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From: Dexuan Cui <decui@microsoft.com>
To: Michael Kelley <mikelley@microsoft.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>,
	vkuznets <vkuznets@redhat.com>, KY Srinivasan <kys@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	"sashal@kernel.org" <sashal@kernel.org>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"bp@alien8.de" <bp@alien8.de>, "hpa@zytor.com" <hpa@zytor.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"will@kernel.org" <will@kernel.org>,
	"Ganapatrao.Kulkarni@cavium.com" <Ganapatrao.Kulkarni@cavium.com>,
	"james.morse@arm.com" <james.morse@arm.com>,
	"steven.price@arm.com" <steven.price@arm.com>,
	"josephl@nvidia.com" <josephl@nvidia.com>,
	"m.szyprowski@samsung.com" <m.szyprowski@samsung.com>,
	"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>
Subject: RE: [PATCH v2 1/1] x86/hyperv: Initialize clockevents earlier in CPU onlining
Date: Fri, 15 Nov 2019 06:48:45 +0000	[thread overview]
Message-ID: <PU1P153MB0169807BF9CE60FC3CA51B31BF700@PU1P153MB0169.APCP153.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <1573607467-9456-1-git-send-email-mikelley@microsoft.com>

> From: Michael Kelley <mikelley@microsoft.com>
> Sent: Tuesday, November 12, 2019 5:12 PM
> ...
> @@ -190,14 +278,20 @@ void hv_stimer_free(void)
>  void hv_stimer_global_cleanup(void)
>  {
>  	int	cpu;
>  ...
> +	/*
> +	 * hv_stime_legacy_cleanup() will stop the stimer if Direct
> +	 * Mode is not enabled, and fallback to the LAPIC timer.
> +	 */
> +	for_each_present_cpu(cpu) {
> +		hv_stimer_legacy_cleanup(cpu);
>  	}
> +
> +	/*
> +	 * If Direct Mode is enabled, the cpuhp teardown callback
> +	 * (hv_stimer_cleanup) will be run on all CPUs to stop the
> +	 * stimers.
> +	 */
>  	hv_stimer_free();
>  }

In the case of direct_mode_enabled == true: When hv_vmbus unloads,
vmbus_exit() -> hv_stimer_global_cleanup() -> hv_stimer_free() ->
cpuhp_remove_state() disables the direct mode timers.

This does not look symmetric since hv_stimer_alloc() is called before
hv_vmbus loads, but I suppose this is not a real issue because hv_vmbus
should never unload in practice. :-)

Tested-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>


  reply	other threads:[~2019-11-15  6:49 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-13  1:11 [PATCH v2 1/1] x86/hyperv: Initialize clockevents earlier in CPU onlining Michael Kelley
2019-11-15  6:48 ` Dexuan Cui [this message]
2019-11-18  1:23   ` Michael Kelley

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