| Message ID | 20230913163823.7880-23-james.morse@arm.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere, archived |
| Headers | show |
| Series | ACPI/arm64: add support for virtual cpuhotplug | expand |
On Wed, 13 Sep 2023 16:38:10 +0000 James Morse <james.morse@arm.com> wrote: > When called acpi_processor_post_eject() unconditionally make a CPU > not-present and unregisters it. > > To add support for AML events where the CPU has become disabled, but > remains present, the _STA method should be checked before calling > acpi_processor_remove(). > > Rename acpi_processor_post_eject() acpi_processor_remove_possible(), and > check the _STA before calling. > > Adding the function prototype for arch_unregister_cpu() allows the > preprocessor guards to be removed. > > After this change CPUs will remain registered and visible to > user-space as offline if buggy firmware triggers an eject-request, > but doesn't clear the corresponding _STA bits after _EJ0 has been > called. Will be fun to see how many such buggy firmwares are out there. > > Signed-off-by: James Morse <james.morse@arm.com> Comment inline but not directly related to this patch so with or without that change Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > --- > drivers/acpi/acpi_processor.c | 31 +++++++++++++++++++++++++------ > include/linux/cpu.h | 1 + > 2 files changed, 26 insertions(+), 6 deletions(-) > > diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c > index 00dcc23d49a8..2cafea1edc24 100644 > --- a/drivers/acpi/acpi_processor.c > +++ b/drivers/acpi/acpi_processor.c > @@ -457,13 +457,12 @@ static int acpi_processor_add(struct acpi_device *device, > return result; > } > > -#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU > /* Removal */ > -static void acpi_processor_post_eject(struct acpi_device *device) > +static void acpi_processor_make_not_present(struct acpi_device *device) > { > struct acpi_processor *pr; > > - if (!device || !acpi_driver_data(device)) > + if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU)) Would it be possible to do all the ifdef to IS_ENABLED changes in a separate patch? I haven't figure out if any of them have dependencies on the other changes, but they do create a bunch of noise I'd rather not see in the more complex corners of this. > return; > > pr = acpi_driver_data(device); > @@ -501,7 +500,29 @@ static void acpi_processor_post_eject(struct acpi_device *device) > free_cpumask_var(pr->throttling.shared_cpu_map); > kfree(pr); > } > -#endif /* CONFIG_ACPI_HOTPLUG_PRESENT_CPU */ > + > +static void acpi_processor_post_eject(struct acpi_device *device) > +{ > + struct acpi_processor *pr; > + unsigned long long sta; > + acpi_status status; > + > + if (!device) > + return; > + > + pr = acpi_driver_data(device); > + if (!pr || pr->id >= nr_cpu_ids || invalid_phys_cpuid(pr->phys_id)) > + return; > + > + status = acpi_evaluate_integer(pr->handle, "_STA", NULL, &sta); > + if (ACPI_FAILURE(status)) > + return; > + > + if (cpu_present(pr->id) && !(sta & ACPI_STA_DEVICE_PRESENT)) { > + acpi_processor_make_not_present(device); > + return; > + } > +} > > #ifdef CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC > bool __init processor_physically_present(acpi_handle handle) > @@ -626,9 +647,7 @@ static const struct acpi_device_id processor_device_ids[] = { > static struct acpi_scan_handler processor_handler = { > .ids = processor_device_ids, > .attach = acpi_processor_add, > -#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU > .post_eject = acpi_processor_post_eject, > -#endif > .hotplug = { > .enabled = true, > }, > diff --git a/include/linux/cpu.h b/include/linux/cpu.h > index a71691d7c2ca..e117c06e0c6b 100644 > --- a/include/linux/cpu.h > +++ b/include/linux/cpu.h > @@ -81,6 +81,7 @@ struct device *cpu_device_create(struct device *parent, void *drvdata, > const struct attribute_group **groups, > const char *fmt, ...); > extern int arch_register_cpu(int cpu); > +extern void arch_unregister_cpu(int cpu); > #ifdef CONFIG_HOTPLUG_CPU > extern void unregister_cpu(struct cpu *cpu); > extern ssize_t arch_cpu_probe(const char *, size_t);
