[mirror_edk2.git] / OvmfPkg / VirtioBlkDxe / VirtioBlk.c

/** @file\r
\r
  This driver produces Block I/O Protocol instances for virtio-blk devices.\r
\r
  The implementation is basic:\r
\r
  - No attach/detach (ie. removable media).\r
\r
  - Although the non-blocking interfaces of EFI_BLOCK_IO2_PROTOCOL could be a\r
    good match for multiple in-flight virtio-blk requests, we stick to\r
    synchronous requests and EFI_BLOCK_IO_PROTOCOL for now.\r
\r
  Copyright (C) 2012, Red Hat, Inc.\r
  Copyright (c) 2012, Intel Corporation. All rights reserved.<BR>\r
\r
  This program and the accompanying materials are licensed and made available\r
  under the terms and conditions of the BSD License which accompanies this\r
  distribution. The full text of the license may be found at\r
  http://opensource.org/licenses/bsd-license.php\r
\r
  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT\r
  WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
\r
**/\r
\r
#include <IndustryStandard/Pci.h>\r
#include <IndustryStandard/VirtioBlk.h>\r
#include <Library/BaseMemoryLib.h>\r
#include <Library/DebugLib.h>\r
#include <Library/MemoryAllocationLib.h>\r
#include <Library/UefiBootServicesTableLib.h>\r
#include <Library/UefiLib.h>\r
#include <Library/VirtioLib.h>\r
\r
#include "VirtioBlk.h"\r
\r
/**\r
\r
  Convenience macros to read and write region 0 IO space elements of the\r
  virtio-blk PCI device, for configuration purposes.\r
\r
  The following macros make it possible to specify only the "core parameters"\r
  for such accesses and to derive the rest. By the time VIRTIO_CFG_WRITE()\r
  returns, the transaction will have been completed.\r
\r
  @param[in] Dev       Pointer to the VBLK_DEV structure whose PCI IO space\r
                       we're accessing. Dev->PciIo must be valid.\r
\r
  @param[in] Field     A field name from VBLK_HDR, identifying the virtio-blk\r
                       configuration item to access.\r
\r
  @param[in] Value     (VIRTIO_CFG_WRITE() only.) The value to write to the\r
                       selected configuration item.\r
\r
  @param[out] Pointer  (VIRTIO_CFG_READ() only.) The object to receive the\r
                       value read from the configuration item. Its type must be\r
                       one of UINT8, UINT16, UINT32, UINT64.\r
\r
\r
  @return  Status code returned by VirtioWrite() / VirtioRead().\r
\r
**/\r
\r
#define VIRTIO_CFG_WRITE(Dev, Field, Value)  (VirtioWrite (             \\r
                                                (Dev)->PciIo,           \\r
                                                OFFSET_OF_VBLK (Field), \\r
                                                SIZE_OF_VBLK (Field),   \\r
                                                (Value)                 \\r
                                                ))\r
\r
#define VIRTIO_CFG_READ(Dev, Field, Pointer) (VirtioRead (              \\r
                                                (Dev)->PciIo,           \\r
                                                OFFSET_OF_VBLK (Field), \\r
                                                SIZE_OF_VBLK (Field),   \\r
                                                sizeof *(Pointer),      \\r
                                                (Pointer)               \\r
                                                ))\r
\r
\r
//\r
// UEFI Spec 2.3.1 + Errata C, 12.8 EFI Block I/O Protocol\r
// Driver Writer's Guide for UEFI 2.3.1 v1.01,\r
//   24.2 Block I/O Protocol Implementations\r
//\r
EFI_STATUS\r
EFIAPI\r
VirtioBlkReset (\r
  IN EFI_BLOCK_IO_PROTOCOL *This,\r
  IN BOOLEAN               ExtendedVerification\r
  )\r
{\r
  //\r
  // If we managed to initialize and install the driver, then the device is\r
  // working correctly.\r
  //\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
\r
  Verify correctness of the read/write (not flush) request submitted to the\r
  EFI_BLOCK_IO_PROTOCOL instance.\r
\r
  This function provides most verification steps described in:\r
\r
    UEFI Spec 2.3.1 + Errata C, 12.8 EFI Block I/O Protocol, 12.8 EFI Block I/O\r
    Protocol,\r
    - EFI_BLOCK_IO_PROTOCOL.ReadBlocks()\r
    - EFI_BLOCK_IO_PROTOCOL.WriteBlocks()\r
\r
    Driver Writer's Guide for UEFI 2.3.1 v1.01,\r
    - 24.2.2. ReadBlocks() and ReadBlocksEx() Implementation\r
    - 24.2.3 WriteBlocks() and WriteBlockEx() Implementation\r
\r
