OvmfPkg/XenPvBlkDxe: Xen PV Block device, initial skeleton

A ParaVirtualize block driver.

Change in V4:
- Replace the license by the commonly used file header text.
- Add brief description for the driver.

Change in V3:
- enable compilation for Ia32 and Ia32X64
- fix version (driver binding)

Change in V2:
- Add minimal support for controller name
- Remove stuff about BlockIo2
- Little cleanup
- Licenses and file headers
- Rename XenbusIo into XenBusIo

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16272 6f19259b-4bc3-4df7-8a09-765794883524

OvmfPkg/OvmfPkgIa32.dsc

@@ -429,6 +429,7 @@
   OvmfPkg/VirtioScsiDxe/VirtioScsi.inf
   OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf
   OvmfPkg/XenBusDxe/XenBusDxe.inf
+  OvmfPkg/XenPvBlkDxe/XenPvBlkDxe.inf
   OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.inf {
     <LibraryClasses>
       PlatformFvbLib|OvmfPkg/Library/EmuVariableFvbLib/EmuVariableFvbLib.inf

OvmfPkg/OvmfPkgIa32.fdf

@@ -228,6 +228,7 @@ INF  OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf
 INF  OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.inf
 INF  MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteDxe.inf
 INF  OvmfPkg/XenBusDxe/XenBusDxe.inf
+INF  OvmfPkg/XenPvBlkDxe/XenPvBlkDxe.inf
 
 !if $(SECURE_BOOT_ENABLE) == TRUE
   INF  SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableRuntimeDxe.inf

OvmfPkg/OvmfPkgIa32X64.dsc

@@ -436,6 +436,7 @@
   OvmfPkg/VirtioScsiDxe/VirtioScsi.inf
   OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf
   OvmfPkg/XenBusDxe/XenBusDxe.inf
+  OvmfPkg/XenPvBlkDxe/XenPvBlkDxe.inf
   OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.inf {
     <LibraryClasses>
       PlatformFvbLib|OvmfPkg/Library/EmuVariableFvbLib/EmuVariableFvbLib.inf

OvmfPkg/OvmfPkgIa32X64.fdf

@@ -228,6 +228,7 @@ INF  OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf
 INF  OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.inf
 INF  MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteDxe.inf
 INF  OvmfPkg/XenBusDxe/XenBusDxe.inf
+INF  OvmfPkg/XenPvBlkDxe/XenPvBlkDxe.inf
 
 !if $(SECURE_BOOT_ENABLE) == TRUE
   INF  SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableRuntimeDxe.inf

OvmfPkg/OvmfPkgX64.dsc

@@ -434,6 +434,7 @@
   OvmfPkg/VirtioScsiDxe/VirtioScsi.inf
   OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf
   OvmfPkg/XenBusDxe/XenBusDxe.inf
+  OvmfPkg/XenPvBlkDxe/XenPvBlkDxe.inf
   OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.inf {
     <LibraryClasses>
       PlatformFvbLib|OvmfPkg/Library/EmuVariableFvbLib/EmuVariableFvbLib.inf

OvmfPkg/OvmfPkgX64.fdf

@@ -228,6 +228,7 @@ INF  OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf
 INF  OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.inf
 INF  MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteDxe.inf
 INF  OvmfPkg/XenBusDxe/XenBusDxe.inf
+INF  OvmfPkg/XenPvBlkDxe/XenPvBlkDxe.inf
 
 !if $(SECURE_BOOT_ENABLE) == TRUE
   INF  SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableRuntimeDxe.inf

