When running as a Xen PVH guest, there is no CMOS to read the memory
size from.  Rework GetSystemMemorySize(Below|Above)4gb() so they can
work without CMOS by reading the e820 table.

Rework XenPublishRamRegions to also care for the reserved and ACPI
entry in the e820 table. The region that was added by InitializeXen()
isn't needed as that same entry is in the e820 table provided by
hvmloader.

MTRR settings aren't modified anymore, on HVM it's already done by
hvmloader, on PVH it is supposed to have sane default. MTRR will need
to be done properly but keeping what's already been done by programs
that have run before OVMF will do for now.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1689
Signed-off-by: Anthony PERARD <anthony.per...@citrix.com>
Acked-by: Laszlo Ersek <ler...@redhat.com>
---

Notes:
    v5:
    - fix coding style
    - fix typo in commit message
    - Handle all possible cases of a E820 reserved range overlapping with the
      LAPIC range.
    
    v4:
    - some coding style
    - Added AddReservedMemoryRangeHob, and using it.
    - this patch now replace "OvmfPkg/XenPlatformPei: Reserve hvmloader's 
memory only when it has run"
      from v3.  hvmloader have added an entry in the e820 table, there is no
      need for a special case.
    - now, everything that is in the e820 table is added to OVMF's memory
      map, no more skipping ACPI entries or hvmloader's reserved entries.
      Instead, we look for the local APIC region and avoid it if it is
      present in the e820.
    - rework commit message

 OvmfPkg/XenPlatformPei/Platform.h  | 13 ++++++
 OvmfPkg/XenPlatformPei/MemDetect.c | 69 +++++++++++++++++++++++++++
 OvmfPkg/XenPlatformPei/Platform.c  | 11 +++++
 OvmfPkg/XenPlatformPei/Xen.c       | 75 +++++++++++++++++++++---------
 4 files changed, 147 insertions(+), 21 deletions(-)

diff --git a/OvmfPkg/XenPlatformPei/Platform.h 
b/OvmfPkg/XenPlatformPei/Platform.h
index db9a62572f..7661f4a8de 100644
--- a/OvmfPkg/XenPlatformPei/Platform.h
+++ b/OvmfPkg/XenPlatformPei/Platform.h
@@ -44,6 +44,13 @@ AddReservedMemoryBaseSizeHob (
   BOOLEAN                     Cacheable
   );
 
+VOID
+AddReservedMemoryRangeHob (
+  EFI_PHYSICAL_ADDRESS        MemoryBase,
+  EFI_PHYSICAL_ADDRESS        MemoryLimit,
+  BOOLEAN                     Cacheable
+  );
+
 VOID
 AddressWidthInitialization (
   VOID
@@ -114,6 +121,12 @@ XenPublishRamRegions (
   VOID
   );
 
+EFI_STATUS
+XenGetE820Map (
+  EFI_E820_ENTRY64 **Entries,
+  UINT32 *Count
+  );
+
 extern EFI_BOOT_MODE mBootMode;
 
 extern UINT8 mPhysMemAddressWidth;
diff --git a/OvmfPkg/XenPlatformPei/MemDetect.c 
b/OvmfPkg/XenPlatformPei/MemDetect.c
index cf95f9c474..1f81eee407 100644
--- a/OvmfPkg/XenPlatformPei/MemDetect.c
+++ b/OvmfPkg/XenPlatformPei/MemDetect.c
@@ -96,6 +96,45 @@ Q35TsegMbytesInitialization (
   mQ35TsegMbytes = ExtendedTsegMbytes;
 }
 