  Request sizes are limited to 1 GB (checked). This is not a practical\r
  limitation, just conformance to virtio-0.9.5, 2.3.2 Descriptor Table: "no\r
  descriptor chain may be more than 2^32 bytes long in total".\r
\r
  Some Media characteristics are hardcoded in VirtioBlkInit() below (like\r
  non-removable media, no restriction on buffer alignment etc); we rely on\r
  those here without explicit mention.\r
\r
  @param[in] Media               The EFI_BLOCK_IO_MEDIA characteristics for\r
                                 this driver instance, extracted from the\r
                                 underlying virtio-blk device at initialization\r
                                 time. We validate the request against this set\r
                                 of attributes.\r
\r
\r
  @param[in] Lba                 Logical Block Address: number of logical\r
                                 blocks to skip from the beginning of the\r
                                 device.\r
\r
  @param[in] PositiveBufferSize  Size of buffer to transfer, in bytes. The\r
                                 caller is responsible to ensure this parameter\r
                                 is positive.\r
\r
  @param[in] RequestIsWrite      TRUE iff data transfer goes from guest to\r
                                 device.\r
\r
\r
  @@return                       Validation result to be forwarded outwards by\r
                                 ReadBlocks() and WriteBlocks, as required by\r
                                 the specs above.\r
\r
**/\r
STATIC\r
EFI_STATUS\r
EFIAPI\r
VerifyReadWriteRequest (\r
  IN  EFI_BLOCK_IO_MEDIA *Media,\r
  IN  EFI_LBA            Lba,\r
  IN  UINTN              PositiveBufferSize,\r
  IN  BOOLEAN            RequestIsWrite\r
  )\r
{\r
  UINTN BlockCount;\r
\r
  ASSERT (PositiveBufferSize > 0);\r
\r
  if (PositiveBufferSize > SIZE_1GB ||\r
      PositiveBufferSize % Media->BlockSize > 0) {\r
    return EFI_BAD_BUFFER_SIZE;\r
  }\r
  BlockCount = PositiveBufferSize / Media->BlockSize;\r
\r
  //\r
  // Avoid unsigned wraparound on either side in the second comparison.\r
  //\r
  if (Lba > Media->LastBlock || BlockCount - 1 > Media->LastBlock - Lba) {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
\r
  if (RequestIsWrite && Media->ReadOnly) {\r
    return EFI_WRITE_PROTECTED;\r
  }\r
\r
  return EFI_SUCCESS;\r
}\r
\r
\r
\r
\r
/**\r
\r
  Format a read / write / flush request as three consecutive virtio\r
  descriptors, push them to the host, and poll for the response.\r
\r
  This is the main workhorse function. Two use cases are supported, read/write\r
  and flush. The function may only be called after the request parameters have\r
  been verified by\r
  - specific checks in ReadBlocks() / WriteBlocks() / FlushBlocks(), and\r
  - VerifyReadWriteRequest() (for read/write only).\r
\r
  Parameters handled commonly:\r
\r
    @param[in] Dev             The virtio-blk device the request is targeted\r
                               at.\r
\r
  Flush request:\r
\r
    @param[in] Lba             Must be zero.\r
\r
    @param[in] BufferSize      Must be zero.\r
\r
    @param[in out] Buffer      Ignored by the function.\r
\r
    @param[in] RequestIsWrite  Must be TRUE.\r
\r
  Read/Write request:\r
\r
    @param[in] Lba             Logical Block Address: number of logical blocks\r
                               to skip from the beginning of the device.\r
\r
    @param[in] BufferSize      Size of buffer to transfer, in bytes. The caller\r
                               is responsible to ensure this parameter is\r
                               positive.\r
\r
    @param[in out] Buffer      The guest side area to read data from the device\r
                               into, or write data to the device from.\r
\r
    @param[in] RequestIsWrite  TRUE iff data transfer goes from guest to\r
                               device.\r
\r
  Return values are common to both use cases, and are appropriate to be\r
  forwarded by the EFI_BLOCK_IO_PROTOCOL functions (ReadBlocks(),\r
  WriteBlocks(), FlushBlocks()).\r
\r
\r
  @retval EFI_SUCCESS          Transfer complete.\r
\r
  @retval EFI_DEVICE_ERROR     Failed to notify host side via PCI write, or\r
                               unable to parse host response, or host response\r
                               is not VIRTIO_BLK_S_OK.\r
\r
**/\r
\r
STATIC\r
EFI_STATUS\r