OvmfPkg/XenPvBlkDxe/ComponentName.c

@@ -0,0 +1,176 @@
+/** @file
+  Component Name functions implementation for XenPvBlk driver.
+
+  Copyright (C) 2014, Citrix Ltd.
+
+  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 "XenPvBlkDxe.h"
+
+///
+/// Component Name Protocol instance
+///
+GLOBAL_REMOVE_IF_UNREFERENCED
+EFI_COMPONENT_NAME_PROTOCOL  gXenPvBlkDxeComponentName = {
+  (EFI_COMPONENT_NAME_GET_DRIVER_NAME)    XenPvBlkDxeComponentNameGetDriverName,
+  (EFI_COMPONENT_NAME_GET_CONTROLLER_NAME)XenPvBlkDxeComponentNameGetControllerName,
+  "eng"
+};
+
+///
+/// Component Name 2 Protocol instance
+///
+GLOBAL_REMOVE_IF_UNREFERENCED
+EFI_COMPONENT_NAME2_PROTOCOL  gXenPvBlkDxeComponentName2 = {
+  XenPvBlkDxeComponentNameGetDriverName,
+  XenPvBlkDxeComponentNameGetControllerName,
+  "en"
+};
+
+///
+/// Table of driver names
+///
+GLOBAL_REMOVE_IF_UNREFERENCED
+EFI_UNICODE_STRING_TABLE mXenPvBlkDxeDriverNameTable[] = {
+  { "eng;en", (CHAR16 *)L"Xen PV Block Driver" },
+  { NULL, NULL }
+};
+
+///
+/// Table of controller names
+///
+GLOBAL_REMOVE_IF_UNREFERENCED
+EFI_UNICODE_STRING_TABLE mXenPvBlkDxeControllerNameTable[] = {
+  { "eng;en", (CHAR16 *)L"Xen PV Block Device" },
+  { NULL, NULL }
+};
+
+/**
+  Retrieves a Unicode string that is the user-readable name of the EFI Driver.
+
+  @param  This       A pointer to the EFI_COMPONENT_NAME_PROTOCOL instance.
+  @param  Language   A pointer to a three-character ISO 639-2 language identifier.
+                     This is the language of the driver name that that the caller
+                     is requesting, and it must match one of the languages specified
+                     in SupportedLanguages.  The number of languages supported by a
+                     driver is up to the driver writer.
+  @param  DriverName A pointer to the Unicode string to return.  This Unicode string
+                     is the name of the driver specified by This in the language
+                     specified by Language.
+
+  @retval EFI_SUCCESS           The Unicode string for the Driver specified by This
+                                and the language specified by Language was returned
+                                in DriverName.
+  @retval EFI_INVALID_PARAMETER Language is NULL.
+  @retval EFI_INVALID_PARAMETER DriverName is NULL.
+  @retval EFI_UNSUPPORTED       The driver specified by This does not support the
+                                language specified by Language.
+
+**/
+EFI_STATUS
+EFIAPI
+XenPvBlkDxeComponentNameGetDriverName (
+  IN EFI_COMPONENT_NAME2_PROTOCOL  *This,
+  IN  CHAR8                        *Language,
+  OUT CHAR16                       **DriverName
+  )
+{
+  return LookupUnicodeString2 (
+           Language,
+           This->SupportedLanguages,
+           mXenPvBlkDxeDriverNameTable,
+           DriverName,
+           (BOOLEAN)(This != &gXenPvBlkDxeComponentName2)
+           );
+}
+
+/**
+  Retrieves a Unicode string that is the user readable name of the controller
+  that is being managed by an EFI Driver.
+
+  @param  This             A pointer to the EFI_COMPONENT_NAME_PROTOCOL instance.
+  @param  ControllerHandle The handle of a controller that the driver specified by
+                           This is managing.  This handle specifies the controller
+                           whose name is to be returned.
+  @param  ChildHandle      The handle of the child controller to retrieve the name
+                           of.  This is an optional parameter that may be NULL.  It
+                           will be NULL for device drivers.  It will also be NULL
+                           for a bus drivers that wish to retrieve the name of the
+                           bus controller.  It will not be NULL for a bus driver
+                           that wishes to retrieve the name of a child controller.
+  @param  Language         A pointer to a three character ISO 639-2 language
+                           identifier.  This is the language of the controller name
+                           that the caller is requesting, and it must match one
+                           of the languages specified in SupportedLanguages.  The
+                           number of languages supported by a driver is up to the
+                           driver writer.
+  @param  ControllerName   A pointer to the Unicode string to return.  This Unicode
+                           string is the name of the controller specified by
+                           ControllerHandle and ChildHandle in the language specified
+                           by Language, from the point of view of the driver specified
+                           by This.
+
+  @retval EFI_SUCCESS           The Unicode string for the user-readable name in the
+                                language specified by Language for the driver
+                                specified by This was returned in DriverName.
+  @retval EFI_INVALID_PARAMETER ControllerHandle is NULL.
+  @retval EFI_INVALID_PARAMETER ChildHandle is not NULL and it is not a valid EFI_HANDLE.
+  @retval EFI_INVALID_PARAMETER Language is NULL.
+  @retval EFI_INVALID_PARAMETER ControllerName is NULL.
+  @retval EFI_UNSUPPORTED       The driver specified by This is not currently managing
+                                the controller specified by ControllerHandle and
+                                ChildHandle.
+  @retval EFI_UNSUPPORTED       The driver specified by This does not support the
+                                language specified by Language.
+
+**/
+EFI_STATUS
+EFIAPI
+XenPvBlkDxeComponentNameGetControllerName (
+  IN  EFI_COMPONENT_NAME2_PROTOCOL  *This,
+  IN  EFI_HANDLE                    ControllerHandle,
+  IN  EFI_HANDLE                    ChildHandle        OPTIONAL,
+  IN  CHAR8                         *Language,
+  OUT CHAR16                        **ControllerName
+  )
+{
+  EFI_STATUS  Status;
+
+  //
+  // ChildHandle must be NULL for a Device Driver
+  //
+  if (ChildHandle != NULL) {
+    return EFI_UNSUPPORTED;
+  }
+
+  //
+  // Make sure this driver is currently managing ControllerHandle
+  //
+  Status = EfiTestManagedDevice (
+             ControllerHandle,
+             gXenPvBlkDxeDriverBinding.DriverBindingHandle,
+             &gXenBusProtocolGuid
+             );
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  //
+  // Lookup name of controller specified by ControllerHandle
+  //
+  return LookupUnicodeString2 (
+           Language,
+           This->SupportedLanguages,
+           mXenPvBlkDxeControllerNameTable,
+           ControllerName,
+           (BOOLEAN)(This != &gXenPvBlkDxeComponentName2)
+           );
+}

