| Message ID | 20250611133330.1514028-19-tabba@google.com |
|---|---|
| State | New |
| Headers | show |
| Series | KVM: Mapping guest_memfd backed memory at the host for software protected VMs | expand |
On 6/11/2025 7:03 PM, Fuad Tabba wrote: > Expand the guest_memfd selftests to include testing mapping guest > memory for VM types that support it. > > Reviewed-by: James Houghton <jthoughton@google.com> > Reviewed-by: Gavin Shan <gshan@redhat.com> > Co-developed-by: Ackerley Tng <ackerleytng@google.com> > Signed-off-by: Ackerley Tng <ackerleytng@google.com> > Signed-off-by: Fuad Tabba <tabba@google.com> > --- > .../testing/selftests/kvm/guest_memfd_test.c | 201 ++++++++++++++++-- > 1 file changed, 180 insertions(+), 21 deletions(-) > > diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c > index 341ba616cf55..5da2ed6277ac 100644 > --- a/tools/testing/selftests/kvm/guest_memfd_test.c > +++ b/tools/testing/selftests/kvm/guest_memfd_test.c > @@ -13,6 +13,8 @@ > > #include <linux/bitmap.h> > #include <linux/falloc.h> > +#include <setjmp.h> > +#include <signal.h> > #include <sys/mman.h> > #include <sys/types.h> > #include <sys/stat.h> > @@ -34,12 +36,83 @@ static void test_file_read_write(int fd) > "pwrite on a guest_mem fd should fail"); > } > > -static void test_mmap(int fd, size_t page_size) > +static void test_mmap_supported(int fd, size_t page_size, size_t total_size) > +{ > + const char val = 0xaa; > + char *mem; > + size_t i; > + int ret; > + > + mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); > + TEST_ASSERT(mem == MAP_FAILED, "Copy-on-write not allowed by guest_memfd."); > + > + mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); > + TEST_ASSERT(mem != MAP_FAILED, "mmap() for shared guest memory should succeed."); > + > + memset(mem, val, total_size); > + for (i = 0; i < total_size; i++) > + TEST_ASSERT_EQ(READ_ONCE(mem[i]), val); > + > + ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 0, > + page_size); > + TEST_ASSERT(!ret, "fallocate the first page should succeed."); > + > + for (i = 0; i < page_size; i++) > + TEST_ASSERT_EQ(READ_ONCE(mem[i]), 0x00); > + for (; i < total_size; i++) > + TEST_ASSERT_EQ(READ_ONCE(mem[i]), val); > + > + memset(mem, val, page_size); > + for (i = 0; i < total_size; i++) > + TEST_ASSERT_EQ(READ_ONCE(mem[i]), val); > + > + ret = munmap(mem, total_size); > + TEST_ASSERT(!ret, "munmap() should succeed."); > +} > + > +static sigjmp_buf jmpbuf; > +void fault_sigbus_handler(int signum) > +{ > + siglongjmp(jmpbuf, 1); > +} > + > +static void test_fault_overflow(int fd, size_t page_size, size_t total_size) > +{ > + struct sigaction sa_old, sa_new = { > + .sa_handler = fault_sigbus_handler, > + }; > + size_t map_size = total_size * 4; > + const char val = 0xaa; > + char *mem; > + size_t i; > + int ret; > + > + mem = mmap(NULL, map_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); > + TEST_ASSERT(mem != MAP_FAILED, "mmap() for shared guest memory should succeed."); > + > + sigaction(SIGBUS, &sa_new, &sa_old); > + if (sigsetjmp(jmpbuf, 1) == 0) { > + memset(mem, 0xaa, map_size); > + TEST_ASSERT(false, "memset() should have