[PATCH RFC 11/14] OvmfPkg/XenOvmf: Adding XenTimerLocalApic

[Anthony PERARD <anthony.perard@citrix.com>]

And replacing the ACPI Timer by this one based on the local APIC.

ACPI Timer does not work in a PVH guest, but local APIC works on both
PVH and HVM.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
---
 OvmfPkg/XenOvmf.dsc                             |  18 +-
 OvmfPkg/XenOvmf.fdf                             |   2 +-
 OvmfPkg/XenTimerLocalApic/Timer.h               | 191 ++++++++++++
 OvmfPkg/XenTimerLocalApic/XenTimerLocalApic.c   | 386 ++++++++++++++++++++++++
 OvmfPkg/XenTimerLocalApic/XenTimerLocalApic.inf |  51 ++++
 5 files changed, 640 insertions(+), 8 deletions(-)
 create mode 100644 OvmfPkg/XenTimerLocalApic/Timer.h
 create mode 100644 OvmfPkg/XenTimerLocalApic/XenTimerLocalApic.c
 create mode 100644 OvmfPkg/XenTimerLocalApic/XenTimerLocalApic.inf

diff --git a/OvmfPkg/XenOvmf.dsc b/OvmfPkg/XenOvmf.dsc
index ef32c33..31a2185 100644
--- a/OvmfPkg/XenOvmf.dsc
+++ b/OvmfPkg/XenOvmf.dsc
@@ -81,7 +81,7 @@
 ################################################################################
 [LibraryClasses]
   PcdLib|MdePkg/Library/BasePcdLibNull/BasePcdLibNull.inf
-  TimerLib|OvmfPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.inf
+  TimerLib|MdePkg/Library/SecPeiDxeTimerLibCpu/SecPeiDxeTimerLibCpu.inf
   PrintLib|MdePkg/Library/BasePrintLib/BasePrintLib.inf
   BaseMemoryLib|MdePkg/Library/BaseMemoryLibRepStr/BaseMemoryLibRepStr.inf
   BaseLib|MdePkg/Library/BaseLib/BaseLib.inf
@@ -175,7 +175,7 @@
 !endif
 
 [LibraryClasses.common.SEC]
-  TimerLib|OvmfPkg/Library/AcpiTimerLib/BaseRomAcpiTimerLib.inf
+  TimerLib|MdePkg/Library/SecPeiDxeTimerLibCpu/SecPeiDxeTimerLibCpu.inf
   QemuFwCfgLib|OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgSecLib.inf
 !ifdef $(DEBUG_ON_SERIAL_PORT)
   DebugLib|MdePkg/Library/BaseDebugLibSerialPort/BaseDebugLibSerialPort.inf
@@ -251,7 +251,7 @@
 
 [LibraryClasses.common.DXE_RUNTIME_DRIVER]
   PcdLib|MdePkg/Library/DxePcdLib/DxePcdLib.inf
-  TimerLib|OvmfPkg/Library/AcpiTimerLib/DxeAcpiTimerLib.inf
+  TimerLib|MdePkg/Library/SecPeiDxeTimerLibCpu/SecPeiDxeTimerLibCpu.inf
   HobLib|MdePkg/Library/DxeHobLib/DxeHobLib.inf
   DxeCoreEntryPoint|MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.inf
   MemoryAllocationLib|MdePkg/Library/UefiMemoryAllocationLib/UefiMemoryAllocationLib.inf
@@ -269,7 +269,7 @@
 
 [LibraryClasses.common.UEFI_DRIVER]
   PcdLib|MdePkg/Library/DxePcdLib/DxePcdLib.inf
-  TimerLib|OvmfPkg/Library/AcpiTimerLib/DxeAcpiTimerLib.inf
+  TimerLib|MdePkg/Library/SecPeiDxeTimerLibCpu/SecPeiDxeTimerLibCpu.inf
   HobLib|MdePkg/Library/DxeHobLib/DxeHobLib.inf
   DxeCoreEntryPoint|MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.inf