OvmfPkg/XenPvBlkDxe/ComponentName.h

@@ -0,0 +1,94 @@
+/** @file
+  Component Name functions declaration for XenPvBlk driver.
+
+  Copyright (C) 2014, Citrix Ltd.
+
+  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.
+
+**/
+
+/**
+  Retrieves a Unicode string that is the user-readable name of the EFI Driver.
+
+  @param  This       A pointer to the EFI_COMPONENT_NAME_PROTOCOL instance.
+  @param  Language   A pointer to a three-character ISO 639-2 language identifier.
+                     This is the language of the driver name that that the caller
+                     is requesting, and it must match one of the languages specified
+                     in SupportedLanguages.  The number of languages supported by a
+                     driver is up to the driver writer.
+  @param  DriverName A pointer to the Unicode string to return.  This Unicode string
+                     is the name of the driver specified by This in the language
+                     specified by Language.
+
+  @retval EFI_SUCCESS           The Unicode string for the Driver specified by This
+                                and the language specified by Language was returned
+                                in DriverName.
+  @retval EFI_INVALID_PARAMETER Language is NULL.
+  @retval EFI_INVALID_PARAMETER DriverName is NULL.
+  @retval EFI_UNSUPPORTED       The driver specified by This does not support the
+                                language specified by Language.
+
+**/
+EFI_STATUS
+EFIAPI
+XenPvBlkDxeComponentNameGetDriverName (
+  IN EFI_COMPONENT_NAME2_PROTOCOL  *This,
+  IN  CHAR8                        *Language,
+  OUT CHAR16                       **DriverName
+  );
+
+/**
+  Retrieves a Unicode string that is the user readable name of the controller
+  that is being managed by an EFI Driver.
+
+  @param  This             A pointer to the EFI_COMPONENT_NAME_PROTOCOL instance.
+  @param  ControllerHandle The handle of a controller that the driver specified by
+                           This is managing.  This handle specifies the controller
+                           whose name is to be returned.
+  @param  ChildHandle      The handle of the child controller to retrieve the name
+                           of.  This is an optional parameter that may be NULL.  It
+                           will be NULL for device drivers.  It will also be NULL
+                           for a bus drivers that wish to retrieve the name of the
+                           bus controller.  It will not be NULL for a bus driver
+                           that wishes to retrieve the name of a child controller.
+  @param  Language         A pointer to a three character ISO 639-2 language
+                           identifier.  This is the language of the controller name
+                           that the caller is requesting, and it must match one
+                           of the languages specified in SupportedLanguages.  The
+                           number of languages supported by a driver is up to the
+                           driver writer.
+  @param  ControllerName   A pointer to the Unicode string to return.  This Unicode
+                           string is the name of the controller specified by
+                           ControllerHandle and ChildHandle in the language specified
+                           by Language, from the point of view of the driver specified
+                           by This.
+
+  @retval EFI_SUCCESS           The Unicode string for the user-readable name in the
+                                language specified by Language for the driver
+                                specified by This was returned in DriverName.
+  @retval EFI_INVALID_PARAMETER ControllerHandle is NULL.
+  @retval EFI_INVALID_PARAMETER ChildHandle is not NULL and it is not a valid EFI_HANDLE.
+  @retval EFI_INVALID_PARAMETER Language is NULL.
+  @retval EFI_INVALID_PARAMETER ControllerName is NULL.
+  @retval EFI_UNSUPPORTED       The driver specified by This is not currently managing
+                                the controller specified by ControllerHandle and
+                                ChildHandle.
+  @retval EFI_UNSUPPORTED       The driver specified by This does not support the
+                                language specified by Language.
+
+**/
+EFI_STATUS
+EFIAPI
+XenPvBlkDxeComponentNameGetControllerName (
+  IN  EFI_COMPONENT_NAME2_PROTOCOL  *This,
+  IN  EFI_HANDLE                    ControllerHandle,
+  IN  EFI_HANDLE                    ChildHandle        OPTIONAL,
+  IN  CHAR8                         *Language,
+  OUT CHAR16                        **ControllerName
+  );

