diff --git a/OvmfPkg/Csm/Include/Protocol/LegacyInterrupt.h b/OvmfPkg/Csm/Include/Protocol/LegacyInterrupt.h
deleted file mode 100644
index 8287ad5b5c..0000000000
--- a/OvmfPkg/Csm/Include/Protocol/LegacyInterrupt.h
+++ /dev/null
@@ -1,121 +0,0 @@
-/** @file
-  This protocol abstracts the PIRQ programming from the generic EFI Compatibility Support Modules (CSMs).
-
-Copyright (c) 2007 - 2018, Intel Corporation. All rights reserved.<BR>
-SPDX-License-Identifier: BSD-2-Clause-Patent
-
-  @par Revision Reference:
-  This protocol is defined in Framework for the EFI Compatibility Support Module specification.
-  Version 0.97.
-
-**/
-
-#ifndef _EFI_LEGACY_INTERRUPT_H_
-#define _EFI_LEGACY_INTERRUPT_H_
-
-#define EFI_LEGACY_INTERRUPT_PROTOCOL_GUID \
-  { \
-    0x31ce593d, 0x108a, 0x485d, {0xad, 0xb2, 0x78, 0xf2, 0x1f, 0x29, 0x66, 0xbe } \
-  }
-
-typedef struct _EFI_LEGACY_INTERRUPT_PROTOCOL EFI_LEGACY_INTERRUPT_PROTOCOL;
-
-/**
-  Get the number of PIRQs this hardware supports.
-
-  @param  This                  The protocol instance pointer.
-  @param  NumberPirsq           The number of PIRQs that are supported.
-
-  @retval EFI_SUCCESS           The number of PIRQs was returned successfully.
-
-**/
-typedef
-EFI_STATUS
-(EFIAPI *EFI_LEGACY_INTERRUPT_GET_NUMBER_PIRQS)(
-  IN EFI_LEGACY_INTERRUPT_PROTOCOL            *This,
-  OUT UINT8                                   *NumberPirqs
-  );
-
-/**
-  Gets the PCI location associated with this protocol.
-
-  @param  This                  The Protocol instance pointer.
-  @param  Bus                   The PCI Bus.
-  @param  Device                The PCI Device.
-  @param  Function              The PCI Function.
-
-  @retval EFI_SUCCESS           The Bus, Device, and Function were returned successfully.
-
-**/
-typedef
-EFI_STATUS
-(EFIAPI *EFI_LEGACY_INTERRUPT_GET_LOCATION)(
-  IN EFI_LEGACY_INTERRUPT_PROTOCOL            *This,
-  OUT UINT8                                   *Bus,
-  OUT UINT8                                   *Device,
-  OUT UINT8                                   *Function
-  );
-
-/**
-  Read the PIRQ register and return the data
-
-  @param  This                  The protocol instance pointer.
-  @param  PirqNumber            The PIRQ register to read.
-  @param  PirqData              The data read.
-
-  @retval EFI_SUCCESS           The data was read.
-  @retval EFI_INVALID_PARAMETER Invalid PIRQ number.
-
-**/
-typedef
-EFI_STATUS
-(EFIAPI *EFI_LEGACY_INTERRUPT_READ_PIRQ)(
-  IN EFI_LEGACY_INTERRUPT_PROTOCOL           *This,
-  IN  UINT8                                  PirqNumber,
-  OUT UINT8                                  *PirqData
-  );
-
-/**
-  Write the specified PIRQ register with the given data.
-
-  @param  This                  The protocol instance pointer.
-  @param  PirqNumber            A PIRQ register to read.
-  @param  PirqData              The data to write.
-
-  @retval EFI_SUCCESS           The PIRQ was programmed.
-  @retval EFI_INVALID_PARAMETER Invalid PIRQ number.
-
-**/
-typedef
-EFI_STATUS
-(EFIAPI *EFI_LEGACY_INTERRUPT_WRITE_PIRQ)(
-  IN EFI_LEGACY_INTERRUPT_PROTOCOL           *This,
-  IN  UINT8                                  PirqNumber,
-  IN UINT8                                   PirqData
-  );
-
-struct _EFI_LEGACY_INTERRUPT_PROTOCOL {
-  ///
-  ///   Gets the number of PIRQs supported.
-  ///
-  EFI_LEGACY_INTERRUPT_GET_NUMBER_PIRQS    GetNumberPirqs;
-
-  ///
-  /// Gets the PCI bus, device, and function that is associated with this protocol.
-  ///
-  EFI_LEGACY_INTERRUPT_GET_LOCATION        GetLocation;
-
-  ///
-  /// Reads the indicated PIRQ register.
-  ///
-  EFI_LEGACY_INTERRUPT_READ_PIRQ           ReadPirq;
-
-  ///
-  /// Writes to the indicated PIRQ register.
-  ///
-  EFI_LEGACY_INTERRUPT_WRITE_PIRQ          WritePirq;
-};
-
-extern EFI_GUID  gEfiLegacyInterruptProtocolGuid;
-
-#endif
diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index 9c2e84ca60..32543e466a 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -183,7 +183,6 @@
   gXenIoProtocolGuid                    = {0x6efac84f, 0x0ab0, 0x4747, {0x81, 0xbe, 0x85, 0x55, 0x62, 0x59, 0x04, 0x49}}
   gIoMmuAbsentProtocolGuid              = {0xf8775d50, 0x8abd, 0x4adf, {0x92, 0xac, 0x85, 0x3e, 0x51, 0xf6, 0xc8, 0xdc}}
   gEfiLegacy8259ProtocolGuid            = {0x38321dba, 0x4fe0, 0x4e17, {0x8a, 0xec, 0x41, 0x30, 0x55, 0xea, 0xed, 0xc1}}
-  gEfiLegacyInterruptProtocolGuid       = {0x31ce593d, 0x108a, 0x485d, {0xad, 0xb2, 0x78, 0xf2, 0x1f, 0x29, 0x66, 0xbe}}
   gOvmfLoadedX86LinuxKernelProtocolGuid = {0xa3edc05d, 0xb618, 0x4ff6, {0x95, 0x52, 0x76, 0xd7, 0x88, 0x63, 0x43, 0xc8}}
   gOvmfSevMemoryAcceptanceProtocolGuid  = {0xc5a010fe, 0x38a7, 0x4531, {0x8a, 0x4a, 0x05, 0x00, 0xd2, 0xfd, 0x16, 0x49}}
   gQemuAcpiTableNotifyProtocolGuid      = {0x928939b2, 0x4235, 0x462f, {0x95, 0x80, 0xf6, 0xa2, 0xb2, 0xc2, 0x1a, 0x4f}}