   MemoryAllocationLib|MdePkg/Library/UefiMemoryAllocationLib/UefiMemoryAllocationLib.inf
@@ -284,7 +284,7 @@
 
 [LibraryClasses.common.DXE_DRIVER]
   PcdLib|MdePkg/Library/DxePcdLib/DxePcdLib.inf
-  TimerLib|OvmfPkg/Library/AcpiTimerLib/DxeAcpiTimerLib.inf
+  TimerLib|MdePkg/Library/SecPeiDxeTimerLibCpu/SecPeiDxeTimerLibCpu.inf
   HobLib|MdePkg/Library/DxeHobLib/DxeHobLib.inf
   MemoryAllocationLib|MdePkg/Library/UefiMemoryAllocationLib/UefiMemoryAllocationLib.inf
   ReportStatusCodeLib|MdeModulePkg/Library/DxeReportStatusCodeLib/DxeReportStatusCodeLib.inf
@@ -314,7 +314,7 @@
 
 [LibraryClasses.common.UEFI_APPLICATION]
   PcdLib|MdePkg/Library/DxePcdLib/DxePcdLib.inf
-  TimerLib|OvmfPkg/Library/AcpiTimerLib/DxeAcpiTimerLib.inf
+  TimerLib|MdePkg/Library/SecPeiDxeTimerLibCpu/SecPeiDxeTimerLibCpu.inf
   HobLib|MdePkg/Library/DxeHobLib/DxeHobLib.inf
   MemoryAllocationLib|MdePkg/Library/UefiMemoryAllocationLib/UefiMemoryAllocationLib.inf
   ReportStatusCodeLib|MdeModulePkg/Library/DxeReportStatusCodeLib/DxeReportStatusCodeLib.inf
@@ -546,7 +546,11 @@
 !endif
 
   MdeModulePkg/Universal/EbcDxe/EbcDxe.inf
-  PcAtChipsetPkg/8259InterruptControllerDxe/8259.inf
+  OvmfPkg/XenTimerLocalApic/XenTimerLocalApic.inf
+  #{
+  #<LibraryClasses>
+    #LocalApicLib|UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.inf
+  #}
   UefiCpuPkg/CpuIo2Dxe/CpuIo2Dxe.inf
   UefiCpuPkg/CpuDxe/CpuDxe.inf
   PcAtChipsetPkg/8254TimerDxe/8254Timer.inf
diff --git a/OvmfPkg/XenOvmf.fdf b/OvmfPkg/XenOvmf.fdf
index c211f61..f6876d7 100644
--- a/OvmfPkg/XenOvmf.fdf
+++ b/OvmfPkg/XenOvmf.fdf
@@ -207,7 +207,7 @@ INF  MdeModulePkg/Universal/PCD/Dxe/Pcd.inf
 INF  MdeModulePkg/Core/RuntimeDxe/RuntimeDxe.inf
 INF  MdeModulePkg/Universal/SecurityStubDxe/SecurityStubDxe.inf
 INF  MdeModulePkg/Universal/EbcDxe/EbcDxe.inf
-INF  PcAtChipsetPkg/8259InterruptControllerDxe/8259.inf
+INF  OvmfPkg/XenTimerLocalApic/XenTimerLocalApic.inf
 INF  UefiCpuPkg/CpuIo2Dxe/CpuIo2Dxe.inf
 INF  UefiCpuPkg/CpuDxe/CpuDxe.inf
 INF  PcAtChipsetPkg/8254TimerDxe/8254Timer.inf
diff --git a/OvmfPkg/XenTimerLocalApic/Timer.h b/OvmfPkg/XenTimerLocalApic/Timer.h
new file mode 100644
index 0000000..8d6f37c
--- /dev/null
+++ b/OvmfPkg/XenTimerLocalApic/Timer.h
@@ -0,0 +1,191 @@
+/** @file
+  Private data structures
+
+Copyright (c) 2005 - 2016, Intel Corporation. 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.
+**/
+
+#ifndef _TIMER_H_
+#define _TIMER_H_
+
+#include <PiDxe.h>
+
+#include <Protocol/Cpu.h>
+#include <Protocol/Legacy8259.h>
+#include <Protocol/Timer.h>
+
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+#include <Library/IoLib.h>
+
+//
+// The PCAT 8253/8254 has an input clock at 1.193182 MHz and Timer 0 is
+// initialized as a 16 bit free running counter that generates an interrupt(IRQ0)
+// each time the counter rolls over.
