From: stefano.stabellini@eu.citrix.com (Stefano Stabellini)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/2] arm: psci: don't call CPU_OFF blindly
Date: Fri, 5 Sep 2014 21:48:46 +0100 [thread overview]
Message-ID: <alpine.DEB.2.02.1409052132450.2334@kaball.uk.xensource.com> (raw)
In-Reply-To: <1409916139-20127-3-git-send-email-mark.rutland@arm.com>
On Fri, 5 Sep 2014, Mark Rutland wrote:
> The generic PSCI operations for arm check the presence of a CPU_OFF ID
> far too late, and in the absence of an ID will panic(), rather than
> producing a warning.
>
> This patch adds a psci_cpu_disable callback which tests the presence of
> a CPU_OFF id. As this is called earlier than psci_cpu_die, the failure
> can be handled gracefully without brining down the system. Additionally
> a check is added for a UP trusted OS in the presence of PSCI 0.2+. Full
> support will require the use of MIGRATE, but for now rejecting hotplug
> will prevent psci_cpu_die from brining down the system.
>
> The now redundant check for scpi_ops.cpu_off is removed from
> psci_cpu_die. At the same time, the whitespace is corrected from seven
> spaces to tabs.
>
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Ashwin Chaugule <ashwin.chaugule@linaro.org>
> Cc: Rob Herring <robh@kernel.org>
> Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> Cc: Ian Campbell <ian.campbell@citrix.com>
> Cc: Christoffer Dall <christoffer.dall@linaro.org>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> ---
> arch/arm/kernel/psci_smp.c | 36 +++++++++++++++++++++++++++++-------
> 1 file changed, 29 insertions(+), 7 deletions(-)
>
> Stefano, I've followed your lead with the __ref annotation here, but I couldn't
> figure out why they exist on cpu_die and cpu_kill; it feels rather dodgy. Do
> you know why they were added, or if they are superfluous?
I don't think that __ref is needed.
That particular snipped of code came from Rob Herring, maybe he knows
why it was added in the first place.
> There are some other cleanups that should happen here (static,
> CPU_METHOD_OF_DECLARE), but those will come as a later cleanups series.
>
> diff --git a/arch/arm/kernel/psci_smp.c b/arch/arm/kernel/psci_smp.c
> index 28a1db4..2b00d3c 100644
> --- a/arch/arm/kernel/psci_smp.c
> +++ b/arch/arm/kernel/psci_smp.c
> @@ -56,17 +56,38 @@ static int psci_boot_secondary(unsigned int cpu, struct task_struct *idle)
> }
>
> #ifdef CONFIG_HOTPLUG_CPU
> +int __ref psci_cpu_disable(unsigned int cpu)
> +{
> + /* Fail early if we don't have CPU_OFF support */
> + if (!psci_ops.cpu_off)
> + return -EOPNOTSUPP;
> +
> + /*
> + * In the presence of a UP trusted OS, it might not be possible to
> + * hotplug certain CPUs, and CPU_OFF may return (which would be bad).
> + * Supporting a UP trusted OS requires careful use of
> + * MIGRATE_INFO_UP_CPU and MIGRATE, so for now fail in the presence of
> + * a UP Trusted OS.
> + */
> + if (psci_ops.migrate_info_type &&
> + psci_ops.migrate_info_type() != PSCI_0_2_TOS_MP) {
> + pr_warn("Unable to handle UP trusted OS\n");
> + return -EPERM;
> + }
> +
> + return 0;
> +}
> +
> void __ref psci_cpu_die(unsigned int cpu)
> {
> - const struct psci_power_state ps = {
> - .type = PSCI_POWER_STATE_TYPE_POWER_DOWN,
> - };
> + const struct psci_power_state ps = {
> + .type = PSCI_POWER_STATE_TYPE_POWER_DOWN,
> + };
>
> - if (psci_ops.cpu_off)
> - psci_ops.cpu_off(ps);
> + psci_ops.cpu_off(ps);
>
> - /* We should never return */
> - panic("psci: cpu %d failed to shutdown\n", cpu);
> + /* We should never return */
> + panic("psci: cpu %d failed to shutdown\n", cpu);
> }
>
> int __ref psci_cpu_kill(unsigned int cpu)
> @@ -109,6 +130,7 @@ bool __init psci_smp_available(void)
> struct smp_operations __initdata psci_smp_ops = {
> .smp_boot_secondary = psci_boot_secondary,
> #ifdef CONFIG_HOTPLUG_CPU
> + .cpu_disable = psci_cpu_disable,
> .cpu_die = psci_cpu_die,
> .cpu_kill = psci_cpu_kill,
> #endif
> --
> 1.9.1
>
next prev parent reply other threads:[~2014-09-05 20:48 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-05 11:22 [PATCH 0/2] PSCI: don't call CPU_OFF when it might fail Mark Rutland
2014-09-05 11:22 ` [PATCH 1/2] arm64: psci: respect MIGRATE_INFO_TYPE Mark Rutland
2014-09-05 11:58 ` Sergei Shtylyov
2014-09-05 12:39 ` Mark Rutland
2014-09-05 11:22 ` [PATCH 2/2] arm: psci: don't call CPU_OFF blindly Mark Rutland
2014-09-05 20:48 ` Stefano Stabellini [this message]
2014-09-08 10:22 ` Mark Rutland
2014-09-05 20:53 ` [PATCH 0/2] PSCI: don't call CPU_OFF when it might fail Stefano Stabellini
2014-09-08 10:24 ` Mark Rutland
2014-09-08 21:44 ` Stefano Stabellini
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