OvmfPkg/XenPvBlkDxe/DriverBinding.h

@@ -0,0 +1,143 @@
+
+/** @file
+  Driver Binding functions declaration for XenPvBlk driver.
+
+  Copyright (C) 2014, Citrix Ltd.
+
+  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.
+
+**/
+
+/**
+  Tests to see if this driver supports a given controller. If a child device is provided,
+  it further tests to see if this driver supports creating a handle for the specified child device.
+
+  This function checks to see if the driver specified by This supports the device specified by
+  ControllerHandle. Drivers will typically use the device path attached to
+  ControllerHandle and/or the services from the bus I/O abstraction attached to
+  ControllerHandle to determine if the driver supports ControllerHandle. This function
+  may be called many times during platform initialization. In order to reduce boot times, the tests
+  performed by this function must be very small, and take as little time as possible to execute. This
+  function must not change the state of any hardware devices, and this function must be aware that the
+  device specified by ControllerHandle may already be managed by the same driver or a
+  different driver. This function must match its calls to AllocatePages() with FreePages(),
+  AllocatePool() with FreePool(), and OpenProtocol() with CloseProtocol().
+  Because ControllerHandle may have been previously started by the same driver, if a protocol is
+  already in the opened state, then it must not be closed with CloseProtocol(). This is required
+  to guarantee the state of ControllerHandle is not modified by this function.
+
+  @param[in]  This                 A pointer to the EFI_DRIVER_BINDING_PROTOCOL instance.
+  @param[in]  ControllerHandle     The handle of the controller to test. This handle
+                                   must support a protocol interface that supplies
+                                   an I/O abstraction to the driver.
+  @param[in]  RemainingDevicePath  A pointer to the remaining portion of a device path.  This
+                                   parameter is ignored by device drivers, and is optional for bus
+                                   drivers. For bus drivers, if this parameter is not NULL, then
+                                   the bus driver must determine if the bus controller specified
+                                   by ControllerHandle and the child controller specified
+                                   by RemainingDevicePath are both supported by this
+                                   bus driver.
+
+  @retval EFI_SUCCESS              The device specified by ControllerHandle and
+                                   RemainingDevicePath is supported by the driver specified by This.
+  @retval EFI_ALREADY_STARTED      The device specified by ControllerHandle and
+                                   RemainingDevicePath is already being managed by the driver
+                                   specified by This.
+  @retval EFI_ACCESS_DENIED        The device specified by ControllerHandle and
+                                   RemainingDevicePath is already being managed by a different
+                                   driver or an application that requires exclusive access.
+                                   Currently not implemented.
+  @retval EFI_UNSUPPORTED          The device specified by ControllerHandle and
+                                   RemainingDevicePath is not supported by the driver specified by This.
+**/
+EFI_STATUS
+EFIAPI
+XenPvBlkDxeDriverBindingSupported (
+  IN EFI_DRIVER_BINDING_PROTOCOL  *This,
+  IN EFI_HANDLE                   ControllerHandle,
+  IN EFI_DEVICE_PATH_PROTOCOL     *RemainingDevicePath OPTIONAL
+  );
+
+/**
+  Starts a device controller or a bus controller.
+
+  The Start() function is designed to be invoked from the EFI boot service ConnectController().
+  As a result, much of the error checking on the parameters to Start() has been moved into this
+  common boot service. It is legal to call Start() from other locations,
+  but the following calling restrictions must be followed, or the system behavior will not be deterministic.
+  1. ControllerHandle must be a valid EFI_HANDLE.
+  2. If RemainingDevicePath is not NULL, then it must be a pointer to a naturally aligned
+     EFI_DEVICE_PATH_PROTOCOL.
+  3. Prior to calling Start(), the Supported() function for the driver specified by This must
+     have been called with the same calling parameters, and Supported() must have returned EFI_SUCCESS.
+
+  @param[in]  This                 A pointer to the EFI_DRIVER_BINDING_PROTOCOL instance.
+  @param[in]  ControllerHandle     The handle of the controller to start. This handle
+                                   must support a protocol interface that supplies
+                                   an I/O abstraction to the driver.
+  @param[in]  RemainingDevicePath  A pointer to the remaining portion of a device path.  This
+                                   parameter is ignored by device drivers, and is optional for bus
+                                   drivers. For a bus driver, if this parameter is NULL, then handles
+                                   for all the children of Controller are created by this driver.
+                                   If this parameter is not NULL and the first Device Path Node is
+                                   not the End of Device Path Node, then only the handle for the
+                                   child device specified by the first Device Path Node of
+                                   RemainingDevicePath is created by this driver.
+                                   If the first Device Path Node of RemainingDevicePath is
+                                   the End of Device Path Node, no child handle is created by this
+                                   driver.
+
+  @retval EFI_SUCCESS              The device was started.
+  @retval EFI_DEVICE_ERROR         The device could not be started due to a device error.Currently not implemented.
+  @retval EFI_OUT_OF_RESOURCES     The request could not be completed due to a lack of resources.
+  @retval Others                   The driver failded to start the device.
+
+**/
+EFI_STATUS
+EFIAPI
+XenPvBlkDxeDriverBindingStart (
+  IN EFI_DRIVER_BINDING_PROTOCOL  *This,
+  IN EFI_HANDLE                   ControllerHandle,
+  IN EFI_DEVICE_PATH_PROTOCOL     *RemainingDevicePath OPTIONAL
+  );
+
+/**
+  Stops a device controller or a bus controller.
+
+  The Stop() function is designed to be invoked from the EFI boot service DisconnectController().
+  As a result, much of the error checking on the parameters to Stop() has been moved
+  into this common boot service. It is legal to call Stop() from other locations,
+  but the following calling restrictions must be followed, or the system behavior will not be deterministic.
+  1. ControllerHandle must be a valid EFI_HANDLE that was used on a previous call to this
+     same driver's Start() function.
+  2. The first NumberOfChildren handles of ChildHandleBuffer must all be a valid
+     EFI_HANDLE. In addition, all of these handles must have been created in this driver's
+     Start() function, and the Start() function must have called OpenProtocol() on
+     ControllerHandle with an Attribute of EFI_OPEN_PROTOCOL_BY_CHILD_CONTROLLER.
+
+  @param[in]  This              A pointer to the EFI_DRIVER_BINDING_PROTOCOL instance.
+  @param[in]  ControllerHandle  A handle to the device being stopped. The handle must
+                                support a bus specific I/O protocol for the driver
+                                to use to stop the device.
+  @param[in]  NumberOfChildren  The number of child device handles in ChildHandleBuffer.
+  @param[in]  ChildHandleBuffer An array of child handles to be freed. May be NULL
+                                if NumberOfChildren is 0.
+
+  @retval EFI_SUCCESS           The device was stopped.
+  @retval EFI_DEVICE_ERROR      The device could not be stopped due to a device error.
+
+**/
+EFI_STATUS
+EFIAPI
+XenPvBlkDxeDriverBindingStop (
+  IN EFI_DRIVER_BINDING_PROTOCOL  *This,
+  IN  EFI_HANDLE                  ControllerHandle,
+  IN  UINTN                       NumberOfChildren,
+  IN  EFI_HANDLE                  *ChildHandleBuffer OPTIONAL
+  );

