audk/OvmfPkg/VirtioGpuDxe/Commands.c

/** @file

  VirtIo GPU initialization, and commands (primitives) for the GPU device.

  Copyright (C) 2016, Red Hat, Inc.
  Copyright (c) 2017, AMD Inc, All rights reserved.<BR>

  This program and the accompanying materials are licensed and made available
  under the terms and conditions of the BSD License which accompanies this
  distribution. The full text of the license may be found at
  http://opensource.org/licenses/bsd-license.php

  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
  WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include <Library/VirtioLib.h>

#include "VirtioGpu.h"

/**
  Configure the VirtIo GPU device that underlies VgpuDev.

  @param[in,out] VgpuDev  The VGPU_DEV object to set up VirtIo messaging for.
                          On input, the caller is responsible for having
                          initialized VgpuDev->VirtIo. On output, VgpuDev->Ring
                          has been initialized, and synchronous VirtIo GPU
                          commands (primitives) can be submitted to the device.

  @retval EFI_SUCCESS      VirtIo GPU configuration successful.

  @retval EFI_UNSUPPORTED  The host-side configuration of the VirtIo GPU is not
                           supported by this driver.

  @retval                  Error codes from underlying functions.
**/
EFI_STATUS
VirtioGpuInit (
  IN OUT VGPU_DEV *VgpuDev
  )
{
  UINT8      NextDevStat;
  EFI_STATUS Status;
  UINT64     Features;
  UINT16     QueueSize;
  UINT64     RingBaseShift;

  //
  // Execute virtio-v1.0-cs04, 3.1.1 Driver Requirements: Device
  // Initialization.
  //
  // 1. Reset the device.
  //
  NextDevStat = 0;
  Status = VgpuDev->VirtIo->SetDeviceStatus (VgpuDev->VirtIo, NextDevStat);
  if (EFI_ERROR (Status)) {
    goto Failed;
  }

  //
  // 2. Set the ACKNOWLEDGE status bit [...]
  //
  NextDevStat |= VSTAT_ACK;
  Status = VgpuDev->VirtIo->SetDeviceStatus (VgpuDev->VirtIo, NextDevStat);
  if (EFI_ERROR (Status)) {
    goto Failed;
  }

  //
  // 3. Set the DRIVER status bit [...]
  //
  NextDevStat |= VSTAT_DRIVER;
  Status = VgpuDev->VirtIo->SetDeviceStatus (VgpuDev->VirtIo, NextDevStat);
  if (EFI_ERROR (Status)) {
    goto Failed;
  }

  //
  // 4. Read device feature bits...
  //
  Status = VgpuDev->VirtIo->GetDeviceFeatures (VgpuDev->VirtIo, &Features);
  if (EFI_ERROR (Status)) {
    goto Failed;
  }
  if ((Features & VIRTIO_F_VERSION_1) == 0) {
    Status = EFI_UNSUPPORTED;
    goto Failed;
  }
  //
  // We only want the most basic 2D features.
  //
  Features &= VIRTIO_F_VERSION_1 | VIRTIO_F_IOMMU_PLATFORM;

  //
  // ... and write the subset of feature bits understood by the [...] driver to
  // the device. [...]
  // 5. Set the FEATURES_OK status bit.
  // 6. Re-read device status to ensure the FEATURES_OK bit is still set [...]
  //
  Status = Virtio10WriteFeatures (VgpuDev->VirtIo, Features, &NextDevStat);
  if (EFI_ERROR (Status)) {
    goto Failed;
  }

  //
  // 7. Perform device-specific setup, including discovery of virtqueues for
  // the device [...]
  //
  Status = VgpuDev->VirtIo->SetQueueSel (VgpuDev->VirtIo,
                              VIRTIO_GPU_CONTROL_QUEUE);
  if (EFI_ERROR (Status)) {
    goto Failed;
  }
  Status = VgpuDev->VirtIo->GetQueueNumMax (VgpuDev->VirtIo, &QueueSize);
  if (EFI_ERROR (Status)) {
    goto Failed;
  }

  //
  // We implement each VirtIo GPU command that we use with two descriptors:
  // request, response.
  //
  if (QueueSize < 2) {
    Status = EFI_UNSUPPORTED;
    goto Failed;
  }

