OvmfPkg/VirtioFsDxe: implement EFI_SIMPLE_FILE_SYSTEM_PROTOCOL.OpenVolume()

[mirror_edk2.git] / OvmfPkg / Include / IndustryStandard / VirtioFs.h

/** @file\r
  Type and macro definitions specific to the Virtio Filesystem device.\r
\r
  At the time of this writing, the latest released Virtio specification (v1.1)\r
  does not include the virtio-fs device. The development version of the\r
  specification defines it however; see the latest version at\r
  <https://github.com/oasis-tcs/virtio-spec/blob/87fa6b5d8155/virtio-fs.tex>.\r
\r
  This header file is minimal, and only defines the types and macros that are\r
  necessary for the OvmfPkg implementation.\r
\r
  Copyright (C) 2020, Red Hat, Inc.\r
\r
  SPDX-License-Identifier: BSD-2-Clause-Patent\r
**/\r
\r
#ifndef VIRTIO_FS_H_\r
#define VIRTIO_FS_H_\r
\r
#include <IndustryStandard/Virtio.h>\r
\r
//\r
// Lowest numbered queue for sending normal priority requests.\r
//\r
#define VIRTIO_FS_REQUEST_QUEUE 1\r
\r
//\r
// Number of bytes in the "VIRTIO_FS_CONFIG.Tag" field.\r
//\r
#define VIRTIO_FS_TAG_BYTES 36\r
\r
//\r
// Device configuration layout.\r
//\r
#pragma pack (1)\r
typedef struct {\r
  //\r
  // The Tag field can be considered the filesystem label, or a mount point\r
  // hint. It is UTF-8 encoded, and padded to full size with NUL bytes. If the\r
  // encoded bytes take up the entire Tag field, then there is no NUL\r
  // terminator.\r
  //\r
  UINT8 Tag[VIRTIO_FS_TAG_BYTES];\r
  //\r
  // The total number of request virtqueues exposed by the device (i.e.,\r
  // excluding the "hiprio" queue).\r
  //\r
  UINT32 NumReqQueues;\r
} VIRTIO_FS_CONFIG;\r
#pragma pack ()\r
\r
//\r
// FUSE-related definitions follow.\r
//\r
// From virtio-v1.1-cs01-87fa6b5d8155, 5.11 File System Device: "[...] The\r
// driver acts as the FUSE client mounting the file system. The virtio file\r
// system device provides the mechanism for transporting FUSE requests [...]"\r
//\r
// Unfortunately, the documentation of the FUSE wire protocol is lacking. The\r
// Virtio spec (as of this writing) simply defers to\r
// "include/uapi/linux/fuse.h" in the Linux kernel source -- see the reference\r
// in virtio spec file "introduction.tex", at commit 87fa6b5d8155.\r
//\r
// Of course, "include/uapi/linux/fuse.h" is a moving target (the virtio spec\r
// does not specify a particular FUSE interface version). The OvmfPkg code\r
// targets version 7.31, because that's the lowest version that the QEMU\r
// virtio-fs daemon supports at this time -- see QEMU commit 72c42e2d6551\r
// ("virtiofsd: Trim out compatibility code", 2020-01-23).\r
//\r
// Correspondingly, Linux's "include/uapi/linux/fuse.h" is consulted as checked\r
// out at commit (c6ff213fe5b8^) = d78092e4937d ("fuse: fix page dereference\r
// after free", 2020-09-18); that is, right before commit c6ff213fe5b8 ("fuse:\r
// add submount support to <uapi/linux/fuse.h>", 2020-09-18) introduces FUSE\r
// interface version 7.32.\r
//\r
#define VIRTIO_FS_FUSE_MAJOR  7\r
#define VIRTIO_FS_FUSE_MINOR 31\r
\r
//\r
// The inode number of the root directory.\r
//\r
#define VIRTIO_FS_FUSE_ROOT_DIR_NODE_ID 1\r
\r
//\r
// FUSE operation codes.\r
//\r
typedef enum {\r
  VirtioFsFuseOpRelease     = 18,\r
  VirtioFsFuseOpInit        = 26,\r
  VirtioFsFuseOpOpenDir     = 27,\r
  VirtioFsFuseOpReleaseDir  = 29,\r
} VIRTIO_FS_FUSE_OPCODE;\r
\r
#pragma pack (1)\r
//\r
// Request-response headers common to all request types.\r
//\r
typedef struct {\r
  UINT32 Len;\r
  UINT32 Opcode;\r
  UINT64 Unique;\r
  UINT64 NodeId;\r
  UINT32 Uid;\r
  UINT32 Gid;\r
  UINT32 Pid;\r
  UINT32 Padding;\r
} VIRTIO_FS_FUSE_REQUEST;\r
\r
typedef struct {\r
  UINT32 Len;\r
  INT32  Error;\r
  UINT64 Unique;\r
} VIRTIO_FS_FUSE_RESPONSE;\r
\r
//\r
// Header for VirtioFsFuseOpRelease and VirtioFsFuseOpReleaseDir.\r
//\r
typedef struct {\r
  UINT64 FileHandle;\r
  UINT32 Flags;\r
  UINT32 ReleaseFlags;\r
  UINT64 LockOwner;\r
} VIRTIO_FS_FUSE_RELEASE_REQUEST;\r
\r
//\r
// Headers for VirtioFsFuseOpInit.\r
//\r
typedef struct {\r
  UINT32 Major;\r
  UINT32 Minor;\r
  UINT32 MaxReadahead;\r
  UINT32 Flags;\r
} VIRTIO_FS_FUSE_INIT_REQUEST;\r
\r
typedef struct {\r
  UINT32 Major;\r
  UINT32 Minor;\r
  UINT32 MaxReadahead;\r
  UINT32 Flags;\r
  UINT16 MaxBackground;\r
  UINT16 CongestionThreshold;\r
  UINT32 MaxWrite;\r
  UINT32 TimeGran;\r
  UINT16 MaxPages;\r
  UINT16 MapAlignment;\r
  UINT32 Unused[8];\r
} VIRTIO_FS_FUSE_INIT_RESPONSE;\r
\r
//\r
// Headers for VirtioFsFuseOpOpenDir.\r
//\r
typedef struct {\r
  UINT32 Flags;\r
  UINT32 Unused;\r
} VIRTIO_FS_FUSE_OPEN_REQUEST;\r
\r
typedef struct {\r
  UINT64 FileHandle;\r
  UINT32 OpenFlags;\r
  UINT32 Padding;\r
} VIRTIO_FS_FUSE_OPEN_RESPONSE;\r
#pragma pack ()\r
\r
#endif // VIRTIO_FS_H_\r