OvmfPkg/VirtioFsDxe: implement the wrapper function for FUSE_OPEN

Add the VirtioFsFuseOpen() function, for sending the FUSE_OPEN command to
the Virtio Filesystem device.

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: <20201216211125.19496-19-lersek@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@arm.com>

OvmfPkg/Include/IndustryStandard/VirtioFs.h

@@ -81,11 +81,18 @@ typedef struct {
 //
 #define VIRTIO_FS_FUSE_ROOT_DIR_NODE_ID 1
 
+//
+// Flags for VirtioFsFuseOpOpen.
+//
+#define VIRTIO_FS_FUSE_OPEN_REQ_F_RDONLY 0
+#define VIRTIO_FS_FUSE_OPEN_REQ_F_RDWR   2
+
 //
 // FUSE operation codes.
 //
 typedef enum {
   VirtioFsFuseOpForget      =  2,
+  VirtioFsFuseOpOpen        = 14,
   VirtioFsFuseOpRelease     = 18,
   VirtioFsFuseOpFsync       = 20,
   VirtioFsFuseOpFlush       = 25,
@@ -123,6 +130,20 @@ typedef struct {
   UINT64 NumberOfLookups;
 } VIRTIO_FS_FUSE_FORGET_REQUEST;
 
+//
+// Headers for VirtioFsFuseOpOpen and VirtioFsFuseOpOpenDir.
+//
+typedef struct {
+  UINT32 Flags;
+  UINT32 Unused;
+} VIRTIO_FS_FUSE_OPEN_REQUEST;
+
+typedef struct {
+  UINT64 FileHandle;
+  UINT32 OpenFlags;
+  UINT32 Padding;
+} VIRTIO_FS_FUSE_OPEN_RESPONSE;
+
 //
 // Header for VirtioFsFuseOpRelease and VirtioFsFuseOpReleaseDir.
 //
@@ -175,20 +196,6 @@ typedef struct {
   UINT16 MapAlignment;
   UINT32 Unused[8];
 } VIRTIO_FS_FUSE_INIT_RESPONSE;
-
-//
-// Headers for VirtioFsFuseOpOpenDir.
-//
-typedef struct {
-  UINT32 Flags;
-  UINT32 Unused;
-} VIRTIO_FS_FUSE_OPEN_REQUEST;
-
-typedef struct {
-  UINT64 FileHandle;
-  UINT32 OpenFlags;
-  UINT32 Padding;
-} VIRTIO_FS_FUSE_OPEN_RESPONSE;
 #pragma pack ()
 
