[v2] powerpc/powernv/idle: Disable LOSE_FULL_CONTEXT states when stop-api fails

[Michael Ellerman]

On Tue, 2017-08-08 at 08:43:15 UTC, "Gautham R. Shenoy" wrote:
> From: "Gautham R. Shenoy" <ego at linux.vnet.ibm.com>
> 
> Currently, we use the opal call opal_slw_set_reg() to inform the
> Sleep-Winkle Engine (SLW) to restore the contents of some of the
> Hypervisor state on wakeup from deep idle states that lose full
> hypervisor context (characterized by the flag
> OPAL_PM_LOSE_FULL_CONTEXT).
> 
> However, the current code has a bug in that if opal_slw_set_reg()
> fails, we don't disable the use of these deep states (winkle on
> POWER8, stop4 onwards on POWER9).
> 
> This patch fixes this bug by ensuring that if programing the
> sleep-winkle engine to restore the hypervisor states in
> pnv_save_sprs_for_deep_states() fails, then we exclude such states by
> clearing the OPAL_PM_LOSE_FULL_CONTEXT flag from
> supported_cpuidle_states. As a result POWER8 will be prevented from
> using winkle for CPU-Hotplug, and POWER9 will put the offlined CPUs to
> the default stop state when available.
> 
> Further, we ensure in the initialization of the cpuidle-powernv driver
> to only include those states whose flags are present in
> supported_cpuidle_states, thereby skipping OPAL_PM_LOSE_FULL_CONTEXT
> states when they have been disabled due to stop-api failure.
> 
> Fixes: 1e1601b38e6 ("powerpc/powernv/idle: Restore SPRs for deep idle
> states via stop API.")
> 
> Signed-off-by: Gautham R. Shenoy <ego at linux.vnet.ibm.com>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/785a12afdb4a52903447fd890633c8

cheers