Hi,

In this patch series we use winkle for offlined cores. I successfully
tested the working of this with subcore functionality.

Test scenario was as follows:
1. Set SMT mode to 1, Set subores-per-core to 1
2. Offline a core, in this case cpu 32 (sending it to winkle)
3. Set subcores-per-core to 4
4. Online the core
5. Start a guest (Topology 1 core 2 threads) on a subcore, in this case
on cpu 36

This works without any glitch.

Thanks,
Shreyas

On Monday 25 August 2014 11:31 PM, Shreyas B. Prabhu wrote:

Fast sleep is an idle state, where the core and the L1 and L2
caches are brought down to a threshold voltage. This also means that
the communication between L2 and L3 caches have to be fenced. However
the current P8 chips have a bug wherein this fencing between L2 and
L3 caches get delayed by a cpu cycle. This can delay L3 response to
the other cpus if they request for data during this time. Thus they
would fetch the same data from the memory which could lead to data
corruption if L3 cache is not flushed.
Patch 4 adds support to work around this.

'Deep Winkle' is a deeper idle state where core and private L2 are powered
off. While it offers higher power savings, it is at the cost of losing
hypervisor register state and higher latency.
Patch 5-9 adds support for winkle and uses it for offline cpus.

Patch 1 - Moves parameters required discover idle states to a location 
common to both cpuidle driver and powernv core code
Patch 2 - Populates idle state details from device tree
Patch 3 - Enables cpus to run guest after waking up from fastsleep/winkle


Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <redacted>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Rafael J. Wysocki <redacted>
Cc: Srivatsa S. Bhat <redacted>
Cc: Preeti U. Murthy <redacted>
Cc: Vaidyanathan Srinivasan <redacted>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Grant Likely <redacted>
Cc: devicetree@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org

Preeti U Murthy (2):
  cpuidle/powernv: Populate cpuidle state details by querying the
    device-tree
  powerpc/powernv/cpuidle: Add workaround to enable fastsleep

Shreyas B. Prabhu (6):
  powerpc/kvm/book3s_hv: Enable CPUs to run guest after waking up from
    fast-sleep
  powerpc/powernv: Add OPAL call to save and restore
  powerpc: Adding macro for accessing Thread Switch Control Register
  powerpc/powernv: Add winkle infrastructure
  powerpc/powernv: Discover and enable winkle
  powerpc/powernv: Enter deepest supported idle state in offline

Srivatsa S. Bhat (1):
  powerpc/powernv: Enable Offline CPUs to enter deep idle states

 arch/powerpc/include/asm/machdep.h             |   4 +
 arch/powerpc/include/asm/opal.h                |  10 ++
 arch/powerpc/include/asm/paca.h                |   3 +
 arch/powerpc/include/asm/ppc-opcode.h          |   2 +
 arch/powerpc/include/asm/processor.h           |   6 +-
 arch/powerpc/include/asm/reg.h                 |   1 +
 arch/powerpc/kernel/asm-offsets.c              |   1 +
 arch/powerpc/kernel/exceptions-64s.S           |  37 ++---
 arch/powerpc/kernel/idle.c                     |  30 ++++
 arch/powerpc/kernel/idle_power7.S              |  83 +++++++++-
 arch/powerpc/platforms/powernv/opal-wrappers.S |   2 +
 arch/powerpc/platforms/powernv/powernv.h       |   8 +
 arch/powerpc/platforms/powernv/setup.c         | 217 +++++++++++++++++++++++++
 arch/powerpc/platforms/powernv/smp.c           |  13 +-
 arch/powerpc/platforms/powernv/subcore.c       |  15 ++
 drivers/cpuidle/cpuidle-powernv.c              |  40 ++++-
 16 files changed, 439 insertions(+), 33 deletions(-)