+//
+//   65536 counts
+// ---------------- * 1,000,000 uS/S = 54925.4 uS = 549254 * 100 ns
+//   1,193,182 Hz
+//
+
+//
+// The maximum tick duration for 8254 timer
+//
+#define MAX_TIMER_TICK_DURATION     549254
+//
+// The default timer tick duration is set to 10 ms = 100000 100 ns units
+//
+#define DEFAULT_TIMER_TICK_DURATION 100000
+#define TIMER_CONTROL_PORT          0x43
+#define TIMER0_COUNT_PORT           0x40
+
+//
+// Function Prototypes
+//
+/**
+  Initialize the Timer Architectural Protocol driver
+
+  @param ImageHandle     ImageHandle of the loaded driver
+  @param SystemTable     Pointer to the System Table
+
+  @retval EFI_SUCCESS            Timer Architectural Protocol created
+  @retval EFI_OUT_OF_RESOURCES   Not enough resources available to initialize driver.
+  @retval EFI_DEVICE_ERROR       A device error occured attempting to initialize the driver.
+
+**/
+EFI_STATUS
+EFIAPI
+TimerDriverInitialize (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+;
+
+/**
+
+  This function adjusts the period of timer interrupts to the value specified
+  by TimerPeriod.  If the timer period is updated, then the selected timer
+  period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned.  If
+  the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.
+  If an error occurs while attempting to update the timer period, then the
+  timer hardware will be put back in its state prior to this call, and
+  EFI_DEVICE_ERROR is returned.  If TimerPeriod is 0, then the timer interrupt
+  is disabled.  This is not the same as disabling the CPU's interrupts.
+  Instead, it must either turn off the timer hardware, or it must adjust the
+  interrupt controller so that a CPU interrupt is not generated when the timer
+  interrupt fires.
+
+
+  @param This            The EFI_TIMER_ARCH_PROTOCOL instance.
+  @param NotifyFunction  The rate to program the timer interrupt in 100 nS units.  If
+                         the timer hardware is not programmable, then EFI_UNSUPPORTED is
+                         returned.  If the timer is programmable, then the timer period
+                         will be rounded up to the nearest timer period that is supported
+                         by the timer hardware.  If TimerPeriod is set to 0, then the
+                         timer interrupts will be disabled.
+
+  @retval        EFI_SUCCESS       The timer period was changed.
+  @retval        EFI_UNSUPPORTED   The platform cannot change the period of the timer interrupt.
+  @retval        EFI_DEVICE_ERROR  The timer period could not be changed due to a device error.
+
+**/
+EFI_STATUS
+EFIAPI
+TimerDriverRegisterHandler (
+  IN EFI_TIMER_ARCH_PROTOCOL  *This,
+  IN EFI_TIMER_NOTIFY         NotifyFunction
+  )
+;
+
+/**
+
+  This function adjusts the period of timer interrupts to the value specified
+  by TimerPeriod.  If the timer period is updated, then the selected timer
+  period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned.  If
+  the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.
+  If an error occurs while attempting to update the timer period, then the
+  timer hardware will be put back in its state prior to this call, and
+  EFI_DEVICE_ERROR is returned.  If TimerPeriod is 0, then the timer interrupt
+  is disabled.  This is not the same as disabling the CPU's interrupts.
+  Instead, it must either turn off the timer hardware, or it must adjust the
+  interrupt controller so that a CPU interrupt is not generated when the timer
+  interrupt fires.
+
+
+  @param This            The EFI_TIMER_ARCH_PROTOCOL instance.
+  @param TimerPeriod     The rate to program the timer interrupt in 100 nS units.  If
+                         the timer hardware is not programmable, then EFI_UNSUPPORTED is
+                         returned.  If the timer is programmable, then the timer period
+                         will be rounded up to the nearest timer period that is supported
+                         by the timer hardware.  If TimerPeriod is set to 0, then the
+                         timer interrupts will be disabled.
+
+  @retval        EFI_SUCCESS       The timer period was changed.
+  @retval        EFI_UNSUPPORTED   The platform cannot change the period of the timer interrupt.
+  @retval        EFI_DEVICE_ERROR  The timer period could not be changed due to a device error.
+
+**/
+EFI_STATUS
+EFIAPI
+TimerDriverSetTimerPeriod (
+  IN EFI_TIMER_ARCH_PROTOCOL  *This,
+  IN UINT64                   TimerPeriod
+  )
+;
+
+/**
+
+  This function retrieves the period of timer interrupts in 100 ns units,
+  returns that value in TimerPeriod, and returns EFI_SUCCESS.  If TimerPeriod
+  is NULL, then EFI_INVALID_PARAMETER is returned.  If a TimerPeriod of 0 is
+  returned, then the timer is currently disabled.