  //
  // [...] population of virtqueues [...]
  //
  Status = VirtioRingInit (VgpuDev->VirtIo, QueueSize, &VgpuDev->Ring);
  if (EFI_ERROR (Status)) {
    goto Failed;
  }
  //
  // If anything fails from here on, we have to release the ring.
  //
  Status = VirtioRingMap (
             VgpuDev->VirtIo,
             &VgpuDev->Ring,
             &RingBaseShift,
             &VgpuDev->RingMap
             );
  if (EFI_ERROR (Status)) {
    goto ReleaseQueue;
  }
  //
  // If anything fails from here on, we have to unmap the ring.
  //
  Status = VgpuDev->VirtIo->SetQueueAddress (
                              VgpuDev->VirtIo,
                              &VgpuDev->Ring,
                              RingBaseShift
                              );
  if (EFI_ERROR (Status)) {
    goto UnmapQueue;
  }

  //
  // 8. Set the DRIVER_OK status bit.
  //
  NextDevStat |= VSTAT_DRIVER_OK;
  Status = VgpuDev->VirtIo->SetDeviceStatus (VgpuDev->VirtIo, NextDevStat);
  if (EFI_ERROR (Status)) {
    goto UnmapQueue;
  }

  return EFI_SUCCESS;

UnmapQueue:
  VgpuDev->VirtIo->UnmapSharedBuffer (VgpuDev->VirtIo, VgpuDev->RingMap);

ReleaseQueue:
  VirtioRingUninit (VgpuDev->VirtIo, &VgpuDev->Ring);

Failed:
  //
  // If any of these steps go irrecoverably wrong, the driver SHOULD set the
  // FAILED status bit to indicate that it has given up on the device (it can
  // reset the device later to restart if desired). [...]
  //
  // VirtIo access failure here should not mask the original error.
  //
  NextDevStat |= VSTAT_FAILED;
  VgpuDev->VirtIo->SetDeviceStatus (VgpuDev->VirtIo, NextDevStat);

  return Status;
}

/**
  De-configure the VirtIo GPU device that underlies VgpuDev.

  @param[in,out] VgpuDev  The VGPU_DEV object to tear down VirtIo messaging
                          for. On input, the caller is responsible for having
                          called VirtioGpuInit(). On output, VgpuDev->Ring has
                          been uninitialized; VirtIo GPU commands (primitives)
                          can no longer be submitted to the device.
**/
VOID
VirtioGpuUninit (
  IN OUT VGPU_DEV *VgpuDev
  )
{
  //
  // Resetting the VirtIo device makes it release its resources and forget its
  // configuration.
  //
  VgpuDev->VirtIo->SetDeviceStatus (VgpuDev->VirtIo, 0);
  VgpuDev->VirtIo->UnmapSharedBuffer (VgpuDev->VirtIo, VgpuDev->RingMap);
  VirtioRingUninit (VgpuDev->VirtIo, &VgpuDev->Ring);
}

/**
  Allocate, zero and map memory, for bus master common buffer operation, to be
  attached as backing store to a host-side VirtIo GPU resource.

  @param[in]  VgpuDev        The VGPU_DEV object that represents the VirtIo GPU
                             device.

  @param[in]  NumberOfPages  The number of whole pages to allocate and map.

  @param[out] HostAddress    The system memory address of the allocated area.

  @param[out] DeviceAddress  The bus master device address of the allocated
                             area. The VirtIo GPU device may be programmed to
                             access the allocated area through DeviceAddress;
                             DeviceAddress is to be passed to the
                             VirtioGpuResourceAttachBacking() function, as the
                             BackingStoreDeviceAddress parameter.

  @param[out] Mapping        A resulting token to pass to
                             VirtioGpuUnmapAndFreeBackingStore().

  @retval EFI_SUCCESS  The requested number of pages has been allocated, zeroed
                       and mapped.

