linux-kernel - Re: [v2] powerpc/powernv/idle: Disable LOSE_FULL

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Message-Id: <3xSC0h6Tj7z9sN5@ozlabs.org>
Date:   Wed,  9 Aug 2017 23:34:12 +1000 (AEST)
From:   Michael Ellerman <patch-notifications@...erman.id.au>
To:     "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>,
        Michael Neuling <mikey@...ling.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
        Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Akshay Adiga <akshay.adiga@...ux.vnet.ibm.com>
Cc:     "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [v2] powerpc/powernv/idle: Disable LOSE_FULL_CONTEXT states when stop-api fails

On Tue, 2017-08-08 at 08:43:15 UTC, "Gautham R. Shenoy" wrote:
> From: "Gautham R. Shenoy" <ego@...ux.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@...ux.vnet.ibm.com>

Applied to powerpc fixes, thanks.

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

cheers