+
+
+  @param This            The EFI_TIMER_ARCH_PROTOCOL instance.
+  @param TimerPeriod     A pointer to the timer period to retrieve in 100 ns units.  If
+                         0 is returned, then the timer is currently disabled.
+
+  @retval EFI_SUCCESS            The timer period was returned in TimerPeriod.
+  @retval EFI_INVALID_PARAMETER  TimerPeriod is NULL.
+
+**/
+EFI_STATUS
+EFIAPI
+TimerDriverGetTimerPeriod (
+  IN EFI_TIMER_ARCH_PROTOCOL   *This,
+  OUT UINT64                   *TimerPeriod
+  )
+;
+
+/**
+
+  This function generates a soft timer interrupt. If the platform does not support soft
+  timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned.
+  If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler()
+  service, then a soft timer interrupt will be generated. If the timer interrupt is
+  enabled when this service is called, then the registered handler will be invoked. The
+  registered handler should not be able to distinguish a hardware-generated timer
+  interrupt from a software-generated timer interrupt.
+
+
+  @param This              The EFI_TIMER_ARCH_PROTOCOL instance.
+
+  @retval EFI_SUCCESS       The soft timer interrupt was generated.
+  @retval EFI_UNSUPPORTED   The platform does not support the generation of soft timer interrupts.
+
+**/
+EFI_STATUS
+EFIAPI
+TimerDriverGenerateSoftInterrupt (
+  IN EFI_TIMER_ARCH_PROTOCOL  *This
+  )
+;
+
+#endif
diff --git a/OvmfPkg/XenTimerLocalApic/XenTimerLocalApic.c b/OvmfPkg/XenTimerLocalApic/XenTimerLocalApic.c
new file mode 100644
index 0000000..7f3a8f0
--- /dev/null
+++ b/OvmfPkg/XenTimerLocalApic/XenTimerLocalApic.c
@@ -0,0 +1,386 @@
+/** @file
+  Timer Architectural Protocol as defined in the DXE CIS
+
+Copyright (c) 2005 - 2016, Intel Corporation. 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 <Register/LocalApic.h>
+#include <Library/LocalApicLib.h>
+#include <Library/PcdLib.h>
+#include "Timer.h"
+
+//
+// The handle onto which the Timer Architectural Protocol will be installed
+//
+EFI_HANDLE                mTimerHandle = NULL;
+
+//
+// The Timer Architectural Protocol that this driver produces
+//
+EFI_TIMER_ARCH_PROTOCOL   mTimer = {
+  TimerDriverRegisterHandler,
+  TimerDriverSetTimerPeriod,
+  TimerDriverGetTimerPeriod,
+  TimerDriverGenerateSoftInterrupt
+};
+
+//
+// Pointer to the CPU Architectural Protocol instance
+//
+EFI_CPU_ARCH_PROTOCOL     *mCpu;
+
+//
+// The notification function to call on every timer interrupt.
+// A bug in the compiler prevents us from initializing this here.
+//
+EFI_TIMER_NOTIFY mTimerNotifyFunction;
+
+//
+// The current period of the timer interrupt
+//
+volatile UINT64           mTimerPeriod = 0;
+
+//
+// Worker Functions
+//
+/**
+  8254 Timer #0 Interrupt Handler.
+
+  @param InterruptType    The type of interrupt that occured
+  @param SystemContext    A pointer to the system context when the interrupt occured
+**/
+VOID
+EFIAPI
+TimerInterruptHandler (
+  IN EFI_EXCEPTION_TYPE   InterruptType,
+  IN EFI_SYSTEM_CONTEXT   SystemContext
+  )
+{
+  EFI_TPL OriginalTPL;
+
+  OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
+
+  /* mLegacy8259->EndOfInterrupt (mLegacy8259, Efi8259Irq0); */
+
+  if (mTimerNotifyFunction != NULL) {
+    //
+    // @bug : This does not handle missed timer interrupts
+    //
+    mTimerNotifyFunction (mTimerPeriod);
+  }
+  SendApicEoi();
+
+  gBS->RestoreTPL (OriginalTPL);
+}
+
+/**
+
+  This function registers the handler NotifyFunction so it is called every time
+  the timer interrupt fires.  It also passes the amount of time since the last
+  handler call to the NotifyFunction.  If NotifyFunction is NULL, then the
+  handler is unregistered.  If the handler is registered, then EFI_SUCCESS is
+  returned.  If the CPU does not support registering a timer interrupt handler,
+  then EFI_UNSUPPORTED is returned.  If an attempt is made to register a handler
+  when a handler is already registered, then EFI_ALREADY_STARTED is returned.