EFIAPI\r
SynchronousRequest (\r
  IN              VBLK_DEV *Dev,\r
  IN              EFI_LBA  Lba,\r
  IN              UINTN    BufferSize,\r
  IN OUT volatile VOID     *Buffer,\r
  IN              BOOLEAN  RequestIsWrite\r
  )\r
{\r
  UINT32                  BlockSize;\r
  volatile VIRTIO_BLK_REQ Request;\r
  volatile UINT8          HostStatus;\r
  DESC_INDICES            Indices;\r
\r
  BlockSize = Dev->BlockIoMedia.BlockSize;\r
\r
  //\r
  // ensured by VirtioBlkInit()\r
  //\r
  ASSERT (BlockSize > 0);\r
  ASSERT (BlockSize % 512 == 0);\r
\r
  //\r
  // ensured by contract above, plus VerifyReadWriteRequest()\r
  //\r
  ASSERT (BufferSize % BlockSize == 0);\r
\r
  //\r
  // Prepare virtio-blk request header, setting zero size for flush.\r
  // IO Priority is homogeneously 0.\r
  //\r
  Request.Type   = RequestIsWrite ?\r
                   (BufferSize == 0 ? VIRTIO_BLK_T_FLUSH : VIRTIO_BLK_T_OUT) :\r
                   VIRTIO_BLK_T_IN;\r
  Request.IoPrio = 0;\r
  Request.Sector = MultU64x32(Lba, BlockSize / 512);\r
\r
  VirtioPrepare (&Dev->Ring, &Indices);\r
\r
  //\r
  // preset a host status for ourselves that we do not accept as success\r
  //\r
  HostStatus = VIRTIO_BLK_S_IOERR;\r
\r
  //\r
  // ensured by VirtioBlkInit() -- this predicate, in combination with the\r
  // lock-step progress, ensures we don't have to track free descriptors.\r
  //\r
  ASSERT (Dev->Ring.QueueSize >= 3);\r
\r
  //\r
  // virtio-blk header in first desc\r
  //\r
  VirtioAppendDesc (&Dev->Ring, (UINTN) &Request, sizeof Request,\r
    VRING_DESC_F_NEXT, &Indices);\r
\r
  //\r
  // data buffer for read/write in second desc\r
  //\r
  if (BufferSize > 0) {\r
    //\r
    // From virtio-0.9.5, 2.3.2 Descriptor Table:\r
    // "no descriptor chain may be more than 2^32 bytes long in total".\r
    //\r
    // The predicate is ensured by the call contract above (for flush), or\r
    // VerifyReadWriteRequest() (for read/write). It also implies that\r
    // converting BufferSize to UINT32 will not truncate it.\r
    //\r
    ASSERT (BufferSize <= SIZE_1GB);\r
\r
    //\r
    // VRING_DESC_F_WRITE is interpreted from the host's point of view.\r
    //\r
    VirtioAppendDesc (&Dev->Ring, (UINTN) Buffer, (UINT32) BufferSize,\r
      VRING_DESC_F_NEXT | (RequestIsWrite ? 0 : VRING_DESC_F_WRITE),\r
      &Indices);\r
  }\r
\r
  //\r
  // host status in last (second or third) desc\r
  //\r
  VirtioAppendDesc (&Dev->Ring, (UINTN) &HostStatus, sizeof HostStatus,\r
    VRING_DESC_F_WRITE, &Indices);\r
\r
  //\r
  // virtio-blk's only virtqueue is #0, called "requestq" (see Appendix D).\r
  //\r
  if (VirtioFlush (Dev->PciIo, 0, &Dev->Ring, &Indices) == EFI_SUCCESS &&\r
      HostStatus == VIRTIO_BLK_S_OK) {\r
    return EFI_SUCCESS;\r
  }\r
\r
  return EFI_DEVICE_ERROR;\r
}\r
\r
\r
/**\r
\r
  ReadBlocks() operation for virtio-blk.\r
\r
  See\r
  - UEFI Spec 2.3.1 + Errata C, 12.8 EFI Block I/O Protocol, 12.8 EFI Block I/O\r
    Protocol, EFI_BLOCK_IO_PROTOCOL.ReadBlocks().\r
  - Driver Writer's Guide for UEFI 2.3.1 v1.01, 24.2.2. ReadBlocks() and\r
    ReadBlocksEx() Implementation.\r
\r
  Parameter checks and conformant return values are implemented in\r
  VerifyReadWriteRequest() and SynchronousRequest().\r
\r
  A zero BufferSize doesn't seem to be prohibited, so do nothing in that case,\r
  successfully.\r
\r
**/\r
\r
EFI_STATUS\r
EFIAPI\r
VirtioBlkReadBlocks (\r
  IN  EFI_BLOCK_IO_PROTOCOL *This,\r
  IN  UINT32                MediaId,\r
  IN  EFI_LBA               Lba,\r
  IN  UINTN                 BufferSize,\r
  OUT VOID                  *Buffer\r
  )\r
{\r
  VBLK_DEV   *Dev;\r
  EFI_STATUS Status;\r
\r
  if (BufferSize == 0) {\r
    return EFI_SUCCESS;\r
  }\r
\r
  Dev = VIRTIO_BLK_FROM_BLOCK_IO (This);\r
  Status = VerifyReadWriteRequest (\r
             &Dev->BlockIoMedia,\r
             Lba,\r
             BufferSize,\r
             FALSE               // RequestIsWrite\r
             );\r
  if (EFI_ERROR (Status)) {\r
    return Status;\r
  }\r
\r
  return SynchronousRequest (\r
           Dev,\r
           Lba,\r
           BufferSize,\r
           Buffer,\r
           FALSE       // RequestIsWrite\r
           );\r
}\r
\r
/**\r
\r
  WriteBlocks() operation for virtio-blk.\r
\r
  See\r
  - UEFI Spec 2.3.1 + Errata C, 12.8 EFI Block I/O Protocol, 12.8 EFI Block I/O\r
    Protocol, EFI_BLOCK_IO_PROTOCOL.WriteBlocks().\r
