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[PATCH v6 2/3] x86: Implement acpi_get_cpu_uid()

Chengwen Feng posted 3 patches 3 weeks, 5 days ago
There is a newer version of this series
[PATCH v6 2/3] x86: Implement acpi_get_cpu_uid()
Posted by Chengwen Feng 3 weeks, 5 days ago 
Add acpi_get_cpu_uid() implementation for x86, replacing the existing
cpu_acpi_id() function. This completes the unified ACPI Processor UID
retrieval interface across all ACPI-enabled architectures.

Cc: stable@vger.kernel.org
Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
---
 arch/x86/include/asm/cpu.h   |  1 -
 arch/x86/include/asm/smp.h   |  1 -
 arch/x86/kernel/cpu/common.c | 15 +++++++++++++++
 arch/x86/xen/enlighten_hvm.c |  5 +++--
 include/linux/acpi.h         |  2 --
 5 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
index ad235dda1ded..57a0786dfd75 100644
--- a/arch/x86/include/asm/cpu.h
+++ b/arch/x86/include/asm/cpu.h
@@ -11,7 +11,6 @@
 
 #ifndef CONFIG_SMP
 #define cpu_physical_id(cpu)			boot_cpu_physical_apicid
-#define cpu_acpi_id(cpu)			0
 #endif /* CONFIG_SMP */
 
 #ifdef CONFIG_HOTPLUG_CPU
diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 84951572ab81..05d1d479b4cf 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -130,7 +130,6 @@ __visible void smp_call_function_interrupt(struct pt_regs *regs);
 __visible void smp_call_function_single_interrupt(struct pt_regs *r);
 
 #define cpu_physical_id(cpu)	per_cpu(x86_cpu_to_apicid, cpu)
-#define cpu_acpi_id(cpu)	per_cpu(x86_cpu_to_acpiid, cpu)
 
 /*
  * This function is needed by all SMP systems. It must _always_ be valid
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 1c3261cae40c..3081557542c7 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -28,6 +28,7 @@
 #include <linux/stackprotector.h>
 #include <linux/utsname.h>
 #include <linux/efi.h>
+#include <linux/acpi.h>
 
 #include <asm/alternative.h>
 #include <asm/cmdline.h>
@@ -57,6 +58,7 @@
 #include <asm/asm.h>
 #include <asm/bugs.h>
 #include <asm/cpu.h>
+#include <asm/smp.h>
 #include <asm/mce.h>
 #include <asm/msr.h>
 #include <asm/cacheinfo.h>
@@ -2643,3 +2645,16 @@ void __init arch_cpu_finalize_init(void)
 	 */
 	mem_encrypt_init();
 }
+
+int acpi_get_cpu_uid(unsigned int cpu, u32 *uid)
+{
+	if (cpu >= nr_cpu_ids)
+		return -EINVAL;
+#ifndef CONFIG_SMP
+	*uid = 0;
+#else
+	*uid = per_cpu(x86_cpu_to_acpiid, cpu);
+#endif
+	return 0;
+}
+EXPORT_SYMBOL_GPL(acpi_get_cpu_uid);
diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
index fe57ff85d004..2f9fa27e5a3c 100644
--- a/arch/x86/xen/enlighten_hvm.c
+++ b/arch/x86/xen/enlighten_hvm.c
@@ -151,6 +151,7 @@ static void xen_hvm_crash_shutdown(struct pt_regs *regs)
 
 static int xen_cpu_up_prepare_hvm(unsigned int cpu)
 {
+	u32 cpu_uid;
 	int rc = 0;
 
 	/*
@@ -161,8 +162,8 @@ static int xen_cpu_up_prepare_hvm(unsigned int cpu)
 	 */
 	xen_uninit_lock_cpu(cpu);
 
-	if (cpu_acpi_id(cpu) != CPU_ACPIID_INVALID)
-		per_cpu(xen_vcpu_id, cpu) = cpu_acpi_id(cpu);
+	if (acpi_get_cpu_uid(cpu, &cpu_uid) == 0)
+		per_cpu(xen_vcpu_id, cpu) = cpu_uid;
 	else
 		per_cpu(xen_vcpu_id, cpu) = cpu;
 	xen_vcpu_setup(cpu);
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 035094a55f18..90a1fdcb7eb9 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -324,7 +324,6 @@ int acpi_unmap_cpu(int cpu);
 
 acpi_handle acpi_get_processor_handle(int cpu);
 
-#ifndef CONFIG_X86
 /*
  * acpi_get_cpu_uid() - Get ACPI Processor UID of a specified CPU from MADT table
  * @cpu: Logical CPU number (0-based)
@@ -335,7 +334,6 @@ acpi_handle acpi_get_processor_handle(int cpu);
  *         -ENODEV if the ACPI Processor UID for the specified CPU is not found.
  */
 int acpi_get_cpu_uid(unsigned int cpu, u32 *uid);
-#endif
 
