dmaengine: idxd: process batch descriptor completion record faults

Add event log processing for faulting of user batch descriptor completion
record.

When encountering an event log entry for a page fault on a completion
record, the driver is expected to do the following:
1. If the "first error in batch" bit in event log entry error info is
set, discard any previously recorded errors associated with the
"batch identifier".
2. Fix the page fault according to the fault address in the event log. If
successful, write the completion record to the fault address in user space.
3. If an error is encountered while writing the completion record and it is
associated to a descriptor in the batch, the driver associates the error
with the batch identifier of the event log entry and tracks it until the
event log entry for the corresponding batch desc is encountered.

While processing an event log entry for a batch descriptor with error
indicating that one or more descs in the batch had event log entries,
the driver will do the following before writing the batch completion
record:
1. If the status field of the completion record is 0x1, the driver will
change it to error code 0x5 (one or more operations in batch completed
with status not successful) and changes the result field to 1.
2. If the status is error code 0x6 (page fault on batch descriptor list
address), change the result field to 1.
3. If status is any other value, the completion record is not changed.
4. Clear the recorded error in preparation for next batch with same batch
identifier.

The result field is for user software to determine whether to set the
"Batch Error" flag bit in the descriptor for continuation of partial
batch descriptor completion. See DSA spec 2.0 for additional information.

If no error has been recorded for the batch, the batch completion record is
written to user space as is.

Tested-by: Tony Zhu <tony.zhu@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Co-developed-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: https://lore.kernel.org/r/20230407203143.2189681-12-fenghua.yu@intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/dma/idxd/registers.h b/drivers/dma/idxd/registers.h
index 148db94f9373..9f3959d001b6 100644
--- a/drivers/dma/idxd/registers.h
+++ b/drivers/dma/idxd/registers.h
@@ -35,7 +35,7 @@ union gen_cap_reg {
 		u64 drain_readback:1;
 		u64 rsvd2:3;
 		u64 evl_support:2;
-		u64 rsvd4:1;
+		u64 batch_continuation:1;
 		u64 max_xfer_shift:5;
 		u64 max_batch_shift:4;
 		u64 max_ims_mult:6;
@@ -577,6 +577,8 @@ union evl_status_reg {
 	u64 bits;
 } __packed;
 
+#define IDXD_MAX_BATCH_IDENT	256
+
 struct __evl_entry {
 	u64 rsvd:2;
 	u64 desc_valid:1;