Patch "powerpc/ioda: Set "read" permission when "write" is set" has been added to the 4.4-stable tree

Patch "powerpc/ioda: Set "read" permission when "write" is set" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

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

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     powerpc-ioda-set-read-permission-when-write-is-set.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 6ecad912a0073c768db1491c27ca55ad2d0ee68f Mon Sep 17 00:00:00 2001
From: Alexey Kardashevskiy <aik@ozlabs.ru>
Date: Wed, 17 Feb 2016 18:26:31 +1100
Subject: powerpc/ioda: Set "read" permission when "write" is set

From: Alexey Kardashevskiy <aik@ozlabs.ru>

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>

---
 arch/powerpc/platforms/powernv/pci.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- 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 *tb
 	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
 
 	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);


Patches currently in stable-queue which might be from aik@ozlabs.ru are

queue-4.4/powerpc-ioda-set-read-permission-when-write-is-set.patch