 #endif // VIRTIO_FS_H_

OvmfPkg/VirtioFsDxe/FuseOpen.c

@@ -0,0 +1,126 @@
+/** @file
+  FUSE_OPEN wrapper for the Virtio Filesystem device.
+
+  Copyright (C) 2020, Red Hat, Inc.
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include "VirtioFsDxe.h"
+
+/**
+  Send a FUSE_OPEN request to the Virtio Filesystem device, for opening a
+  regular file.
+
+  The function may only be called after VirtioFsFuseInitSession() returns
+  successfully and before VirtioFsUninit() is called.
+
+  @param[in,out] VirtioFs  The Virtio Filesystem device to send the FUSE_OPEN
+                           request to. On output, the FUSE request counter
+                           "VirtioFs->RequestId" will have been incremented.
+
+  @param[in] NodeId        The inode number of the regular file to open.
+
+  @param[in] ReadWrite     If TRUE, open the regular file in read-write mode.
+                           If FALSE, open the regular file in read-only mode.
+
+  @param[out] FuseHandle   The open handle to the regular file, returned by the
+                           Virtio Filesystem device.
+
+  @retval EFI_SUCCESS  The regular file has been opened.
+
+  @return              The "errno" value mapped to an EFI_STATUS code, if the
+                       Virtio Filesystem device explicitly reported an error.
+
+  @return              Error codes propagated from VirtioFsSgListsValidate(),
+                       VirtioFsFuseNewRequest(), VirtioFsSgListsSubmit(),
+                       VirtioFsFuseCheckResponse().
+**/
+EFI_STATUS
+VirtioFsFuseOpen (
+  IN OUT VIRTIO_FS *VirtioFs,
+  IN     UINT64    NodeId,
+  IN     BOOLEAN   ReadWrite,
+     OUT UINT64    *FuseHandle
+  )
+{
+  VIRTIO_FS_FUSE_REQUEST        CommonReq;
+  VIRTIO_FS_FUSE_OPEN_REQUEST   OpenReq;
+  VIRTIO_FS_IO_VECTOR           ReqIoVec[2];
+  VIRTIO_FS_SCATTER_GATHER_LIST ReqSgList;
+  VIRTIO_FS_FUSE_RESPONSE       CommonResp;
+  VIRTIO_FS_FUSE_OPEN_RESPONSE  OpenResp;
+  VIRTIO_FS_IO_VECTOR           RespIoVec[2];
+  VIRTIO_FS_SCATTER_GATHER_LIST RespSgList;
+  EFI_STATUS                    Status;
+
+  //
+  // Set up the scatter-gather lists.
+  //
+  ReqIoVec[0].Buffer = &CommonReq;
+  ReqIoVec[0].Size   = sizeof CommonReq;
+  ReqIoVec[1].Buffer = &OpenReq;
+  ReqIoVec[1].Size   = sizeof OpenReq;
+  ReqSgList.IoVec    = ReqIoVec;
+  ReqSgList.NumVec   = ARRAY_SIZE (ReqIoVec);
+
+  RespIoVec[0].Buffer = &CommonResp;
+  RespIoVec[0].Size   = sizeof CommonResp;
+  RespIoVec[1].Buffer = &OpenResp;
+  RespIoVec[1].Size   = sizeof OpenResp;
+  RespSgList.IoVec    = RespIoVec;
+  RespSgList.NumVec   = ARRAY_SIZE (RespIoVec);
+
+  //
+  // Validate the scatter-gather lists; calculate the total transfer sizes.
+  //
+  Status = VirtioFsSgListsValidate (VirtioFs, &ReqSgList, &RespSgList);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  //
+  // Populate the common request header.
+  //
+  Status = VirtioFsFuseNewRequest (VirtioFs, &CommonReq, ReqSgList.TotalSize,
+             VirtioFsFuseOpOpen, NodeId);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  //
+  // Populate the FUSE_OPEN-specific fields.
+  //
+  OpenReq.Flags  = (ReadWrite ?
+                    VIRTIO_FS_FUSE_OPEN_REQ_F_RDWR :
+                    VIRTIO_FS_FUSE_OPEN_REQ_F_RDONLY);
+  OpenReq.Unused = 0;
+
+  //
+  // Submit the request.
+  //
+  Status = VirtioFsSgListsSubmit (VirtioFs, &ReqSgList, &RespSgList);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  //
+  // Verify the response (all response buffers are fixed size).
+  //
+  Status = VirtioFsFuseCheckResponse (&RespSgList, CommonReq.Unique, NULL);
+  if (EFI_ERROR (Status)) {
+    if (Status == EFI_DEVICE_ERROR) {
+      DEBUG ((DEBUG_ERROR, "%a: Label=\"%s\" NodeId=%Lu ReadWrite=%d "
+        "Errno=%d\n", __FUNCTION__, VirtioFs->Label, NodeId, ReadWrite,
+        CommonResp.Error));
+      Status = VirtioFsErrnoToEfiStatus (CommonResp.Error);
+    }
+    return Status;
+  }
+
+  //
+  // Output the open handle.
+  //
+  *FuseHandle = OpenResp.FileHandle;
+  return EFI_SUCCESS;
+}

OvmfPkg/VirtioFsDxe/VirtioFsDxe.h

@@ -235,6 +235,14 @@ VirtioFsFuseForget (
   IN     UINT64    NodeId
   );
 
+EFI_STATUS
+VirtioFsFuseOpen (
+  IN OUT VIRTIO_FS *VirtioFs,
+  IN     UINT64    NodeId,
+  IN     BOOLEAN   ReadWrite,
+     OUT UINT64    *FuseHandle
+  );
+
 EFI_STATUS
 VirtioFsFuseReleaseFileOrDir (
   IN OUT VIRTIO_FS *VirtioFs,

OvmfPkg/VirtioFsDxe/VirtioFsDxe.inf

@@ -86,6 +86,7 @@
   FuseForget.c
   FuseFsync.c
   FuseInit.c
+  FuseOpen.c
   FuseOpenDir.c
   FuseRelease.c
   Helpers.c