From: james.morse@arm•com (James Morse)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v4 11/13] firmware: arm_sdei: add support for CPU private events
Date: Wed, 01 Nov 2017 15:59:52 +0000 [thread overview]
Message-ID: <59F9EF78.8090107@arm.com> (raw)
In-Reply-To: <59EF798A.9000609@arm.com>
Hi Will,
On 24/10/17 18:34, James Morse wrote:
> On 18/10/17 18:19, Will Deacon wrote:
>> On Tue, Oct 17, 2017 at 06:44:30PM +0100, James Morse wrote:
>>> Private SDE events are per-cpu, and need to be registered and enabled
>>> on each CPU.
>>>
>>> Hide this detail from the caller by adapting our {,un}register and
>>> {en,dis}able calls to send an IPI to each CPU if the event is private.
>>>
>>> CPU private events are unregistered when the CPU is powered-off, and
>>> re-registered when the CPU is brought back online. This saves bringing
>>> secondary cores back online to call private_reset() on shutdown, kexec
>>> and resume from hibernate.
>
>>> diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
>>> index 28e4c4cbb16d..5598d9ba8b5d 100644
>>> --- a/drivers/firmware/arm_sdei.c
>>> +++ b/drivers/firmware/arm_sdei.c
>>> @@ -610,6 +813,7 @@ static int sdei_device_freeze(struct device *dev)
>>> {
>>> int err;
>>>
>>> + frozen = true;
>>> err = sdei_event_unregister_all();
>
>> Are the release semantics from spin_unlock in sdei_event_unregister_all
>> sufficient for the ordering guarantees you need?
>
> ... ordering ...
>
> The hotplug notifiers don't touch that lock, so at the first level: no.
>
> It looks like I was relying on the cpu-hotplug code using stop-machine for its
> work, and the spinlocks changing the pre-empt count for this to work. Which is
> not something I want to debug if it changes!
>
> I'll post a patch changing this bool to a more sensible atomic type.
Here I show my ignorance: atomic_t didn't do what I thought. But I do take the
spinlock inside the hotplug callback, so I'll move the variable in there.
Thanks,
James
next prev parent reply other threads:[~2017-11-01 15:59 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-17 17:44 [PATCH v4 00/13] arm64/firmware: Software Delegated Exception Interface James Morse
2017-10-17 17:44 ` [PATCH v4 01/13] KVM: arm64: Store vcpu on the stack during __guest_enter() James Morse
2017-10-17 17:44 ` [PATCH v4 02/13] KVM: arm/arm64: Convert kvm_host_cpu_state to a static per-cpu allocation James Morse
2017-10-17 17:44 ` [PATCH v4 03/13] KVM: arm64: Change hyp_panic()s dependency on tpidr_el2 James Morse
2017-10-17 17:44 ` [PATCH v4 04/13] arm64: alternatives: use tpidr_el2 on VHE hosts James Morse
2017-10-18 11:00 ` Catalin Marinas
2017-10-17 17:44 ` [PATCH v4 05/13] KVM: arm64: Stop save/restoring host tpidr_el1 on VHE James Morse
2017-10-17 17:44 ` [PATCH v4 06/13] Docs: dt: add devicetree binding for describing arm64 SDEI firmware James Morse
2017-10-17 17:44 ` [PATCH v4 07/13] firmware: arm_sdei: Add driver for Software Delegated Exceptions James Morse
2017-10-18 11:09 ` Catalin Marinas
2017-10-17 17:44 ` [PATCH v4 08/13] arm64: Add vmap_stack header file James Morse
2017-10-18 11:10 ` Catalin Marinas
2017-10-17 17:44 ` [PATCH v4 09/13] arm64: kernel: Add arch-specific SDEI entry code and CPU masking James Morse
2017-10-18 11:18 ` Catalin Marinas
2017-10-17 17:44 ` [PATCH v4 10/13] firmware: arm_sdei: Add support for CPU and system power states James Morse
2017-10-18 11:11 ` Catalin Marinas
2017-10-18 17:17 ` Will Deacon
2017-10-24 17:34 ` James Morse
2017-10-25 14:43 ` Will Deacon
2017-10-17 17:44 ` [PATCH v4 11/13] firmware: arm_sdei: add support for CPU private events James Morse
2017-10-18 11:11 ` Catalin Marinas
2017-10-18 17:19 ` Will Deacon
2017-10-24 17:34 ` James Morse
2017-11-01 15:59 ` James Morse [this message]
2017-10-17 17:44 ` [PATCH v4 12/13] arm64: acpi: Remove __init from acpi_psci_use_hvc() for use by SDEI James Morse
2017-10-18 11:11 ` Catalin Marinas
2017-10-17 17:44 ` [PATCH v4 13/13] firmware: arm_sdei: Discover SDEI support via ACPI James Morse
2017-10-18 11:12 ` Catalin Marinas
2017-10-18 17:16 ` [PATCH v4 00/13] arm64/firmware: Software Delegated Exception Interface Will Deacon
2017-10-30 15:58 ` [PATCH v4 14/13] firmware: arm_sdei: Move cpuhotplug registration later James Morse
2017-11-01 15:59 ` [PATCH 15/13] firmware: arm_sdei: move the frozen flag under the spinlock James Morse
2017-11-08 15:11 ` James Morse
2017-11-08 16:06 ` [PATCH v4 15/13] firmware: arm_sdei: be more robust against cpu-hotplug James Morse
2017-11-13 11:01 ` Will Deacon
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