KVM_CAP_VM_TYPES advertises the bitmap of VM types that KVM_CREATE_VM
accepts, but nothing verified that the ioctl actually enforces it: that
every advertised type can be created and every non-advertised type is
rejected. sev_init2_tests carried a TODO for this ("check that
unsupported types cannot be created. Probably a separate selftest"),
but the check is not specific to SEV or KVM_SEV_INIT2, and not even to
x86.Add a standalone test that walks the type space and, for each value, asserts that KVM_CREATE_VM succeeds iff the corresponding bit is set in KVM_CAP_VM_TYPES, and otherwise fails with -EINVAL. The walk extends past bit 31 so that out-of-range type values, which can never be advertised in the u32 bitmap, are also confirmed to be rejected. The test only depends on KVM_CAP_VM_TYPES, so it lives in the common set and is skipped on architectures that don't advertise the capability. Drop the now-addressed TODO from sev_init2_tests.c. Tested on an AMD SEV-SNP capable host. With KVM_CAP_VM_TYPES=0x15 (DEFAULT/SEV/SNP), only the advertised types are created and everything else is rejected: $ strace -e trace=ioctl ./vm_types_test 2>&1 | grep KVM_CREATE_VM ioctl(3, KVM_CREATE_VM, 0) = 4 # DEFAULT ioctl(3, KVM_CREATE_VM, 0x1) = -1 EINVAL # SW_PROTECTED ioctl(3, KVM_CREATE_VM, 0x2) = 4 # SEV ioctl(3, KVM_CREATE_VM, 0x3) = -1 EINVAL # SEV-ES ioctl(3, KVM_CREATE_VM, 0x4) = 4 # SNP ioctl(3, KVM_CREATE_VM, 0x5) = -1 EINVAL # TDX ... 0x6..0x3f all -1 EINVAL ... Reloading kvm_amd with sev_snp=0 drops the bitmap to 0x5 and only types 0 and 2 are then created, confirming the test tracks the advertised set rather than hard-coded types. Signed-off-by: Hemanth Selam <[email protected]> --- Changes in v3: - Reworked into a separate, generic test that checks all VM types against KVM_CAP_VM_TYPES (per review), instead of adding negative checks to sev_init2_tests; also cover out-of-range types. Dropped the manual fd cleanup and the redundant errno in the assert message, and removed the addressed TODO from sev_init2_tests.c. - Dropped the separate "SEV: Sanity check the launch measurement" patch that accompanied v1/v2; this revision is a single patch. v2: https://lore.kernel.org/all/[email protected]/ v1: https://lore.kernel.org/all/[email protected]/ tools/testing/selftests/kvm/Makefile.kvm | 1 + tools/testing/selftests/kvm/vm_types_test.c | 50 +++++++++++++++++++ .../selftests/kvm/x86/sev_init2_tests.c | 4 -- 3 files changed, 51 insertions(+), 4 deletions(-) create mode 100644 tools/testing/selftests/kvm/vm_types_test.c diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm index d28a057fa6c2..ad74d0b98694 100644 --- a/tools/testing/selftests/kvm/Makefile.kvm +++ b/tools/testing/selftests/kvm/Makefile.kvm @@ -66,6 +66,7 @@ TEST_GEN_PROGS_COMMON += kvm_page_table_test TEST_GEN_PROGS_COMMON += set_memory_region_test TEST_GEN_PROGS_COMMON += memslot_modification_stress_test TEST_GEN_PROGS_COMMON += memslot_perf_test +TEST_GEN_PROGS_COMMON += vm_types_test # Compiled test targets TEST_GEN_PROGS_x86 = $(TEST_GEN_PROGS_COMMON) diff --git a/tools/testing/selftests/kvm/vm_types_test.c b/tools/testing/selftests/kvm/vm_types_test.c new file mode 100644 index 000000000000..e8ef3b018f6c --- /dev/null +++ b/tools/testing/selftests/kvm/vm_types_test.c @@ -0,0 +1,50 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Verify that KVM_CREATE_VM accepts exactly the VM types enumerated by + * KVM_CAP_VM_TYPES, and rejects every other type with -EINVAL. + */ +#include <errno.h> +#include <stdbool.h> +#include <unistd.h> + +#include <linux/kvm.h> + +#include "kvm_util.h" +#include "test_util.h" + +int main(void) +{ + unsigned int supported_types; + unsigned long type; + int kvm_fd, fd; + + TEST_REQUIRE(kvm_has_cap(KVM_CAP_VM_TYPES)); + + kvm_fd = open_kvm_dev_path_or_exit(); + supported_types = kvm_check_cap(KVM_CAP_VM_TYPES); + pr_info("KVM_CAP_VM_TYPES: 0x%x\n", supported_types); + + /* + * KVM_CAP_VM_TYPES is a u32 bitmap, so only types 0..31 can ever be + * advertised. Walk past that range as well to confirm that any + * out-of-range type is rejected rather than silently accepted. + */ + for (type = 0; type < 64; type++) { + bool supported = type < 32 && (supported_types & (1U << type)); + + fd = __kvm_ioctl(kvm_fd, KVM_CREATE_VM, (void *)type); + + if (supported) { + TEST_ASSERT(fd >= 0, + "KVM_CREATE_VM(%lu) should succeed, KVM_CAP_VM_TYPES=0x%x", + type, supported_types); + close(fd); + } else { + TEST_ASSERT(fd < 0 && errno == EINVAL, + "KVM_CREATE_VM(%lu) should fail with EINVAL, KVM_CAP_VM_TYPES=0x%x", + type, supported_types); + } + } + + return 0; +} diff --git a/tools/testing/selftests/kvm/x86/sev_init2_tests.c b/tools/testing/selftests/kvm/x86/sev_init2_tests.c index 8db88c355f16..d4227dc922ab 100644 --- a/tools/testing/selftests/kvm/x86/sev_init2_tests.c +++ b/tools/testing/selftests/kvm/x86/sev_init2_tests.c @@ -77,10 +77,6 @@ void test_vm_types(void) { test_init2(KVM_X86_SEV_VM, &(struct kvm_sev_init){}); - /* - * TODO: check that unsupported types cannot be created. Probably - * a separate selftest. - */ if (have_sev_es) test_init2(KVM_X86_SEV_ES_VM, &(struct kvm_sev_init){}); -- 2.43.7
