From 5ff6bd6ff1f10e03d9dbb6006e7485bcfb591226 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Tue, 20 Apr 2021 01:54:04 -0300
Subject: powerpc/pseries/iommu: Fix window size for direct mapping with pmem

From: Leonardo Bras <leobras.c@gmail.com>

[ Upstream commit a9d2f9bb225fd2a764aef57738ab6c7f38d782ae ]

As of today, if the DDW is big enough to fit (1 << MAX_PHYSMEM_BITS)
it's possible to use direct DMA mapping even with pmem region.

But, if that happens, the window size (len) is set to (MAX_PHYSMEM_BITS
- page_shift) instead of MAX_PHYSMEM_BITS, causing a pagesize times
smaller DDW to be created, being insufficient for correct usage.

Fix this so the correct window size is used in this case.

Fixes: bf6e2d562bbc4 ("powerpc/dma: Fallback to dma_ops when persistent memory present")
Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210420045404.438735-1-leobras.c@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/powerpc/platforms/pseries/iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 9fc5217f0c8e..836cbbe0ecc5 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -1229,7 +1229,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	if (pmem_present) {
 		if (query.largest_available_block >=
 		    (1ULL << (MAX_PHYSMEM_BITS - page_shift)))
-			len = MAX_PHYSMEM_BITS - page_shift;
+			len = MAX_PHYSMEM_BITS;
 		else
 			dev_info(&dev->dev, "Skipping ibm,pmemory");
 	}
-- 
2.30.2