Commit 6ecad912 authored Feb 17, 2016 by Alexey Kardashevskiy Committed by Michael Ellerman Feb 17, 2016

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



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: 10b35b2b ("powerpc/powernv: Do not set "read" flag if direction==DMA_NONE")
Cc: stable@vger.kernel.org # 4.2+
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>

parent c777e2a8

arch/powerpc/platforms/powernv/pci.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -599,6 +599,9 @@ 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);
		@@ -620,6 +623,9 @@ 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);