On Mon, 17 Jul 2017 16:43:19 -0700 Haren Myneni <haren@xxxxxxxxxxxxxxxxxx> wrote: > [PATCH V2 0/6] Enable NX 842 compression engine on Power9 > > P9 introduces Virtual Accelerator Switchboard (VAS) to communicate > with NX 842 engine. icswx function is used to access NX before. > On powerNV systems, NX-842 driver invokes VAS functions for > configuring RxFIFO (receive window) per each NX engine. VAS uses > this FIFO to communicate the request to NX. The kernel opens send > window which is used to transfer compression/decompression requests > to VAS. It maps the send window to the corresponding RxFIFO. > copy/paste instructions are used to pass the CRB to VAS. > > This patch series adds P9 NX support for 842 compression engine. > First 4 patches reorganize the current code so that VAS function > can be added. > - nx842_powernv_function points to VAS function if VAS feature is > available. Otherwise icswx function is used. > - Move configure CRB code nx842_cfg_crb() > - In addition to freeing co-processor structs for initialization > failures and exit, both send and receive windows have to closed > for VAS. > - Move updating coprocessor info list to nx842_add_coprocs_list(). > > The last 2 patches adds configuring and invoking VAS, and also > checking P9 NX specific errors that are provided in co-processor > status block (CSB) for failures. > > Patches have been tested on P9 DD1 system using VAS changes and > on P8 HW to make sure no regression. > > This patchset depends on VAS kernel changes: > https://lists.ozlabs.org/pipermail/linuxppc-dev/2017-May/158178.html Just a question, we no longer invalidate the copy buffer on context switch after this patch: 07d2a628bc ("powerpc/64s: Avoid cpabort in context switch when possible") If your vas address mappings are visible only to kernel, only used in process / kthread context, and only used with kernel preemption disabled, this is okay. If userspace can possibly copy/paste to the mappings or if you need to sleep or call this from interrupt context, we need to work out how to invalidate the copy buffer. Thanks, Nick
