[PATCH 1/2] powerpc/vas: Report proper error for address translation failure

[Haren Myneni]

DMA controller uses CC=5 internally for translation fault handling. So
OS should be using CC=250 and should report this error to the user space
when NX encounters address translation failure on the request buffer.
Not an issue in earlier releases as NX does not get faults on
kernel addresses.

This patch defines CSB_CC_ADDRESS_TRANSLATION(250) and updates
CSB.CC with this proper error code for user space.

Signed-off-by: Haren Myneni <haren at linux.ibm.com>
---
 Documentation/powerpc/vas-api.rst          | 2 +-
 arch/powerpc/include/asm/icswx.h           | 2 ++
 arch/powerpc/platforms/powernv/vas-fault.c | 2 +-
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/Documentation/powerpc/vas-api.rst b/Documentation/powerpc/vas-api.rst
index 1217c2f..78627cc 100644
--- a/Documentation/powerpc/vas-api.rst
+++ b/Documentation/powerpc/vas-api.rst
@@ -213,7 +213,7 @@ request buffers are not in memory. The operating system handles the fault by
 updating CSB with the following data:
 
 	csb.flags = CSB_V;
-	csb.cc = CSB_CC_TRANSLATION;
+	csb.cc = CSB_CC_ADDRESS_TRANSLATION;
 	csb.ce = CSB_CE_TERMINATION;
 	csb.address = fault_address;
 
diff --git a/arch/powerpc/include/asm/icswx.h b/arch/powerpc/include/asm/icswx.h
index 965b1f3..b1c9a57 100644
--- a/arch/powerpc/include/asm/icswx.h
+++ b/arch/powerpc/include/asm/icswx.h
@@ -77,6 +77,8 @@ struct coprocessor_completion_block {
 #define CSB_CC_CHAIN		(37)
 #define CSB_CC_SEQUENCE		(38)
 #define CSB_CC_HW		(39)
+/* User space address traslation failure */
+#define	CSB_CC_ADDRESS_TRANSLATION	(250)
 
 #define CSB_SIZE		(0x10)
 #define CSB_ALIGN		CSB_SIZE
diff --git a/arch/powerpc/platforms/powernv/vas-fault.c b/arch/powerpc/platforms/powernv/vas-fault.c
index 266a6ca..33e89d4 100644
--- a/arch/powerpc/platforms/powernv/vas-fault.c
+++ b/arch/powerpc/platforms/powernv/vas-fault.c
@@ -79,7 +79,7 @@ static void update_csb(struct vas_window *window,
 	csb_addr = (void __user *)be64_to_cpu(crb->csb_addr);
 
 	memset(&csb, 0, sizeof(csb));
-	csb.cc = CSB_CC_TRANSLATION;
+	csb.cc = CSB_CC_ADDRESS_TRANSLATION;
 	csb.ce = CSB_CE_TERMINATION;
 	csb.cs = 0;
 	csb.count = 0;
-- 
1.8.3.1