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From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	linux-pm@vger.kernel.org, loongarch@lists.linux.dev,
	linux-acpi@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-riscv@lists.infradead.org, kvmarm@lists.linux.dev,
	x86@kernel.org, acpica-devel@lists.linuxfoundation.org,
	linux-csky@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-ia64@vger.kernel.org, linux-parisc@vger.kernel.org,
	Salil Mehta <salil.mehta@huawei.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	jianyong.wu@arm.com, justin.he@arm.com,
	James Morse <james.morse@arm.com>
Subject: Re: [PATCH RFC v3 01/21] ACPI: Only enumerate enabled (or functional) devices
Date: Mon, 29 Jan 2024 14:55:21 +0000	[thread overview]
Message-ID: <Zbe8WQRASx6D6RaG@shell.armlinux.org.uk> (raw)
In-Reply-To: <20240112115205.000043b0@Huawei.com>

Hi Jonathan,

On Fri, Jan 12, 2024 at 11:52:05AM +0000, Jonathan Cameron wrote:
> On Thu, 11 Jan 2024 10:26:15 +0000
> "Russell King (Oracle)" <linux@armlinux.org.uk> wrote:
> > @@ -2381,16 +2388,38 @@ EXPORT_SYMBOL_GPL(acpi_dev_clear_dependencies);
> >   * acpi_dev_ready_for_enumeration - Check if the ACPI device is ready for enumeration
> >   * @device: Pointer to the &struct acpi_device to check
> >   *
> > - * Check if the device is present and has no unmet dependencies.
> > + * Check if the device is functional or enabled and has no unmet dependencies.
> >   *
> > - * Return true if the device is ready for enumeratino. Otherwise, return false.
> > + * Return true if the device is ready for enumeration. Otherwise, return false.
> >   */
> >  bool acpi_dev_ready_for_enumeration(const struct acpi_device *device)
> >  {
> >  	if (device->flags.honor_deps && device->dep_unmet)
> >  		return false;
> >  
> > -	return acpi_device_is_present(device);
> > +	/*
> > +	 * ACPI 6.5's 6.3.7 "_STA (Device Status)" allows firmware to return
> > +	 * (!present && functional) for certain types of devices that should be
> > +	 * enumerated. Note that the enabled bit should not be set unless the
> > +	 * present bit is set.
> > +	 *
> > +	 * However, limit this only to processor devices to reduce possible
> > +	 * regressions with firmware.
> > +	 */
> > +	if (device->status.functional)
> > +		return true;

I have a report from within Oracle that this causes testing failures
with QEMU using -smp cpus=2,maxcpus=4. I think it needs to be:

	if (!device->status.present)
		return device->status.functional;

	if (device->status.enabled)
		return true;

	return !acpi_device_is_processor(device);

So we can better understand the history here, let's list it as a
truth table. P=present, F=functional, E=enabled, Orig=how the code
is in mainline, James=James' original proposal, Rafael=the proposed
replacement but seems to be buggy, Rmk=the fixed version that passes
tests:

P F E	Orig	James	Rafael		Rmk
0 0 0	0	0	0		0
0 0 1	0	0	0		0
0 1 0	1	1	1		1
0 1 1	1	0	1		1
1 0 0	1	0	!processor	!processor
1 0 1	1	1	1		1
1 1 0	1	0	1		!processor
1 1 1	1	1	1		1

Any objections to this?

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!

  reply	other threads:[~2024-01-29 14:55 UTC|newest]