OvmfPkg/XenPvBlkDxe/XenPvBlkDxe.c

@@ -0,0 +1,316 @@
+/** @file
+  This driver produce a BlockIo protocol instance for a Xen PV block device.
+
+  This driver support XenBus protocol of type 'vbd'. Every function that
+  comsume XenBus protocol are in BlockFront, which the implementation to access
+  a Xen PV device. The BlockIo implementation is in it's one file and will call
+  BlockFront functions.
+
+  Copyright (C) 2014, Citrix Ltd.
+
+  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 "XenPvBlkDxe.h"
+
+
+///
+/// Driver Binding Protocol instance
+///
+EFI_DRIVER_BINDING_PROTOCOL gXenPvBlkDxeDriverBinding = {
+  XenPvBlkDxeDriverBindingSupported,
+  XenPvBlkDxeDriverBindingStart,
+  XenPvBlkDxeDriverBindingStop,
+  XEN_PV_BLK_DXE_VERSION,
+  NULL,
+  NULL
+};
+
+
+/**
+  Unloads an image.
+
+  @param  ImageHandle           Handle that identifies the image to be unloaded.
+
+  @retval EFI_SUCCESS           The image has been unloaded.
+  @retval EFI_INVALID_PARAMETER ImageHandle is not a valid image handle.
+
+**/
+EFI_STATUS
+EFIAPI
+XenPvBlkDxeUnload (
+  IN EFI_HANDLE  ImageHandle
+  )
+{
+  EFI_STATUS  Status;
+
+  EFI_HANDLE  *HandleBuffer;
+  UINTN       HandleCount;
+  UINTN       Index;
+
+
+  //
+  // Retrieve array of all handles in the handle database
+  //
+  Status = gBS->LocateHandleBuffer (
+                  AllHandles,
+                  NULL,
+                  NULL,
+                  &HandleCount,
+                  &HandleBuffer
+                  );
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  //
+  // Disconnect the current driver from handles in the handle database
+  //
+  for (Index = 0; Index < HandleCount; Index++) {
+    gBS->DisconnectController (HandleBuffer[Index], gImageHandle, NULL);
+  }
+
+  //
+  // Free the array of handles
+  //
+  FreePool (HandleBuffer);
+
+
+  //
+  // Uninstall protocols installed in the driver entry point
+  //
+  Status = gBS->UninstallMultipleProtocolInterfaces (
+                  ImageHandle,
+                  &gEfiDriverBindingProtocolGuid, &gXenPvBlkDxeDriverBinding,
+                  &gEfiComponentNameProtocolGuid,  &gXenPvBlkDxeComponentName,
+                  &gEfiComponentName2ProtocolGuid, &gXenPvBlkDxeComponentName2,
+                  NULL
+                  );
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  return EFI_SUCCESS;
+}
+
+/**
+  This is the declaration of an EFI image entry point. This entry point is
+  the same for UEFI Applications, UEFI OS Loaders, and UEFI Drivers including
+  both device drivers and bus drivers.
+
+  @param  ImageHandle           The firmware allocated handle for the UEFI image.
+  @param  SystemTable           A pointer to the EFI System Table.
+
+  @retval EFI_SUCCESS           The operation completed successfully.
+  @retval Others                An unexpected error occurred.
+**/
+EFI_STATUS
+EFIAPI
+XenPvBlkDxeDriverEntryPoint (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  EFI_STATUS  Status;
+
+  //
+  // Install UEFI Driver Model protocol(s).
+  //
+  Status = EfiLibInstallDriverBindingComponentName2 (
+             ImageHandle,
+             SystemTable,
+             &gXenPvBlkDxeDriverBinding,
+             ImageHandle,
+             &gXenPvBlkDxeComponentName,
+             &gXenPvBlkDxeComponentName2
+             );
+  ASSERT_EFI_ERROR (Status);
+
+  return Status;
+}
+
+
+/**
+  Tests to see if this driver supports a given controller. If a child device is provided,
+  it further tests to see if this driver supports creating a handle for the specified child device.
+
+  This function checks to see if the driver specified by This supports the device specified by
+  ControllerHandle. Drivers will typically use the device path attached to
+  ControllerHandle and/or the services from the bus I/O abstraction attached to
+  ControllerHandle to determine if the driver supports ControllerHandle. This function
+  may be called many times during platform initialization. In order to reduce boot times, the tests
+  performed by this function must be very small, and take as little time as possible to execute. This
+  function must not change the state of any hardware devices, and this function must be aware that the
