The previous limits were estimated locally in a single step
basead on bound values, however it was not correct since
when given certain scatterlist the function nx_build_sg_lists
was consuming more sg entries than allocated causing a
memory corruption and crashes.

e.g.: in the worst case we could have one sg entry for a single byte.

This patch fixes it modifying the logic of the bound limit
moving it to nx_sg_build_lists and set a correct sg_max limit,
adding a trim function to ensure the bound in sg_list. Also fixing
nx_build_sg_list  NULL and untreated return in case of overflow.
Signed-off-by: NLeonidas S. Barbosa <leosilva@linux.vnet.ibm.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

This patch includes one more parameter to nx_build_sg_lists() to skip
the given number of bytes from beginning of each sg list.

This is needed in order to implement the fixes for the AES modes to make
them able to process larger chunks of data.
Reviewed-by: NJoy Latten <jmlatten@linux.vnet.ibm.com>
Signed-off-by: NMarcelo Cerri <mhcerri@linux.vnet.ibm.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

The NX driver uses the transformation context to store several fields
containing data related to the state of the operations in progress.
Since a single tfm can be used by different kernel threads at the same
time, we need to protect the data stored into the context.

This patch makes use of spin locks to protect the data where a race
condition can happen.
Reviewed-by: NFionnuala Gunter <fin@linux.vnet.ibm.com>
Reviewed-by: NJoy Latten <jmlatten@linux.vnet.ibm.com>
Signed-off-by: NMarcelo Cerri <mhcerri@linux.vnet.ibm.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

These routines add the base device driver code supporting the Power7+
in-Nest encryption accelerator (nx) device.
Signed-off-by: NKent Yoder <key@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>