  @return              Status codes propagated from
                       VgpuDev->VirtIo->AllocateSharedPages() and
                       VirtioMapAllBytesInSharedBuffer().
**/
EFI_STATUS
VirtioGpuAllocateZeroAndMapBackingStore (
  IN  VGPU_DEV             *VgpuDev,
  IN  UINTN                NumberOfPages,
  OUT VOID                 **HostAddress,
  OUT EFI_PHYSICAL_ADDRESS *DeviceAddress,
  OUT VOID                 **Mapping
  )
{
  EFI_STATUS Status;
  VOID       *NewHostAddress;

  Status = VgpuDev->VirtIo->AllocateSharedPages (
                              VgpuDev->VirtIo,
                              NumberOfPages,
                              &NewHostAddress
                              );
  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // Avoid exposing stale data to the device even temporarily: zero the area
  // before mapping it.
  //
  ZeroMem (NewHostAddress, EFI_PAGES_TO_SIZE (NumberOfPages));

  Status = VirtioMapAllBytesInSharedBuffer (
             VgpuDev->VirtIo,                      // VirtIo
             VirtioOperationBusMasterCommonBuffer, // Operation
             NewHostAddress,                       // HostAddress
             EFI_PAGES_TO_SIZE (NumberOfPages),    // NumberOfBytes
             DeviceAddress,                        // DeviceAddress
             Mapping                               // Mapping
             );
  if (EFI_ERROR (Status)) {
    goto FreeSharedPages;
  }

  *HostAddress = NewHostAddress;
  return EFI_SUCCESS;

FreeSharedPages:
  VgpuDev->VirtIo->FreeSharedPages (
                     VgpuDev->VirtIo,
                     NumberOfPages,
                     NewHostAddress
                     );
  return Status;
}

/**
  Unmap and free memory originally allocated and mapped with
  VirtioGpuAllocateZeroAndMapBackingStore().

  If the memory allocated and mapped with
  VirtioGpuAllocateZeroAndMapBackingStore() was attached to a host-side VirtIo
  GPU resource with VirtioGpuResourceAttachBacking(), then the caller is
  responsible for detaching the backing store from the same resource, with
  VirtioGpuResourceDetachBacking(), before calling this function.

  @param[in] VgpuDev        The VGPU_DEV object that represents the VirtIo GPU
                            device.

  @param[in] NumberOfPages  The NumberOfPages parameter originally passed to
                            VirtioGpuAllocateZeroAndMapBackingStore().

  @param[in] HostAddress    The HostAddress value originally output by
                            VirtioGpuAllocateZeroAndMapBackingStore().

  @param[in] Mapping        The token that was originally output by
                            VirtioGpuAllocateZeroAndMapBackingStore().
**/
VOID
VirtioGpuUnmapAndFreeBackingStore (
  IN VGPU_DEV *VgpuDev,
  IN UINTN    NumberOfPages,
  IN VOID     *HostAddress,
  IN VOID     *Mapping
  )
{
  VgpuDev->VirtIo->UnmapSharedBuffer (
                     VgpuDev->VirtIo,
                     Mapping
                     );
  VgpuDev->VirtIo->FreeSharedPages (
                     VgpuDev->VirtIo,
                     NumberOfPages,
                     HostAddress
                     );
}

/**
  EFI_EVENT_NOTIFY function for the VGPU_DEV.ExitBoot event. It resets the
  VirtIo device, causing it to release its resources and to forget its
  configuration.

  This function may only be called (that is, VGPU_DEV.ExitBoot may only be
  signaled) after VirtioGpuInit() returns and before VirtioGpuUninit() is
  called.

  @param[in] Event    Event whose notification function is being invoked.

  @param[in] Context  Pointer to the associated VGPU_DEV object.
**/
VOID
EFIAPI
VirtioGpuExitBoot (
  IN EFI_EVENT Event,
  IN VOID      *Context
  )
{
  VGPU_DEV *VgpuDev;

  DEBUG ((DEBUG_VERBOSE, "%a: Context=0x%p\n", __FUNCTION__, Context));
  VgpuDev = Context;
  VgpuDev->VirtIo->SetDeviceStatus (VgpuDev->VirtIo, 0);
}

/**
  Internal utility function that sends a request to the VirtIo GPU device
  model, awaits the answer from the host, and returns a status.

  @param[in,out] VgpuDev  The VGPU_DEV object that represents the VirtIo GPU
                          device. The caller is responsible to have
                          successfully invoked VirtioGpuInit() on VgpuDev
                          previously, while VirtioGpuUninit() must not have
                          been called on VgpuDev.