On 9/14/23 02:38, James Morse wrote: > When called acpi_processor_post_eject() unconditionally make a CPU > not-present and unregisters it. > > To add support for AML events where the CPU has become disabled, but > remains present, the _STA method should be checked before calling > acpi_processor_remove(). > > Rename acpi_processor_post_eject() acpi_processor_remove_possible(), and > check the _STA before calling. > > Adding the function prototype for arch_unregister_cpu() allows the > preprocessor guards to be removed. > > After this change CPUs will remain registered and visible to > user-space as offline if buggy firmware triggers an eject-request, > but doesn't clear the corresponding _STA bits after _EJ0 has been > called. > > Signed-off-by: James Morse <james.morse@arm.com> > --- > drivers/acpi/acpi_processor.c | 31 +++++++++++++++++++++++++------ > include/linux/cpu.h | 1 + > 2 files changed, 26 insertions(+), 6 deletions(-) > > diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c > index 00dcc23d49a8..2cafea1edc24 100644 > --- a/drivers/acpi/acpi_processor.c > +++ b/drivers/acpi/acpi_processor.c > @@ -457,13 +457,12 @@ static int acpi_processor_add(struct acpi_device *device, > return result; > } > > -#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU > /* Removal */ > -static void acpi_processor_post_eject(struct acpi_device *device) > +static void acpi_processor_make_not_present(struct acpi_device *device) > { > struct acpi_processor *pr; > > - if (!device || !acpi_driver_data(device)) > + if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU)) > return; > In order to use IS_ENABLED(), > pr = acpi_driver_data(device); > @@ -501,7 +500,29 @@ static void acpi_processor_post_eject(struct acpi_device *device) > free_cpumask_var(pr->throttling.shared_cpu_map); > kfree(pr); > } > -#endif /* CONFIG_ACPI_HOTPLUG_PRESENT_CPU */ > + > +static void acpi_processor_post_eject(struct acpi_device *device) > +{ > + struct acpi_processor *pr; > + unsigned long long sta; > + acpi_status status; > + > + if (!device) > + return; > + > + pr = acpi_driver_data(device); > + if (!pr || pr->id >= nr_cpu_ids || invalid_phys_cpuid(pr->phys_id)) > + return; > + Do we really need to validate the logic and hardware CPU IDs here? I think the ACPI processor device can't be added successfully if one of them is invalid. > + status = acpi_evaluate_integer(pr->handle, "_STA", NULL, &sta); > + if (ACPI_FAILURE(status)) > + return; > + > + if (cpu_present(pr->id) && !(sta & ACPI_STA_DEVICE_PRESENT)) { > + acpi_processor_make_not_present(device); > + return; > + } > +} > > #ifdef CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC > bool __init processor_physically_present(acpi_handle handle) > @@ -626,9 +647,7 @@ static const struct acpi_device_id processor_device_ids[] = { > static struct acpi_scan_handler processor_handler = { > .ids = processor_device_ids, > .attach = acpi_processor_add, > -#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU > .post_eject = acpi_processor_post_eject, > -#endif > .hotplug = { > .enabled = true, > }, > diff --git a/include/linux/cpu.h b/include/linux/cpu.h > index a71691d7c2ca..e117c06e0c6b 100644 > --- a/include/linux/cpu.h > +++ b/include/linux/cpu.h > @@ -81,6 +81,7 @@ struct device *cpu_device_create(struct device *parent, void *drvdata, > const struct attribute_group **groups, > const char *fmt, ...); > extern int arch_register_cpu(int cpu); > +extern void arch_unregister_cpu(int cpu); arch_unregister_cpu() is protected by CONFIG_HOTPLUG_CPU in the individual architectures, for example arch/ia64/kernel/topology.c > #ifdef CONFIG_HOTPLUG_CPU > extern void unregister_cpu(struct cpu *cpu); > extern ssize_t arch_cpu_probe(const char *, size_t); Thanks, Gavin
On Thu, Sep 14, 2023 at 03:31:10PM +0100, Jonathan Cameron wrote: > On Wed, 13 Sep 2023 16:38:10 +0000 > James Morse <james.morse@arm.com> wrote: > > -#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU > > /* Removal */ > > -static void acpi_processor_post_eject(struct acpi_device *device) > > +static void acpi_processor_make_not_present(struct acpi_device *device) > > { > > struct acpi_processor *pr; > > > > - if (!device || !acpi_driver_data(device)) > > + if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU)) > > Would it be possible to do all the ifdef to IS_ENABLED changes in a separate > patch? I haven't figure out if any of them have dependencies on the other > changes, but they do create a bunch of noise I'd rather not see in the more > complex corners of this. I'm also wondering why we want to do this check here, rather than... > > +static void acpi_processor_post_eject(struct acpi_device *device) > > +{ > > + struct acpi_processor *pr; > > + unsigned long long sta; > > + acpi_status status; ... here, because none of the code below has any effect if acpi_processor_make_not_present() merely returns. So the below seems like a waste of code space when CONFIG_ACPI_HOTPLUG_PRESENT_CPU is disabled. > > + > > + if (!device) > > + return; > > + > > + pr = acpi_driver_data(device); > > + if (!pr || pr->id >= nr_cpu_ids || invalid_phys_cpuid(pr->phys_id)) > > + return; > > + > > + status = acpi_evaluate_integer(pr->handle, "_STA", NULL, &sta); > > + if (ACPI_FAILURE(status)) > > + return; > > + > > + if (cpu_present(pr->id) && !(sta & ACPI_STA_DEVICE_PRESENT)) { > > + acpi_processor_make_not_present(device); > > + return; > > + } > > +}