triggered SIGBUS."); > + } > + sigaction(SIGBUS, &sa_old, NULL); > + > + for (i = 0; i < total_size; i++) > + TEST_ASSERT_EQ(READ_ONCE(mem[i]), val); > + > + ret = munmap(mem, map_size); > + TEST_ASSERT(!ret, "munmap() should succeed."); > +} > + > +static void test_mmap_not_supported(int fd, size_t page_size, size_t total_size) > { > char *mem; > > mem = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); > TEST_ASSERT_EQ(mem, MAP_FAILED); > + > + mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); > + TEST_ASSERT_EQ(mem, MAP_FAILED); > } > > static void test_file_size(int fd, size_t page_size, size_t total_size) > @@ -120,26 +193,19 @@ static void test_invalid_punch_hole(int fd, size_t page_size, size_t total_size) > } > } > > -static void test_create_guest_memfd_invalid(struct kvm_vm *vm) > +static void test_create_guest_memfd_invalid_sizes(struct kvm_vm *vm, > + uint64_t guest_memfd_flags, > + size_t page_size) > { > - size_t page_size = getpagesize(); > - uint64_t flag; > size_t size; > int fd; > > for (size = 1; size < page_size; size++) { > - fd = __vm_create_guest_memfd(vm, size, 0); > - TEST_ASSERT(fd == -1 && errno == EINVAL, > + fd = __vm_create_guest_memfd(vm, size, guest_memfd_flags); > + TEST_ASSERT(fd < 0 && errno == EINVAL, > "guest_memfd() with non-page-aligned page size '0x%lx' should fail with EINVAL", > size); > } > - > - for (flag = BIT(0); flag; flag <<= 1) { > - fd = __vm_create_guest_memfd(vm, page_size, flag); > - TEST_ASSERT(fd == -1 && errno == EINVAL, > - "guest_memfd() with flag '0x%lx' should fail with EINVAL", > - flag); > - } > } > > static void test_create_guest_memfd_multiple(struct kvm_vm *vm) > @@ -171,30 +237,123 @@ static void test_create_guest_memfd_multiple(struct kvm_vm *vm) > close(fd1); > } > > -int main(int argc, char *argv[]) > +static bool check_vm_type(unsigned long vm_type) > { > - size_t page_size; > + /* > + * Not all architectures support KVM_CAP_VM_TYPES. However, those that > + * support guest_memfd have that support for the default VM type. > + */ > + if (vm_type == VM_TYPE_DEFAULT) > + return true; > + > + return kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(vm_type); > +} > + > +static void test_with_type(unsigned long vm_type, uint64_t guest_memfd_flags, > + bool expect_mmap_allowed) > +{ > + struct kvm_vm *vm; > size_t total_size; > + size_t page_size; > int fd; > - struct kvm_vm *vm; > > - TEST_REQUIRE(kvm_has_cap(KVM_CAP_GUEST_MEMFD)); > + if (!check_vm_type(vm_type)) > + return; > > page_size = getpagesize(); > total_size = page_size * 4; > > - vm = vm_create_barebones(); > + vm = vm_create_barebones_type(vm_type); > > - test_create_guest_memfd_invalid(vm); > test_create_guest_memfd_multiple(vm); > + test_create_guest_memfd_invalid_sizes(vm, guest_memfd_flags, page_size); > > - fd = vm_create_guest_memfd(vm, total_size, 0); > + fd = vm_create_guest_memfd(vm, total_size, guest_memfd_flags); > > test_file_read_write(fd); > - test_mmap(fd, page_size); > + > + if (expect_mmap_allowed) { > + test_mmap_supported(fd, page_size, total_size); > + test_fault_overflow(fd, page_size, total_size); > + > + } else { > + test_mmap_not_supported(fd, page_size, total_size); > + } > + > test_file_size(fd, page_size, total_size); > test_fallocate(fd, page_size, total_size); > test_invalid_punch_hole(fd, page_size, total_size); > > close(fd); > + kvm_vm_free(vm); > +} > + > +static void test_vm_type_gmem_flag_validity(unsigned long vm_type, > + uint64_t expected_valid_flags) > +{ > + size_t page_size = getpagesize(); > + struct kvm_vm *vm; > + uint64_t flag = 0; > + int fd; > + > + if (!check_vm_type(vm_type)) > + return; > + > + vm = vm_create_barebones_type(vm_type); > + > + for (flag = BIT(0); flag; flag <<= 1) { > + fd = __vm_create_guest_memfd(vm, page_size, flag); > + > + if (flag & expected_valid_flags) { > + TEST_ASSERT(fd >= 0, > + "guest_memfd() with flag '0x%lx' should be valid", > + flag); > + close(fd); > + } else { > + TEST_ASSERT(fd < 0 && errno == EINVAL, > + "guest_memfd() with flag '0x%lx' should fail with EINVAL", > + flag); > + } > + } > + > + kvm_vm_free(vm); > +} > + > +static void test_gmem_flag_validity(void) > +{ > + uint64_t non_coco_vm_valid_flags = 0; > + > + if (kvm_has_cap(KVM_CAP_GMEM_SHARED_MEM)) > + non_coco_vm_valid_flags = GUEST_MEMFD_FLAG_SUPPORT_SHARED; > + > + test_vm_type_gmem_flag_validity(VM_TYPE_DEFAULT, non_coco_vm_valid_flags); > + > +#ifdef __x86_64__ > + test_vm_type_gmem_flag_validity(KVM_X86_SW_PROTECTED_VM, non_coco_vm_valid_flags); > + test_vm_type_gmem_flag_validity(KVM_X86_SEV_VM, 0); > + test_vm_type_gmem_flag_validity(KVM_X86_SEV_ES_VM, 0); > + test_vm_type_gmem_flag_validity(KVM_X86_SNP_VM, 0); > + test_vm_type_gmem_flag_validity(KVM_X86_TDX_VM, 0); > +#endif > +} > + > +int main(int argc, char *argv[]) > +{ > + TEST_REQUIRE(kvm_has_cap(KVM_CAP_GUEST_MEMFD)); > + > + test_gmem_flag_validity(); > + > + test_with_type(VM_TYPE_DEFAULT, 0, false); > + if (kvm_has_cap(KVM_CAP_GMEM_SHARED_MEM)) { > + test_with_type(VM_TYPE_DEFAULT, GUEST_MEMFD_FLAG_SUPPORT_SHARED, > + true); > + } > + > +#ifdef __x86_64__ > + test_with_type(KVM_X86_SW_PROTECTED_VM, 0, false); > + if (kvm_has_cap(KVM_CAP_GMEM_SHARED_MEM)) { > + test_with_type(KVM_X86_SW_PROTECTED_VM, > + GUEST_MEMFD_FLAG_SUPPORT_SHARED, true); > + } > +#endif > } Reviewed-by: Shivank Garg <shivankg@amd.com>
diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c index 341ba616cf55..5da2ed6277ac 100644 --- a/tools/testing/selftests/kvm/guest_memfd_test.c +++ b/tools/testing/selftests/kvm/guest_memfd_test.c @@ -13,6 +13,8 @@ #include <linux/bitmap.h> #include <linux/falloc.h> +#include <setjmp.h> +#include <signal.h> #include <sys/mman.h> #include <sys/types.h> #include <sys/stat.h> @@ -34,12 +36,83 @@ static void test_file_read_write(int fd) "pwrite on a guest_mem fd should fail"); } -static void test_mmap(int fd, size_t page_size) +static void test_mmap_supported(int fd, size_t page_size, size_t total_size) +{ + const char val = 0xaa; + char *mem; + size_t i; + int ret; + + mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); + TEST_ASSERT(mem == MAP_FAILED, "Copy-on-write not allowed by guest_memfd."); + + mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); + TEST_ASSERT(mem != MAP_FAILED, "mmap() for