diff options
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 5 | ||||
| -rw-r--r-- | include/uapi/linux/kvm.h | 3 | ||||
| -rw-r--r-- | tools/testing/selftests/kvm/guest_memfd_test.c | 15 | ||||
| -rw-r--r-- | virt/kvm/guest_memfd.c | 6 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 3 |
5 files changed, 26 insertions, 6 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 7ba92f2ced38..754b662a453c 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6438,6 +6438,11 @@ specified via KVM_CREATE_GUEST_MEMFD. Currently defined flags: ============================ ================================================ GUEST_MEMFD_FLAG_MMAP Enable using mmap() on the guest_memfd file descriptor. + GUEST_MEMFD_FLAG_INIT_SHARED Make all memory in the file shared during + KVM_CREATE_GUEST_MEMFD (memory files created + without INIT_SHARED will be marked private). + Shared memory can be faulted into host userspace + page tables. Private memory cannot. ============================ ================================================ When the KVM MMU performs a PFN lookup to service a guest fault and the backing diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index b1d52d0c56ec..52f6000ab020 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1599,7 +1599,8 @@ struct kvm_memory_attributes { #define KVM_MEMORY_ATTRIBUTE_PRIVATE (1ULL << 3) #define KVM_CREATE_GUEST_MEMFD _IOWR(KVMIO, 0xd4, struct kvm_create_guest_memfd) -#define GUEST_MEMFD_FLAG_MMAP (1ULL << 0) +#define GUEST_MEMFD_FLAG_MMAP (1ULL << 0) +#define GUEST_MEMFD_FLAG_INIT_SHARED (1ULL << 1) struct kvm_create_guest_memfd { __u64 size; diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c index 3e58bd496104..0de56ce3c4e2 100644 --- a/tools/testing/selftests/kvm/guest_memfd_test.c +++ b/tools/testing/selftests/kvm/guest_memfd_test.c @@ -239,8 +239,9 @@ static void test_create_guest_memfd_multiple(struct kvm_vm *vm) close(fd1); } -static void test_guest_memfd_flags(struct kvm_vm *vm, uint64_t valid_flags) +static void test_guest_memfd_flags(struct kvm_vm *vm) { + uint64_t valid_flags = vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_FLAGS); size_t page_size = getpagesize(); uint64_t flag; int fd; @@ -274,6 +275,10 @@ static void test_guest_memfd(unsigned long vm_type) vm = vm_create_barebones_type(vm_type); flags = vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_FLAGS); + /* This test doesn't yet support testing mmap() on private memory. */ + if (!(flags & GUEST_MEMFD_FLAG_INIT_SHARED)) + flags &= ~GUEST_MEMFD_FLAG_MMAP; + test_create_guest_memfd_multiple(vm); test_create_guest_memfd_invalid_sizes(vm, flags, page_size); @@ -292,7 +297,7 @@ static void test_guest_memfd(unsigned long vm_type) test_fallocate(fd, page_size, total_size); test_invalid_punch_hole(fd, page_size, total_size); - test_guest_memfd_flags(vm, flags); + test_guest_memfd_flags(vm); close(fd); kvm_vm_free(vm); @@ -334,9 +339,13 @@ static void test_guest_memfd_guest(void) TEST_ASSERT(vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_FLAGS) & GUEST_MEMFD_FLAG_MMAP, "Default VM type should support MMAP, supported flags = 0x%x", vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_FLAGS)); + TEST_ASSERT(vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_FLAGS) & GUEST_MEMFD_FLAG_INIT_SHARED, + "Default VM type should support INIT_SHARED, supported flags = 0x%x", + vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_FLAGS)); size = vm->page_size; - fd = vm_create_guest_memfd(vm, size, GUEST_MEMFD_FLAG_MMAP); + fd = vm_create_guest_memfd(vm, size, GUEST_MEMFD_FLAG_MMAP | + GUEST_MEMFD_FLAG_INIT_SHARED); vm_set_user_memory_region2(vm, slot, KVM_MEM_GUEST_MEMFD, gpa, size, NULL, fd, 0); mem = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 94bafd6c558c..cf3afba23a6b 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -328,6 +328,9 @@ static vm_fault_t kvm_gmem_fault_user_mapping(struct vm_fault *vmf) if (((loff_t)vmf->pgoff << PAGE_SHIFT) >= i_size_read(inode)) return VM_FAULT_SIGBUS; + if (!((u64)inode->i_private & GUEST_MEMFD_FLAG_INIT_SHARED)) + return VM_FAULT_SIGBUS; + folio = kvm_gmem_get_folio(inode, vmf->pgoff); if (IS_ERR(folio)) { int err = PTR_ERR(folio); @@ -525,7 +528,8 @@ int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args) u64 valid_flags = 0; if (kvm_arch_supports_gmem_mmap(kvm)) - valid_flags |= GUEST_MEMFD_FLAG_MMAP; + valid_flags |= GUEST_MEMFD_FLAG_MMAP | + GUEST_MEMFD_FLAG_INIT_SHARED; if (flags & ~valid_flags) return -EINVAL; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index e3a268757621..5f644ca54af3 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4930,7 +4930,8 @@ static int kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) return 1; case KVM_CAP_GUEST_MEMFD_FLAGS: if (!kvm || kvm_arch_supports_gmem_mmap(kvm)) - return GUEST_MEMFD_FLAG_MMAP; + return GUEST_MEMFD_FLAG_MMAP | + GUEST_MEMFD_FLAG_INIT_SHARED; return 0; #endif |