diff options
| -rw-r--r-- | tools/testing/selftests/kvm/.gitignore | 1 | ||||
| -rw-r--r-- | tools/testing/selftests/kvm/Makefile | 3 | ||||
| -rw-r--r-- | tools/testing/selftests/kvm/lib/kvm_util.c | 2 | ||||
| -rw-r--r-- | tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c | 560 |
4 files changed, 565 insertions, 1 deletions
diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore index 5468db7dd674..5008bf90772b 100644 --- a/tools/testing/selftests/kvm/.gitignore +++ b/tools/testing/selftests/kvm/.gitignore @@ -18,6 +18,7 @@ /x86_64/sync_regs_test /x86_64/tsc_msrs_test /x86_64/user_msr_test +/x86_64/userspace_msr_exit_test /x86_64/vmx_apic_access_test /x86_64/vmx_close_while_nested_test /x86_64/vmx_dirty_log_test diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index 4febf4d5ead9..d54870db21c4 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -50,6 +50,8 @@ TEST_GEN_PROGS_x86_64 += x86_64/state_test TEST_GEN_PROGS_x86_64 += x86_64/vmx_preemption_timer_test TEST_GEN_PROGS_x86_64 += x86_64/svm_vmcall_test TEST_GEN_PROGS_x86_64 += x86_64/sync_regs_test +TEST_GEN_PROGS_x86_64 += x86_64/user_msr_test +TEST_GEN_PROGS_x86_64 += x86_64/userspace_msr_exit_test TEST_GEN_PROGS_x86_64 += x86_64/vmx_apic_access_test TEST_GEN_PROGS_x86_64 += x86_64/vmx_close_while_nested_test TEST_GEN_PROGS_x86_64 += x86_64/vmx_dirty_log_test @@ -58,7 +60,6 @@ TEST_GEN_PROGS_x86_64 += x86_64/vmx_tsc_adjust_test TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test TEST_GEN_PROGS_x86_64 += x86_64/debug_regs TEST_GEN_PROGS_x86_64 += x86_64/tsc_msrs_test -TEST_GEN_PROGS_x86_64 += x86_64/user_msr_test TEST_GEN_PROGS_x86_64 += demand_paging_test TEST_GEN_PROGS_x86_64 += dirty_log_test TEST_GEN_PROGS_x86_64 += dirty_log_perf_test diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index b2c426adb87f..88ef7067f1e6 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -1806,6 +1806,8 @@ static struct exit_reason { {KVM_EXIT_OSI, "OSI"}, {KVM_EXIT_PAPR_HCALL, "PAPR_HCALL"}, {KVM_EXIT_DIRTY_RING_FULL, "DIRTY_RING_FULL"}, + {KVM_EXIT_X86_RDMSR, "RDMSR"}, + {KVM_EXIT_X86_WRMSR, "WRMSR"}, #ifdef KVM_EXIT_MEMORY_NOT_PRESENT {KVM_EXIT_MEMORY_NOT_PRESENT, "MEMORY_NOT_PRESENT"}, #endif diff --git a/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c b/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c new file mode 100644 index 000000000000..e8b6918cdea0 --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c @@ -0,0 +1,560 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2020, Google LLC. + * + * Tests for exiting into userspace on registered MSRs + */ + +#define _GNU_SOURCE /* for program_invocation_short_name */ +#include <sys/ioctl.h> + +#include "test_util.h" +#include "kvm_util.h" +#include "vmx.h" + +/* Forced emulation prefix, used to invoke the emulator unconditionally. */ +#define KVM_FEP "ud2; .byte 'k', 'v', 'm';" +#define KVM_FEP_LENGTH 5 +static int fep_available = 1; + +#define VCPU_ID 1 +#define MSR_NON_EXISTENT 0x474f4f00 + +u64 deny_bits = 0; +struct kvm_msr_filter filter = { + .flags = KVM_MSR_FILTER_DEFAULT_ALLOW, + .ranges = { + { + .flags = KVM_MSR_FILTER_READ | + KVM_MSR_FILTER_WRITE, + .nmsrs = 1, + /* Test an MSR the kernel knows about. */ + .base = MSR_IA32_XSS, + .bitmap = (uint8_t*)&deny_bits, + }, { + .flags = KVM_MSR_FILTER_READ | + KVM_MSR_FILTER_WRITE, + .nmsrs = 1, + /* Test an MSR