+STATIC
+UINT64
+GetHighestSystemMemoryAddress (
+  BOOLEAN       Below4gb
+  )
+{
+  EFI_E820_ENTRY64    *E820Map;
+  UINT32              E820EntriesCount;
+  EFI_E820_ENTRY64    *Entry;
+  EFI_STATUS          Status;
+  UINT32              Loop;
+  UINT64              HighestAddress;
+  UINT64              EntryEnd;
+
+  HighestAddress = 0;
+
+  Status = XenGetE820Map (&E820Map, &E820EntriesCount);
+  ASSERT_EFI_ERROR (Status);
+
+  for (Loop = 0; Loop < E820EntriesCount; Loop++) {
+    Entry = E820Map + Loop;
+    EntryEnd = Entry->BaseAddr + Entry->Length;
+
+    if (Entry->Type == EfiAcpiAddressRangeMemory &&
+        EntryEnd > HighestAddress) {
+
+      if (Below4gb && (EntryEnd <= BASE_4GB)) {
+        HighestAddress = EntryEnd;
+      } else if (!Below4gb && (EntryEnd >= BASE_4GB)) {
+        HighestAddress = EntryEnd;
+      }
+    }
+  }
+
+  //
+  // Round down the end address.
+  //
+  return HighestAddress & ~(UINT64)EFI_PAGE_MASK;
+}
 
 UINT32
 GetSystemMemorySizeBelow4gb (
@@ -105,6 +144,19 @@ GetSystemMemorySizeBelow4gb (
   UINT8 Cmos0x34;
   UINT8 Cmos0x35;
 
+  //
+  // In PVH case, there is no CMOS, we have to calculate the memory size
+  // from parsing the E820
+  //
+  if (XenPvhDetected ()) {
+    UINT64  HighestAddress;
+
+    HighestAddress = GetHighestSystemMemoryAddress (TRUE);
+    ASSERT (HighestAddress > 0 && HighestAddress <= BASE_4GB);
+
+    return HighestAddress;
+  }
+
   //
   // CMOS 0x34/0x35 specifies the system memory above 16 MB.
   // * CMOS(0x35) is the high byte
@@ -129,6 +181,23 @@ GetSystemMemorySizeAbove4gb (
   UINT32 Size;
   UINTN  CmosIndex;
 
+  //
+  // In PVH case, there is no CMOS, we have to calculate the memory size
+  // from parsing the E820
+  //
+  if (XenPvhDetected ()) {
+    UINT64  HighestAddress;
+
+    HighestAddress = GetHighestSystemMemoryAddress (FALSE);
+    ASSERT (HighestAddress == 0 || HighestAddress >= BASE_4GB);
+
+    if (HighestAddress >= BASE_4GB) {
+      HighestAddress -= BASE_4GB;
+    }
+
+    return HighestAddress;
+  }
+
   //
   // 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 6aaafc3ee9..2f42ca6ccd 100644
--- a/OvmfPkg/XenPlatformPei/Platform.c
+++ b/OvmfPkg/XenPlatformPei/Platform.c
@@ -102,6 +102,17 @@ AddReservedMemoryBaseSizeHob (
     );
 }
 
+VOID
+AddReservedMemoryRangeHob (
+  EFI_PHYSICAL_ADDRESS        MemoryBase,
+  EFI_PHYSICAL_ADDRESS        MemoryLimit,
+  BOOLEAN                     Cacheable
+  )
+{
+  AddReservedMemoryBaseSizeHob (MemoryBase,
+    (UINT64)(MemoryLimit - MemoryBase), Cacheable);
+}
+
 VOID
 AddIoMemoryRangeHob (
   EFI_PHYSICAL_ADDRESS        MemoryBase,
diff --git a/OvmfPkg/XenPlatformPei/Xen.c b/OvmfPkg/XenPlatformPei/Xen.c
index 72f6f37b46..c4506def9a 100644
--- a/OvmfPkg/XenPlatformPei/Xen.c
+++ b/OvmfPkg/XenPlatformPei/Xen.c
@@ -276,9 +276,14 @@ XenPublishRamRegions (
   VOID
   )
 {
-  EFI_E820_ENTRY64  *E820Map;
-  UINT32            E820EntriesCount;
-  EFI_STATUS        Status;
+  EFI_E820_ENTRY64      *E820Map;
+  UINT32                E820EntriesCount;
+  EFI_STATUS            Status;
+  EFI_E820_ENTRY64      *Entry;
+  UINTN                 Index;
+  UINT64                LapicBase;
+  UINT64                LapicEnd;
+
 
