[PATCH RFC 06/14] OvmfPkg/XenPlatformPei: Add xen PVH specific code

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

- learn about memory size from the E820
- ignore error if host bridge devid is 0xffff, PVH does not have PCI and
  reading from unexisting device return -1.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
---
 OvmfPkg/XenPlatformPei/MemDetect.c | 71 ++++++++++++++++++++++++++++++++++++++
 OvmfPkg/XenPlatformPei/Platform.c  |  5 +++
 OvmfPkg/XenPlatformPei/Platform.h  | 10 ++++++
 3 files changed, 86 insertions(+)

diff --git a/OvmfPkg/XenPlatformPei/MemDetect.c b/OvmfPkg/XenPlatformPei/MemDetect.c
index 4ecdf5e..0d80775 100644
--- a/OvmfPkg/XenPlatformPei/MemDetect.c
+++ b/OvmfPkg/XenPlatformPei/MemDetect.c
@@ -42,6 +42,70 @@ UINT8 mPhysMemAddressWidth;
 STATIC UINT32 mS3AcpiReservedMemoryBase;
 STATIC UINT32 mS3AcpiReservedMemorySize;
 
+STATIC UINT32 mXenLowerMemorySize = 0;
+STATIC UINT64 mXenHighMemorySize = 0;
+
+VOID
+XenReadMemorySizes (
+  VOID
+  )
+{
+  EFI_E820_ENTRY64  *E820Map;
+  UINT32            E820EntriesCount;
+  EFI_STATUS Status;
+
+  Status = XenGetE820Map (&E820Map, &E820EntriesCount);
+  ASSERT_EFI_ERROR (Status);
+
+  mXenLowerMemorySize = 0;
+  mXenHighMemorySize = 0;
+
+  if (E820EntriesCount > 0) {
+    EFI_E820_ENTRY64 *Entry;
+    UINT32 Loop;
+
+    for (Loop = 0; Loop < E820EntriesCount; Loop++) {
+      Entry = E820Map + Loop;
+
+      //
+      // Only care about RAM
+      //
+      if (Entry->Type != EfiAcpiAddressRangeMemory) {
+        continue;
+      }
+
+      if ((Entry->BaseAddr + Entry->Length) <= SIZE_16MB) {
+        continue;
+      }
+
+      if (Entry->BaseAddr < SIZE_16MB) {
+        UINT64 bottom = Entry->BaseAddr;
+        UINT64 size = Entry->Length;
+        size -= SIZE_16MB - bottom;
+        bottom = SIZE_16MB;
+        mXenLowerMemorySize += size;
+        continue;
+      }
+      if (Entry->BaseAddr <= SIZE_4GB) {
+        UINT64 size = Entry->Length;
+        mXenLowerMemorySize += size;
+        continue;
+      }
+
+      if (Entry->BaseAddr == SIZE_4GB) {
+        mXenHighMemorySize = Entry->Length;
+        continue;
+      }
+
+      DEBUG ((EFI_D_INFO, "%a: ignored XenE820 entry (0x%llx, 0x%llx)\n",
+              __FUNCTION__,
+              Entry->BaseAddr,
+              Entry->Length));
+    }
+    mXenLowerMemorySize += SIZE_16MB;
+  }
+}
+
 UINT32
 GetSystemMemorySizeBelow4gb (
   VOID
@@ -50,6 +114,9 @@ GetSystemMemorySizeBelow4gb (
   UINT8 Cmos0x34;
   UINT8 Cmos0x35;
 
+  if (mXen && mXenLowerMemorySize)
+    return mXenLowerMemorySize;
+
   //
   // CMOS 0x34/0x35 specifies the system memory above 16 MB.
   // * CMOS(0x35) is the high byte
@@ -74,6 +141,10 @@ GetSystemMemorySizeAbove4gb (
   UINT32 Size;
   UINTN  CmosIndex;
 
+  // if lower memory is specified that way, return also high memory
+  if (mXen && mXenLowerMemorySize)
+    return mXenHighMemorySize;
+
   //
   // CMOS 0x5b-0x5d specifies the system memory above 4GB MB.
   // * CMOS(0x5d) is the most significant size byte
diff --git a/OvmfPkg/XenPlatformPei/Platform.c b/OvmfPkg/XenPlatformPei/Platform.c
index bf78878..9fc713c 100644
--- a/OvmfPkg/XenPlatformPei/Platform.c
+++ b/OvmfPkg/XenPlatformPei/Platform.c
@@ -362,6 +362,10 @@ MiscInitialization (
       AcpiCtlReg = POWER_MGMT_REGISTER_Q35 (ICH9_ACPI_CNTL);
       AcpiEnBit  = ICH9_ACPI_CNTL_ACPI_EN;
       break;
+    case 0xffff:
+      // xen PVH, ignore
+      PcdStatus = PcdSet16S (PcdOvmfHostBridgePciDevId, mHostBridgeDevId);
+      return;
     default:
       DEBUG ((EFI_D_ERROR, "%a: Unknown Host Bridge Device ID: 0x%04x\n",
         __FUNCTION__, mHostBridgeDevId));
@@ -503,6 +507,7 @@ InitializeXenPlatform (
   DebugDumpCmos ();
 
   XenDetect ();
+  XenReadMemorySizes ();
 
   BootModeInitialization ();
   AddressWidthInitialization ();
diff --git a/OvmfPkg/XenPlatformPei/Platform.h b/OvmfPkg/XenPlatformPei/Platform.h
index eda765b..2948853 100644
--- a/OvmfPkg/XenPlatformPei/Platform.h
+++ b/OvmfPkg/XenPlatformPei/Platform.h
@@ -101,4 +101,14 @@ extern BOOLEAN mS3Supported;
 
 extern UINT8 mPhysMemAddressWidth;
 
+EFI_STATUS
+XenGetE820Map (
+  EFI_E820_ENTRY64 **Entries,
+  UINT32 *Count
+  );
+VOID
+XenReadMemorySizes (
+  VOID
+  );
+
 #endif // _PLATFORM_PEI_H_INCLUDED_
-- 
Anthony PERARD