+  If an attempt is made to unregister a handler when a handler is not registered,
+  then EFI_INVALID_PARAMETER is returned.  If an error occurs attempting to
+  register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR
+  is returned.
+
+
+  @param This             The EFI_TIMER_ARCH_PROTOCOL instance.
+  @param NotifyFunction   The function to call when a timer interrupt fires.  This
+                          function executes at TPL_HIGH_LEVEL.  The DXE Core will
+                          register a handler for the timer interrupt, so it can know
+                          how much time has passed.  This information is used to
+                          signal timer based events.  NULL will unregister the handler.
+
+  @retval        EFI_SUCCESS            The timer handler was registered.
+  @retval        EFI_UNSUPPORTED        The platform does not support timer interrupts.
+  @retval        EFI_ALREADY_STARTED    NotifyFunction is not NULL, and a handler is already
+                                        registered.
+  @retval        EFI_INVALID_PARAMETER  NotifyFunction is NULL, and a handler was not
+                                        previously registered.
+  @retval        EFI_DEVICE_ERROR       The timer handler could not be registered.
+
+**/
+EFI_STATUS
+EFIAPI
+TimerDriverRegisterHandler (
+  IN EFI_TIMER_ARCH_PROTOCOL  *This,
+  IN EFI_TIMER_NOTIFY         NotifyFunction
+  )
+{
+  //
+  // Check for invalid parameters
+  //
+  DEBUG((EFI_D_ERROR, "%a %d\n", __FUNCTION__, __LINE__));
+  if (NotifyFunction == NULL && mTimerNotifyFunction == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  if (NotifyFunction != NULL && mTimerNotifyFunction != NULL) {
+    return EFI_ALREADY_STARTED;
+  }
+  DEBUG((EFI_D_ERROR, "%a %d\n", __FUNCTION__, __LINE__));
+
+  mTimerNotifyFunction = NotifyFunction;
+
+  return EFI_SUCCESS;
+}
+
+/**
+
+  This function adjusts the period of timer interrupts to the value specified
+  by TimerPeriod.  If the timer period is updated, then the selected timer
+  period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned.  If
+  the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.
+  If an error occurs while attempting to update the timer period, then the
+  timer hardware will be put back in its state prior to this call, and
+  EFI_DEVICE_ERROR is returned.  If TimerPeriod is 0, then the timer interrupt
+  is disabled.  This is not the same as disabling the CPU's interrupts.
+  Instead, it must either turn off the timer hardware, or it must adjust the
+  interrupt controller so that a CPU interrupt is not generated when the timer
+  interrupt fires.
+
+
+  @param This            The EFI_TIMER_ARCH_PROTOCOL instance.
+  @param TimerPeriod     The rate to program the timer interrupt in 100 nS units.  If
+                         the timer hardware is not programmable, then EFI_UNSUPPORTED is
+                         returned.  If the timer is programmable, then the timer period
+                         will be rounded up to the nearest timer period that is supported
+                         by the timer hardware.  If TimerPeriod is set to 0, then the
+                         timer interrupts will be disabled.
+
+  @retval        EFI_SUCCESS       The timer period was changed.
+  @retval        EFI_UNSUPPORTED   The platform cannot change the period of the timer interrupt.
+  @retval        EFI_DEVICE_ERROR  The timer period could not be changed due to a device error.
+
+**/
+EFI_STATUS
+EFIAPI
+TimerDriverSetTimerPeriod (
+  IN EFI_TIMER_ARCH_PROTOCOL  *This,
+  IN UINT64                   TimerPeriod
+  )
+{
+  UINT64  TimerCount;
+  UINT32  TimerFrequency;
+  UINTN   DivideValue;
+
+  GetApicTimerState(&DivideValue, NULL, NULL);
+
+  // XXX rework comment, copy from other lib
+  //
+  //  The basic clock is 1.19318 MHz or 0.119318 ticks per 100 ns.