  @param[in] RequestType  The type of the request. The caller is responsible
                          for providing a VirtioGpuCmd* RequestType which, on
                          success, elicits a VirtioGpuRespOkNodata response
                          from the host.

  @param[in] Fence        Whether to enable fencing for this request. Fencing
                          forces the host to complete the command before
                          producing a response. If Fence is TRUE, then
                          VgpuDev->FenceId is consumed, and incremented.

  @param[in,out] Header   Pointer to the caller-allocated request object. The
                          request must start with VIRTIO_GPU_CONTROL_HEADER.
                          This function overwrites all fields of Header before
                          submitting the request to the host:

                          - it sets Type from RequestType,

                          - it sets Flags and FenceId based on Fence,

                          - it zeroes CtxId and Padding.

  @param[in] RequestSize  Size of the entire caller-allocated request object,
                          including the leading VIRTIO_GPU_CONTROL_HEADER.

  @retval EFI_SUCCESS            Operation successful.

  @retval EFI_DEVICE_ERROR       The host rejected the request. The host error
                                 code has been logged on the EFI_D_ERROR level.

  @return                        Codes for unexpected errors in VirtIo
                                 messaging, or request/response
                                 mapping/unmapping.
**/
STATIC
EFI_STATUS
VirtioGpuSendCommand (
  IN OUT VGPU_DEV                           *VgpuDev,
  IN     VIRTIO_GPU_CONTROL_TYPE            RequestType,
  IN     BOOLEAN                            Fence,
  IN OUT volatile VIRTIO_GPU_CONTROL_HEADER *Header,
  IN     UINTN                              RequestSize
  )
{
  DESC_INDICES                       Indices;
  volatile VIRTIO_GPU_CONTROL_HEADER Response;
  EFI_STATUS                         Status;
  UINT32                             ResponseSize;
  EFI_PHYSICAL_ADDRESS               RequestDeviceAddress;
  VOID                               *RequestMap;
  EFI_PHYSICAL_ADDRESS               ResponseDeviceAddress;
  VOID                               *ResponseMap;

  //
  // Initialize Header.
  //
  Header->Type      = RequestType;
  if (Fence) {
    Header->Flags   = VIRTIO_GPU_FLAG_FENCE;
    Header->FenceId = VgpuDev->FenceId++;
  } else {
    Header->Flags   = 0;
    Header->FenceId = 0;
  }
  Header->CtxId     = 0;
  Header->Padding   = 0;

  ASSERT (RequestSize >= sizeof *Header);
  ASSERT (RequestSize <= MAX_UINT32);

  //
  // Map request and response to bus master device addresses.
  //
  Status = VirtioMapAllBytesInSharedBuffer (
             VgpuDev->VirtIo,
             VirtioOperationBusMasterRead,
             (VOID *)Header,
             RequestSize,
             &RequestDeviceAddress,
             &RequestMap
             );
  if (EFI_ERROR (Status)) {
    return Status;
  }
  Status = VirtioMapAllBytesInSharedBuffer (
             VgpuDev->VirtIo,
             VirtioOperationBusMasterWrite,
             (VOID *)&Response,
             sizeof Response,
             &ResponseDeviceAddress,
             &ResponseMap
             );
  if (EFI_ERROR (Status)) {
    goto UnmapRequest;
  }

  //
  // Compose the descriptor chain.
  //
  VirtioPrepare (&VgpuDev->Ring, &Indices);
  VirtioAppendDesc (
    &VgpuDev->Ring,
    RequestDeviceAddress,
    (UINT32)RequestSize,
    VRING_DESC_F_NEXT,
    &Indices
    );
  VirtioAppendDesc (
    &VgpuDev->Ring,
    ResponseDeviceAddress,
    (UINT32)sizeof Response,
    VRING_DESC_F_WRITE,
    &Indices
    );

  //
  // Send the command.
  //
  Status = VirtioFlush (VgpuDev->VirtIo, VIRTIO_GPU_CONTROL_QUEUE,
             &VgpuDev->Ring, &Indices, &ResponseSize);
  if (EFI_ERROR (Status)) {
    goto UnmapResponse;
  }

  //
  // Verify response size.
  //
  if (ResponseSize != sizeof Response) {
    DEBUG ((EFI_D_ERROR, "%a: malformed response to Request=0x%x\n",
      __FUNCTION__, (UINT32)RequestType));
    Status = EFI_PROTOCOL_ERROR;
    goto UnmapResponse;
  }