+  device specified by ControllerHandle may already be managed by the same driver or a
+  different driver. This function must match its calls to AllocatePages() with FreePages(),
+  AllocatePool() with FreePool(), and OpenProtocol() with CloseProtocol().
+  Because ControllerHandle may have been previously started by the same driver, if a protocol is
+  already in the opened state, then it must not be closed with CloseProtocol(). This is required
+  to guarantee the state of ControllerHandle is not modified by this function.
+
+  @param[in]  This                 A pointer to the EFI_DRIVER_BINDING_PROTOCOL instance.
+  @param[in]  ControllerHandle     The handle of the controller to test. This handle
+                                   must support a protocol interface that supplies
+                                   an I/O abstraction to the driver.
+  @param[in]  RemainingDevicePath  A pointer to the remaining portion of a device path.  This
+                                   parameter is ignored by device drivers, and is optional for bus
+                                   drivers. For bus drivers, if this parameter is not NULL, then
+                                   the bus driver must determine if the bus controller specified
+                                   by ControllerHandle and the child controller specified
+                                   by RemainingDevicePath are both supported by this
+                                   bus driver.
+
+  @retval EFI_SUCCESS              The device specified by ControllerHandle and
+                                   RemainingDevicePath is supported by the driver specified by This.
+  @retval EFI_ALREADY_STARTED      The device specified by ControllerHandle and
+                                   RemainingDevicePath is already being managed by the driver
+                                   specified by This.
+  @retval EFI_ACCESS_DENIED        The device specified by ControllerHandle and
+                                   RemainingDevicePath is already being managed by a different
+                                   driver or an application that requires exclusive access.
+                                   Currently not implemented.
+  @retval EFI_UNSUPPORTED          The device specified by ControllerHandle and
+                                   RemainingDevicePath is not supported by the driver specified by This.
+**/
+EFI_STATUS
+EFIAPI
+XenPvBlkDxeDriverBindingSupported (
+  IN EFI_DRIVER_BINDING_PROTOCOL  *This,
+  IN EFI_HANDLE                   ControllerHandle,
+  IN EFI_DEVICE_PATH_PROTOCOL     *RemainingDevicePath OPTIONAL
+  )
+{
+  EFI_STATUS Status;
+  XENBUS_PROTOCOL *XenBusIo;
+
+  Status = gBS->OpenProtocol (
+                ControllerHandle,
+                &gXenBusProtocolGuid,
+                (VOID **)&XenBusIo,
+                This->DriverBindingHandle,
+                ControllerHandle,
+                EFI_OPEN_PROTOCOL_BY_DRIVER
+                );
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+  if (AsciiStrCmp (XenBusIo->Type, "vbd") == 0) {
+    Status = EFI_SUCCESS;
+  } else {
+    Status = EFI_UNSUPPORTED;
+  }
+
+  gBS->CloseProtocol (ControllerHandle, &gXenBusProtocolGuid,
+                      This->DriverBindingHandle, ControllerHandle);
+
+  return Status;
+}
+
+/**
+  Starts a device controller.
+
+  The Start() function is designed to be invoked from the EFI boot service ConnectController().
+  As a result, much of the error checking on the parameters to Start() has been moved into this
+  common boot service. It is legal to call Start() from other locations,
+  but the following calling restrictions must be followed, or the system behavior will not be deterministic.
+  1. ControllerHandle must be a valid EFI_HANDLE.
+  2. If RemainingDevicePath is not NULL, then it must be a pointer to a naturally aligned
+     EFI_DEVICE_PATH_PROTOCOL.
+  3. Prior to calling Start(), the Supported() function for the driver specified by This must
+     have been called with the same calling parameters, and Supported() must have returned EFI_SUCCESS.
+
+  @param[in]  This                 A pointer to the EFI_DRIVER_BINDING_PROTOCOL instance.