 #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
 int acpi_get_ioapic_id(acpi_handle handle, u32 gsi_base, u64 *phys_addr);
-- 
2.17.1
Re: [PATCH v6 2/3] x86: Implement acpi_get_cpu_uid()
Posted by Peter Zijlstra 3 weeks, 5 days ago 
On Thu, Mar 12, 2026 at 03:23:15PM +0800, Chengwen Feng wrote:
> Add acpi_get_cpu_uid() implementation for x86, replacing the existing
> cpu_acpi_id() function. This completes the unified ACPI Processor UID
> retrieval interface across all ACPI-enabled architectures.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
> ---
>  arch/x86/include/asm/cpu.h   |  1 -
>  arch/x86/include/asm/smp.h   |  1 -
>  arch/x86/kernel/cpu/common.c | 15 +++++++++++++++
>  arch/x86/xen/enlighten_hvm.c |  5 +++--
>  include/linux/acpi.h         |  2 --
>  5 files changed, 18 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
> index ad235dda1ded..57a0786dfd75 100644
> --- a/arch/x86/include/asm/cpu.h
> +++ b/arch/x86/include/asm/cpu.h
> @@ -11,7 +11,6 @@
>  
>  #ifndef CONFIG_SMP
>  #define cpu_physical_id(cpu)			boot_cpu_physical_apicid
> -#define cpu_acpi_id(cpu)			0
>  #endif /* CONFIG_SMP */
>  
>  #ifdef CONFIG_HOTPLUG_CPU
> diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
> index 84951572ab81..05d1d479b4cf 100644
> --- a/arch/x86/include/asm/smp.h
> +++ b/arch/x86/include/asm/smp.h
> @@ -130,7 +130,6 @@ __visible void smp_call_function_interrupt(struct pt_regs *regs);
>  __visible void smp_call_function_single_interrupt(struct pt_regs *r);
>  
>  #define cpu_physical_id(cpu)	per_cpu(x86_cpu_to_apicid, cpu)
> -#define cpu_acpi_id(cpu)	per_cpu(x86_cpu_to_acpiid, cpu)
>  
>  /*
>   * This function is needed by all SMP systems. It must _always_ be valid
> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> index 1c3261cae40c..3081557542c7 100644
> --- a/arch/x86/kernel/cpu/common.c
> +++ b/arch/x86/kernel/cpu/common.c
> @@ -28,6 +28,7 @@
>  #include <linux/stackprotector.h>
>  #include <linux/utsname.h>
>  #include <linux/efi.h>
> +#include <linux/acpi.h>
>  
>  #include <asm/alternative.h>
>  #include <asm/cmdline.h>
> @@ -57,6 +58,7 @@
>  #include <asm/asm.h>
>  #include <asm/bugs.h>
>  #include <asm/cpu.h>
> +#include <asm/smp.h>
>  #include <asm/mce.h>
>  #include <asm/msr.h>
>  #include <asm/cacheinfo.h>
> @@ -2643,3 +2645,16 @@ void __init arch_cpu_finalize_init(void)
>  	 */
>  	mem_encrypt_init();
>  }
> +
> +int acpi_get_cpu_uid(unsigned int cpu, u32 *uid)
> +{
> +	if (cpu >= nr_cpu_ids)
> +		return -EINVAL;
> +#ifndef CONFIG_SMP
> +	*uid = 0;
> +#else
> +	*uid = per_cpu(x86_cpu_to_acpiid, cpu);
> +#endif
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(acpi_get_cpu_uid);
> diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
> index fe57ff85d004..2f9fa27e5a3c 100644
> --- a/arch/x86/xen/enlighten_hvm.c
> +++ b/arch/x86/xen/enlighten_hvm.c
> @@ -151,6 +151,7 @@ static void xen_hvm_crash_shutdown(struct pt_regs *regs)
>  
>  static int xen_cpu_up_prepare_hvm(unsigned int cpu)
>  {
> +	u32 cpu_uid;
>  	int rc = 0;
>  
>  	/*
> @@ -161,8 +162,8 @@ static int xen_cpu_up_prepare_hvm(unsigned int cpu)
>  	 */
>  	xen_uninit_lock_cpu(cpu);
>  
> -	if (cpu_acpi_id(cpu) != CPU_ACPIID_INVALID)
> -		per_cpu(xen_vcpu_id, cpu) = cpu_acpi_id(cpu);
> +	if (acpi_get_cpu_uid(cpu, &cpu_uid) == 0)
> +		per_cpu(xen_vcpu_id, cpu) = cpu_uid;
>  	else
>  		per_cpu(xen_vcpu_id, cpu) = cpu;
>  	xen_vcpu_setup(cpu);

