Re: [PATCH v3 11/19] OvmfPkg/Microvm: PlatformPei/MemDetect tweaks

["Gerd Hoffmann" <kraxel@redhat.com>]

> > Sure.  Suggestions?  Add a Pcd and set it in Microvm.dsc?
> > Or is there some better way?
> 
> It's all a question of how much we want to overengineer things :)
> 
> I'm tempted to suggest a balanced version would be adding
>   GCC: *_*_*_CC_FLAGS = -D PLATFORM_IS_MICROVM
> to [BuildOptions] in the .dsc, and test for that.

How about the approach below?

take care,
  Gerd

commit 2d48e3eba022ba92eadcbad2c55e10ed281631c2
Author: Gerd Hoffmann <kraxel@redhat.com>
Date:   Tue Jun 1 12:38:38 2021 +0200

    OvmfPkg/Microvm: PlatformPei/MemDetect tweaks
    
    Set mHostBridgeDevId to MICROVM_PSEUDO_DEVICE_ID using a
    compile time switch.
    
    Skip host bridge setup on microvm.
    
    Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3599
    Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
    Acked-by: Jiewen Yao <Jiewen.yao@intel.com>

diff --git a/OvmfPkg/Microvm/MicrovmX64.dsc b/OvmfPkg/Microvm/MicrovmX64.dsc
index 019b50de7d8f..a000c195d866 100644
--- a/OvmfPkg/Microvm/MicrovmX64.dsc
+++ b/OvmfPkg/Microvm/MicrovmX64.dsc
@@ -73,6 +73,9 @@ [Defines]
 !endif
 
 [BuildOptions]
+  GCC:*_*_*_CC_FLAGS                   = -DPLATFORM_IS_MICROVM
+  INTEL:*_*_*_CC_FLAGS                 = /D PLATFORM_IS_MICROVM
+  MSFT:*_*_*_CC_FLAGS                  = /D PLATFORM_IS_MICROVM
   GCC:RELEASE_*_*_CC_FLAGS             = -DMDEPKG_NDEBUG
   INTEL:RELEASE_*_*_CC_FLAGS           = /D MDEPKG_NDEBUG
   MSFT:RELEASE_*_*_CC_FLAGS            = /D MDEPKG_NDEBUG
diff --git a/OvmfPkg/PlatformPei/MemDetect.c b/OvmfPkg/PlatformPei/MemDetect.c
index 2c2c4641ec8a..8125644bc91a 100644
--- a/OvmfPkg/PlatformPei/MemDetect.c
+++ b/OvmfPkg/PlatformPei/MemDetect.c
@@ -15,6 +15,7 @@ Module Name:
 //
 #include <IndustryStandard/E820.h>
 #include <IndustryStandard/I440FxPiix4.h>
+#include <IndustryStandard/Microvm.h>
 #include <IndustryStandard/Q35MchIch9.h>
 #include <PiPei.h>
 #include <Register/Intel/SmramSaveStateMap.h>
@@ -135,6 +136,10 @@ QemuUc32BaseInitialization (
   UINT32 LowerMemorySize;
   UINT32 Uc32Size;
 
+  if (mHostBridgeDevId == MICROVM_PSEUDO_DEVICE_ID) {
+    return;
+  }
+
   if (mHostBridgeDevId == INTEL_Q35_MCH_DEVICE_ID) {
     //
     // On q35, the 32-bit area that we'll mark as UC, through variable MTRRs,
diff --git a/OvmfPkg/PlatformPei/Platform.c b/OvmfPkg/PlatformPei/Platform.c
index d3a20122a2ea..ed93d11c8ac6 100644
--- a/OvmfPkg/PlatformPei/Platform.c
+++ b/OvmfPkg/PlatformPei/Platform.c
@@ -31,6 +31,7 @@
 #include <Library/ResourcePublicationLib.h>
 #include <Ppi/MasterBootMode.h>
 #include <IndustryStandard/I440FxPiix4.h>
+#include <IndustryStandard/Microvm.h>
 #include <IndustryStandard/Pci22.h>
 #include <IndustryStandard/Q35MchIch9.h>
 #include <IndustryStandard/QemuCpuHotplug.h>
@@ -714,7 +715,11 @@ InitializePlatform (
   //
   // Query Host Bridge DID
   //
+#ifdef PLATFORM_IS_MICROVM
+  mHostBridgeDevId = MICROVM_PSEUDO_DEVICE_ID;
+#else
   mHostBridgeDevId = PciRead16 (OVMF_HOSTBRIDGE_DID);
+#endif
 
   MaxCpuCountInitialization ();