  //
  // Unmap response and request, in reverse order of mapping. On error, the
  // respective mapping is invalidated anyway, only the data may not have been
  // committed to system memory (in case of VirtioOperationBusMasterWrite).
  //
  Status = VgpuDev->VirtIo->UnmapSharedBuffer (VgpuDev->VirtIo, ResponseMap);
  if (EFI_ERROR (Status)) {
    goto UnmapRequest;
  }
  Status = VgpuDev->VirtIo->UnmapSharedBuffer (VgpuDev->VirtIo, RequestMap);
  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // Parse the response.
  //
  if (Response.Type == VirtioGpuRespOkNodata) {
    return EFI_SUCCESS;
  }

  DEBUG ((EFI_D_ERROR, "%a: Request=0x%x Response=0x%x\n", __FUNCTION__,
    (UINT32)RequestType, Response.Type));
  return EFI_DEVICE_ERROR;

UnmapResponse:
  VgpuDev->VirtIo->UnmapSharedBuffer (VgpuDev->VirtIo, ResponseMap);

UnmapRequest:
  VgpuDev->VirtIo->UnmapSharedBuffer (VgpuDev->VirtIo, RequestMap);

  return Status;
}

/**
  The following functions send requests to the VirtIo GPU device model, await
  the answer from the host, and return a status. They share the following
  interface details:

  @param[in,out] VgpuDev  The VGPU_DEV object that represents the VirtIo GPU
                          device. The caller is responsible to have
                          successfully invoked VirtioGpuInit() on VgpuDev
                          previously, while VirtioGpuUninit() must not have
                          been called on VgpuDev.

  @retval EFI_INVALID_PARAMETER  Invalid command-specific parameters were
                                 detected by this driver.

  @retval EFI_SUCCESS            Operation successful.

  @retval EFI_DEVICE_ERROR       The host rejected the request. The host error
                                 code has been logged on the EFI_D_ERROR level.

  @return                        Codes for unexpected errors in VirtIo
                                 messaging.

  For the command-specific parameters, please consult the GPU Device section of
  the VirtIo 1.0 specification (see references in
  "OvmfPkg/Include/IndustryStandard/VirtioGpu.h").
**/
EFI_STATUS
VirtioGpuResourceCreate2d (
  IN OUT VGPU_DEV           *VgpuDev,
  IN     UINT32             ResourceId,
  IN     VIRTIO_GPU_FORMATS Format,
  IN     UINT32             Width,
  IN     UINT32             Height
  )
{
  volatile VIRTIO_GPU_RESOURCE_CREATE_2D Request;

  if (ResourceId == 0) {
    return EFI_INVALID_PARAMETER;
  }

  Request.ResourceId = ResourceId;
  Request.Format     = (UINT32)Format;
  Request.Width      = Width;
  Request.Height     = Height;

  return VirtioGpuSendCommand (
           VgpuDev,
           VirtioGpuCmdResourceCreate2d,
           FALSE,                        // Fence
           &Request.Header,
           sizeof Request
           );
}

EFI_STATUS
VirtioGpuResourceUnref (
  IN OUT VGPU_DEV *VgpuDev,
  IN     UINT32   ResourceId
  )
{
  volatile VIRTIO_GPU_RESOURCE_UNREF Request;

  if (ResourceId == 0) {
    return EFI_INVALID_PARAMETER;
  }

  Request.ResourceId = ResourceId;
  Request.Padding    = 0;

  return VirtioGpuSendCommand (
           VgpuDev,
           VirtioGpuCmdResourceUnref,
           FALSE,                     // Fence
           &Request.Header,
           sizeof Request
           );
}

EFI_STATUS
VirtioGpuResourceAttachBacking (
  IN OUT VGPU_DEV             *VgpuDev,
  IN     UINT32               ResourceId,
  IN     EFI_PHYSICAL_ADDRESS BackingStoreDeviceAddress,
  IN     UINTN                NumberOfPages
  )
{
  volatile VIRTIO_GPU_RESOURCE_ATTACH_BACKING Request;

  if (ResourceId == 0) {
    return EFI_INVALID_PARAMETER;
  }

  Request.ResourceId    = ResourceId;
  Request.NrEntries     = 1;
  Request.Entry.Addr    = BackingStoreDeviceAddress;
  Request.Entry.Length  = (UINT32)EFI_PAGES_TO_SIZE (NumberOfPages);
  Request.Entry.Padding = 0;

  return VirtioGpuSendCommand (
           VgpuDev,
           VirtioGpuCmdResourceAttachBacking,
           FALSE,                             // Fence
           &Request.Header,
           sizeof Request
           );
}

