[PATCH] x86/PCI: add 16GB guard between end of memory and new PCI window

[Christian KÃnig]

Add a workaround for buggy BIOS implementations who steal memory for
iGPUs from the OS without reporting it as reserved.

Signed-off-by: Christian KÃnig <christian.koenig@xxxxxxx>
Tested-by: Aaro Koskinen <aaro.koskinen@xxxxxx>
---
 arch/x86/pci/fixup.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/pci/fixup.c b/arch/x86/pci/fixup.c
index e663d6bf1328..e1bdae2cebb6 100644
--- a/arch/x86/pci/fixup.c
+++ b/arch/x86/pci/fixup.c
@@ -713,6 +713,10 @@ static void pci_amd_enable_64bit_bar(struct pci_dev *dev)
 		}
 		res->start = conflict->end + 1;
 	}
+	/* Add 16GB guard between end of memory and new PCI window to work
+	 * around buggy BIOS implementations.
+	 */
+	res->start += 0x400000000ull;
 
 	dev_info(&dev->dev, "adding root bus resource %pR\n", res);
 
-- 
2.11.0


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