powerpc/ioda: Set "read" permission when "write" is set

commit 6ecad912a0073c768db1491c27ca55ad2d0ee68f upstream.

Quite often drivers set only "write" permission assuming that this
includes "read" permission as well and this works on plenty of
platforms. However IODA2 is strict about this and produces an EEH when
"read" permission is not set and reading happens.

This adds a workaround in the IODA code to always add the "read" bit
when the "write" bit is set.

Fixes: 10b35b2b7485 ("powerpc/powernv: Do not set "read" flag if direction==DMA_NONE")
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Tested-by: Douglas Miller <dougmill@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
index c97c76f9ad845e9c160a0cc8c12800c8a0a03e00..ad8c3f4a5e0bec7a839b624ab99c5238f472f18f 100644 (file)
--- a/arch/powerpc/platforms/powernv/pci.c
+++ b/arch/powerpc/platforms/powernv/pci.c
@@ -601,6 +601,9 @@ int pnv_tce_build(struct iommu_table *tbl, long index, long npages,
        u64 rpn = __pa(uaddr) >> tbl->it_page_shift;
        long i;
 
+       if (proto_tce & TCE_PCI_WRITE)
+               proto_tce |= TCE_PCI_READ;
+
        for (i = 0; i < npages; i++) {
                unsigned long newtce = proto_tce |
                        ((rpn + i) << tbl->it_page_shift);
@@ -622,6 +625,9 @@ int pnv_tce_xchg(struct iommu_table *tbl, long index,
 
        BUG_ON(*hpa & ~IOMMU_PAGE_MASK(tbl));
 
+       if (newtce & TCE_PCI_WRITE)
+               newtce |= TCE_PCI_READ;
+
        oldtce = xchg(pnv_tce(tbl, idx), cpu_to_be64(newtce));
        *hpa = be64_to_cpu(oldtce) & ~(TCE_PCI_READ | TCE_PCI_WRITE);
        *direction = iommu_tce_direction(oldtce);