  - Driver Writer's Guide for UEFI 2.3.1 v1.01, 24.2.3 WriteBlocks() and\r
    WriteBlockEx() Implementation.\r
\r
  Parameter checks and conformant return values are implemented in\r
  VerifyReadWriteRequest() and SynchronousRequest().\r
\r
  A zero BufferSize doesn't seem to be prohibited, so do nothing in that case,\r
  successfully.\r
\r
**/\r
\r
EFI_STATUS\r
EFIAPI\r
VirtioBlkWriteBlocks (\r
  IN EFI_BLOCK_IO_PROTOCOL *This,\r
  IN UINT32                MediaId,\r
  IN EFI_LBA               Lba,\r
  IN UINTN                 BufferSize,\r
  IN VOID                  *Buffer\r
  )\r
{\r
  VBLK_DEV   *Dev;\r
  EFI_STATUS Status;\r
\r
  if (BufferSize == 0) {\r
    return EFI_SUCCESS;\r
  }\r
\r
  Dev = VIRTIO_BLK_FROM_BLOCK_IO (This);\r
  Status = VerifyReadWriteRequest (\r
             &Dev->BlockIoMedia,\r
             Lba,\r
             BufferSize,\r
             TRUE                // RequestIsWrite\r
             );\r
  if (EFI_ERROR (Status)) {\r
    return Status;\r
  }\r
\r
  return SynchronousRequest (\r
           Dev,\r
           Lba,\r
           BufferSize,\r
           Buffer,\r
           TRUE        // RequestIsWrite\r
           );\r
}\r
\r
\r
/**\r
\r
  FlushBlocks() operation for virtio-blk.\r
\r
  See\r
  - UEFI Spec 2.3.1 + Errata C, 12.8 EFI Block I/O Protocol, 12.8 EFI Block I/O\r
    Protocol, EFI_BLOCK_IO_PROTOCOL.FlushBlocks().\r
  - Driver Writer's Guide for UEFI 2.3.1 v1.01, 24.2.4 FlushBlocks() and\r
    FlushBlocksEx() Implementation.\r
\r
  If the underlying virtio-blk device doesn't support flushing (ie.\r
  write-caching), then this function should not be called by higher layers,\r
  according to EFI_BLOCK_IO_MEDIA characteristics set in VirtioBlkInit().\r
  Should they do nonetheless, we do nothing, successfully.\r
\r
**/\r
\r
EFI_STATUS\r
EFIAPI\r
VirtioBlkFlushBlocks (\r
  IN EFI_BLOCK_IO_PROTOCOL *This\r
  )\r
{\r
  VBLK_DEV *Dev;\r
\r
  Dev = VIRTIO_BLK_FROM_BLOCK_IO (This);\r
  return Dev->BlockIoMedia.WriteCaching ?\r
           SynchronousRequest (\r
             Dev,\r
             0,    // Lba\r
             0,    // BufferSize\r
             NULL, // Buffer\r
             TRUE  // RequestIsWrite\r
             ) :\r
           EFI_SUCCESS;\r
}\r
\r
\r
/**\r
\r
  Device probe function for this driver.\r
\r
  The DXE core calls this function for any given device in order to see if the\r
  driver can drive the device.\r
\r
  Specs relevant in the general sense:\r
\r
  - UEFI Spec 2.3.1 + Errata C:\r
    - 6.3 Protocol Handler Services -- for accessing the underlying device\r
    - 10.1 EFI Driver Binding Protocol -- for exporting ourselves\r
\r
  - Driver Writer's Guide for UEFI 2.3.1 v1.01:\r
    - 5.1.3.4 OpenProtocol() and CloseProtocol() -- for accessing the\r
      underlying device\r
    - 9 Driver Binding Protocol -- for exporting ourselves\r
\r
  Specs relevant in the specific sense:\r
  - UEFI Spec 2.3.1 + Errata C, 13.4 EFI PCI I/O Protocol\r
  - Driver Writer's Guide for UEFI 2.3.1 v1.01, 18 PCI Driver Design\r
    Guidelines, 18.3 PCI drivers.\r
\r
  @param[in]  This                The EFI_DRIVER_BINDING_PROTOCOL object\r
                                  incorporating this driver (independently of\r
                                  any device).\r
\r
  @param[in] DeviceHandle         The device to probe.\r
\r
  @param[in] RemainingDevicePath  Relevant only for bus drivers, ignored.\r
\r
\r
  @retval EFI_SUCCESS      The driver supports the device being probed.\r
\r
  @retval EFI_UNSUPPORTED  Based on virtio-blk PCI discovery, we do not support\r
                           the device.\r
\r
  @return                  Error codes from the OpenProtocol() boot service or\r
                           the PciIo protocol.\r
\r
**/\r
\r
EFI_STATUS\r
EFIAPI\r
VirtioBlkDriverBindingSupported (\r
  IN EFI_DRIVER_BINDING_PROTOCOL *This,\r
  IN EFI_HANDLE                  DeviceHandle,\r
  IN EFI_DEVICE_PATH_PROTOCOL    *RemainingDevicePath\r
  )\r
{\r
  EFI_STATUS          Status;\r
  EFI_PCI_IO_PROTOCOL *PciIo;\r
  PCI_TYPE00          Pci;\r
\r
  //\r
  // Attempt to open the device with the PciIo set of interfaces. On success,\r
  // the protocol is "instantiated" for the PCI device. Covers duplicate open\r
  // attempts (EFI_ALREADY_STARTED).\r
  //\r
  Status = gBS->OpenProtocol (\r
                  DeviceHandle,               // candidate device\r
