[PATCH v8 00/10] Enable VAS

Tue Aug 29 16:23:30 AEST 2017

Power9 introduces a hardware subsystem referred to as the Virtual
Accelerator Switchboard (VAS). VAS allows kernel subsystems and user
space processes to directly access the Nest Accelerator (NX) engines
which implement compression and encryption algorithms in the hardware.

NX has been in Power processors since Power7+, but access to the NX
engines was through the 'icswx' instruction which is only available
to the kernel/hypervisor. Starting with Power9, access to the NX
engines is provided to both kernel and user space processes through
VAS.

The switchboard (i.e VAS) multiplexes accesses between "receivers" and
"senders", where the "receivers" are typically the NX engines and
"senders" are the kernel subsystems and user processors that wish to
access the receivers (NX engines).  Once a sender is "connected" to
a receiver through the switchboard, the senders can submit compression/
encryption requests to the hardware using the new (PowerISA 3.0)
"copy" and "paste" instructions.

In the initial OPAL and PowerNV kernel patchsets, the "senders" can
only be kernel subsystems (eg NX-842 driver) and receivers can only
be the NX-842 engine. Follow-on patch sets will allow senders/receivers
to be user-space processes and receivers to be NX-GZIP engines.

Provides:

	This kernel patch set configures the VAS subsystems and provides
	kernel interfaces to drivers like NX-842 to open receive and send
	windows in VAS and to submit compression requests to the NX engine.

Requires:

	This patch set needs corresponding VAS/NX skiboot patches which
	were merged into skiboot tree. i.e skiboot must include:
	commit b503dcf ("vas: Set mmio enable bits in DD2")

Tests:
        In-kernel compression requests were tested on DD1 and DD2 POWER9
	hardware using compression self-test module and the following
	NX-842 patch set from Haren Myneni:

        https://lists.ozlabs.org/pipermail/linuxppc-dev/2017-July/160620.html

	and by dropping the last parameters to both vas_copy_crb() and
	vas_paste_crb() calls in drivers/crypto/nx/nx-842-powernv.c.
	See also PATCH 10/10.

Git Tree:

        https://github.com/sukadev/linux/ 
	Branch: vas-kern-v8

Thanks to input from Ben Herrenschmidt, Michael Neuling, Michael Ellerman
and Haren Myneni.

Changelog[v8]:
	- [Michael Ellerman] Use kernel int types (u64, u32 etc); make VAS
	  a built-in rather than a module; drop unnecessary fields from
	  struct vas_instance; Update ISA references; use 0 or 1 with
	  SET_FIELD macros instead of bool; skip writing to SPARE registers;
	  minor cleanup of debug/error messages; retry if ida_get_new()
	  fails with EAGAIN; fix couple of leaks in ids in error handling;
	  drop vas_initialized() check; drop vas_win_id() and vas_paste_addr()
	  interfaces as they are not yet used; Set task_state() and fix
	  parameter to schedule_timeout(); Reuse existing copy/paste macros
	  drop unnecessary parameters and add cr0 to clobbers list

Changelog[v7]:
	- Drop support for user space send/receive FTW windows (will be
	  posted separately) Simplifies the rx-win-open interface a bit.
	- [Michael Ellerman] Move GET_FIELD/SET_FIELD macros from 
	  uapi/asm/vas.h to asm/vas.h.

Changelog[v6]
	- Add support for user space send/receive FTW windows
	- Add a new, NX-FTW driver which provides the FTW user interface

Changelog[v5]
	- [Ben Herrenschmidt] Make VAS a platform device in the device tree
	  and use the core platform functions to parse the VAS properties.
	  Map the VAS MMIO regions as non-cachable and paste regions as
	  cachable. Use CONFIG_PPC_VAS rather than CONFIG_VAS; Don't assume
	  VAS ids are sequential.
	- Copy the FIFO address as is into LFIFO_BAR (don't shift it).

Changelog[v4]
	Comments from Michael Neuling:
	- Move VAS code from drivers/misc/vas to arch/powerpc/platforms/powernv
	  since VAS only provides interfaces to other drivers like NX-842.
	- Drop vas-internal.h and use vas.h in separate dirs for VAS
	  internal, kernel API and user API
	- Rather than create 6 separate device tree properties windows
	  and window context, combine them into 6 "reg" properties.
	- Drop vas_window_reset() since windows are reset/cleared before
	  being assigned to kernel/users.
	- Use ilog2() and radix_enabled() helpers

Changelog[v3]
	- Rebase to v4.11-rc1
	- Add interfaces to initialize send/receive window attributes to
	  defaults that drivers can use (see arch/powerpc/include/asm/vas.h)
	- Modify interface vas_paste() to return 0 or error code
	- Fix a bug in setting Translation Control Mode (0b11 not 0x11)
	- Enable send-window-credit checking 
	- Reorg code  in vas_win_close()
	- Minor reorgs and tweaks to register field settings to make it
	  easier to add support for user space windows.
	- Skip writing to read-only registers
	- Start window indexing from 0 rather than 1

Changelog[v2]
	- Use vas-id, HVWC, UWC and paste address, entries from device tree
	  rather than defining/computing them in kernel and reorg code.

Sukadev Bhattiprolu (10):
  powerpc/vas: Define macros, register fields and structures
  Move GET_FIELD/SET_FIELD to vas.h
  powerpc/vas: Define vas_init() and vas_exit()
  powerpc/vas: Define helpers to access MMIO regions
  powerpc/vas: Define helpers to init window context
  powerpc/vas: Define helpers to alloc/free windows
  powerpc/vas: Define vas_rx_win_open() interface
  powerpc/vas: Define vas_win_close() interface
  powerpc/vas: Define vas_tx_win_open()
  powerpc/vas: Define copy/paste interfaces

 .../devicetree/bindings/powerpc/ibm,vas.txt        |   23 +
 MAINTAINERS                                        |    9 +
 arch/powerpc/include/asm/ppc-opcode.h              |    2 +
 arch/powerpc/include/asm/vas.h                     |  160 +++
 arch/powerpc/platforms/powernv/Kconfig             |   14 +
 arch/powerpc/platforms/powernv/Makefile            |    1 +
 arch/powerpc/platforms/powernv/copy-paste.h        |   46 +
 arch/powerpc/platforms/powernv/vas-window.c        | 1134 ++++++++++++++++++++
 arch/powerpc/platforms/powernv/vas.c               |  151 +++
 arch/powerpc/platforms/powernv/vas.h               |  467 ++++++++
 drivers/crypto/nx/nx-842-powernv.c                 |    7 +-
 drivers/crypto/nx/nx-842.h                         |    5 -
 12 files changed, 2011 insertions(+), 8 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/powerpc/ibm,vas.txt
 create mode 100644 arch/powerpc/include/asm/vas.h
 create mode 100644 arch/powerpc/platforms/powernv/copy-paste.h
 create mode 100644 arch/powerpc/platforms/powernv/vas-window.c
 create mode 100644 arch/powerpc/platforms/powernv/vas.c
 create mode 100644 arch/powerpc/platforms/powernv/vas.h

-- 
2.7.4