+  //  TimerPeriod * 0.119318 = 8254 timer divisor. Using integer arithmetic
+  //  TimerCount = (TimerPeriod * 119318)/1000000.
+  //
+  //  Round up to next highest integer. This guarantees that the timer is
+  //  equal to or slightly longer than the requested time.
+  //  TimerCount = ((TimerPeriod * 119318) + 500000)/1000000
+  //
+  // Note that a TimerCount of 0 is equivalent to a count of 65,536
+  //
+  if (TimerPeriod == 0) {
+    //
+    // Disable timer interrupt for a TimerPeriod of 0
+    //
+    DisableApicTimerInterrupt();
+  } else {
+    TimerFrequency = PcdGet32(PcdFSBClock) / DivideValue;
+
+    DEBUG((EFI_D_ERROR, "%a %d, fsbclock %d, freq %d\n",
+           __FUNCTION__, __LINE__,
+           PcdGet32(PcdFSBClock),
+           TimerFrequency));
+
+    //
+    // Convert TimerPeriod into local apic counts
+    //
+
+    TimerCount = DivU64x32 (MultU64x32 (TimerFrequency,
+                                        (UINT32) TimerPeriod) + 500000,
+                            1000000);
+
+    DEBUG((EFI_D_ERROR, "%a %d, new init val: %d\n", __FUNCTION__, __LINE__, TimerCount));
+
+    //
+    // Program the timer with the new count value
+    //
+    WriteLocalApicReg (XAPIC_TIMER_INIT_COUNT_OFFSET, TimerCount);
+
+    //
+    // Enable timer interrupt
+    //
+    EnableApicTimerInterrupt();
+  }
+  //
+  // Save the new timer period
+  //
+  mTimerPeriod = TimerPeriod;
+
+  return EFI_SUCCESS;
+}
+
+/**
+
+  This function retrieves the period of timer interrupts in 100 ns units,
+  returns that value in TimerPeriod, and returns EFI_SUCCESS.  If TimerPeriod
+  is NULL, then EFI_INVALID_PARAMETER is returned.  If a TimerPeriod of 0 is
+  returned, then the timer is currently disabled.
+
+
+  @param This            The EFI_TIMER_ARCH_PROTOCOL instance.
+  @param TimerPeriod     A pointer to the timer period to retrieve in 100 ns units.  If
+                         0 is returned, then the timer is currently disabled.
+
+  @retval EFI_SUCCESS            The timer period was returned in TimerPeriod.
+  @retval EFI_INVALID_PARAMETER  TimerPeriod is NULL.
+
+**/
+EFI_STATUS
+EFIAPI
+TimerDriverGetTimerPeriod (
+  IN EFI_TIMER_ARCH_PROTOCOL   *This,
+  OUT UINT64                   *TimerPeriod
+  )
+{
+  if (TimerPeriod == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  *TimerPeriod = mTimerPeriod;
+
+  return EFI_SUCCESS;
+}
+
+/**
+
+  This function generates a soft timer interrupt. If the platform does not support soft
+  timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned.
+  If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler()
+  service, then a soft timer interrupt will be generated. If the timer interrupt is
+  enabled when this service is called, then the registered handler will be invoked. The
+  registered handler should not be able to distinguish a hardware-generated timer
+  interrupt from a software-generated timer interrupt.
+
+
+  @param This              The EFI_TIMER_ARCH_PROTOCOL instance.
+
+  @retval EFI_SUCCESS       The soft timer interrupt was generated.
+  @retval EFI_UNSUPPORTED   The platform does not support the generation of soft timer interrupts.
+
+**/
+EFI_STATUS
+EFIAPI
+TimerDriverGenerateSoftInterrupt (
+  IN EFI_TIMER_ARCH_PROTOCOL  *This
+  )
+{
+  EFI_TPL     OriginalTPL;
+
+  if (GetApicTimerInterruptState()) {
+    //
+    // Invoke the registered handler
+    //
+    OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
+
+    DisableApicTimerInterrupt();
+    if (mTimerNotifyFunction != NULL) {
+      //
+      // @bug : This does not handle missed timer interrupts
+      //
+      mTimerNotifyFunction (mTimerPeriod);
+    }
+
+    gBS->RestoreTPL (OriginalTPL);
+  } else {
+    return EFI_UNSUPPORTED;
+  }
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Initialize the Timer Architectural Protocol driver
+
+  @param ImageHandle     ImageHandle of the loaded driver
+  @param SystemTable     Pointer to the System Table
+
+  @retval EFI_SUCCESS            Timer Architectural Protocol created
+  @retval EFI_OUT_OF_RESOURCES   Not enough resources available to initialize driver.
