[3.16.y-ckt stable] Patch "config: Enable NEED_DMA_MAP_STATE by default when SWIOTLB is selected" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    config: Enable NEED_DMA_MAP_STATE by default when SWIOTLB is selected

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt13.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 13242f9325fc927df3d3f32b0b5685bf419aa994 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Date: Fri, 17 Apr 2015 15:04:48 -0400
Subject: config: Enable NEED_DMA_MAP_STATE by default when SWIOTLB is selected

commit a6dfa128ce5c414ab46b1d690f7a1b8decb8526d upstream.

A huge amount of NIC drivers use the DMA API, however if
compiled under 32-bit an very important part of the DMA API can
be ommitted leading to the drivers not working at all
(especially if used with 'swiotlb=force iommu=soft').

As Prashant Sreedharan explains it: "the driver [tg3] uses
DEFINE_DMA_UNMAP_ADDR(), dma_unmap_addr_set() to keep a copy of
the dma "mapping" and dma_unmap_addr() to get the "mapping"
value. On most of the platforms this is a no-op, but ... with
"iommu=soft and swiotlb=force" this house keeping is required,
... otherwise we pass 0 while calling pci_unmap_/pci_dma_sync_
instead of the DMA address."

As such enable this even when using 32-bit kernels.

Reported-by: Ian Jackson <Ian.Jackson at eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Acked-by: David S. Miller <davem at davemloft.net>
Acked-by: Prashant Sreedharan <prashant at broadcom.com>
Cc: Borislav Petkov <bp at alien8.de>
Cc: H. Peter Anvin <hpa at zytor.com>
Cc: Linus Torvalds <torvalds at linux-foundation.org>
Cc: Michael Chan <mchan at broadcom.com>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: boris.ostrovsky at oracle.com
Cc: cascardo at linux.vnet.ibm.com
Cc: david.vrabel at citrix.com
Cc: sanjeevb at broadcom.com
Cc: siva.kallam at broadcom.com
Cc: vyasevich at gmail.com
Cc: xen-devel at lists.xensource.com
Link: http://lkml.kernel.org/r/20150417190448.GA9462@l.oracle.com
Signed-off-by: Ingo Molnar <mingo at kernel.org>
Cc: Ben Hutchings <ben at decadent.org.uk>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/x86/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 12c8ea635f4d..04fe4a66c3ec 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -164,7 +164,7 @@ config SBUS

 config NEED_DMA_MAP_STATE
 	def_bool y
-	depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG
+	depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB

 config NEED_SG_DMA_LENGTH
 	def_bool y