                  &gEfiPciIoProtocolGuid,     // for generic PCI access\r
                  (VOID **)&PciIo,            // handle to instantiate\r
                  This->DriverBindingHandle,  // requestor driver identity\r
                  DeviceHandle,               // ControllerHandle, according to\r
                                              // the UEFI Driver Model\r
                  EFI_OPEN_PROTOCOL_BY_DRIVER // get exclusive PciIo access to\r
                                              // the device; to be released\r
                  );\r
  if (EFI_ERROR (Status)) {\r
    return Status;\r
  }\r
\r
  //\r
  // Read entire PCI configuration header for more extensive check ahead.\r
  //\r
  Status = PciIo->Pci.Read (\r
                        PciIo,                        // (protocol, device)\r
                                                      // handle\r
                        EfiPciIoWidthUint32,          // access width & copy\r
                                                      // mode\r
                        0,                            // Offset\r
                        sizeof Pci / sizeof (UINT32), // Count\r
                        &Pci                          // target buffer\r
                        );\r
\r
  if (Status == EFI_SUCCESS) {\r
    //\r
    // virtio-0.9.5, 2.1 PCI Discovery\r
    //\r
    Status = (Pci.Hdr.VendorId == 0x1AF4 &&\r
              Pci.Hdr.DeviceId >= 0x1000 && Pci.Hdr.DeviceId <= 0x103F &&\r
              Pci.Hdr.RevisionID == 0x00 &&\r
              Pci.Device.SubsystemID == VIRTIO_SUBSYSTEM_BLOCK_DEVICE) ? EFI_SUCCESS : EFI_UNSUPPORTED;\r
  }\r
\r
  //\r
  // We needed PCI IO access only transitorily, to see whether we support the\r
  // device or not.\r
  //\r
  gBS->CloseProtocol (DeviceHandle, &gEfiPciIoProtocolGuid,\r
         This->DriverBindingHandle, DeviceHandle);\r
  return Status;\r
}\r
\r
\r
/**\r
\r
  Set up all BlockIo and virtio-blk aspects of this driver for the specified\r
  device.\r
\r
  @param[in out] Dev  The driver instance to configure. The caller is\r
                      responsible for Dev->PciIo's validity (ie. working IO\r
                      access to the underlying virtio-blk PCI device).\r
\r
  @retval EFI_SUCCESS      Setup complete.\r
\r
  @retval EFI_UNSUPPORTED  The driver is unable to work with the virtio ring or\r
                           virtio-blk attributes the host provides.\r
\r
  @return                  Error codes from VirtioRingInit() or\r
                           VIRTIO_CFG_READ() / VIRTIO_CFG_WRITE().\r
\r
**/\r
\r
STATIC\r
EFI_STATUS\r
EFIAPI\r
VirtioBlkInit (\r
  IN OUT VBLK_DEV *Dev\r
  )\r
{\r
  UINT8      NextDevStat;\r
  EFI_STATUS Status;\r
\r
  UINT32     Features;\r
  UINT64     NumSectors;\r
  UINT32     BlockSize;\r
  UINT16     QueueSize;\r
\r
  //\r
  // Execute virtio-0.9.5, 2.2.1 Device Initialization Sequence.\r
  //\r
  NextDevStat = 0;             // step 1 -- reset device\r
  Status = VIRTIO_CFG_WRITE (Dev, Generic.VhdrDeviceStatus, NextDevStat);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
\r
  NextDevStat |= VSTAT_ACK;    // step 2 -- acknowledge device presence\r
  Status = VIRTIO_CFG_WRITE (Dev, Generic.VhdrDeviceStatus, NextDevStat);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
\r
  NextDevStat |= VSTAT_DRIVER; // step 3 -- we know how to drive it\r
  Status = VIRTIO_CFG_WRITE (Dev, Generic.VhdrDeviceStatus, NextDevStat);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
\r
  //\r
  // step 4a -- retrieve and validate features\r
  //\r
  Status = VIRTIO_CFG_READ (Dev, Generic.VhdrDeviceFeatureBits, &Features);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
  Status = VIRTIO_CFG_READ (Dev, VhdrCapacity, &NumSectors);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
  if (NumSectors == 0) {\r
    Status = EFI_UNSUPPORTED;\r
    goto Failed;\r
  }\r
\r
  if (Features & VIRTIO_BLK_F_BLK_SIZE) {\r
    Status = VIRTIO_CFG_READ (Dev, VhdrBlkSize, &BlockSize);\r
    if (EFI_ERROR (Status)) {\r
      goto Failed;\r
    }\r
    if (BlockSize == 0 || BlockSize % 512 != 0 ||\r
        ModU64x32 (NumSectors, BlockSize / 512) != 0) {\r
      //\r
      // We can only handle a logical block consisting of whole sectors,\r
      // and only a disk composed of whole logical blocks.\r
      //\r
      Status = EFI_UNSUPPORTED;\r