+  @param[in]  ControllerHandle     The handle of the controller to start. This handle
+                                   must support a protocol interface that supplies
+                                   an I/O abstraction to the driver.
+  @param[in]  RemainingDevicePath  A pointer to the remaining portion of a device path.  This
+                                   parameter is ignored by device drivers, and is optional for bus
+                                   drivers. For a bus driver, if this parameter is NULL, then handles
+                                   for all the children of Controller are created by this driver.
+                                   If this parameter is not NULL and the first Device Path Node is
+                                   not the End of Device Path Node, then only the handle for the
+                                   child device specified by the first Device Path Node of
+                                   RemainingDevicePath is created by this driver.
+                                   If the first Device Path Node of RemainingDevicePath is
+                                   the End of Device Path Node, no child handle is created by this
+                                   driver.
+
+  @retval EFI_SUCCESS              The device was started.
+  @retval EFI_DEVICE_ERROR         The device could not be started due to a device error.Currently not implemented.
+  @retval EFI_OUT_OF_RESOURCES     The request could not be completed due to a lack of resources.
+  @retval Others                   The driver failded to start the device.
+
+**/
+EFI_STATUS
+EFIAPI
+XenPvBlkDxeDriverBindingStart (
+  IN EFI_DRIVER_BINDING_PROTOCOL  *This,
+  IN EFI_HANDLE                   ControllerHandle,
+  IN EFI_DEVICE_PATH_PROTOCOL     *RemainingDevicePath OPTIONAL
+  )
+{
+  EFI_STATUS Status;
+  XENBUS_PROTOCOL *XenBusIo;
+
+  Status = gBS->OpenProtocol (
+                ControllerHandle,
+                &gXenBusProtocolGuid,
+                (VOID **)&XenBusIo,
+                This->DriverBindingHandle,
+                ControllerHandle,
+                EFI_OPEN_PROTOCOL_BY_DRIVER
+                );
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Stops a device controller.
+
+  The Stop() function is designed to be invoked from the EFI boot service DisconnectController().
+  As a result, much of the error checking on the parameters to Stop() has been moved
+  into this common boot service. It is legal to call Stop() from other locations,
+  but the following calling restrictions must be followed, or the system behavior will not be deterministic.
+  1. ControllerHandle must be a valid EFI_HANDLE that was used on a previous call to this
+     same driver's Start() function.
+  2. The first NumberOfChildren handles of ChildHandleBuffer must all be a valid
+     EFI_HANDLE. In addition, all of these handles must have been created in this driver's
+     Start() function, and the Start() function must have called OpenProtocol() on
+     ControllerHandle with an Attribute of EFI_OPEN_PROTOCOL_BY_CHILD_CONTROLLER.
+
+  @param[in]  This              A pointer to the EFI_DRIVER_BINDING_PROTOCOL instance.
+  @param[in]  ControllerHandle  A handle to the device being stopped. The handle must
+                                support a bus specific I/O protocol for the driver
+                                to use to stop the device.
+  @param[in]  NumberOfChildren  The number of child device handles in ChildHandleBuffer.
+  @param[in]  ChildHandleBuffer An array of child handles to be freed. May be NULL
+                                if NumberOfChildren is 0.
+
+  @retval EFI_SUCCESS           The device was stopped.
+  @retval EFI_DEVICE_ERROR      The device could not be stopped due to a device error.
+
+**/
+EFI_STATUS
+EFIAPI
+XenPvBlkDxeDriverBindingStop (
+  IN EFI_DRIVER_BINDING_PROTOCOL  *This,
+  IN EFI_HANDLE                   ControllerHandle,
+  IN UINTN                        NumberOfChildren,
+  IN EFI_HANDLE                   *ChildHandleBuffer OPTIONAL
+  )
+{
+  gBS->CloseProtocol (ControllerHandle, &gXenBusProtocolGuid,
+         This->DriverBindingHandle, ControllerHandle);
+
+  return EFI_SUCCESS;
+}

