc_start < 4000000000) { + if ((data->wake_count != old_wake_count) && + (data->hlt_count != old_hlt_count)) + break; + } + GUEST_ASSERT((data->wake_count != old_wake_count) && + (data->hlt_count != old_hlt_count)); +} + +/* Sender vCPU loops sending IPI to halter vCPU every ~1sec */ +static void sender_guest_code(struct guest_stats *data) +{ + uint32_t icr_val; + uint32_t icr2_val; + uint64_t old_hlt_count = 0; + uint64_t old_wake_count = 0; + + xapic_enable(); + /* Init interrupt command register for sending IPIs */ + icr_val = (APIC_DEST_PHYSICAL | APIC_DM_FIXED | IPI_VECTOR); + icr2_val = SET_APIC_DEST_FIELD(data->halter_apic_id); + + for (;;) { + /* + * Send IPI to halted vCPU + * First IPI sends here as already waited before sender vCPU + * thread creation + */ + xapic_write_reg(APIC_ICR2, icr2_val); + xapic_write_reg(APIC_ICR, icr_val); + sender_wait_loop(data, old_hlt_count, old_wake_count); + old_wake_count = data->wake_count; + old_hlt_count = data->hlt_count; + } +} + +static void *vcpu_thread(void *arg) +{ + struct kvm_vcpu *vcpu = (struct kvm_vcpu *)arg; + int old; + int r; + + r = pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &old); + TEST_ASSERT(r == 0, + "pthread_setcanceltype failed on vcpu_id=%u with errno=%d", + vcpu->id, r); + fprintf(stderr, "vCPU thread running vCPU %u\n", vcpu->id); + vcpu_run(vcpu); + return NULL; +} + +static void cancel_join_vcpu_thread(pthread_t thread, struct kvm_vcpu *vcpu) +{ + void *retval; + int r; + + r = pthread_cancel(thread); + TEST_ASSERT(r == 0, + "pthread_cancel on vcpu_id=%d failed with errno=%d", + vcpu->id, r); + + r = pthread_join(thread, &retval); + TEST_ASSERT(r == 0, + "pthread_join on vcpu_id=%d failed with errno=%d", + vcpu->id, r); +} + +static void vm_run_with_threads(struct kvm_vcpu *halter_vcpu, + struct kvm_vcpu *sender_vcpu) +{ + int r; + pthread_t threads[2]; + + /* Start halter vCPU thread and wait for it to execute first HLT. */ + r = pthread_create(&threads[0], NULL, vcpu_thread, halter_vcpu); + TEST_ASSERT(r == 0, + "pthread_create halter failed errno=%d", errno); + fprintf(stderr, "Halter vCPU thread started\n"); + + sleep(1); + + /* + * After guest halter vCPU executed first HLT, start the sender + * vCPU thread to wakeup halter vCPU + */ + r = pthread_create(&threads[1], NULL, vcpu_thread, sender_vcpu); + TEST_ASSERT(r == 0, "pthread_create sender failed errno=%d", errno); + + sleep(LOOP_DURATION); + + cancel_join_vcpu_thread(threads[0], halter_vcpu); + cancel_join_vcpu_thread(threads[1], sender_vcpu); +} + +/* + * Test case 1: + * Normal VM running with one vCPU keeps executing HLTs, + * another vCPU sending IPIs to wake it up, should expect + * all HLTs exiting to host + * and Test case 2: + * VM scoped exits disabling, HLT instructions + * stay inside guest without exits + */ +static void test_vm_disable_exits_cap(bool cap_enabled) +{ + uint64_t kvm_halt_exits; + struct kvm_vm *vm; + struct kvm_vcpu *halter_vcpu; + struct kvm_vcpu *sender_vcpu; + struct guest_stats *data; + vm_vaddr_t guest_stats_page_vaddr; + + /* Create VM */ + vm = vm_create(2); + + /* + * Before adding any vCPUs, enable the KVM_X86_DISABLE_EXITS cap + * with flag KVM_X86_DISABLE_EXITS_HLT + */ + if (cap_enabled) + vm_enable_cap(vm, KVM_CAP_X86_DISABLE_EXITS, + KVM_X86_DISABLE_EXITS_HLT); + + /* Add vCPU with loops halting */ + halter_vcpu = vm_vcpu_add(vm, 0, halter_guest_code); + + vm_init_descriptor_tables(vm); + vcpu_init_descriptor_tables(halter_vcpu); + vm_install_exception_handler(vm, IPI_VECTOR, guest_ipi_handler); + virt_pg_map(vm, APIC_DEFAULT_GPA, APIC_DEFAULT_GPA); + + /* Add vCPU with IPIs waking up halter vCPU */ + sender_vcpu = vm_vcpu_add(vm, 1, sender_guest_code); + + guest_stats_page_vaddr = vm_vaddr_alloc_page(vm); + data = addr_gva2hva(vm, guest_stats_page_vaddr); + memset(data, 0, sizeof(*data)); + + vcpu_args_set(halter_vcpu, 1, guest_stats_page_vaddr); + vcpu_args_set(sender_vcpu, 1, guest_stats_page_vaddr); + + vm_run_with_threads(halter_vcpu, sender_vcpu); + kvm_halt_exits = read_vcpu_stats_halt_exits(halter_vcpu); + if (cap_enabled) + TEST_ASSERT(kvm_halt_exits == 0, + "Halter vCPU had unexpected halt