When running with /sys/module/kvm_intel/parameters/unrestricted_guest=N, test that a kernel warning does not occur informing us that vcpu->mmio_needed=1. This can happen when KVM_RUN is called after a triple fault. This test was made to detect a bug that was reported by Syzkaller (https://groups.google.com/forum/#!topic/syzkaller/lHfau8E3SOE) and fixed with commit bbeac2830f4de ("KVM: X86: Fix residual mmio emulation request to userspace"). Signed-off-by: Aaron Lewis <aaronlewis@xxxxxxxxxx> Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx> Reviewed-by: Peter Shier <pshier@xxxxxxxxxx> --- tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile | 1 + .../testing/selftests/kvm/include/kvm_util.h | 2 + .../selftests/kvm/include/x86_64/processor.h | 2 + tools/testing/selftests/kvm/lib/kvm_util.c | 36 +++++ .../selftests/kvm/lib/x86_64/processor.c | 16 +++ .../selftests/kvm/x86_64/mmio_warning_test.c | 126 ++++++++++++++++++ 7 files changed, 184 insertions(+) create mode 100644 tools/testing/selftests/kvm/x86_64/mmio_warning_test.c diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore index df1bf9230a74..41266af0d3dc 100644 --- a/tools/testing/selftests/kvm/.gitignore +++ b/tools/testing/selftests/kvm/.gitignore @@ -2,6 +2,7 @@ /x86_64/evmcs_test /x86_64/hyperv_cpuid /x86_64/kvm_create_max_vcpus +/x86_64/mmio_warning_test /x86_64/platform_info_test /x86_64/set_sregs_test /x86_64/smm_test diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index 79c524395ebe..670b938f1049 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -22,6 +22,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/vmx_close_while_nested_test TEST_GEN_PROGS_x86_64 += x86_64/smm_test TEST_GEN_PROGS_x86_64 += x86_64/kvm_create_max_vcpus TEST_GEN_PROGS_x86_64 += x86_64/vmx_set_nested_state_test +TEST_GEN_PROGS_x86_64 += x86_64/mmio_warning_test TEST_GEN_PROGS_x86_64 += dirty_log_test TEST_GEN_PROGS_x86_64 += clear_dirty_log_test diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h index 8c6b9619797d..c5c427c86598 100644 --- a/tools/testing/selftests/kvm/include/kvm_util.h +++ b/tools/testing/selftests/kvm/include/kvm_util.h @@ -137,6 +137,8 @@ struct kvm_vm *vm_create_default(uint32_t vcpuid, uint64_t extra_mem_size, void *guest_code); void vm_vcpu_add_default(struct kvm_vm *vm, uint32_t vcpuid, void *guest_code); +bool vm_is_unrestricted_guest(struct kvm_vm *vm); + struct kvm_userspace_memory_region * kvm_userspace_memory_region_find(struct kvm_vm *vm, uint64_t start, uint64_t end); diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h index 6063d5b2f356..af4d26de32d1 100644 --- a/tools/testing/selftests/kvm/include/x86_64/processor.h +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h @@ -303,6 +303,8 @@ static inline unsigned long get_xmm(int n) return 0; } +bool is_intel_cpu(void); + struct kvm_x86_state; struct kvm_x86_state *vcpu_save_state(struct kvm_vm *vm, uint32_t vcpuid); void vcpu_load_state(struct kvm_vm *vm, uint32_t vcpuid, diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index e9113857f44e..b93b09ad9a11 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -1584,3 +1584,39 @@ void *addr_gva2hva(struct kvm_vm *vm, vm_vaddr_t gva) { return addr_gpa2hva(vm, addr_gva2gpa(vm, gva)); } + +/* + * Is Unrestricted Guest + * + * Input Args: + * vm - Virtual Machine + * + * Output Args: None + * + * Return: True if the unrestricted guest is set to 'Y', otherwise return false. + * + * Check if the unrestricted guest flag is enabled. + */ +bool vm_is_unrestricted_guest(struct kvm_vm *vm) +{ + char val = 'N'; + size_t count; + FILE *f; + + if (vm == NULL) { + /* Ensure that the KVM vendor-specific module is loaded. */ + f = fopen(KVM_DEV_PATH, "r"); + TEST_ASSERT(f != NULL, "Error in opening KVM dev file: %d", + errno); + fclose(f); + } + + f = fopen("/sys/module/kvm_intel/parameters/unrestricted_guest", "r"); + if (f) { + count = fread(&val, sizeof(char), 1, f); + TEST_ASSERT(count == 1, "Unable to read from param file."); + fclose(f); + } + + return val == 'Y'; +} diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c index dc7fae9fa424..bcc0e70e1856 100644 --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c @@ -1139,3 +1139,19 @@ void vcpu_load_state(struct kvm_vm *vm, uint32_t vcpuid, struct kvm_x86_state *s r); } } + +bool is_intel_cpu(void) +{ + int eax, ebx, ecx, edx; + const uint32_t *chunk; + const int leaf = 0; + + __asm__ __volatile__( + "cpuid" + : /* output */ "=a"(eax), "=b"(ebx), + "=c"(ecx), "=d"(edx) + : /* input */ "0"(leaf), "2"(0)); + + chunk = (const uint32_t *)("GenuineIntel"); + return (ebx == chunk[0] && edx == chunk[1] && ecx == chunk[2]); +} diff --git a/tools/testing/selftests/kvm/x86_64/mmio_warning_test.c b/tools/testing/selftests/kvm/x86_64/mmio_warning_test.c new file mode 100644 index 000000000000..00bb97d76000 --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/mmio_warning_test.c @@ -0,0 +1,126 @@ +/* + * mmio_warning_test + * + * Copyright (C) 2019, Google LLC. + * + * This work is licensed under the terms of the GNU GPL, version 2. + * + * Test that we don't get a kernel warning when we call KVM_RUN after a + * triple fault occurs. To get the triple fault to occur we call KVM_RUN + * on a VCPU that hasn't been properly setup. + * + */ + +#define _GNU_SOURCE +#include <fcntl.h> +#include <kvm_util.h> +#include <linux/kvm.h> +#include <processor.h> +#include <pthread.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/ioctl.h> +#include <sys/mman.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <sys/wait.h> +#include <test_util.h> +#include <unistd.h> + +#define NTHREAD 4 +#define NPROCESS 5 + +struct thread_context { + int kvmcpu; + struct kvm_run *run; +}; + +void *thr(void *arg) +{ + struct thread_context *tc = (struct thread_context *)arg; + int res; + int kvmcpu = tc->kvmcpu; + struct kvm_run *run = tc->run; + + res = ioctl(kvmcpu, KVM_RUN, 0); + printf("ret1=%d exit_reason=%d suberror=%d\n", + res, run->exit_reason, run->internal.suberror); + + return 0; +} + +void test(void) +{ + int i, kvm, kvmvm, kvmcpu; + pthread_t th[NTHREAD]; + struct kvm_run *run; + struct thread_context tc; + + kvm = open("/dev/kvm", O_RDWR); + TEST_ASSERT(kvm != -1, "failed to open /dev/kvm"); + kvmvm = ioctl(kvm, KVM_CREATE_VM, 0); + TEST_ASSERT(kvmvm != -1, "KVM_CREATE_VM failed"); + kvmcpu = ioctl(kvmvm, KVM_CREATE_VCPU, 0); + TEST_ASSERT(kvmcpu != -1, "KVM_CREATE_VCPU failed"); + run = (struct kvm_run *)mmap(0, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, + kvmcpu, 0); + tc.kvmcpu = kvmcpu; + tc.run = run; + srand(getpid()); + for (i = 0; i < NTHREAD; i++) { + pthread_create(&th[i], NULL, thr, (void *)(uintptr_t)&tc); + usleep(rand() % 10000); + } + for (i = 0; i < NTHREAD; i++) + pthread_join(th[i], NULL); +} + +int get_warnings_count(void) +{ + int warnings; + FILE *f; + + f = popen("dmesg | grep \"WARNING:\" | wc -l", "r"); + fscanf(f, "%d", &warnings); + fclose(f); + + return warnings; +} + +int main(void) +{ + int warnings_before, warnings_after; + + if (!is_intel_cpu()) { + printf("Must be run on an Intel CPU, skipping test\n"); + exit(KSFT_SKIP); + } + + if (vm_is_unrestricted_guest(NULL)) { + printf("Unrestricted guest must be disabled, skipping test\n"); + exit(KSFT_SKIP); + } + + warnings_before = get_warnings_count(); + + for (int i = 0; i < NPROCESS; ++i) { + int status; + int pid = fork(); + + if (pid < 0) + exit(1); + if (pid == 0) { + test(); + exit(0); + } + while (waitpid(pid, &status, __WALL) != pid) + ; + } + + warnings_after = get_warnings_count(); + TEST_ASSERT(warnings_before == warnings_after, + "Warnings found in kernel. Run 'dmesg' to inspect them."); + + return 0; +} -- 2.22.0.rc1.311.g5d7573a151-goog
