RE: [PATCH v6 04/16] ACPI: processor: Move checks and availability of acpi_processor earlier

Salil Mehta
2024-04-17T15:08:23Z

> From: Jonathan Cameron <jonathan.cameron@huawei.com>
> Sent: Wednesday, April 17, 2024 2:19 PM
>
> Make the per_cpu(processors, cpu) entries available earlier so that they are
> available in arch_register_cpu() as ARM64 will need access to the
> acpi_handle to distinguish between acpi_processor_add() and earlier
> registration attempts (which will fail as _STA cannot be checked).
>
> Reorder the remove flow to clear this per_cpu() after
> arch_unregister_cpu() has completed, allowing it to be used in there as
> well.
>
> Note that on x86 for the CPU hotplug case, the pr->id prior to
> acpi_map_cpu() may be invalid. Thus the per_cpu() structures must be
> initialized after that call or after checking the ID is valid (not hotplug path).
>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> ---
> v6: As per discussion in v5 thread, don't use the cpu->dev and
> make this data available earlier by moving the assignment checks
> int acpi_processor_get_info().
> ---
> drivers/acpi/acpi_processor.c | 79 +++++++++++++++++++++--------------
> 1 file changed, 47 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> index ba0a6f0ac841..2c164451ab53 100644
> --- a/drivers/acpi/acpi_processor.c
> +++ b/drivers/acpi/acpi_processor.c
> @@ -184,7 +184,35 @@ static void __init acpi_pcc_cpufreq_init(void) {}
>
> /* Initialization */
> #ifdef CONFIG_ACPI_HOTPLUG_CPU
> -static int acpi_processor_hotadd_init(struct acpi_processor *pr)
> +static DEFINE_PER_CPU(void *, processor_device_array);
> +
> +static void acpi_processor_set_per_cpu(struct acpi_processor *pr,
> + struct acpi_device *device)
> +{
> + BUG_ON(pr->id >= nr_cpu_ids);
> + /*
> + * Buggy BIOS check.
> + * ACPI id of processors can be reported wrongly by the BIOS.
> + * Don't trust it blindly
> + */
> + if (per_cpu(processor_device_array, pr->id) != NULL &&
> + per_cpu(processor_device_array, pr->id) != device) {
> + dev_warn(&device->dev,
> + "BIOS reported wrong ACPI id %d for the processor\n",
> + pr->id);
> + /* Give up, but do not abort the namespace scan. */
> + return;
> + }
> + /*
> + * processor_device_array is not cleared on errors to allow buggy BIOS
> + * checks.
> + */
> + per_cpu(processor_device_array, pr->id) = device;
> + per_cpu(processors, pr->id) = pr;
> +}
> +
> +static int acpi_processor_hotadd_init(struct acpi_processor *pr,
> + struct acpi_device *device)
> {
> int ret;
>
> @@ -198,6 +226,8 @@ static int acpi_processor_hotadd_init(struct
> acpi_processor *pr)
> if (ret)
> goto out;
>
> + acpi_processor_set_per_cpu(pr, device);
> +
> ret = arch_register_cpu(pr->id);
> if (ret) {
> acpi_unmap_cpu(pr->id);
> @@ -217,7 +247,8 @@ static int acpi_processor_hotadd_init(struct
> acpi_processor *pr)
> return ret;
> }
> #else
> -static inline int acpi_processor_hotadd_init(struct acpi_processor *pr)
> +static inline int acpi_processor_hotadd_init(struct acpi_processor *pr,
> + struct acpi_device *device)
> {
> return -ENODEV;
> }
> @@ -232,6 +263,7 @@ static int acpi_processor_get_info(struct acpi_device
> *device)
> acpi_status status = AE_OK;
> static int cpu0_initialized;
> unsigned long long value;
> + int ret;
>
> acpi_processor_errata();
>
> @@ -316,10 +348,12 @@ static int acpi_processor_get_info(struct
> acpi_device *device)
> * because cpuid <-> apicid mapping is persistent now.
> */
> if (invalid_logical_cpuid(pr->id) || !cpu_present(pr->id)) {
> - int ret = acpi_processor_hotadd_init(pr);
> + ret = acpi_processor_hotadd_init(pr, device);
>
> if (ret)
> - return ret;
> + goto err;
> + } else {
> + acpi_processor_set_per_cpu(pr, device);
> }
>
> /*
> @@ -357,6 +391,10 @@ static int acpi_processor_get_info(struct
> acpi_device *device)
> arch_fix_phys_package_id(pr->id, value);
>
> return 0;
> +
> +err:
> + per_cpu(processors, pr->id) = NULL;
> + return ret;
> }
>
> /*
> @@ -365,8 +403,6 @@ static int acpi_processor_get_info(struct acpi_device
> *device)
> * (cpu_data(cpu)) values, like CPU feature flags, family, model, etc.
> * Such things have to be put in and set up by the processor driver's
> .probe().
> */
> -static DEFINE_PER_CPU(void *, processor_device_array);
> -
> static int acpi_processor_add(struct acpi_device *device,
> const struct acpi_device_id *id)
> {
> @@ -395,28 +431,6 @@ static int acpi_processor_add(struct acpi_device
> *device,
> if (result) /* Processor is not physically present or unavailable */
> return 0;
>
> - BUG_ON(pr->id >= nr_cpu_ids);
> -
> - /*
> - * Buggy BIOS check.
> - * ACPI id of processors can be reported wrongly by the BIOS.
> - * Don't trust it blindly
> - */
> - if (per_cpu(processor_device_array, pr->id) != NULL &&
> - per_cpu(processor_device_array, pr->id) != device) {
> - dev_warn(&device->dev,
> - "BIOS reported wrong ACPI id %d for the processor\n",
> - pr->id);
> - /* Give up, but do not abort the namespace scan. */
> - goto err;
> - }
> - /*
> - * processor_device_array is not cleared on errors to allow buggy BIOS
> - * checks.
> - */
> - per_cpu(processor_device_array, pr->id) = device;
> - per_cpu(processors, pr->id) = pr;
> -
> dev = get_cpu_device(pr->id);
> if (!dev) {
> result = -ENODEV;
> @@ -469,15 +483,16 @@ static void acpi_processor_remove(struct
> acpi_device *device)
> device_release_driver(pr->dev);
> acpi_unbind_one(pr->dev);
>
> - /* Clean up. */
> - per_cpu(processor_device_array, pr->id) = NULL;
> - per_cpu(processors, pr->id) = NULL;
> -
> cpu_maps_update_begin();
> cpus_write_lock();
>
> /* Remove the CPU. */
> arch_unregister_cpu(pr->id);
> +
> + /* Clean up. */
> + per_cpu(processor_device_array, pr->id) = NULL;
> + per_cpu(processors, pr->id) = NULL;
> +

Shouldn't above change come after acpi_unmap_cpu() i.e. after next line?

> acpi_unmap_cpu(pr->id);
>
> cpus_write_unlock();
> --
> 2.39.2