ArmVirtPkg/VirtFdtDxe: set /chosen/linux,pci-probe-only to 1 in DTB

[mirror_edk2.git] / ArmVirtPkg / VirtFdtDxe / VirtFdtDxe.c

diff --git a/ArmVirtPkg/VirtFdtDxe/VirtFdtDxe.c b/ArmVirtPkg/VirtFdtDxe/VirtFdtDxe.c
index 74f80d1d2b78bc30c1e2a56eb3e15b688f4b31a2..437b2a8792160626d826970bde84d6c8da67db4d 100644 (file)
--- a/ArmVirtPkg/VirtFdtDxe/VirtFdtDxe.c
+++ b/ArmVirtPkg/VirtFdtDxe/VirtFdtDxe.c
@@ -304,6 +304,7 @@ InitializeVirtFdtDxe (
   UINT64                         FwCfgDataSize;\r
   UINT64                         FwCfgDmaAddress;\r
   UINT64                         FwCfgDmaSize;\r
+  BOOLEAN                        HavePci;\r
 \r
   Hob = GetFirstGuidHob(&gFdtHobGuid);\r
   if (Hob == NULL || GET_GUID_HOB_DATA_SIZE (Hob) != sizeof (UINT64)) {\r
@@ -322,6 +323,7 @@ InitializeVirtFdtDxe (
   DEBUG ((EFI_D_INFO, "%a: DTB @ 0x%p\n", __FUNCTION__, DeviceTreeBase));\r
 \r
   RtcNode = -1;\r
+  HavePci = FALSE;\r
   //\r
   // Now enumerate the nodes and install peripherals that we are interested in,\r
   // i.e., GIC, RTC and virtio MMIO nodes\r
@@ -356,6 +358,7 @@ InitializeVirtFdtDxe (
       ASSERT (Len == 2 * sizeof (UINT64));\r
       Status = ProcessPciHost (DeviceTreeBase, Node, RegProp);\r
       ASSERT_EFI_ERROR (Status);\r
+      HavePci = TRUE;\r
       break;\r
 \r
     case PropertyTypeFwCfg:\r
@@ -579,5 +582,28 @@ InitializeVirtFdtDxe (
         "disabled") != 0) {\r
     DEBUG ((EFI_D_WARN, "Failed to set PL031 status to 'disabled'\n"));\r
   }\r
+\r
+  if (HavePci) {\r
+    //\r
+    // Set the /chosen/linux,pci-probe-only property to 1, so that the PCI\r
+    // setup we will perform in the firmware is honored by the Linux OS,\r
+    // rather than torn down and done from scratch. This is generally a more\r
+    // sensible approach, and aligns with what ACPI based OSes do in general.\r
+    //\r
+    // In case we are exposing an emulated VGA PCI device to the guest, which\r
+    // may subsequently get exposed via the Graphics Output protocol and\r
+    // driven as an efifb by Linux, we need this setting to prevent the\r
+    // framebuffer from becoming unresponsive.\r
+    //\r
+    Node = fdt_path_offset (DeviceTreeBase, "/chosen");\r
+    if (Node < 0) {\r
+      Node = fdt_add_subnode (DeviceTreeBase, 0, "/chosen");\r
+    }\r
+    if (Node < 0 ||\r
+        fdt_setprop_u32 (DeviceTreeBase, Node, "linux,pci-probe-only", 1) < 0) {\r
+      DEBUG ((EFI_D_WARN, "Failed to set /chosen/linux,pci-probe-only property\n"));\r
+    }\r
+  }\r
+\r
   return EFI_SUCCESS;\r
 }\r