shared guest memory should succeed."); + + memset(mem, val, total_size); + for (i = 0; i < total_size; i++) + TEST_ASSERT_EQ(READ_ONCE(mem[i]), val); + + ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 0, + page_size); + TEST_ASSERT(!ret, "fallocate the first page should succeed."); + + for (i = 0; i < page_size; i++) + TEST_ASSERT_EQ(READ_ONCE(mem[i]), 0x00); + for (; i < total_size; i++) + TEST_ASSERT_EQ(READ_ONCE(mem[i]), val); + + memset(mem, val, page_size); + for (i = 0; i < total_size; i++) + TEST_ASSERT_EQ(READ_ONCE(mem[i]), val); + + ret = munmap(mem, total_size); + TEST_ASSERT(!ret, "munmap() should succeed."); +} + +static sigjmp_buf jmpbuf; +void fault_sigbus_handler(int signum) +{ + siglongjmp(jmpbuf, 1); +} + +static void test_fault_overflow(int fd, size_t page_size, size_t total_size) +{ + struct sigaction sa_old, sa_new = { + .sa_handler = fault_sigbus_handler, + }; + size_t map_size = total_size * 4; + const char val = 0xaa; + char *mem; + size_t i; + int ret; + + mem = mmap(NULL, map_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); + TEST_ASSERT(mem != MAP_FAILED, "mmap() for shared guest memory should succeed."); + + sigaction(SIGBUS, &sa_new, &sa_old); + if (sigsetjmp(jmpbuf, 1) == 0) { + memset(mem, 0xaa, map_size); + TEST_ASSERT(false, "memset() should have triggered SIGBUS."); + } + sigaction(SIGBUS, &sa_old, NULL); + + for (i = 0; i < total_size; i++) + TEST_ASSERT_EQ(READ_ONCE(mem[i]), val); + + ret = munmap(mem, map_size); + TEST_ASSERT(!ret, "munmap() should succeed."); +} + +static void test_mmap_not_supported(int fd, size_t page_size, size_t total_size) { char *mem; mem = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); TEST_ASSERT_EQ(mem, MAP_FAILED); + + mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); + TEST_ASSERT_EQ(mem, MAP_FAILED); } static void test_file_size(int fd, size_t page_size, size_t total_size) @@ -120,26 +193,19 @@ static void test_invalid_punch_hole(int fd, size_t page_size, size_t total_size) } } -static void test_create_guest_memfd_invalid(struct kvm_vm *vm) +static void test_create_guest_memfd_invalid_sizes(struct kvm_vm *vm, + uint64_t guest_memfd_flags, + size_t page_size) { - size_t page_size = getpagesize(); - uint64_t flag; size_t size; int fd; for (size = 1; size < page_size; size++) { - fd = __vm_create_guest_memfd(vm, size, 0); - TEST_ASSERT(fd == -1 && errno == EINVAL, + fd = __vm_create_guest_memfd(vm, size, guest_memfd_flags); + TEST_ASSERT(fd < 0 && errno == EINVAL, "guest_memfd() with non-page-aligned page size '0x%lx' should fail with EINVAL", size); } - - for (flag = BIT(0); flag; flag <<= 1) { - fd = __vm_create_guest_memfd(vm, page_size, flag); - TEST_ASSERT(fd == -1 && errno == EINVAL, - "guest_memfd() with flag '0x%lx' should fail with EINVAL", - flag); - } } static void test_create_guest_memfd_multiple(struct kvm_vm *vm) @@ -171,30 +237,123 @@ static void test_create_guest_memfd_multiple(struct kvm_vm *vm) close(fd1); } -int main(int argc, char *argv[]) +static bool check_vm_type(unsigned long vm_type) { - size_t page_size; + /* + * Not all architectures support