There is a possibility of having just one DMA window available with
a limited capacity which the existing code does not handle that well.
If the window is big enough for the system RAM but less than
MAX_PHYSMEM_BITS (which we want when persistent memory is present),
we create 1:1 window and leave persistent memory without DMA.
This disables 1:1 mapping entirely if there is persistent memory and
either:
- the huge DMA window does not cover the entire address space;
- the default DMA window is removed.
This relies on reverted 54fc3c681ded
("powerpc/pseries/ddw: Extend upper limit for huge DMA window for persistent
memory")
to return the actual amount RAM in ddw_memory_hotplug_max() (posted
separately).
Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
---
arch/powerpc/platforms/pseries/iommu.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/iommu.c
b/arch/powerpc/platforms/pseries/iommu.c
index 301fa5b3d528..8f998e55735b 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -1356,8 +1356,10 @@ static bool enable_ddw(struct pci_dev *dev, struct
device_node *pdn)
len = order_base_2(query.largest_available_block << page_shift);
win_name = DMA64_PROPNAME;
} else {
- direct_mapping = true;
- win_name = DIRECT64_PROPNAME;
+ direct_mapping = !default_win_removed ||
+ (len == MAX_PHYSMEM_BITS) ||
+ (!pmem_present && (len == max_ram_len));
+ win_name = direct_mapping ? DIRECT64_PROPNAME : DMA64_PROPNAME;
}
ret = create_ddw(dev, ddw_avail, &create, page_shift, len);
--
2.30.2
