* Mike Rapoport <[email protected]> [251125 13:39]: > From: Nikita Kalyazin <[email protected]> > > The test demonstrates that a minor userfaultfd event in guest_memfd can > be resolved via a memcpy followed by a UFFDIO_CONTINUE ioctl. > > Signed-off-by: Nikita Kalyazin <[email protected]> > Co-developed-by: Mike Rapoport (Microsoft) <[email protected]> > Signed-off-by: Mike Rapoport (Microsoft) <[email protected]>
Acked-by: Liam R. Howlett <[email protected]> > --- > .../testing/selftests/kvm/guest_memfd_test.c | 103 ++++++++++++++++++ > 1 file changed, 103 insertions(+) > > diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c > b/tools/testing/selftests/kvm/guest_memfd_test.c > index e7d9aeb418d3..a5d3ed21d7bb 100644 > --- a/tools/testing/selftests/kvm/guest_memfd_test.c > +++ b/tools/testing/selftests/kvm/guest_memfd_test.c > @@ -10,13 +10,17 @@ > #include <errno.h> > #include <stdio.h> > #include <fcntl.h> > +#include <pthread.h> > > #include <linux/bitmap.h> > #include <linux/falloc.h> > #include <linux/sizes.h> > +#include <linux/userfaultfd.h> > #include <sys/mman.h> > #include <sys/types.h> > #include <sys/stat.h> > +#include <sys/syscall.h> > +#include <sys/ioctl.h> > > #include "kvm_util.h" > #include "test_util.h" > @@ -254,6 +258,104 @@ static void test_guest_memfd_flags(struct kvm_vm *vm) > } > } > > +struct fault_args { > + char *addr; > + volatile char value; > +}; > + > +static void *fault_thread_fn(void *arg) > +{ > + struct fault_args *args = arg; > + > + /* Trigger page fault */ > + args->value = *args->addr; > + return NULL; > +} > + > +static void test_uffd_minor(int fd, size_t total_size) > +{ > + struct uffdio_api uffdio_api = { > + .api = UFFD_API, > + .features = UFFD_FEATURE_MINOR_GENERIC, > + }; > + struct uffdio_register uffd_reg; > + struct uffdio_continue uffd_cont; > + struct uffd_msg msg; > + struct fault_args args; > + pthread_t fault_thread; > + void *mem, *mem_nofault, *buf = NULL; > + int uffd, ret; > + off_t offset = page_size; > + void *fault_addr; > + > + ret = posix_memalign(&buf, page_size, total_size); > + TEST_ASSERT_EQ(ret, 0); > + > + memset(buf, 0xaa, total_size); > + > + uffd = syscall(__NR_userfaultfd, O_CLOEXEC); > + TEST_ASSERT(uffd != -1, "userfaultfd creation should succeed"); > + > + ret = ioctl(uffd, UFFDIO_API, &uffdio_api); > + TEST_ASSERT(ret != -1, "ioctl(UFFDIO_API) should succeed"); > + > + mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); > + TEST_ASSERT(mem != MAP_FAILED, "mmap should succeed"); > + > + mem_nofault = mmap(NULL, total_size, PROT_READ | PROT_WRITE, > MAP_SHARED, fd, 0); > + TEST_ASSERT(mem_nofault != MAP_FAILED, "mmap should succeed"); > + > + uffd_reg.range.start = (unsigned long)mem; > + uffd_reg.range.len = total_size; > + uffd_reg.mode = UFFDIO_REGISTER_MODE_MINOR; > + ret = ioctl(uffd, UFFDIO_REGISTER, &uffd_reg); > + TEST_ASSERT(ret != -1, "ioctl(UFFDIO_REGISTER) should succeed"); > + > + ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, > + offset, page_size); > + TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) should succeed"); > + > + fault_addr = mem + offset; > + args.addr = fault_addr; > + > + ret = pthread_create(&fault_thread, NULL, fault_thread_fn, &args); > + TEST_ASSERT(ret == 0, "pthread_create should succeed"); > + > + ret = read(uffd, &msg, sizeof(msg)); > + TEST_ASSERT(ret != -1, "read from userfaultfd should succeed"); > + TEST_ASSERT(msg.event == UFFD_EVENT_PAGEFAULT, "event type should be > pagefault"); > + TEST_ASSERT((void *)(msg.arg.pagefault.address & ~(page_size - 1)) == > fault_addr, > + "pagefault should occur at expected address"); > + > + memcpy(mem_nofault + offset, buf + offset, page_size); > + > + uffd_cont.range.start = (unsigned long)fault_addr; > + uffd_cont.range.len = page_size; > + uffd_cont.mode = 0; > + ret = ioctl(uffd, UFFDIO_CONTINUE, &uffd_cont); > + TEST_ASSERT(ret != -1, "ioctl(UFFDIO_CONTINUE) should succeed"); > + > + /* > + * wait for fault_thread to finish to make sure fault happened and was > + * resolved before we verify the values > + */ > + ret = pthread_join(fault_thread, NULL); > + TEST_ASSERT(ret == 0, "pthread_join should succeed"); > + > + TEST_ASSERT(args.value == *(char *)(mem_nofault + offset), > + "memory should contain the value that was copied"); > + TEST_ASSERT(args.value == *(char *)(mem + offset), > + "no further fault is expected"); > + > + ret = munmap(mem_nofault, total_size); > + TEST_ASSERT(!ret, "munmap should succeed"); > + > + ret = munmap(mem, total_size); > + TEST_ASSERT(!ret, "munmap should succeed"); > + free(buf); > + close(uffd); > +} > + > #define gmem_test(__test, __vm, __flags) \ > do { \ > int fd = vm_create_guest_memfd(__vm, page_size * 4, __flags); \ > @@ -273,6 +375,7 @@ static void __test_guest_memfd(struct kvm_vm *vm, > uint64_t flags) > if (flags & GUEST_MEMFD_FLAG_INIT_SHARED) { > gmem_test(mmap_supported, vm, flags); > gmem_test(fault_overflow, vm, flags); > + gmem_test(uffd_minor, vm, flags); > } else { > gmem_test(fault_private, vm, flags); > } > -- > 2.50.1 >