      goto Failed;\r
    }\r
  }\r
  else {\r
    BlockSize = 512;\r
  }\r
\r
  //\r
  // step 4b -- allocate virtqueue\r
  //\r
  Status = VIRTIO_CFG_WRITE (Dev, Generic.VhdrQueueSelect, 0);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
  Status = VIRTIO_CFG_READ (Dev, Generic.VhdrQueueSize, &QueueSize);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
  if (QueueSize < 3) { // SynchronousRequest() uses at most three descriptors\r
    Status = EFI_UNSUPPORTED;\r
    goto Failed;\r
  }\r
\r
  Status = VirtioRingInit (QueueSize, &Dev->Ring);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
\r
  //\r
  // step 4c -- Report GPFN (guest-physical frame number) of queue. If anything\r
  // fails from here on, we must release the ring resources.\r
  //\r
  Status = VIRTIO_CFG_WRITE (Dev, Generic.VhdrQueueAddress,\r
             (UINTN) Dev->Ring.Base >> EFI_PAGE_SHIFT);\r
  if (EFI_ERROR (Status)) {\r
    goto ReleaseQueue;\r
  }\r
\r
  //\r
  // step 5 -- Report understood features. There are no virtio-blk specific\r
  // features to negotiate in virtio-0.9.5, plus we do not want any of the\r
  // device-independent (known or unknown) VIRTIO_F_* capabilities (see\r
  // Appendix B).\r
  //\r
  Status = VIRTIO_CFG_WRITE (Dev, Generic.VhdrGuestFeatureBits, 0);\r
  if (EFI_ERROR (Status)) {\r
    goto ReleaseQueue;\r
  }\r
\r
  //\r
  // step 6 -- initialization complete\r
  //\r
  NextDevStat |= VSTAT_DRIVER_OK;\r
  Status = VIRTIO_CFG_WRITE (Dev, Generic.VhdrDeviceStatus, NextDevStat);\r
  if (EFI_ERROR (Status)) {\r
    goto ReleaseQueue;\r
  }\r
\r
  //\r
  // Populate the exported interface's attributes; see UEFI spec v2.3.1 +\r
  // Errata C, 12.8 EFI Block I/O Protocol. We stick to the lowest possible\r
  // EFI_BLOCK_IO_PROTOCOL revision for now.\r
  //\r
  Dev->BlockIo.Revision              = 0;\r
  Dev->BlockIo.Media                 = &Dev->BlockIoMedia;\r
  Dev->BlockIo.Reset                 = &VirtioBlkReset;\r
  Dev->BlockIo.ReadBlocks            = &VirtioBlkReadBlocks;\r
  Dev->BlockIo.WriteBlocks           = &VirtioBlkWriteBlocks;\r
  Dev->BlockIo.FlushBlocks           = &VirtioBlkFlushBlocks;\r
  Dev->BlockIoMedia.MediaId          = 0;\r
  Dev->BlockIoMedia.RemovableMedia   = FALSE;\r
  Dev->BlockIoMedia.MediaPresent     = TRUE;\r
  Dev->BlockIoMedia.LogicalPartition = FALSE;\r
  Dev->BlockIoMedia.ReadOnly         = !!(Features & VIRTIO_BLK_F_RO);\r
  Dev->BlockIoMedia.WriteCaching     = !!(Features & VIRTIO_BLK_F_FLUSH);\r
  Dev->BlockIoMedia.BlockSize        = BlockSize;\r
  Dev->BlockIoMedia.IoAlign          = 0;\r
  Dev->BlockIoMedia.LastBlock        = DivU64x32 (NumSectors,\r
                                         BlockSize / 512) - 1;\r
  return EFI_SUCCESS;\r
\r
ReleaseQueue:\r
  VirtioRingUninit (&Dev->Ring);\r
\r
Failed:\r
  //\r
  // Notify the host about our failure to setup: virtio-0.9.5, 2.2.2.1 Device\r
  // Status. PCI IO access failure here should not mask the original error.\r
  //\r
  NextDevStat |= VSTAT_FAILED;\r
  VIRTIO_CFG_WRITE (Dev, Generic.VhdrDeviceStatus, NextDevStat);\r
\r
  return Status; // reached only via Failed above\r
}\r
\r
\r
/**\r
\r
  Uninitialize the internals of a virtio-blk device that has been successfully\r
  set up with VirtioBlkInit().\r
\r
  @param[in out]  Dev  The device to clean up.\r
\r
**/\r
\r
STATIC\r
VOID\r
EFIAPI\r
VirtioBlkUninit (\r
  IN OUT VBLK_DEV *Dev\r
  )\r
{\r
  //\r
  // Reset the virtual device -- see virtio-0.9.5, 2.2.2.1 Device Status. When\r
  // VIRTIO_CFG_WRITE() returns, the host will have learned to stay away from\r
  // the old comms area.\r
  //\r
  VIRTIO_CFG_WRITE (Dev, Generic.VhdrDeviceStatus, 0);\r
\r
  VirtioRingUninit (&Dev->Ring);\r
\r
  SetMem (&Dev->BlockIo,      sizeof Dev->BlockIo,      0x00);\r
  SetMem (&Dev->BlockIoMedia, sizeof Dev->BlockIoMedia, 0x00);\r
}\r
\r
\r
/**\r
\r
  After we've pronounced support for a specific device in\r
  DriverBindingSupported(), we start managing said device (passed in by the\r
  Driver Exeuction Environment) with the following service.\r
\r
  See DriverBindingSupported() for specification references.\r
\r
  @param[in]  This                The EFI_DRIVER_BINDING_PROTOCOL object\r
                                  incorporating this driver (independently of\r
                                  any device).\r
\r
  @param[in] DeviceHandle         The supported device to drive.\r