the kernel doesn't know about. */ + .base = MSR_IA32_FLUSH_CMD, + .bitmap = (uint8_t*)&deny_bits, + }, { + .flags = KVM_MSR_FILTER_READ | + KVM_MSR_FILTER_WRITE, + .nmsrs = 1, + /* Test a fabricated MSR that no one knows about. */ + .base = MSR_NON_EXISTENT, + .bitmap = (uint8_t*)&deny_bits, + }, + }, +}; + +struct kvm_msr_filter filter_fs = { + .flags = KVM_MSR_FILTER_DEFAULT_ALLOW, + .ranges = { + { + .flags = KVM_MSR_FILTER_READ | + KVM_MSR_FILTER_WRITE, + .nmsrs = 1, + .base = MSR_FS_BASE, + .bitmap = (uint8_t*)&deny_bits, + }, + }, +}; + +struct kvm_msr_filter filter_gs = { + .flags = KVM_MSR_FILTER_DEFAULT_ALLOW, + .ranges = { + { + .flags = KVM_MSR_FILTER_READ | + KVM_MSR_FILTER_WRITE, + .nmsrs = 1, + .base = MSR_GS_BASE, + .bitmap = (uint8_t*)&deny_bits, + }, + }, +}; + +uint64_t msr_non_existent_data; +int guest_exception_count; + +/* + * Note: Force test_rdmsr() to not be inlined to prevent the labels, + * rdmsr_start and rdmsr_end, from being defined multiple times. + */ +static noinline uint64_t test_rdmsr(uint32_t msr) +{ + uint32_t a, d; + + guest_exception_count = 0; + + __asm__ __volatile__("rdmsr_start: rdmsr; rdmsr_end:" : + "=a"(a), "=d"(d) : "c"(msr) : "memory"); + + return a | ((uint64_t) d << 32); +} + +/* + * Note: Force test_wrmsr() to not be inlined to prevent the labels, + * wrmsr_start and wrmsr_end, from being defined multiple times. + */ +static noinline void test_wrmsr(uint32_t msr, uint64_t value) +{ + uint32_t a = value; + uint32_t d = value >> 32; + + guest_exception_count = 0; + + __asm__ __volatile__("wrmsr_start: wrmsr; wrmsr_end:" :: + "a"(a), "d"(d), "c"(msr) : "memory"); +} + +extern char rdmsr_start, rdmsr_end; +extern char wrmsr_start, wrmsr_end; + +/* + * Note: Force test_em_rdmsr() to not be inlined to prevent the labels, + * rdmsr_start and rdmsr_end, from being defined multiple times. + */ +static noinline uint64_t test_em_rdmsr(uint32_t msr) +{ + uint32_t a, d; + + guest_exception_count = 0; + + __asm__ __volatile__(KVM_FEP "em_rdmsr_start: rdmsr; em_rdmsr_end:" : + "=a"(a), "=d"(d) : "c"(msr) : "memory"); + + return a | ((uint64_t) d << 32); +} + +/* + * Note: Force test_em_wrmsr() to not be inlined to prevent the labels, + * wrmsr_start and wrmsr_end, from being defined multiple times. + */ +static noinline void test_em_wrmsr(uint32_t msr, uint64_t value) +{ + uint32_t a = value; + uint32_t d = value >> 32; + + guest_exception_count = 0; + + __asm__ __volatile__(KVM_FEP "em_wrmsr_start: wrmsr; em_wrmsr_end:" :: + "a"(a), "d"(d), "c"(msr) : "memory"); +} + +extern char em_rdmsr_start, em_rdmsr_end; +extern char em_wrmsr_start, em_wrmsr_end; + +static void guest_code(void) +{ + uint64_t data; + + /* + * Test userspace intercepting rdmsr / wrmsr for MSR_IA32_XSS. + * + * A GP is thrown if anything other than 0 is written to + * MSR_IA32_XSS. + */ + data = test_rdmsr(MSR_IA32_XSS); + GUEST_ASSERT(data == 0); + GUEST_ASSERT(guest_exception_count == 0); + + test_wrmsr(MSR_IA32_XSS, 0); + GUEST_ASSERT(guest_exception_count == 0); + + test_wrmsr(MSR_IA32_XSS, 1); + GUEST_ASSERT(guest_exception_count == 1); + + /* + * Test userspace intercepting rdmsr / wrmsr for MSR_IA32_FLUSH_CMD. + * + * A GP is thrown if MSR_IA32_FLUSH_CMD is read + * from or if a value other than 1 is written to it. + */ + test_rdmsr(MSR_IA32_FLUSH_CMD); + GUEST_ASSERT(guest_exception_count == 1); + + test_wrmsr(MSR_IA32_FLUSH_CMD, 0); + GUEST_ASSERT(guest_exception_count == 1); + + test_wrmsr(MSR_IA32_FLUSH_CMD, 1); + GUEST_ASSERT(guest_exception_count == 0); + + /* + * Test userspace intercepting rdmsr / wrmsr for MSR_NON_EXISTENT. + * + * Test that a fabricated MSR can pass through the kernel + * and be handled in userspace. + */ + test_wrmsr(MSR_NON_EXISTENT, 2); + GUEST_ASSERT(guest_exception_count == 0); + + data = test_rdmsr(MSR_NON_EXISTENT); + GUEST_ASSERT(data == 2); + GUEST_ASSERT(guest_exception_count == 0); + + /* + * Test to see if the instruction emulator is available (ie: the module + * parameter 'kvm.force_emulation_prefix=1' is set). This instruction + * will #UD if it isn't available. + */ + __asm__ __volatile__(KVM_FEP "nop"); + + if (fep_available) { + /* Let userspace know we aren't done. */ + GUEST_SYNC(0); + + /* + * Now run the same tests with the instruction emulator. + */ + data = test_em_rdmsr(MSR_IA32_XSS); + GUEST_ASSERT(data == 0); + GUEST_ASSERT(guest_exception_count == 0); + test_em_wrmsr(MSR_IA32_XSS, 0); + GUEST_ASSERT(guest_exception_count == 0); + test_em_wrmsr(MSR_IA32_XSS, 1); + GUEST_ASSERT(guest_exception_count == 1); + + test_em_rdmsr(MSR_IA32_FLUSH_CMD); + GUEST_ASSERT(guest_exception_count == 1); + test_em_wrmsr(MSR_IA32_FLUSH_CMD, 0); + GUEST_ASSERT(guest_exception_count == 1); + test_em_wrmsr(MSR_IA32_FLUSH_CMD, 1); + GUEST_ASSERT(guest_exception_count == 0); + + test_em_wrmsr(MSR_NON_EXISTENT, 2); + GUEST_ASSERT(guest_exception_count == 0); + data = test_em_rdmsr(MSR_NON_EXISTENT); + GUEST_ASSERT(data == 2); + GUEST_ASSERT(guest_exception_count == 0); + } + + GUEST_DONE(); +} + + +static void guest_code_permission_bitmap(void) +{ + uint64_t data; + + test_wrmsr(MSR_FS_BASE, 0); + data = test_rdmsr(MSR_FS_BASE); + GUEST_ASSERT(data == MSR_FS_BASE); + + test_wrmsr(MSR_GS_BASE, 0); + data = test_rdmsr(MSR_GS_BASE); + GUEST_ASSERT(data == 0); + + /* Let userspace know to switch the filter */ + GUEST_SYNC(0); + + test_wrmsr(MSR_FS_BASE, 0); + data = test_rdmsr(MSR_FS_BASE); + GUEST_ASSERT(data == 0); + + test_wrmsr(MSR_GS_BASE, 0); + data = test_rdmsr(MSR_GS_BASE); + GUEST_ASSERT(data == MSR_GS_BASE); + + GUEST_DONE(); +} + +static void __guest_gp_handler(struct ex_regs *regs, + char *r_start, char *r_end, + char *w_start, char *w_end) +{ + if (regs->rip == (uintptr_t)r_start) { + regs->rip = (uintptr_t)r_end; + regs->rax = 0; + regs->rdx = 0; + } else if (regs->rip == (uintptr_t)w_start) { + regs->rip = (uintptr_t)w_end; + } else { + GUEST_ASSERT(!"RIP is at an unknown location!"); + } + + ++guest_exception_count; +} + +static void guest_gp_handler(struct ex_regs *regs) +{ + __guest_gp_handler(regs, &rdmsr_start, &rdmsr_end, + &wrmsr_start, &wrmsr_end); +} + +static void guest_fep_gp_handler(struct ex_regs *regs) +{ + __guest_gp_handler(regs, &em_rdmsr_start, &em_rdmsr_end, + &em_wrmsr_start, &em_wrmsr_end); +} + +static void guest_ud_handler(struct ex_regs *regs) +{ + fep_available = 0; + regs->rip += KVM_FEP_LENGTH; +} + +static void run_guest(struct kvm_vm *vm) +{ + int rc; + + rc = _vcpu_run(vm, VCPU_ID); + TEST_ASSERT(rc == 0, "vcpu_run failed: %d\n", rc); +} + +static void check_for_guest_assert(struct kvm_vm *vm) +{ + struct kvm_run *run = vcpu_state(vm, VCPU_ID); + struct ucall uc; + + if (run->exit_reason == KVM_EXIT_IO && + get_ucall(vm, VCPU_ID, &uc) == UCALL_ABORT) { + TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0], + __FILE__, uc.args[1]); + } +} + +static void process_rdmsr(struct kvm_vm *vm, uint32_t msr_index) +{ + struct kvm_run *run = vcpu_state(vm, VCPU_ID); + + check_for_guest_assert(vm); + + TEST_ASSERT(run->exit_reason == KVM_EXIT_X86_RDMSR, + "Unexpected exit reason: %u (%s),\n", + run->exit_reason, + exit_reason_str(run->exit_reason)); + TEST_ASSERT(run->msr.index == msr_index, + "Unexpected msr (0x%04x), expected 0x%04x", + run->msr.index, msr_index); + + switch (run->msr.index) { + case MSR_IA32_XSS: + run->msr.data = 0; + break; + case MSR_IA32_FLUSH_CMD: + run->msr.error = 1; + break; + case MSR_NON_EXISTENT: + run->msr.data = msr_non_existent_data; + break; + case MSR_FS_BASE: + run->msr.data = MSR_FS_BASE; + break; + case MSR_GS_BASE: + run->msr.data = MSR_GS_BASE; + break; + default: + TEST_ASSERT(false, "Unexpected MSR: 0x%04x", run->msr.index); + } +} + +static void process_wrmsr(struct kvm_vm *vm, uint32_t msr_index) +{ + struct kvm_run *run = vcpu_state(vm, VCPU_ID); + + check_for_guest_assert(vm); + + TEST_ASSERT(run->exit_reason == KVM_EXIT_X86_WRMSR, + "Unexpected exit reason: %u (%s),\n", + run->exit_reason, + exit_reason_str(run->exit_reason)); + TEST_ASSERT(run->msr.index == msr_index, + "Unexpected msr (0x%04x), expected 0x%04x", + run->msr.index, msr_index); + + switch (run->msr.index) { + case MSR_IA32_XSS: + if (run->msr.data != 0) + run->msr.error = 1; + break; + case MSR_IA32_FLUSH_CMD: + if (run->msr.data != 1) + run->msr.error = 1; + break; + case MSR_NON_EXISTENT: + msr_non_existent_data = run->msr.data; + break; + case MSR_FS_BASE: + case MSR_GS_BASE: + break; + default: + TEST_ASSERT(false, "Unexpected MSR: 0x%04x", run->msr.index); + } +} + +static void process_ucall_done(struct kvm_vm *vm) +{ + struct kvm_run *run = vcpu_state(vm, VCPU_ID); + struct ucall uc; + + check_for_guest_assert(vm); + + TEST_ASSERT(run->exit_reason == KVM_EXIT_IO, + "Unexpected exit reason: %u (%s)", + run->exit_reason, + exit_reason_str(run->exit_reason)); + + TEST_ASSERT(get_ucall(vm, VCPU_ID, &uc) == UCALL_DONE, + "Unexpected ucall command: %lu, expected UCALL_DONE (%d)", + uc.cmd, UCALL_DONE); +} + +static uint64_t process_ucall(struct kvm_vm *vm) +{ + struct kvm_run *run = vcpu_state(vm, VCPU_ID); + struct ucall uc = {}; + + check_for_guest_assert(vm); + + TEST_ASSERT(run->exit_reason == KVM_EXIT_IO, + "Unexpected exit reason: %u (%s)", + run->exit_reason, + exit_reason_str(run->exit_reason)); + + switch (get_ucall(vm, VCPU_ID, &uc)) { + case UCALL_SYNC: + break; + case UCALL_ABORT: + check_for_guest_assert(vm); + break; + case UCALL_DONE: + process_ucall_done(vm); + break; + default: + TEST_ASSERT(false, "Unexpected ucall"); + } + + return uc.cmd; +} + +static void run_guest_then_process_rdmsr(struct kvm_vm *vm, uint32_t msr_index) +{ + run_guest(vm); + process_rdmsr(vm, msr_index); +} + +static void run_guest_then_process_wrmsr(struct kvm_vm *vm, uint32_t msr_index) +{ + run_guest(vm); + process_wrmsr(vm, msr_index); +} + +static uint64_t run_guest_then_process_ucall(struct kvm_vm *vm) +{ + run_guest(vm); + return process_ucall(vm); +} + +static void run_guest_then_process_ucall_done(struct kvm_vm *vm) +{ + run_guest(vm); + process_ucall_done(vm); +} + +static void test_msr_filter(void) { + struct