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OvmfPkg/XenSupport: turn off address decoding before BAR sizing

On Xen, hvmloader firmware leaves address decoding enabled for
enumerated PCI device before jumping into OVMF. OVMF seems to
expect it to be disabled and tries to size PCI BARs in several places
without disabling it which causes BAR64, for example, being
incorrectly placed by QEMU.

Fix it by disabling PCI address decoding explicitly before the
first attempt to size BARs on Xen.

Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
Igor Druzhinin 5 vuotta sitten
vanhempi
commit
0c40c9c925
1 muutettua tiedostoa jossa 21 lisäystä ja 0 poistoa
  1. 21 0
      OvmfPkg/Library/PciHostBridgeLib/XenSupport.c

+ 21 - 0
OvmfPkg/Library/PciHostBridgeLib/XenSupport.c

@@ -49,6 +49,22 @@ PcatPciRootBridgeBarExisted (
   EnableInterrupts ();
 }
 
+#define PCI_COMMAND_DECODE ((UINT16)(EFI_PCI_COMMAND_IO_SPACE | \
+                                     EFI_PCI_COMMAND_MEMORY_SPACE))
+STATIC
+VOID
+PcatPciRootBridgeDecodingDisable (
+  IN  UINTN                          Address
+  )
+{
+  UINT16                             Value;
+
+  Value = PciRead16 (Address);
+  if (Value & PCI_COMMAND_DECODE) {
+    PciWrite16 (Address, Value & ~(UINT32)PCI_COMMAND_DECODE);
+  }
+}
+
 STATIC
 VOID
 PcatPciRootBridgeParseBars (
@@ -75,6 +91,11 @@ PcatPciRootBridgeParseBars (
   UINT64                            Limit;
   PCI_ROOT_BRIDGE_APERTURE          *MemAperture;
 
+  // Disable address decoding for every device before OVMF starts sizing it
+  PcatPciRootBridgeDecodingDisable (
+    PCI_LIB_ADDRESS (Bus, Device, Function, PCI_COMMAND_OFFSET)
+  );
+
   for (Offset = BarOffsetBase; Offset < BarOffsetEnd; Offset += sizeof (UINT32)) {
     PcatPciRootBridgeBarExisted (
       PCI_LIB_ADDRESS (Bus, Device, Function, Offset),