This doesn't look right, it will now set CPU_ACPIID_INVALID, while
previously it would not.
Re: [PATCH v6 2/3] x86: Implement acpi_get_cpu_uid()
Posted by fengchengwen 3 weeks, 4 days ago 
On 3/12/2026 7:02 PM, Peter Zijlstra wrote:
> On Thu, Mar 12, 2026 at 03:23:15PM +0800, Chengwen Feng wrote:
>> Add acpi_get_cpu_uid() implementation for x86, replacing the existing
>> cpu_acpi_id() function. This completes the unified ACPI Processor UID
>> retrieval interface across all ACPI-enabled architectures.
>>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
>> ---
>>  arch/x86/include/asm/cpu.h   |  1 -
>>  arch/x86/include/asm/smp.h   |  1 -
>>  arch/x86/kernel/cpu/common.c | 15 +++++++++++++++
>>  arch/x86/xen/enlighten_hvm.c |  5 +++--
>>  include/linux/acpi.h         |  2 --
>>  5 files changed, 18 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
>> index ad235dda1ded..57a0786dfd75 100644
>> --- a/arch/x86/include/asm/cpu.h
>> +++ b/arch/x86/include/asm/cpu.h
>> @@ -11,7 +11,6 @@
>>  
>>  #ifndef CONFIG_SMP
>>  #define cpu_physical_id(cpu)			boot_cpu_physical_apicid
>> -#define cpu_acpi_id(cpu)			0
>>  #endif /* CONFIG_SMP */
>>  
>>  #ifdef CONFIG_HOTPLUG_CPU
>> diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
>> index 84951572ab81..05d1d479b4cf 100644
>> --- a/arch/x86/include/asm/smp.h
>> +++ b/arch/x86/include/asm/smp.h
>> @@ -130,7 +130,6 @@ __visible void smp_call_function_interrupt(struct pt_regs *regs);
>>  __visible void smp_call_function_single_interrupt(struct pt_regs *r);
>>  
>>  #define cpu_physical_id(cpu)	per_cpu(x86_cpu_to_apicid, cpu)
>> -#define cpu_acpi_id(cpu)	per_cpu(x86_cpu_to_acpiid, cpu)
>>  
>>  /*
>>   * This function is needed by all SMP systems. It must _always_ be valid
>> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
>> index 1c3261cae40c..3081557542c7 100644
>> --- a/arch/x86/kernel/cpu/common.c
>> +++ b/arch/x86/kernel/cpu/common.c
>> @@ -28,6 +28,7 @@
>>  #include <linux/stackprotector.h>
>>  #include <linux/utsname.h>
>>  #include <linux/efi.h>
>> +#include <linux/acpi.h>
>>  
>>  #include <asm/alternative.h>
>>  #include <asm/cmdline.h>
>> @@ -57,6 +58,7 @@
>>  #include <asm/asm.h>
>>  #include <asm/bugs.h>
>>  #include <asm/cpu.h>
>> +#include <asm/smp.h>
>>  #include <asm/mce.h>
>>  #include <asm/msr.h>
>>  #include <asm/cacheinfo.h>
>> @@ -2643,3 +2645,16 @@ void __init arch_cpu_finalize_init(void)
>>  	 */
>>  	mem_encrypt_init();
>>  }
>> +
>> +int acpi_get_cpu_uid(unsigned int cpu, u32 *uid)
>> +{
>> +	if (cpu >= nr_cpu_ids)
>> +		return -EINVAL;
>> +#ifndef CONFIG_SMP
>> +	*uid = 0;
>> +#else
>> +	*uid = per_cpu(x86_cpu_to_acpiid, cpu);
>> +#endif
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(acpi_get_cpu_uid);
>> diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
>> index fe57ff85d004..2f9fa27e5a3c 100644
>> --- a/arch/x86/xen/enlighten_hvm.c
>> +++ b/arch/x86/xen/enlighten_hvm.c
>> @@ -151,6 +151,7 @@ static void xen_hvm_crash_shutdown(struct pt_regs *regs)
>>  
>>  static int xen_cpu_up_prepare_hvm(unsigned int cpu)
>>  {
>> +	u32 cpu_uid;
>>  	int rc = 0;
>>  
>>  	/*
>> @@ -161,8 +162,8 @@ static int xen_cpu_up_prepare_hvm(unsigned int cpu)
>>  	 */
>>  	xen_uninit_lock_cpu(cpu);
>>  
>> -	if (cpu_acpi_id(cpu) != CPU_ACPIID_INVALID)
>> -		per_cpu(xen_vcpu_id, cpu) = cpu_acpi_id(cpu);
>> +	if (acpi_get_cpu_uid(cpu, &cpu_uid) == 0)
>> +		per_cpu(xen_vcpu_id, cpu) = cpu_uid;
>>  	else
>>  		per_cpu(xen_vcpu_id, cpu) = cpu;
>>  	xen_vcpu_setup(cpu);
> 
> This doesn't look right, it will now set CPU_ACPIID_INVALID, while
> previously it would not.

This is indeed an issue, it has been fixed in v7 (by treating CPU_ACPIID_INVALID as an error).

Thanks

> 
>
Re: [PATCH v6 2/3] x86: Implement acpi_get_cpu_uid()
Posted by Jonathan Cameron 3 weeks, 5 days ago 
On Thu, 12 Mar 2026 15:23:15 +0800
Chengwen Feng <fengchengwen@huawei.com> wrote:

> Add acpi_get_cpu_uid() implementation for x86, replacing the existing
> cpu_acpi_id() function. This completes the unified ACPI Processor UID
> retrieval interface across all ACPI-enabled architectures.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>

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