[PATCH v4 00/11] Enable VAS

Sukadev Bhattiprolu
2017-03-31T05:14:07Z

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). A follow-on patch set
will allow senders to be user-space processes.

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 requests to the NX engine.

This patch set that has been tested in a Simics Power9 environment using
a modified NX-842 kernel driver and a compression self-test module from
Power8. The corresponding OPAL patchset for VAS support was posted to
skiboot mailing list:

https://lists.ozlabs.org/pipermail/skiboot/2017-January/006193.html

OPAL and kernel patchsets for NX-842 driver will be posted separately.
All four patchsets are needed to effectively use VAS/NX in Power9.

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

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 (11):
Add Power9 PVR
VAS: Define macros, register fields and structures
Move GET_FIELD/SET_FIELD to vas.h
VAS: Define vas_init() and vas_exit()
VAS: Define helpers for access MMIO regions
VAS: Define helpers to init window context
VAS: Define helpers to alloc/free windows
VAS: Define vas_rx_win_open() interface
VAS: Define vas_win_close() interface
VAS: Define vas_tx_win_open()
VAS: Define copy/paste interfaces

arch/powerpc/include/asm/reg.h | 1 +
arch/powerpc/include/asm/vas.h | 141 ++++
arch/powerpc/include/uapi/asm/vas.h | 33 +
arch/powerpc/platforms/powernv/Kconfig | 14 +
arch/powerpc/platforms/powernv/Makefile | 1 +
arch/powerpc/platforms/powernv/copy-paste.h | 74 ++
arch/powerpc/platforms/powernv/vas-window.c | 1003 +++++++++++++++++++++++++++
arch/powerpc/platforms/powernv/vas.c | 145 ++++
arch/powerpc/platforms/powernv/vas.h | 470 +++++++++++++
drivers/crypto/nx/nx-842-powernv.c | 7 +-
drivers/crypto/nx/nx-842.h | 5 -
11 files changed, 1886 insertions(+), 8 deletions(-)
create mode 100644 arch/powerpc/include/asm/vas.h
create mode 100644 arch/powerpc/include/uapi/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

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