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powerpc/vas: Report proper error code for address translation failure 

P9 DD2 NX workbook (Table 4-36) says DMA controller uses CC=5
internally for translation fault handling. NX reserves CC=250 for
OS to notify 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_FAULT_ADDRESS(250) and updates CSB.CC with
this proper error code for user space.

Fixes: c96c4436ab ("powerpc/vas: Update CSB and notify process for fault CRBs")
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
[mpe: Added Fixes tag and fix typo in comment]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/019fd53e7538c6f8f332d175df74b1815ef5aa8c.camel@linux.ibm.com
This commit is contained in:
Haren Myneni 2020-07-10 16:47:19 -07:00 committed by Michael Ellerman
parent b710d27bf7
commit 6068e1a442
3 changed files with 4 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/powerpc/vas-api.rst
View File

@ -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_FAULT_ADDRESS;
csb.ce = CSB_CE_TERMINATION;
csb.address = fault_address;

2
arch/powerpc/include/asm/icswx.h
View File

@ -77,6 +77,8 @@ struct coprocessor_completion_block {
#define CSB_CC_CHAIN (37)
#define CSB_CC_SEQUENCE (38)
#define CSB_CC_HW (39)
/* P9 DD2 NX Workbook 3.2 (Table 4-36): Address translation fault */
#define CSB_CC_FAULT_ADDRESS (250)
#define CSB_SIZE (0x10)
#define CSB_ALIGN CSB_SIZE

2
arch/powerpc/platforms/powernv/vas-fault.c
View File

@ -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_FAULT_ADDRESS;
csb.ce = CSB_CE_TERMINATION;
csb.cs = 0;
csb.count = 0;