On Tue, Sep 19, 2023 at 10:45:39AM +1000, Gavin Shan wrote: > On 9/14/23 02:38, James Morse wrote: > > When called acpi_processor_post_eject() unconditionally make a CPU > > not-present and unregisters it. > > > > To add support for AML events where the CPU has become disabled, but > > remains present, the _STA method should be checked before calling > > acpi_processor_remove(). > > > > Rename acpi_processor_post_eject() acpi_processor_remove_possible(), and > > check the _STA before calling. > > > > Adding the function prototype for arch_unregister_cpu() allows the > > preprocessor guards to be removed. > > > > After this change CPUs will remain registered and visible to > > user-space as offline if buggy firmware triggers an eject-request, > > but doesn't clear the corresponding _STA bits after _EJ0 has been > > called. > > > > Signed-off-by: James Morse <james.morse@arm.com> > > --- > > drivers/acpi/acpi_processor.c | 31 +++++++++++++++++++++++++------ > > include/linux/cpu.h | 1 + > > 2 files changed, 26 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c > > index 00dcc23d49a8..2cafea1edc24 100644 > > --- a/drivers/acpi/acpi_processor.c > > +++ b/drivers/acpi/acpi_processor.c > > @@ -457,13 +457,12 @@ static int acpi_processor_add(struct acpi_device *device, > > return result; > > } > > -#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU > > /* Removal */ > > -static void acpi_processor_post_eject(struct acpi_device *device) > > +static void acpi_processor_make_not_present(struct acpi_device *device) > > { > > struct acpi_processor *pr; > > - if (!device || !acpi_driver_data(device)) > > + if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU)) > > return; > > In order to use IS_ENABLED(), And the rest of this statement is where? > > pr = acpi_driver_data(device); > > @@ -501,7 +500,29 @@ static void acpi_processor_post_eject(struct acpi_device *device) > > free_cpumask_var(pr->throttling.shared_cpu_map); > > kfree(pr); > > } > > -#endif /* CONFIG_ACPI_HOTPLUG_PRESENT_CPU */ > > + > > +static void acpi_processor_post_eject(struct acpi_device *device) > > +{ > > + struct acpi_processor *pr; > > + unsigned long long sta; > > + acpi_status status; > > + > > + if (!device) > > + return; > > + > > + pr = acpi_driver_data(device); > > + if (!pr || pr->id >= nr_cpu_ids || invalid_phys_cpuid(pr->phys_id)) > > + return; > > + > > Do we really need to validate the logic and hardware CPU IDs here? I think > the ACPI processor device can't be added successfully if one of them is > invalid. > > > + status = acpi_evaluate_integer(pr->handle, "_STA", NULL, &sta); > > + if (ACPI_FAILURE(status)) > > + return; > > + > > + if (cpu_present(pr->id) && !(sta & ACPI_STA_DEVICE_PRESENT)) { > > + acpi_processor_make_not_present(device); > > + return; > > + } > > +} > > #ifdef CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC > > bool __init processor_physically_present(acpi_handle handle) > > @@ -626,9 +647,7 @@ static const struct acpi_device_id processor_device_ids[] = { > > static struct acpi_scan_handler processor_handler = { > > .ids = processor_device_ids, > > .attach = acpi_processor_add, > > -#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU > > .post_eject = acpi_processor_post_eject, > > -#endif > > .hotplug = { > > .enabled = true, > > }, > > diff --git a/include/linux/cpu.h b/include/linux/cpu.h > > index a71691d7c2ca..e117c06e0c6b 100644 > > --- a/include/linux/cpu.h > > +++ b/include/linux/cpu.h > > @@ -81,6 +81,7 @@ struct device *cpu_device_create(struct device *parent, void *drvdata, > > const struct attribute_group **groups, > > const char *fmt, ...); > > extern int arch_register_cpu(int cpu); > > +extern void arch_unregister_cpu(int cpu); > > arch_unregister_cpu() is protected by CONFIG_HOTPLUG_CPU in the individual architectures, > for example arch/ia64/kernel/topology.c Yes, I agree, there _may_ be a reference to arch_unregister_cpu() if the compiler doesn't optimise the "if(0) return". As things stand in my "head" tree (which I'll be posting once 6.7-rc1 is out) at the point that this patch exists in the series, there are no architectures which provide arch_unregister_cpu(), and the only implementation of it is the __weak one in drivers/base/cpu.c That implementation is also ifdef'd with CONFIG_HOTPLUG_CPU and also CONFIG_GENERIC_CPU_DEVICES. Meanwhile, acpi_processor.c is always built with ACPI, and while we have IS_ENABLED() clauses with James' patches for both of these symbols, if the compiler doesn't optimise the code away, we will end up with a reference and a link-time error. That being said, the 0-day bot has not reported anything as yet (and it builds my tree.) So, is this a problem that needs to be solved or not?
diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c index 00dcc23d49a8..2cafea1edc24 100644 --- a/drivers/acpi/acpi_processor.c +++ b/drivers/acpi/acpi_processor.c @@ -457,13 +457,12 @@ static int acpi_processor_add(struct acpi_device *device, return result; } -#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU /* Removal */ -static void acpi_processor_post_eject(struct acpi_device *device) +static void acpi_processor_make_not_present(struct acpi_device *device) { struct acpi_processor *pr; - if (!device || !acpi_driver_data(device)) + if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU)) return; pr = acpi_driver_data(device); @@ -501,7 +500,29 @@ static void acpi_processor_post_eject(struct acpi_device *device) free_cpumask_var(pr->throttling.shared_cpu_map); kfree(pr); } -#endif /* CONFIG_ACPI_HOTPLUG_PRESENT_CPU */ + +static void acpi_processor_post_eject(struct acpi_device *device) +{ + struct acpi_processor *pr; + unsigned long long sta; + acpi_status status; + + if (!device) + return; + + pr = acpi_driver_data(device); + if (!pr || pr->id >= nr_cpu_ids || invalid_phys_cpuid(pr->phys_id)) + return; + + status = acpi_evaluate_integer(pr->handle, "_STA", NULL, &sta); + if (ACPI_FAILURE(status)) + return; + + if (cpu_present(pr->id) && !(sta & ACPI_STA_DEVICE_PRESENT)) { + acpi_processor_make_not_present(device); + return; + } +} #ifdef CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC bool __init processor_physically_present(acpi_handle handle) @@ -626,9 +647,7 @@ static const struct acpi_device_id processor_device_ids[] = { static struct acpi_scan_handler processor_handler = { .ids = processor_device_ids, .attach = acpi_processor_add, -#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU .post_eject = acpi_processor_post_eject, -#endif .hotplug = { .enabled = true, }, diff --git a/include/linux/cpu.h b/include/linux/cpu.h index a71691d7c2ca..e117c06e0c6b 100644 --- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -81,6 +81,7 @@ struct device *cpu_device_create(struct device *parent, void *drvdata, const struct attribute_group **groups, const char *fmt, ...); extern int arch_register_cpu(int cpu); +extern void arch_unregister_cpu(int cpu); #ifdef CONFIG_HOTPLUG_CPU extern void unregister_cpu(struct cpu *cpu); extern ssize_t arch_cpu_probe(const char *, size_t);
When called acpi_processor_post_eject() unconditionally make a CPU not-present and unregisters it. To add support for AML events where the CPU has become disabled, but remains present, the _STA method should be checked before calling acpi_processor_remove(). Rename acpi_processor_post_eject() acpi_processor_remove_possible(), and check the _STA before calling. Adding the function prototype for arch_unregister_cpu() allows the preprocessor guards to be removed. After this change CPUs will remain registered and visible to user-space as offline if buggy firmware triggers an eject-request, but doesn't clear the corresponding _STA bits after _EJ0 has been called. Signed-off-by: James Morse <james.morse@arm.com> --- drivers/acpi/acpi_processor.c | 31 +++++++++++++++++++++++++------ include/linux/cpu.h | 1 + 2 files changed, 26 insertions(+), 6 deletions(-)