[PATCH 2/2] OvmfPkg/PlatformInitLib: check 64bit mmio window for resource conflicts

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

Add new operation mode to PlatformScanOrAdd64BitE820Ram() which checks
whenever any reservations from the qemu e820 table overlap with the mmio
window.  Should that be the case move it to avoid the conflict.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 OvmfPkg/Library/PlatformInitLib/MemDetect.c | 47 ++++++++++++++++++---
 1 file changed, 41 insertions(+), 6 deletions(-)

diff --git a/OvmfPkg/Library/PlatformInitLib/MemDetect.c b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
index 1255d6300fdd..4f5a04832a4e 100644
--- a/OvmfPkg/Library/PlatformInitLib/MemDetect.c
+++ b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
@@ -126,6 +126,12 @@ PlatformQemuUc32BaseInitialization (
                           entries that start at or above 4GB.
                           It also produces HOBs for reserved entries.
 
+  @param[in out] PlatformInfoHob  If Lowmemory PlatformInfoHob is not NULL,
+                                  then PlatformScanOrAdd64BitE820Ram() checks
+                                  the 64bit PCI MMIO window against conflicts
+                                  with e820 reservations from qemu.  If needed
+                                  the MMIO window will be moved down.
+
   @param[out] LowMemory  If Lowmemory is not NULL, then Lowmemory MaxAddress
                          holds the amout of emory below 4G on output.
 
@@ -147,9 +153,10 @@ PlatformQemuUc32BaseInitialization (
 STATIC
 EFI_STATUS
 PlatformScanOrAdd64BitE820Ram (
-  IN BOOLEAN  AddHighHob,
-  OUT UINT64  *LowMemory OPTIONAL,
-  OUT UINT64  *MaxAddress OPTIONAL
+  IN BOOLEAN                    AddHighHob,
+  IN OUT EFI_HOB_PLATFORM_INFO  *PlatformInfoHob OPTIONAL,
+  OUT UINT64                    *LowMemory OPTIONAL,
+  OUT UINT64                    *MaxAddress OPTIONAL
   )
 {
   EFI_STATUS            Status;
@@ -249,6 +256,33 @@ PlatformScanOrAdd64BitE820Ram (
           E820Entry.Length
           );
       }
+
+      if (PlatformInfoHob) {
+        UINT64  IntersectionBase = MAX (
+                                     E820Entry.BaseAddr,
+                                     PlatformInfoHob->PcdPciMmio64Base
+                                     );
+        UINT64  IntersectionEnd = MIN (
+                                    E820Entry.BaseAddr + E820Entry.Length,
+                                    PlatformInfoHob->PcdPciMmio64Base +
+                                    PlatformInfoHob->PcdPciMmio64Size
+                                    );
+
+        if (IntersectionBase < IntersectionEnd) {
+          // have overlap, so move mmio window down from end of address space
+          UINT64  NewBase = (PlatformInfoHob->PcdPciMmio64Base -
+                             PlatformInfoHob->PcdPciMmio64Size);
+
+          DEBUG ((
+            DEBUG_INFO,
+            "%a: move mmio: 0x%Lx => %Lx\n",
+            __FUNCTION__,
+            PlatformInfoHob->PcdPciMmio64Base,
+            NewBase
+            ));
+          PlatformInfoHob->PcdPciMmio64Base = NewBase;
+        }
+      }
     }
   }
 
@@ -340,7 +374,7 @@ PlatformGetSystemMemorySizeBelow4gb (
     return (UINT32)GetHighestSystemMemoryAddressFromPvhMemmap (TRUE);
   }
 
-  Status = PlatformScanOrAdd64BitE820Ram (FALSE, &LowerMemorySize, NULL);
+  Status = PlatformScanOrAdd64BitE820Ram (FALSE, NULL, &LowerMemorySize, NULL);
   if ((Status == EFI_SUCCESS) && (LowerMemorySize > 0)) {
     return (UINT32)LowerMemorySize;
   }
@@ -412,7 +446,7 @@ PlatformGetFirstNonAddress (
   // Otherwise, get the flat size of the memory above 4GB from the CMOS (which
   // can only express a size smaller than 1TB), and add it to 4GB.
   //
-  Status = PlatformScanOrAdd64BitE820Ram (FALSE, NULL, &FirstNonAddress);
+  Status = PlatformScanOrAdd64BitE820Ram (FALSE, NULL, NULL, &FirstNonAddress);
   if (EFI_ERROR (Status)) {
     FirstNonAddress = BASE_4GB + PlatformGetSystemMemorySizeAbove4gb ();
   }
@@ -648,6 +682,7 @@ PlatformDynamicMmioWindow (
     DEBUG ((DEBUG_INFO, "%a:   MMIO Space 0x%Lx (%Ld GB)\n", __func__, MmioSpace, RShiftU64 (MmioSpace, 30)));
     PlatformInfoHob->PcdPciMmio64Size = MmioSpace;
     PlatformInfoHob->PcdPciMmio64Base = AddrSpace - MmioSpace;
+    PlatformScanOrAdd64BitE820Ram (FALSE, PlatformInfoHob, NULL, NULL);
   } else {
     DEBUG ((DEBUG_INFO, "%a: using classic mmio window\n", __func__));
   }
@@ -960,7 +995,7 @@ PlatformQemuInitializeRam (
     // entries. Otherwise, create a single memory HOB with the flat >=4GB
     // memory size read from the CMOS.
     //
-    Status = PlatformScanOrAdd64BitE820Ram (TRUE, NULL, NULL);
+    Status = PlatformScanOrAdd64BitE820Ram (TRUE, NULL, NULL, NULL);
     if (EFI_ERROR (Status)) {
       UpperMemorySize = PlatformGetSystemMemorySizeAbove4gb ();
       if (UpperMemorySize != 0) {
-- 
2.39.0