EFI_STATUS
VirtioGpuResourceDetachBacking (
  IN OUT VGPU_DEV *VgpuDev,
  IN     UINT32   ResourceId
  )
{
  volatile VIRTIO_GPU_RESOURCE_DETACH_BACKING Request;

  if (ResourceId == 0) {
    return EFI_INVALID_PARAMETER;
  }

  Request.ResourceId = ResourceId;
  Request.Padding    = 0;

  //
  // In this case, we set Fence to TRUE, because after this function returns,
  // the caller might reasonably want to repurpose the backing pages
  // immediately. Thus we should ensure that the host releases all references
  // to the backing pages before we return.
  //
  return VirtioGpuSendCommand (
           VgpuDev,
           VirtioGpuCmdResourceDetachBacking,
           TRUE,                              // Fence
           &Request.Header,
           sizeof Request
           );
}

EFI_STATUS
VirtioGpuSetScanout (
  IN OUT VGPU_DEV *VgpuDev,
  IN     UINT32   X,
  IN     UINT32   Y,
  IN     UINT32   Width,
  IN     UINT32   Height,
  IN     UINT32   ScanoutId,
  IN     UINT32   ResourceId
  )
{
  volatile VIRTIO_GPU_SET_SCANOUT Request;

  //
  // Unlike for most other commands, ResourceId=0 is valid; it
  // is used to disable a scanout.
  //
  Request.Rectangle.X      = X;
  Request.Rectangle.Y      = Y;
  Request.Rectangle.Width  = Width;
  Request.Rectangle.Height = Height;
  Request.ScanoutId        = ScanoutId;
  Request.ResourceId       = ResourceId;

  return VirtioGpuSendCommand (
           VgpuDev,
           VirtioGpuCmdSetScanout,
           FALSE,                  // Fence
           &Request.Header,
           sizeof Request
           );
}

EFI_STATUS
VirtioGpuTransferToHost2d (
  IN OUT VGPU_DEV *VgpuDev,
  IN     UINT32   X,
  IN     UINT32   Y,
  IN     UINT32   Width,
  IN     UINT32   Height,
  IN     UINT64   Offset,
  IN     UINT32   ResourceId
  )
{
  volatile VIRTIO_GPU_CMD_TRANSFER_TO_HOST_2D Request;

  if (ResourceId == 0) {
    return EFI_INVALID_PARAMETER;
  }

  Request.Rectangle.X      = X;
  Request.Rectangle.Y      = Y;
  Request.Rectangle.Width  = Width;
  Request.Rectangle.Height = Height;
  Request.Offset           = Offset;
  Request.ResourceId       = ResourceId;
  Request.Padding          = 0;

  return VirtioGpuSendCommand (
           VgpuDev,
           VirtioGpuCmdTransferToHost2d,
           FALSE,                        // Fence
           &Request.Header,
           sizeof Request
           );
}

EFI_STATUS
VirtioGpuResourceFlush (
  IN OUT VGPU_DEV *VgpuDev,
  IN     UINT32   X,
  IN     UINT32   Y,
  IN     UINT32   Width,
  IN     UINT32   Height,
  IN     UINT32   ResourceId
  )
{
  volatile VIRTIO_GPU_RESOURCE_FLUSH Request;

  if (ResourceId == 0) {
    return EFI_INVALID_PARAMETER;
  }

  Request.Rectangle.X      = X;
  Request.Rectangle.Y      = Y;
  Request.Rectangle.Width  = Width;
  Request.Rectangle.Height = Height;
  Request.ResourceId       = ResourceId;
  Request.Padding          = 0;

  return VirtioGpuSendCommand (
           VgpuDev,
           VirtioGpuCmdResourceFlush,
           FALSE,                     // Fence
           &Request.Header,
           sizeof Request
           );
}