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authorLaszlo Ersek <lersek@redhat.com>2015-07-14 12:02:34 +0000
committerlersek <lersek@Edk2>2015-07-14 12:02:34 +0000
commit68306ac2f2e7b85fc0d592248f68679139809b1a (patch)
tree3724491ccb5429769459cf9ee9e87346f2601cee /OvmfPkg
parentbdb1c98f036154b53d97cd5a30e49878e85fa8cb (diff)
downloadedk2-platforms-68306ac2f2e7b85fc0d592248f68679139809b1a.tar.xz
OvmfPkg: PciHostBridgeDxe: shorten search for extra root buses
QEMU provides an fw_cfg file called "etc/extra-pci-roots", containing a little-endian UINT64 value that exposes the number of extra root buses. We can use this value to terminate the scan as soon as we find the last extra root bus. Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Regression-tested-by: Gabriel Somlo <somlo@cmu.edu> Reviewed-by: Jordan Justen <jordan.l.justen@intel.com> git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17963 6f19259b-4bc3-4df7-8a09-765794883524
Diffstat (limited to 'OvmfPkg')
-rw-r--r--OvmfPkg/PciHostBridgeDxe/PciHostBridge.c22
-rw-r--r--OvmfPkg/PciHostBridgeDxe/PciHostBridgeDxe.inf2
2 files changed, 23 insertions, 1 deletions
diff --git a/OvmfPkg/PciHostBridgeDxe/PciHostBridge.c b/OvmfPkg/PciHostBridgeDxe/PciHostBridge.c
index 348664438d..efef2ed79e 100644
--- a/OvmfPkg/PciHostBridgeDxe/PciHostBridge.c
+++ b/OvmfPkg/PciHostBridgeDxe/PciHostBridge.c
@@ -15,6 +15,8 @@
**/
+#include <Library/QemuFwCfgLib.h>
+
#include "PciHostBridge.h"
STATIC
@@ -207,6 +209,9 @@ InitializePciHostBridge (
)
{
EFI_STATUS Status;
+ FIRMWARE_CONFIG_ITEM FwCfgItem;
+ UINTN FwCfgSize;
+ UINT64 ExtraRootBridgesLeft;
UINTN LastRootBridgeNumber;
UINTN RootBridgeNumber;
PCI_HOST_BRIDGE_INSTANCE *HostBridge;
@@ -237,6 +242,20 @@ InitializePciHostBridge (
}
//
+ // QEMU provides the number of extra root buses, shortening the exhaustive
+ // search below. If there is no hint, the feature is missing.
+ //
+ Status = QemuFwCfgFindFile ("etc/extra-pci-roots", &FwCfgItem, &FwCfgSize);
+ if (EFI_ERROR (Status) || FwCfgSize != sizeof ExtraRootBridgesLeft) {
+ ExtraRootBridgesLeft = 0;
+ } else {
+ QemuFwCfgSelectItem (FwCfgItem);
+ QemuFwCfgReadBytes (FwCfgSize, &ExtraRootBridgesLeft);
+ DEBUG ((EFI_D_INFO, "%a: %Lu extra root buses reported by QEMU\n",
+ __FUNCTION__, ExtraRootBridgesLeft));
+ }
+
+ //
// The "main" root bus is always there.
//
LastRootBridgeNumber = 0;
@@ -247,7 +266,7 @@ InitializePciHostBridge (
// alive.
//
for (RootBridgeNumber = 1;
- RootBridgeNumber < 256;
+ RootBridgeNumber < 256 && ExtraRootBridgesLeft > 0;
++RootBridgeNumber) {
UINTN Device;
@@ -271,6 +290,7 @@ InitializePciHostBridge (
}
InsertTailList (&HostBridge->Head, &RootBus->Link);
LastRootBridgeNumber = RootBridgeNumber;
+ --ExtraRootBridgesLeft;
}
}
diff --git a/OvmfPkg/PciHostBridgeDxe/PciHostBridgeDxe.inf b/OvmfPkg/PciHostBridgeDxe/PciHostBridgeDxe.inf
index 40f4c3cc34..ca760b5497 100644
--- a/OvmfPkg/PciHostBridgeDxe/PciHostBridgeDxe.inf
+++ b/OvmfPkg/PciHostBridgeDxe/PciHostBridgeDxe.inf
@@ -26,6 +26,7 @@
[Packages]
MdePkg/MdePkg.dec
+ OvmfPkg/OvmfPkg.dec
[LibraryClasses]
UefiDriverEntryPoint
@@ -39,6 +40,7 @@
DevicePathLib
IoLib
PciLib
+ QemuFwCfgLib
[Sources]
PciHostBridge.c