\r
  @param[in] RemainingDevicePath  Relevant only for bus drivers, ignored.\r
\r
\r
  @retval EFI_SUCCESS           Driver instance has been created and\r
                                initialized  for the virtio-blk PCI device, it\r
                                is now accessibla via EFI_BLOCK_IO_PROTOCOL.\r
\r
  @retval EFI_OUT_OF_RESOURCES  Memory allocation failed.\r
\r
  @return                       Error codes from the OpenProtocol() boot\r
                                service, the PciIo protocol, VirtioBlkInit(),\r
                                or the InstallProtocolInterface() boot service.\r
\r
**/\r
\r
EFI_STATUS\r
EFIAPI\r
VirtioBlkDriverBindingStart (\r
  IN EFI_DRIVER_BINDING_PROTOCOL *This,\r
  IN EFI_HANDLE                  DeviceHandle,\r
  IN EFI_DEVICE_PATH_PROTOCOL    *RemainingDevicePath\r
  )\r
{\r
  VBLK_DEV   *Dev;\r
  EFI_STATUS Status;\r
\r
  Dev = (VBLK_DEV *) AllocateZeroPool (sizeof *Dev);\r
  if (Dev == NULL) {\r
    return EFI_OUT_OF_RESOURCES;\r
  }\r
\r
  Status = gBS->OpenProtocol (DeviceHandle, &gEfiPciIoProtocolGuid,\r
                  (VOID **)&Dev->PciIo, This->DriverBindingHandle,\r
                  DeviceHandle, EFI_OPEN_PROTOCOL_BY_DRIVER);\r
  if (EFI_ERROR (Status)) {\r
    goto FreeVirtioBlk;\r
  }\r
\r
  //\r
  // We must retain and ultimately restore the original PCI attributes of the\r
  // device. See Driver Writer's Guide for UEFI 2.3.1 v1.01, 18.3 PCI drivers /\r
  // 18.3.2 Start() and Stop().\r
  //\r
  // The third parameter ("Attributes", input) is ignored by the Get operation.\r
  // The fourth parameter ("Result", output) is ignored by the Enable and Set\r
  // operations.\r
  //\r
  // For virtio-blk we only need IO space access.\r
  //\r
  Status = Dev->PciIo->Attributes (Dev->PciIo, EfiPciIoAttributeOperationGet,\r
                         0, &Dev->OriginalPciAttributes);\r
  if (EFI_ERROR (Status)) {\r
    goto ClosePciIo;\r
  }\r
\r
  Status = Dev->PciIo->Attributes (Dev->PciIo,\r
                         EfiPciIoAttributeOperationEnable,\r
                         EFI_PCI_IO_ATTRIBUTE_IO, NULL);\r
  if (EFI_ERROR (Status)) {\r
    goto ClosePciIo;\r
  }\r
\r
  //\r
  // PCI IO access granted, configure virtio-blk device.\r
  //\r
  Status = VirtioBlkInit (Dev);\r
  if (EFI_ERROR (Status)) {\r
    goto RestorePciAttributes;\r
  }\r
\r
  //\r
  // Setup complete, attempt to export the driver instance's BlockIo interface.\r
  //\r
  Dev->Signature = VBLK_SIG;\r
  Status = gBS->InstallProtocolInterface (&DeviceHandle,\r
                  &gEfiBlockIoProtocolGuid, EFI_NATIVE_INTERFACE,\r
                  &Dev->BlockIo);\r
  if (EFI_ERROR (Status)) {\r
    goto UninitDev;\r
  }\r
\r
  return EFI_SUCCESS;\r
\r
UninitDev:\r
  VirtioBlkUninit (Dev);\r
\r
RestorePciAttributes:\r
  Dev->PciIo->Attributes (Dev->PciIo, EfiPciIoAttributeOperationSet,\r
                Dev->OriginalPciAttributes, NULL);\r
\r
ClosePciIo:\r
  gBS->CloseProtocol (DeviceHandle, &gEfiPciIoProtocolGuid,\r
         This->DriverBindingHandle, DeviceHandle);\r
\r
FreeVirtioBlk:\r
  FreePool (Dev);\r
\r
  return Status;\r
}\r
\r
\r
/**\r
\r
  Stop driving a virtio-blk device and remove its BlockIo interface.\r
\r
  This function replays the success path of DriverBindingStart() in reverse.\r
  The host side virtio-blk device is reset, so that the OS boot loader or the\r
  OS may reinitialize it.\r
\r
  @param[in] This               The EFI_DRIVER_BINDING_PROTOCOL object\r
                                incorporating this driver (independently of any\r
                                device).\r
\r
  @param[in] DeviceHandle       Stop driving this device.\r
\r
  @param[in] NumberOfChildren   Since this function belongs to a device driver\r
                                only (as opposed to a bus driver), the caller\r
                                environment sets NumberOfChildren to zero, and\r
                                we ignore it.\r
\r
  @param[in] ChildHandleBuffer  Ignored (corresponding to NumberOfChildren).\r
\r
**/\r
\r
EFI_STATUS\r
EFIAPI\r
VirtioBlkDriverBindingStop (\r
  IN EFI_DRIVER_BINDING_PROTOCOL *This,\r
  IN EFI_HANDLE                  DeviceHandle,\r
  IN UINTN                       NumberOfChildren,\r
  IN EFI_HANDLE                  *ChildHandleBuffer\r
  )\r
{\r
  EFI_STATUS            Status;\r