Thread overview: 121+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-13 12:47 [RFC PATCH v3 00/21] ACPI/arm64: add support for virtual cpu hotplug Russell King (Oracle)
2023-12-13 12:49 ` [PATCH RFC v3 01/21] ACPI: Only enumerate enabled (or functional) devices Russell King
2023-12-14 17:32   ` Jonathan Cameron
2023-12-14 17:47     ` Rafael J. Wysocki
2023-12-14 18:10       ` Russell King (Oracle)
2023-12-14 18:16         ` Rafael J. Wysocki
2023-12-14 18:37           ` Rafael J. Wysocki
2023-12-15 15:31             ` Russell King (Oracle)
2023-12-15 16:15               ` Jonathan Cameron
2023-12-15 19:47                 ` Rafael J. Wysocki
2024-01-02 14:39                   ` Jonathan Cameron
2024-01-11 10:19                     ` Jonathan Cameron
2024-01-11 10:26                       ` Russell King (Oracle)
2024-01-12 11:52                         ` Jonathan Cameron
2024-01-29 14:55                           ` Russell King (Oracle) [this message]
2024-01-29 15:05                             ` Rafael J. Wysocki
2024-01-29 15:16                               ` Russell King (Oracle)
2024-01-29 15:34                                 ` Rafael J. Wysocki
2024-01-22  7:31                         ` Gavin Shan
2023-12-14 17:55     ` Russell King (Oracle)
2023-12-13 12:49 ` [PATCH RFC v3 02/21] ACPI: processor: Add support for processors described as container packages Russell King
2023-12-14 17:36   ` Jonathan Cameron
2023-12-14 17:57     ` Russell King (Oracle)
2023-12-18 20:17   ` Rafael J. Wysocki
2024-01-09 15:49     ` Russell King (Oracle)
2024-01-09 16:05       ` Rafael J. Wysocki
2024-01-09 16:13         ` Russell King (Oracle)
2024-01-11 16:17           ` Jonathan Cameron
2024-01-11 17:59     ` Jonathan Cameron
2024-01-11 18:46       ` Russell King (Oracle)
2024-01-12  9:25         ` Jonathan Cameron
2024-01-12 15:01           ` Rafael J. Wysocki
2024-01-12 15:03             ` Jonathan Cameron
2024-01-15 10:47             ` Russell King (Oracle)
2023-12-13 12:49 ` [PATCH RFC v3 03/21] ACPI: processor: Register CPUs that are online, but not described in the DSDT Russell King
2023-12-18 20:22   ` Rafael J. Wysocki
2024-01-15 11:06     ` Russell King (Oracle)
2024-01-22 16:02       ` Jonathan Cameron
2024-01-22 16:22         ` Rafael J. Wysocki
2024-01-22 17:30           ` Russell King (Oracle)
2024-01-23  9:27             ` Jonathan Cameron
2024-01-25 13:56               ` Miguel Luis
2024-01-25 14:42                 ` Rafael J. Wysocki
2024-01-29 13:03               ` Jonathan Cameron
2024-01-29 15:32                 ` Russell King (Oracle)
2024-01-22 17:27         ` Russell King (Oracle)
2023-12-13 12:49 ` [PATCH RFC v3 04/21] ACPI: processor: Register all CPUs from acpi_processor_get_info() Russell King
2023-12-14 17:38   ` Jonathan Cameron
2023-12-18 20:30   ` Rafael J. Wysocki
2024-01-22 17:44     ` Jonathan Cameron
2024-01-22 18:03       ` Rafael J. Wysocki
2024-01-22 21:56     ` Russell King (Oracle)
2023-12-13 12:49 ` [PATCH RFC v3 05/21] ACPI: Rename ACPI_HOTPLUG_CPU to include 'present' Russell King
2023-12-14 17:41   ` Jonathan Cameron
2023-12-14 18:00     ` Russell King (Oracle)
2023-12-18 20:35   ` Rafael J. Wysocki
2024-01-22 18:00     ` Jonathan Cameron
2024-01-23 13:28       ` Russell King (Oracle)
2024-01-23 16:15         ` Rafael J. Wysocki
2024-01-23 16:36           ` Russell King (Oracle)
2024-01-23 17:43             ` Rafael J. Wysocki
2024-01-23 18:19               ` Russell King (Oracle)
2024-01-23 18:26                 ` Rafael J. Wysocki
2024-01-23 18:59                   ` Russell King (Oracle)
2024-01-23 19:27                     ` Rafael J. Wysocki
2024-01-23 20:09                       ` Russell King (Oracle)
