[PATCH 5/7] OvmfPkg: control PXEv4 / PXEv6 boot support from the QEMU command line

["Laszlo Ersek" <lersek@redhat.com>]

Add a minimal, NULL class library called "PxeBcPcdProducerLib" for setting
the "PcdIPv4PXESupport" and "PcdIPv6PXESupport" PCDs of NetworkPkg, from
fw_cfg.

These PCDs control whether the UefiPxeBcDxe driver supports PXEv4 / PXEv6
boot. If a PXE version is disabled, the corresponding LoadFile protocol
instance is not produced by UefiPxeBcDxe, and so
EfiBootManagerRefreshAllBootOption() in UefiBootManagerLib does not
generate corresponding *new* boot options either. (Existent boot options
are not deleted.)

Hook the library into the UefiPxeBcDxe driver. (The driver is already
included from "NetworkComponents.dsc.inc", but we can list it again in the
DSC file, for providing <LibraryClasses> overrides.)

In OVMF, the PCDs could be set in PlatformPei too, but ArmVirtQemu does
not have fw_cfg access in the PEI phase. Hence a NULL class library that
can be linked into UefiPxeBcDxe.

When listing the PCDs under [PcdsDynamicDefault], stick with the DEC
default values.

QEMU switches:

  -fw_cfg name=opt/org.tianocore/IPv4PXESupport,string=[yn]

  -fw_cfg name=opt/org.tianocore/IPv6PXESupport,string=[yn]

The "opt/org.tianocore" prefix follows the "opt/RFQDN/" recommendation
from QEMU's "docs/specs/fw_cfg.txt".

Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Per Sundstrom <per_sundstrom@yahoo.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2681
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
 OvmfPkg/OvmfPkgIa32.dsc                                     |  9 +++++
 OvmfPkg/OvmfPkgIa32X64.dsc                                  | 10 +++++
 OvmfPkg/OvmfPkgX64.dsc                                      |  9 +++++
 OvmfPkg/Library/PxeBcPcdProducerLib/PxeBcPcdProducerLib.inf | 33 +++++++++++++++++
 OvmfPkg/Library/PxeBcPcdProducerLib/PxeBcPcd.c              | 39 ++++++++++++++++++++
 5 files changed, 100 insertions(+)

diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
index 5e2972063110..fcd9779b5ba2 100644
--- a/OvmfPkg/OvmfPkgIa32.dsc
+++ b/OvmfPkg/OvmfPkgIa32.dsc
@@ -605,6 +605,10 @@ [PcdsDynamicDefault]
   gEfiSecurityPkgTokenSpaceGuid.PcdTpmInstanceGuid|{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
 !endif
 
+  # IPv4 and IPv6 PXE Boot support.
+  gEfiNetworkPkgTokenSpaceGuid.PcdIPv4PXESupport|0x01
+  gEfiNetworkPkgTokenSpaceGuid.PcdIPv6PXESupport|0x01
+
 [PcdsDynamicHii]
 !if $(TPM_ENABLE) == TRUE && $(TPM_CONFIG_ENABLE) == TRUE
   gEfiSecurityPkgTokenSpaceGuid.PcdTcgPhysicalPresenceInterfaceVer|L"TCG2_VERSION"|gTcg2ConfigFormSetGuid|0x0|"1.3"|NV,BS
@@ -822,6 +826,11 @@ [Components]
   #
 !include NetworkPkg/NetworkComponents.dsc.inc
 
+  NetworkPkg/UefiPxeBcDxe/UefiPxeBcDxe.inf {
+    <LibraryClasses>
+      NULL|OvmfPkg/Library/PxeBcPcdProducerLib/PxeBcPcdProducerLib.inf
+  }
+
 !if $(NETWORK_TLS_ENABLE) == TRUE
   NetworkPkg/TlsAuthConfigDxe/TlsAuthConfigDxe.inf {
     <LibraryClasses>
diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
index 18e6909a33fa..1626d2415a2c 100644
--- a/OvmfPkg/OvmfPkgIa32X64.dsc
+++ b/OvmfPkg/OvmfPkgIa32X64.dsc
@@ -616,6 +616,11 @@ [PcdsDynamicDefault]
   gEfiSecurityPkgTokenSpaceGuid.PcdTpmInstanceGuid|{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
 !endif
 
+[PcdsDynamicDefault.X64]
+  # IPv4 and IPv6 PXE Boot support.
+  gEfiNetworkPkgTokenSpaceGuid.PcdIPv4PXESupport|0x01
+  gEfiNetworkPkgTokenSpaceGuid.PcdIPv6PXESupport|0x01
+
 [PcdsDynamicHii]
 !if $(TPM_ENABLE) == TRUE && $(TPM_CONFIG_ENABLE) == TRUE
   gEfiSecurityPkgTokenSpaceGuid.PcdTcgPhysicalPresenceInterfaceVer|L"TCG2_VERSION"|gTcg2ConfigFormSetGuid|0x0|"1.3"|NV,BS
@@ -834,6 +839,11 @@ [Components.X64]
   #
 !include NetworkPkg/NetworkComponents.dsc.inc
 