OvmfPkg/XenPvBlkDxe/XenPvBlkDxe.h

@@ -0,0 +1,82 @@
+/** @file
+  Main header for XenPvBlkDxe
+
+  Copyright (C) 2014, Citrix Ltd.
+
+  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.
+
+**/
+
+#ifndef __EFI_XEN_PV_BLK_DXE_H__
+#define __EFI_XEN_PV_BLK_DXE_H__
+
+#include <Uefi.h>
+
+//
+// Xen interface version used
+//
+#define __XEN_INTERFACE_VERSION__ 0x00040400
+#define xen_mb() MemoryFence()
+#define xen_rmb() MemoryFence()
+#define xen_wmb() MemoryFence()
+
+//
+// Libraries
+//
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/MemoryAllocationLib.h>
+#include <Library/BaseMemoryLib.h>
+#include <Library/BaseLib.h>
+#include <Library/UefiLib.h>
+#include <Library/DevicePathLib.h>
+#include <Library/DebugLib.h>
+
+
+//
+// UEFI Driver Model Protocols
+//
+#include <Protocol/DriverBinding.h>
+#include <Protocol/ComponentName2.h>
+#include <Protocol/ComponentName.h>
+
+
+//
+// Consumed Protocols
+//
+#include <Protocol/XenBus.h>
+
+
+//
+// Produced Protocols
+//
+#include <Protocol/BlockIo.h>
+
+
+//
+// Driver Version
+//
+#define XEN_PV_BLK_DXE_VERSION  0x00000010
+
+
+//
+// Protocol instances
+//
+extern EFI_DRIVER_BINDING_PROTOCOL  gXenPvBlkDxeDriverBinding;
+extern EFI_COMPONENT_NAME2_PROTOCOL  gXenPvBlkDxeComponentName2;
+extern EFI_COMPONENT_NAME_PROTOCOL  gXenPvBlkDxeComponentName;
+
+
+//
+// Include files with function prototypes
+//
+#include "DriverBinding.h"
+#include "ComponentName.h"
+
+
+#endif

OvmfPkg/XenPvBlkDxe/XenPvBlkDxe.inf

@@ -0,0 +1,59 @@
+## @file
+#  This driver produces a Block I/O protocol for a Xen PV block device.
+#
+#  Copyright (C) 2014, Citrix Ltd.
+#
+#  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.
+#
+##
+
+[Defines]
+  INF_VERSION               = 0x00010005
+  BASE_NAME                 = XenPvBlkDxe
+  FILE_GUID                 = 8c2487ea-9af3-11e3-b966-b8ac6f7d65e6
+  MODULE_TYPE               = UEFI_DRIVER
+
+  VERSION_STRING            = 1.0
+  ENTRY_POINT               = XenPvBlkDxeDriverEntryPoint
+  UNLOAD_IMAGE              = XenPvBlkDxeUnload
+
+
+[Packages]
+  MdePkg/MdePkg.dec
+  OvmfPkg/OvmfPkg.dec
+
+[Sources]
+  XenPvBlkDxe.h
+  XenPvBlkDxe.c
+  ComponentName.c
+  ComponentName.h
+
+
+[LibraryClasses]
+  UefiDriverEntryPoint
+  UefiBootServicesTableLib
+  MemoryAllocationLib
+  BaseMemoryLib
+  BaseLib
+  UefiLib
+  DevicePathLib
+  DebugLib
+
+
+[Protocols]
+  gEfiDriverBindingProtocolGuid
+  gEfiBlockIoProtocolGuid
+  gEfiComponentName2ProtocolGuid
+  gEfiComponentNameProtocolGuid
+  gXenBusProtocolGuid
+  gEfiDevicePathProtocolGuid                    ## TO_START
+
+
+[Guids]
+