Messages in this thread |  | | From | Michael Ellerman <> | Subject | Re: [v3, 1/2] powernv/powerpc:Save/Restore additional SPRs for stop4 cpuidle | Date | Mon, 7 Aug 2017 20:41:53 +1000 (AEST) |
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On Fri, 2017-07-21 at 10:41:37 UTC, "Gautham R. Shenoy" wrote: > From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> > > The stop4 idle state on POWER9 is a deep idle state which loses > hypervisor resources, but whose latency is low enough that it can be > exposed via cpuidle. > > Until now, the deep idle states which lose hypervisor resources (eg: > winkle) were only exposed via CPU-Hotplug. Hence currently on wakeup > from such states, barring a few SPRs which need to be restored to > their older value, rest of the SPRS are reinitialized to their values > corresponding to that at boot time. > > When stop4 is used in the context of cpuidle, we want these additional > SPRs to be restored to their older value, to ensure that the context > on the CPU coming back from idle is same as it was before going idle. > > In this patch, we define a SPR save area in PACA (since we have used > up the volatile register space in the stack) and on POWER9, we restore > SPRN_PID, SPRN_LDBAR, SPRN_FSCR, SPRN_HFSCR, SPRN_MMCRA, SPRN_MMCR1, > SPRN_MMCR2 to the values they had before entering stop. > > Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> > Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Series applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/e1c1cfed54326fd2b17c78f0c85092
cheers
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