   DEBUG ((DEBUG_INFO, "Using memory map provided by Xen\n"));
 
@@ -287,26 +292,60 @@ XenPublishRamRegions (
   //
   E820EntriesCount = 0;
   Status = XenGetE820Map (&E820Map, &E820EntriesCount);
-
   ASSERT_EFI_ERROR (Status);
 
-  if (E820EntriesCount > 0) {
-    EFI_E820_ENTRY64 *Entry;
-    UINT32 Loop;
+  LapicBase = PcdGet32 (PcdCpuLocalApicBaseAddress);
+  LapicEnd = LapicBase + SIZE_1MB;
+  AddIoMemoryRangeHob (LapicBase, LapicEnd);
 
-    for (Loop = 0; Loop < E820EntriesCount; Loop++) {
-      Entry = E820Map + Loop;
+  for (Index = 0; Index < E820EntriesCount; Index++) {
+    UINT64 Base;
+    UINT64 End;
+    UINT64 ReservedBase;
+    UINT64 ReservedEnd;
 
+    Entry = &E820Map[Index];
+
+    //
+    // Round up the start address, and round down the end address.
+    //
+    Base = ALIGN_VALUE (Entry->BaseAddr, (UINT64)EFI_PAGE_SIZE);
+    End = (Entry->BaseAddr + Entry->Length) & ~(UINT64)EFI_PAGE_MASK;
+
+    switch (Entry->Type) {
+    case EfiAcpiAddressRangeMemory:
+      AddMemoryRangeHob (Base, End);
+      break;
+    case EfiAcpiAddressRangeACPI:
+      AddReservedMemoryRangeHob (Base, End, FALSE);
+      break;
+    case EfiAcpiAddressRangeReserved:
       //
-      // Only care about RAM
+      // hvmloader marks a range that overlaps with the local APIC memory
+      // mapped region as reserved, but CpuDxe wants it as mapped IO. We
+      // have already added it as mapped IO, so skip it here.
       //
-      if (Entry->Type != EfiAcpiAddressRangeMemory) {
-        continue;
-      }
 
-      AddMemoryBaseSizeHob (Entry->BaseAddr, Entry->Length);
+      //
+      // add LAPIC predecessor range, if any
+      //
+      ReservedBase = Base;
+      ReservedEnd = MIN (End, LapicBase);
+      if (ReservedBase < ReservedEnd) {
+        AddReservedMemoryRangeHob (ReservedBase, ReservedEnd, FALSE);
+      }
 
-      MtrrSetMemoryAttribute (Entry->BaseAddr, Entry->Length, CacheWriteBack);
+      //
+      // add LAPIC successor range, if any
+      //
+      ReservedBase = MAX (Base, LapicEnd);
+      ReservedEnd = End;
+      if (ReservedBase < ReservedEnd) {
+        AddReservedMemoryRangeHob (ReservedBase, ReservedEnd, FALSE);
+      }
+      break;
+    default:
+      break;
     }
   }
 }
@@ -326,12 +365,6 @@ InitializeXen (
 {
   RETURN_STATUS PcdStatus;
 
-  //
-  // Reserve away HVMLOADER reserved memory [0xFC000000,0xFD000000).
-  // This needs to match HVMLOADER RESERVED_MEMBASE/RESERVED_MEMSIZE.
-  //
-  AddReservedMemoryBaseSizeHob (0xFC000000, 0x1000000, FALSE);
-
   PcdStatus = PcdSetBoolS (PcdPciDisableBusEnumeration, TRUE);
   ASSERT_RETURN_ERROR (PcdStatus);
 
-- 
Anthony PERARD

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