OvmfPkg/VirtioFsDxe: implement EFI_SIMPLE_FILE_SYSTEM_PROTOCOL.OpenVolume()

With the help of the VirtioFsFuseOpenDir() and
VirtioFsFuseReleaseFileOrDir() functions introduced previously, we can now
open and close the root directory. So let's implement
EFI_SIMPLE_FILE_SYSTEM_PROTOCOL.OpenVolume().

OpenVolume() creates a new EFI_FILE_PROTOCOL object -- a reference to the
root directory of the filesystem. Thus, we have to start tracking
references to EFI_SIMPLE_FILE_SYSTEM_PROTOCOL, lest we unbind the
virtio-fs device while files are open.

There are two methods that release an EFI_FILE_PROTOCOL object: the
Close() and the Delete() member functions. In particular, they are not
allowed to fail with regard to resource management -- they must release
resources unconditionally. Thus, for rolling back the resource accounting
that we do in EFI_SIMPLE_FILE_SYSTEM_PROTOCOL.OpenVolume(), we have to
implement the first versions of EFI_FILE_PROTOCOL.Close() and
EFI_FILE_PROTOCOL.Delete() in this patch as well.

With this patch applied, the UEFI shell can enter the root directory of
the Virtio Filesystem (such as with the "FS3:" shell command), and the
"DIR" shell command exercises FUSE_OPENDIR and FUSE_RELEASEDIR, according
to the virtiofsd log. The "DIR" command reports the root directory as if
it were empty; probably because at this time, we only allow the shell to
open and to close the root directory, but not to read it.

Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3097
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20201216211125.19496-12-lersek@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@arm.com>

1 files changed, 117 insertions, 0 deletions

diff --git a/OvmfPkg/VirtioFsDxe/VirtioFsDxe.h b/OvmfPkg/VirtioFsDxe/VirtioFsDxe.h
index a99625d047..34574d0596 100644
--- a/OvmfPkg/VirtioFsDxe/VirtioFsDxe.h
+++ b/OvmfPkg/VirtioFsDxe/VirtioFsDxe.h
@@ -19,6 +19,9 @@
 

 #define VIRTIO_FS_SIG SIGNATURE_64 ('V', 'I', 'R', 'T', 'I', 'O', 'F', 'S')

 

+#define VIRTIO_FS_FILE_SIG \

+  SIGNATURE_64 ('V', 'I', 'O', 'F', 'S', 'F', 'I', 'L')

+

 //

 // Filesystem label encoded in UCS-2, transformed from the UTF-8 representation

 // in "VIRTIO_FS_CONFIG.Tag", and NUL-terminated. Only the printable ASCII code

@@ -46,6 +49,7 @@ typedef struct {
   VOID                            *RingMap;  // VirtioRingMap       2

   UINT64                          RequestId; // FuseInitSession     1

   EFI_EVENT                       ExitBoot;  // DriverBindingStart  0

+  LIST_ENTRY                      OpenFiles; // DriverBindingStart  0

   EFI_SIMPLE_FILE_SYSTEM_PROTOCOL SimpleFs;  // DriverBindingStart  0

 } VIRTIO_FS;

 

@@ -99,6 +103,39 @@ typedef struct {
 } VIRTIO_FS_SCATTER_GATHER_LIST;

 

 //

+// Private context structure that exposes EFI_FILE_PROTOCOL on top of an open

+// FUSE file reference.

+//

+typedef struct {

+  UINT64            Signature;

+  EFI_FILE_PROTOCOL SimpleFile;

+  BOOLEAN           IsDirectory;

+  VIRTIO_FS         *OwnerFs;

+  LIST_ENTRY        OpenFilesEntry;

+  //

+  // In the FUSE wire protocol, every request except FUSE_INIT refers to a

+  // file, namely by the "VIRTIO_FS_FUSE_REQUEST.NodeId" field; that is, by the

+  // inode number of the file. However, some of the FUSE requests that we need

+  // for some of the EFI_FILE_PROTOCOL member functions require an open file

+  // handle *in addition* to the inode number. For simplicity, whenever a

+  // VIRTIO_FS_FILE object is created, primarily defined by its NodeId field,

+  // we also *open* the referenced file at once, and save the returned file

+  // handle in the FuseHandle field. This way, when an EFI_FILE_PROTOCOL member

+  // function must send a FUSE request that needs the file handle *in addition*

+  // to the inode number, FuseHandle will be at our disposal at once.