2024-01-23 20:17                         ` Rafael J. Wysocki
2024-01-23 20:57                           ` Russell King (Oracle)
2024-01-23 21:12                             ` Russell King (Oracle)
2024-01-23 22:05                               ` Rafael J. Wysocki
2024-01-24  8:45                                 ` Russell King (Oracle)
2023-12-13 12:49 ` [PATCH RFC v3 06/21] ACPI: Move acpi_bus_trim_one() before acpi_scan_hot_remove() Russell King
2023-12-13 12:49 ` [PATCH RFC v3 07/21] ACPI: Rename acpi_processor_hotadd_init and remove pre-processor guards Russell King
2023-12-14 17:43   ` Jonathan Cameron
2023-12-14 18:03     ` Russell King (Oracle)
2023-12-13 12:49 ` [PATCH RFC v3 08/21] ACPI: Add post_eject to struct acpi_scan_handler for cpu hotplug Russell King
2023-12-13 12:49 ` [PATCH RFC v3 09/21] ACPI: convert acpi_processor_post_eject() to use IS_ENABLED() Russell King (Oracle)
2023-12-15 16:11   ` Jonathan Cameron
2023-12-13 12:50 ` [PATCH RFC v3 10/21] ACPI: Check _STA present bit before making CPUs not present Russell King
2023-12-15 16:18   ` Jonathan Cameron
2023-12-13 12:50 ` [PATCH RFC v3 11/21] ACPI: Warn when the present bit changes but the feature is not enabled Russell King
2023-12-13 12:50 ` [PATCH RFC v3 12/21] arm64: acpi: Move get_cpu_for_acpi_id() to a header Russell King
2023-12-13 12:50 ` [PATCH RFC v3 13/21] ACPICA: Add new MADT GICC flags fields Russell King
2023-12-15 16:23   ` Jonathan Cameron
2023-12-15 16:53     ` Russell King (Oracle)
2023-12-18  9:23       ` Lorenzo Pieralisi
2023-12-18 13:14         ` Rafael J. Wysocki
2023-12-18 16:28           ` Lorenzo Pieralisi
2023-12-27 11:15           ` Lorenzo Pieralisi
2023-12-13 12:50 ` [PATCH RFC v3 14/21] irqchip/gic-v3: Don't return errors from gic_acpi_match_gicc() Russell King
2023-12-15 16:33   ` Jonathan Cameron
2024-01-09 19:27     ` Russell King (Oracle)
2024-01-23 10:08       ` Jonathan Cameron
2023-12-13 12:50 ` [PATCH RFC v3 15/21] irqchip/gic-v3: Add support for ACPI's disabled but 'online capable' CPUs Russell King
2023-12-15 16:38   ` Jonathan Cameron
2023-12-13 12:50 ` [PATCH RFC v3 16/21] arm64: psci: Ignore DENIED CPUs Russell King
2023-12-15 16:40   ` Jonathan Cameron
2023-12-13 12:50 ` [PATCH RFC v3 17/21] ACPI: add support to register CPUs based on the _STA enabled bit Russell King
2023-12-18 13:03   ` Russell King (Oracle)
2024-01-02 14:53     ` Jonathan Cameron
2024-01-23 10:26       ` Jonathan Cameron
2024-01-23 13:10         ` Russell King (Oracle)
2024-01-23 14:22           ` Jonathan Cameron
2024-01-23 14:59             ` Russell King (Oracle)
2023-12-13 12:50 ` [PATCH RFC v3 18/21] ACPI: processor: Only call arch_unregister_cpu() if HOTPLUG_CPU is selected Russell King
2023-12-15 16:50   ` Jonathan Cameron
2023-12-18 12:58     ` Russell King (Oracle)
2024-01-23 10:29       ` Jonathan Cameron
2023-12-13 12:50 ` [PATCH RFC v3 19/21] arm64: document virtual CPU hotplug's expectations Russell King
2023-12-15 17:04   ` Jonathan Cameron
2023-12-13 12:50 ` [PATCH RFC v3 20/21] ACPI: Add _OSC bits to advertise OS support for toggling CPU present/enabled Russell King
2023-12-15 17:12   ` Jonathan Cameron
2024-01-02 13:07     ` Jose Marinho
2024-01-02 15:16       ` Jonathan Cameron
2024-01-02 15:35         ` Jose Marinho
2024-01-23 10:51           ` Jonathan Cameron
2023-12-13 12:50 ` [PATCH RFC v3 21/21] cpumask: Add enabled cpumask for present CPUs that can be brought online Russell King
2023-12-15 17:18   ` Jonathan Cameron
2023-12-18 12:14     ` Russell King (Oracle)
2024-01-02 15:19       ` Jonathan Cameron
2023-12-15 19:40   ` Thomas Gleixner

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