+  @retval EFI_DEVICE_ERROR       A device error occured attempting to initialize the driver.
+
+**/
+EFI_STATUS
+EFIAPI
+TimerDriverInitialize (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  EFI_STATUS  Status;
+  UINT32      TimerVector;
+
+  //
+  // Initialize the pointer to our notify function.
+  //
+  mTimerNotifyFunction = NULL;
+
+  //
+  // Make sure the Timer Architectural Protocol is not already installed in the system
+  //
+  ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiTimerArchProtocolGuid);
+
+  //
+  // Find the CPU architectural protocol.
+  //
+  Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **) &mCpu);
+  ASSERT_EFI_ERROR (Status);
+
+
+  //
+  // Force the timer to be disabled
+  //
+  DisableApicTimerInterrupt();
+
+  //
+  // Get the interrupt vector number corresponding to IRQ0 from the 8259 driver
+  //
+  TimerVector = 32;
+  InitializeApicTimer(2, 0, 1, TimerVector);
+
+  //
+  // Install interrupt handler for 8254 Timer #0 (ISA IRQ0)
+  //
+  Status = mCpu->RegisterInterruptHandler (mCpu, TimerVector, TimerInterruptHandler);
+  ASSERT_EFI_ERROR (Status);
+
+  //
+  // Force the timer to be enabled at its default period
+  //
+  Status = TimerDriverSetTimerPeriod (&mTimer, DEFAULT_TIMER_TICK_DURATION);
+  ASSERT_EFI_ERROR (Status);
+
+  //
+  // Install the Timer Architectural Protocol onto a new handle
+  //
+  Status = gBS->InstallMultipleProtocolInterfaces (
+                  &mTimerHandle,
+                  &gEfiTimerArchProtocolGuid, &mTimer,
+                  NULL
+                  );
+  ASSERT_EFI_ERROR (Status);
+
+  return Status;
+}
+
diff --git a/OvmfPkg/XenTimerLocalApic/XenTimerLocalApic.inf b/OvmfPkg/XenTimerLocalApic/XenTimerLocalApic.inf
new file mode 100644
index 0000000..43e137c
--- /dev/null
+++ b/OvmfPkg/XenTimerLocalApic/XenTimerLocalApic.inf
@@ -0,0 +1,51 @@
+## @file
+# 8254 timer driver that provides Timer Arch protocol.
+#
+# Copyright (c) 2005 - 2014, Intel Corporation. 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.
+#
+##
+
+[Defines]
+  INF_VERSION                    = 0x00010005
+  BASE_NAME                      = ApicTimer
+  FILE_GUID                      = 52fe8196-f9de-4d07-b22f-51f77a0e7c41
+  MODULE_TYPE                    = DXE_DRIVER
+  VERSION_STRING                 = 1.0
+
+  ENTRY_POINT                    = TimerDriverInitialize
+
+[Packages]
+  MdePkg/MdePkg.dec
+  IntelFrameworkPkg/IntelFrameworkPkg.dec
+  UefiCpuPkg/UefiCpuPkg.dec
+  OvmfPkg/OvmfPkg.dec
+
+[LibraryClasses]
+  UefiBootServicesTableLib
+  BaseLib
+  DebugLib
+  UefiDriverEntryPoint
+  IoLib
+  LocalApicLib
+
+[Sources]
+  Timer.h
+  XenTimerLocalApic.c
+
+[Protocols]
+  gEfiCpuArchProtocolGuid       ## CONSUMES
+  gEfiTimerArchProtocolGuid     ## PRODUCES
+[Pcd.IA32, Pcd.X64]
+  gEfiMdePkgTokenSpaceGuid.PcdFSBClock  ## CONSUMES
+
+[Depex]
+  gEfiCpuArchProtocolGuid# AND gEfiLegacy8259ProtocolGuid
+#[UserExtensions.TianoCore."ExtraFiles"]
+  #TimerExtra.uni
-- 
Anthony PERARD