Linux-libre 4.2.3-gnupck-4.2.3-gnu

1 files changed, 15 insertions, 1 deletions

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 85cbc96ef..8b64f89e6 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -2078,9 +2078,23 @@ static long pnv_pci_ioda2_setup_default_config(struct pnv_ioda_pe *pe)
 	struct iommu_table *tbl = NULL;
 	long rc;
 
+	/*
+	 * crashkernel= specifies the kdump kernel's maximum memory at
+	 * some offset and there is no guaranteed the result is a power
+	 * of 2, which will cause errors later.
+	 */
+	const u64 max_memory = __rounddown_pow_of_two(memory_hotplug_max());
+
+	/*
+	 * In memory constrained environments, e.g. kdump kernel, the
+	 * DMA window can be larger than available memory, which will
+	 * cause errors later.
+	 */
+	const u64 window_size = min((u64)pe->table_group.tce32_size, max_memory);
+
 	rc = pnv_pci_ioda2_create_table(&pe->table_group, 0,
 			IOMMU_PAGE_SHIFT_4K,
-			pe->table_group.tce32_size,
+			window_size,
 			POWERNV_IOMMU_DEFAULT_LEVELS, &tbl);
 	if (rc) {
 		pe_err(pe, "Failed to create 32-bit TCE table, err %ld",