+  //

+  UINT64 NodeId;

+  UINT64 FuseHandle;

+} VIRTIO_FS_FILE;

+

+#define VIRTIO_FS_FILE_FROM_SIMPLE_FILE(SimpleFileReference) \

+  CR (SimpleFileReference, VIRTIO_FS_FILE, SimpleFile, VIRTIO_FS_FILE_SIG);

+

+#define VIRTIO_FS_FILE_FROM_OPEN_FILES_ENTRY(OpenFilesEntryReference) \

+  CR (OpenFilesEntryReference, VIRTIO_FS_FILE, OpenFilesEntry, \

+    VIRTIO_FS_FILE_SIG);

+

+//

 // Initialization and helper routines for the Virtio Filesystem device.

 //

 

@@ -190,4 +227,84 @@ VirtioFsOpenVolume (
   OUT EFI_FILE_PROTOCOL               **Root

   );

 

+//

+// EFI_FILE_PROTOCOL member functions for the Virtio Filesystem driver.

+//

+

+EFI_STATUS

+EFIAPI

+VirtioFsSimpleFileClose (

+  IN EFI_FILE_PROTOCOL *This

+  );

+

+EFI_STATUS

+EFIAPI

+VirtioFsSimpleFileDelete (

+  IN EFI_FILE_PROTOCOL *This

+  );

+

+EFI_STATUS

+EFIAPI

+VirtioFsSimpleFileFlush (

+  IN EFI_FILE_PROTOCOL *This

+  );

+

+EFI_STATUS

+EFIAPI

+VirtioFsSimpleFileGetInfo (

+  IN     EFI_FILE_PROTOCOL *This,

+  IN     EFI_GUID          *InformationType,

+  IN OUT UINTN             *BufferSize,

+     OUT VOID              *Buffer

+  );

+

+EFI_STATUS

+EFIAPI

+VirtioFsSimpleFileGetPosition (

+  IN     EFI_FILE_PROTOCOL *This,

+     OUT UINT64            *Position

+  );

+

+EFI_STATUS

+EFIAPI

+VirtioFsSimpleFileOpen (

+  IN     EFI_FILE_PROTOCOL *This,

+     OUT EFI_FILE_PROTOCOL **NewHandle,

+  IN     CHAR16            *FileName,

+  IN     UINT64            OpenMode,

+  IN     UINT64            Attributes

+  );

+

+EFI_STATUS

+EFIAPI

+VirtioFsSimpleFileRead (

+  IN     EFI_FILE_PROTOCOL *This,

+  IN OUT UINTN             *BufferSize,

+     OUT VOID              *Buffer

+  );

+

+EFI_STATUS

+EFIAPI

+VirtioFsSimpleFileSetInfo (

+  IN EFI_FILE_PROTOCOL *This,

+  IN EFI_GUID          *InformationType,

+  IN UINTN             BufferSize,

+  IN VOID              *Buffer

+  );

+

+EFI_STATUS

+EFIAPI

+VirtioFsSimpleFileSetPosition (

+  IN EFI_FILE_PROTOCOL *This,

+  IN UINT64            Position

+  );

+

+EFI_STATUS

+EFIAPI

+VirtioFsSimpleFileWrite (

+  IN     EFI_FILE_PROTOCOL *This,

+  IN OUT UINTN             *BufferSize,

+  IN     VOID              *Buffer

+  );

+

 #endif // VIRTIO_FS_DXE_H_