KVM_CAP_VM_TYPES. However, those that + * support guest_memfd have that support for the default VM type. + */ + if (vm_type == VM_TYPE_DEFAULT) + return true; + + return kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(vm_type); +} + +static void test_with_type(unsigned long vm_type, uint64_t guest_memfd_flags, + bool expect_mmap_allowed) +{ + struct kvm_vm *vm; size_t total_size; + size_t page_size; int fd; - struct kvm_vm *vm; - TEST_REQUIRE(kvm_has_cap(KVM_CAP_GUEST_MEMFD)); + if (!check_vm_type(vm_type)) + return; page_size = getpagesize(); total_size = page_size * 4; - vm = vm_create_barebones(); + vm = vm_create_barebones_type(vm_type); - test_create_guest_memfd_invalid(vm); test_create_guest_memfd_multiple(vm); + test_create_guest_memfd_invalid_sizes(vm, guest_memfd_flags, page_size); - fd = vm_create_guest_memfd(vm, total_size, 0); + fd = vm_create_guest_memfd(vm, total_size, guest_memfd_flags); test_file_read_write(fd); - test_mmap(fd, page_size); + + if (expect_mmap_allowed) { + test_mmap_supported(fd, page_size, total_size); + test_fault_overflow(fd, page_size, total_size); + + } else { + test_mmap_not_supported(fd, page_size, total_size); + } + test_file_size(fd, page_size, total_size); test_fallocate(fd, page_size, total_size); test_invalid_punch_hole(fd, page_size, total_size); close(fd); + kvm_vm_free(vm); +} + +static void test_vm_type_gmem_flag_validity(unsigned long vm_type, + uint64_t expected_valid_flags) +{ + size_t page_size = getpagesize(); + struct kvm_vm *vm; + uint64_t flag = 0; + int fd; + + if (!check_vm_type(vm_type)) + return; + + vm = vm_create_barebones_type(vm_type); + + for (flag = BIT(0); flag; flag <<= 1) { + fd = __vm_create_guest_memfd(vm, page_size, flag); + + if (flag & expected_valid_flags) { + TEST_ASSERT(fd >= 0, + "guest_memfd() with flag '0x%lx' should be valid", + flag); + close(fd); + } else { + TEST_ASSERT(fd < 0 && errno == EINVAL, + "guest_memfd() with flag '0x%lx' should fail with EINVAL", + flag); + } + } + + kvm_vm_free(vm); +} + +static void test_gmem_flag_validity(void) +{ + uint64_t non_coco_vm_valid_flags = 0; + + if (kvm_has_cap(KVM_CAP_GMEM_SHARED_MEM)) + non_coco_vm_valid_flags = GUEST_MEMFD_FLAG_SUPPORT_SHARED; + + test_vm_type_gmem_flag_validity(VM_TYPE_DEFAULT, non_coco_vm_valid_flags); + +#ifdef __x86_64__ + test_vm_type_gmem_flag_validity(KVM_X86_SW_PROTECTED_VM, non_coco_vm_valid_flags); + test_vm_type_gmem_flag_validity(KVM_X86_SEV_VM, 0); + test_vm_type_gmem_flag_validity(KVM_X86_SEV_ES_VM, 0); + test_vm_type_gmem_flag_validity(KVM_X86_SNP_VM, 0); + test_vm_type_gmem_flag_validity(KVM_X86_TDX_VM, 0); +#endif +} + +int main(int argc, char *argv[]) +{ + TEST_REQUIRE(kvm_has_cap(KVM_CAP_GUEST_MEMFD)); + + test_gmem_flag_validity(); + + test_with_type(VM_TYPE_DEFAULT, 0, false); + if (kvm_has_cap(KVM_CAP_GMEM_SHARED_MEM)) { + test_with_type(VM_TYPE_DEFAULT, GUEST_MEMFD_FLAG_SUPPORT_SHARED, + true); + } + +#ifdef __x86_64__ + test_with_type(KVM_X86_SW_PROTECTED_VM, 0, false); + if (kvm_has_cap(KVM_CAP_GMEM_SHARED_MEM)) { + test_with_type(KVM_X86_SW_PROTECTED_VM, + GUEST_MEMFD_FLAG_SUPPORT_SHARED, true); + } +#endif }