kvm_enable_cap cap = { + .cap = KVM_CAP_X86_USER_SPACE_MSR, + .args[0] = KVM_MSR_EXIT_REASON_FILTER, + }; + struct kvm_vm *vm; + int rc; + + /* Create VM */ + vm = vm_create_default(VCPU_ID, 0, guest_code); + vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid()); + + rc = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR); + TEST_ASSERT(rc, "KVM_CAP_X86_USER_SPACE_MSR is available"); + vm_enable_cap(vm, &cap); + + rc = kvm_check_cap(KVM_CAP_X86_MSR_FILTER); + TEST_ASSERT(rc, "KVM_CAP_X86_MSR_FILTER is available"); + + vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter); + + vm_init_descriptor_tables(vm); + vcpu_init_descriptor_tables(vm, VCPU_ID); + + vm_handle_exception(vm, GP_VECTOR, guest_gp_handler); + + /* Process guest code userspace exits. */ + run_guest_then_process_rdmsr(vm, MSR_IA32_XSS); + run_guest_then_process_wrmsr(vm, MSR_IA32_XSS); + run_guest_then_process_wrmsr(vm, MSR_IA32_XSS); + + run_guest_then_process_rdmsr(vm, MSR_IA32_FLUSH_CMD); + run_guest_then_process_wrmsr(vm, MSR_IA32_FLUSH_CMD); + run_guest_then_process_wrmsr(vm, MSR_IA32_FLUSH_CMD); + + run_guest_then_process_wrmsr(vm, MSR_NON_EXISTENT); + run_guest_then_process_rdmsr(vm, MSR_NON_EXISTENT); + + vm_handle_exception(vm, UD_VECTOR, guest_ud_handler); + run_guest(vm); + vm_handle_exception(vm, UD_VECTOR, NULL); + + if (process_ucall(vm) != UCALL_DONE) { + vm_handle_exception(vm, GP_VECTOR, guest_fep_gp_handler); + + /* Process emulated rdmsr and wrmsr instructions. */ + run_guest_then_process_rdmsr(vm, MSR_IA32_XSS); + run_guest_then_process_wrmsr(vm, MSR_IA32_XSS); + run_guest_then_process_wrmsr(vm, MSR_IA32_XSS); + + run_guest_then_process_rdmsr(vm, MSR_IA32_FLUSH_CMD); + run_guest_then_process_wrmsr(vm, MSR_IA32_FLUSH_CMD); + run_guest_then_process_wrmsr(vm, MSR_IA32_FLUSH_CMD); + + run_guest_then_process_wrmsr(vm, MSR_NON_EXISTENT); + run_guest_then_process_rdmsr(vm, MSR_NON_EXISTENT); + + /* Confirm the guest completed without issues. */ + run_guest_then_process_ucall_done(vm); + } else { + printf("To run the instruction emulated tests set the module parameter 'kvm.force_emulation_prefix=1'\n"); + } + + kvm_vm_free(vm); +} + +static void test_msr_permission_bitmap(void) { + struct kvm_enable_cap cap = { + .cap = KVM_CAP_X86_USER_SPACE_MSR, + .args[0] = KVM_MSR_EXIT_REASON_FILTER, + }; + struct kvm_vm *vm; + int rc; + + /* Create VM */ + vm = vm_create_default(VCPU_ID, 0, guest_code_permission_bitmap); + vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid()); + + rc = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR); + TEST_ASSERT(rc, "KVM_CAP_X86_USER_SPACE_MSR is available"); + vm_enable_cap(vm, &cap); + + rc = kvm_check_cap(KVM_CAP_X86_MSR_FILTER); + TEST_ASSERT(rc, "KVM_CAP_X86_MSR_FILTER is available"); + + vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_fs); + run_guest_then_process_wrmsr(vm, MSR_FS_BASE); + run_guest_then_process_rdmsr(vm, MSR_FS_BASE); + TEST_ASSERT(run_guest_then_process_ucall(vm) == UCALL_SYNC, "Expected ucall state to be UCALL_SYNC."); + vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_gs); + run_guest_then_process_wrmsr(vm, MSR_GS_BASE); + run_guest_then_process_rdmsr(vm, MSR_GS_BASE); + run_guest_then_process_ucall_done(vm); + + kvm_vm_free(vm); +} + +int main(int argc, char *argv[]) +{ + test_msr_filter(); + + test_msr_permission_bitmap(); + + return 0; +} |