+  NetworkPkg/UefiPxeBcDxe/UefiPxeBcDxe.inf {
+    <LibraryClasses>
+      NULL|OvmfPkg/Library/PxeBcPcdProducerLib/PxeBcPcdProducerLib.inf
+  }
+
 !if $(NETWORK_TLS_ENABLE) == TRUE
   NetworkPkg/TlsAuthConfigDxe/TlsAuthConfigDxe.inf {
     <LibraryClasses>
diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
index 3d24cc4c1cfb..65cfe957761b 100644
--- a/OvmfPkg/OvmfPkgX64.dsc
+++ b/OvmfPkg/OvmfPkgX64.dsc
@@ -615,6 +615,10 @@ [PcdsDynamicDefault]
   gEfiSecurityPkgTokenSpaceGuid.PcdTpmInstanceGuid|{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
 !endif
 
+  # IPv4 and IPv6 PXE Boot support.
+  gEfiNetworkPkgTokenSpaceGuid.PcdIPv4PXESupport|0x01
+  gEfiNetworkPkgTokenSpaceGuid.PcdIPv6PXESupport|0x01
+
 [PcdsDynamicHii]
 !if $(TPM_ENABLE) == TRUE && $(TPM_CONFIG_ENABLE) == TRUE
   gEfiSecurityPkgTokenSpaceGuid.PcdTcgPhysicalPresenceInterfaceVer|L"TCG2_VERSION"|gTcg2ConfigFormSetGuid|0x0|"1.3"|NV,BS
@@ -832,6 +836,11 @@ [Components]
   #
 !include NetworkPkg/NetworkComponents.dsc.inc
 
+  NetworkPkg/UefiPxeBcDxe/UefiPxeBcDxe.inf {
+    <LibraryClasses>
+      NULL|OvmfPkg/Library/PxeBcPcdProducerLib/PxeBcPcdProducerLib.inf
+  }
+
 !if $(NETWORK_TLS_ENABLE) == TRUE
   NetworkPkg/TlsAuthConfigDxe/TlsAuthConfigDxe.inf {
     <LibraryClasses>
diff --git a/OvmfPkg/Library/PxeBcPcdProducerLib/PxeBcPcdProducerLib.inf b/OvmfPkg/Library/PxeBcPcdProducerLib/PxeBcPcdProducerLib.inf
new file mode 100644
index 000000000000..948133228111
--- /dev/null
+++ b/OvmfPkg/Library/PxeBcPcdProducerLib/PxeBcPcdProducerLib.inf
@@ -0,0 +1,33 @@
+## @file
+# Configure some PCDs dynamically for
+# "NetworkPkg/UefiPxeBcDxe/UefiPxeBcDxe.inf", from QEMU's fw_cfg.
+#
+# Copyright (C) 2020, Red Hat, Inc.
+#
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+##
+
+[Defines]
+  INF_VERSION                    = 1.29
+  BASE_NAME                      = PxeBcPcdProducerLib
+  FILE_GUID                      = 1da2723f-52df-432a-8d03-6e8fa8acc107
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = NULL
+  CONSTRUCTOR                    = SetPxeBcPcds
+
+[Sources]
+  PxeBcPcd.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  NetworkPkg/NetworkPkg.dec
+  OvmfPkg/OvmfPkg.dec
+
+[LibraryClasses]
+  PcdLib
+  QemuFwCfgSimpleParserLib
+
+[Pcd]
+  gEfiNetworkPkgTokenSpaceGuid.PcdIPv4PXESupport       ## SOMETIMES_PRODUCES
+  gEfiNetworkPkgTokenSpaceGuid.PcdIPv6PXESupport       ## SOMETIMES_PRODUCES
diff --git a/OvmfPkg/Library/PxeBcPcdProducerLib/PxeBcPcd.c b/OvmfPkg/Library/PxeBcPcdProducerLib/PxeBcPcd.c
new file mode 100644
index 000000000000..7ce236326fb4
--- /dev/null
+++ b/OvmfPkg/Library/PxeBcPcdProducerLib/PxeBcPcd.c
@@ -0,0 +1,39 @@
+/** @file
+  Configure some PCDs dynamically for
+  "NetworkPkg/UefiPxeBcDxe/UefiPxeBcDxe.inf", from QEMU's fw_cfg.
+
+  Copyright (C) 2020, Red Hat, Inc.
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include <Library/PcdLib.h>
+#include <Library/QemuFwCfgSimpleParserLib.h>
+
+RETURN_STATUS
+EFIAPI
+SetPxeBcPcds (
+  VOID
+  )
+{
+  BOOLEAN       FwCfgBool;
+  RETURN_STATUS PcdStatus;
+
+  if (!RETURN_ERROR (QemuFwCfgParseBool ("opt/org.tianocore/IPv4PXESupport",
+                       &FwCfgBool))) {
+    PcdStatus = PcdSet8S (PcdIPv4PXESupport, FwCfgBool);
+    if (RETURN_ERROR (PcdStatus)) {
+      return PcdStatus;
+    }
+  }
+
+  if (!RETURN_ERROR (QemuFwCfgParseBool ("opt/org.tianocore/IPv6PXESupport",
+                       &FwCfgBool))) {
+    PcdStatus = PcdSet8S (PcdIPv6PXESupport, FwCfgBool);
+    if (RETURN_ERROR (PcdStatus)) {
+      return PcdStatus;
+    }
+  }
+
+  return RETURN_SUCCESS;
+}
-- 
2.19.1.3.g30247aa5d201