exits occurring after disabling VM-scoped halt exits cap\n"); + else + TEST_ASSERT(kvm_halt_exits == data->hlt_count, + "Halter vCPU had unmatched %lu halt exits - %lu HLTs executed, when not disabling VM halt exits\n", + kvm_halt_exits, data->hlt_count); + fprintf(stderr, "Halter vCPU had %lu halt exits\n", + kvm_halt_exits); + fprintf(stderr, "Guest records %lu HLTs executed, waked %lu times\n", + data->hlt_count, data->wake_count); + + kvm_vm_free(vm); +} + +/* + * Test case 3: + * VM overrides exits disable flags after vCPU created, + * which is not allowed + */ +static void test_vm_disable_exits_cap_with_vcpu_created(void) +{ + int r; + struct kvm_vm *vm; + struct kvm_enable_cap cap = { + .cap = KVM_CAP_X86_DISABLE_EXITS, + .args[0] = KVM_X86_DISABLE_EXITS_HLT | KVM_X86_DISABLE_EXITS_OVERRIDE, + }; + + /* Create VM */ + vm = vm_create(1); + /* Add vCPU with loops halting */ + vm_vcpu_add(vm, 0, halter_guest_code); + + /* + * After creating vCPU, the current VM-scoped ABI should + * discard the cap enable of KVM_CAP_X86_DISABLE_EXITS + * and return non-zero. Since vm_enabled_cap() not able + * to assert the return value, so use the __vm_ioctl() + */ + r = __vm_ioctl(vm, KVM_ENABLE_CAP, &cap); + + TEST_ASSERT(r != 0, + "Setting VM-scoped KVM_CAP_X86_DISABLE_EXITS after vCPUs created is not allowed, but it succeeds here\n"); +} + +/* + * Test case 4: + * vCPU scoped halt exits disabling and enabling tests, + * verify overides are working after vCPU created + */ +static void test_vcpu_toggling_disable_exits_cap(void) +{ + uint64_t kvm_halt_exits; + uint64_t kvm_halt_exits_in_guest; + struct kvm_vm *vm; + struct kvm_vcpu *halter_vcpu; + struct kvm_vcpu *sender_vcpu; + struct guest_stats *data; + vm_vaddr_t guest_stats_page_vaddr; + + /* Create VM */ + vm = vm_create(2); + + /* Add vCPU with loops halting */ + halter_vcpu = vm_vcpu_add(vm, 0, halter_guest_code); + /* Set KVM_CAP_X86_DISABLE_EXITS_HLT for halter vCPU */ + vcpu_enable_cap(halter_vcpu, KVM_CAP_X86_DISABLE_EXITS, + KVM_X86_DISABLE_EXITS_HLT | KVM_X86_DISABLE_EXITS_OVERRIDE); + + vm_init_descriptor_tables(vm); + vcpu_init_descriptor_tables(halter_vcpu); + vm_install_exception_handler(vm, IPI_VECTOR, guest_ipi_handler); + virt_pg_map(vm, APIC_DEFAULT_GPA, APIC_DEFAULT_GPA); + + /* Add vCPU with IPIs waking up halter vCPU */ + sender_vcpu = vm_vcpu_add(vm, 1, sender_guest_code); + + guest_stats_page_vaddr = vm_vaddr_alloc_page(vm); + data = addr_gva2hva(vm, guest_stats_page_vaddr); + memset(data, 0, sizeof(*data)); + + vcpu_args_set(halter_vcpu, 1, guest_stats_page_vaddr); + vcpu_args_set(sender_vcpu, 1, guest_stats_page_vaddr); + + /* + * For the first phase of the running, halt exits + * are disabled, halter vCPU executes HLT instruction + * but never exits to host + */ + vm_run_with_threads(halter_vcpu, sender_vcpu); + kvm_halt_exits_in_guest = data->hlt_count; + fprintf(stderr, "Guest records %lu HLTs with halt exits disabled\n", + data->hlt_count); + /* + * Override and clean KVM_CAP_X86_DISABLE_EXITS flags + * for halter vCPU. Expect to see halt exits occurs then. + */ + vcpu_enable_cap(halter_vcpu, KVM_CAP_X86_DISABLE_EXITS, + KVM_X86_DISABLE_EXITS_OVERRIDE); + /* + * Second phase of the test, after guest halter vCPU + * reenabled halt exits, start the sender + * vCPU thread to wakeup halter vCPU + */ + vm_run_with_threads(halter_vcpu, sender_vcpu); + kvm_halt_exits = read_vcpu_stats_halt_exits(halter_vcpu); + TEST_ASSERT(kvm_halt_exits == data->hlt_count - kvm_halt_exits_in_guest, + "Halter vCPU had unexpected %lu (should be %lu) halt exits\n", + kvm_halt_exits, data->hlt_count - kvm_halt_exits_in_guest); + fprintf(stderr, "Halter vCPU had %lu halt exits\n", + kvm_halt_exits); + fprintf(stderr, "Guest records %lu HLTs executed, waked %lu times\n", + data->hlt_count, data->wake_count); + + kvm_vm_free(vm); +} + +int main(int argc, char *argv[]) +{ + fprintf(stderr, "VM-scoped tests start\n"); + test_vm_disable_exits_cap(false); + test_vm_disable_exits_cap(true); + test_vm_disable_exits_cap_with_vcpu_created(); + fprintf(stderr, "vCPU-scoped test starts\n"); + test_vcpu_toggling_disable_exits_cap(); + return 0; +} -- 2.34.1