  EFI_BLOCK_IO_PROTOCOL *BlockIo;\r
  VBLK_DEV              *Dev;\r
\r
  Status = gBS->OpenProtocol (\r
                  DeviceHandle,                  // candidate device\r
                  &gEfiBlockIoProtocolGuid,      // retrieve the BlockIo iface\r
                  (VOID **)&BlockIo,             // target pointer\r
                  This->DriverBindingHandle,     // requestor driver identity\r
                  DeviceHandle,                  // requesting lookup for dev.\r
                  EFI_OPEN_PROTOCOL_GET_PROTOCOL // lookup only, no ref. added\r
                  );\r
  if (EFI_ERROR (Status)) {\r
    return Status;\r
  }\r
\r
  Dev = VIRTIO_BLK_FROM_BLOCK_IO (BlockIo);\r
\r
  //\r
  // Handle Stop() requests for in-use driver instances gracefully.\r
  //\r
  Status = gBS->UninstallProtocolInterface (DeviceHandle,\r
                  &gEfiBlockIoProtocolGuid, &Dev->BlockIo);\r
  if (EFI_ERROR (Status)) {\r
    return Status;\r
  }\r
\r
  VirtioBlkUninit (Dev);\r
\r
  Dev->PciIo->Attributes (Dev->PciIo, EfiPciIoAttributeOperationSet,\r
                Dev->OriginalPciAttributes, NULL);\r
\r
  gBS->CloseProtocol (DeviceHandle, &gEfiPciIoProtocolGuid,\r
         This->DriverBindingHandle, DeviceHandle);\r
\r
  FreePool (Dev);\r
\r
  return EFI_SUCCESS;\r
}\r
\r
\r
//\r
// The static object that groups the Supported() (ie. probe), Start() and\r
// Stop() functions of the driver together. Refer to UEFI Spec 2.3.1 + Errata\r
// C, 10.1 EFI Driver Binding Protocol.\r
//\r
STATIC EFI_DRIVER_BINDING_PROTOCOL gDriverBinding = {\r
  &VirtioBlkDriverBindingSupported,\r
  &VirtioBlkDriverBindingStart,\r
  &VirtioBlkDriverBindingStop,\r
  0x10, // Version, must be in [0x10 .. 0xFFFFFFEF] for IHV-developed drivers\r
  NULL, // ImageHandle, to be overwritten by\r
        // EfiLibInstallDriverBindingComponentName2() in VirtioBlkEntryPoint()\r
  NULL  // DriverBindingHandle, ditto\r
};\r
\r
\r
//\r
// The purpose of the following scaffolding (EFI_COMPONENT_NAME_PROTOCOL and\r
// EFI_COMPONENT_NAME2_PROTOCOL implementation) is to format the driver's name\r
// in English, for display on standard console devices. This is recommended for\r
// UEFI drivers that follow the UEFI Driver Model. Refer to the Driver Writer's\r
// Guide for UEFI 2.3.1 v1.01, 11 UEFI Driver and Controller Names.\r
//\r
// Device type names ("Virtio Block Device") are not formatted because the\r
// driver supports only that device type. Therefore the driver name suffices\r
// for unambiguous identification.\r
//\r
\r
STATIC\r
EFI_UNICODE_STRING_TABLE mDriverNameTable[] = {\r
  { "eng;en", L"Virtio Block Driver" },\r
  { NULL,     NULL                   }\r
};\r
\r
STATIC\r
EFI_COMPONENT_NAME_PROTOCOL gComponentName;\r
\r
EFI_STATUS\r
EFIAPI\r
VirtioBlkGetDriverName (\r
  IN  EFI_COMPONENT_NAME_PROTOCOL *This,\r
  IN  CHAR8                       *Language,\r
  OUT CHAR16                      **DriverName\r
  )\r
{\r
  return LookupUnicodeString2 (\r
           Language,\r
           This->SupportedLanguages,\r
           mDriverNameTable,\r
           DriverName,\r
           (BOOLEAN)(This == &gComponentName) // Iso639Language\r
           );\r
}\r
\r
EFI_STATUS\r
EFIAPI\r
VirtioBlkGetDeviceName (\r
  IN  EFI_COMPONENT_NAME_PROTOCOL *This,\r
  IN  EFI_HANDLE                  DeviceHandle,\r
  IN  EFI_HANDLE                  ChildHandle,\r
  IN  CHAR8                       *Language,\r
  OUT CHAR16                      **ControllerName\r
  )\r
{\r
  return EFI_UNSUPPORTED;\r
}\r
\r
STATIC\r
EFI_COMPONENT_NAME_PROTOCOL gComponentName = {\r
  &VirtioBlkGetDriverName,\r
  &VirtioBlkGetDeviceName,\r
  "eng" // SupportedLanguages, ISO 639-2 language codes\r
};\r
\r
STATIC\r
EFI_COMPONENT_NAME2_PROTOCOL gComponentName2 = {\r
  (EFI_COMPONENT_NAME2_GET_DRIVER_NAME)     &VirtioBlkGetDriverName,\r
  (EFI_COMPONENT_NAME2_GET_CONTROLLER_NAME) &VirtioBlkGetDeviceName,\r
  "en" // SupportedLanguages, RFC 4646 language codes\r
};\r
\r
\r
//\r
// Entry point of this driver.\r
//\r
EFI_STATUS\r
EFIAPI\r
VirtioBlkEntryPoint (\r
  IN EFI_HANDLE       ImageHandle,\r
  IN EFI_SYSTEM_TABLE *SystemTable\r
  )\r
{\r
  return EfiLibInstallDriverBindingComponentName2 (\r
           ImageHandle,\r
           SystemTable,\r
           &gDriverBinding,\r
           ImageHandle,\r
           &gComponentName,\r
           &gComponentName2\r
           );\r
}\r
\r