[PATCH v1 0/2] ACPI: CPPC: Fix I/O port reads on big endian and clean up code in cpc_read()

[PATCH v1 0/2] ACPI: CPPC: Fix I/O port reads on big endian and clean up code in cpc_read()

[Rafael J. Wysocki]

Hi All,

These patches address a bug report against new code in cpc_read() and clean it
up on top of that.

Thanks!

[PATCH v1 1/2] ACPI: CPPC: Fix up I/O port access in cpc_read()

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The code as currently implemented does not work on big endian systems,
so fix it up.

Fixes: a2c8f92bea5f ("ACPI: CPPC: Implement support for SystemIO registers")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/linux-acpi/20220111092928.GA24968@kili/
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/cppc_acpi.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Index: linux-pm/drivers/acpi/cppc_acpi.c
===================================================================
--- linux-pm.orig/drivers/acpi/cppc_acpi.c
+++ linux-pm/drivers/acpi/cppc_acpi.c
@@ -929,16 +929,18 @@ static int cpc_read(int cpu, struct cpc_
 
 	if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
 		u32 width = 8 << (reg->access_width - 1);
+		u32 val_u32;
 		acpi_status status;
 
 		status = acpi_os_read_port((acpi_io_address)reg->address,
-					   (u32 *)val, width);
+					   &val_u32, width);
 		if (ACPI_FAILURE(status)) {
 			pr_debug("Error: Failed to read SystemIO port %llx\n",
 				 reg->address);
 			return -EFAULT;
 		}
 
+		*val = val_u32;
 		return 0;
 	} else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
 		vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);

[PATCH v1 2/2] ACPI: CPPC: Drop redundant local variable from cpc_read()

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The ret_val local variable in cpc_read() is not necessary, so
eliminate it.

No functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/cppc_acpi.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

Index: linux-pm/drivers/acpi/cppc_acpi.c
===================================================================
--- linux-pm.orig/drivers/acpi/cppc_acpi.c
+++ linux-pm/drivers/acpi/cppc_acpi.c
@@ -915,14 +915,13 @@ int __weak cpc_write_ffh(int cpunum, str
 
 static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
 {
-	int ret_val = 0;
 	void __iomem *vaddr = NULL;
 	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
 	struct cpc_reg *reg = &reg_res->cpc_entry.reg;
 
 	if (reg_res->type == ACPI_TYPE_INTEGER) {
 		*val = reg_res->cpc_entry.int_value;
-		return ret_val;
+		return 0;
 	}
 
 	*val = 0;
@@ -968,10 +967,10 @@ static int cpc_read(int cpu, struct cpc_
 	default:
 		pr_debug("Error: Cannot read %u bit width from PCC for ss: %d\n",
 			 reg->bit_width, pcc_ss_id);
-		ret_val = -EFAULT;
+		return -EFAULT;
 	}
 
-	return ret_val;
+	return 0;
 }
 
 static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)

Re: [PATCH v1 2/2] ACPI: CPPC: Drop redundant local variable from cpc_read()

[Huang Rui]

On Thu, Jan 13, 2022 at 02:27:22AM +0800, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> The ret_val local variable in cpc_read() is not necessary, so
> eliminate it.
> 
> No functional impact.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Acked-by: Huang Rui <ray.huang@amd.com>

> ---
>  drivers/acpi/cppc_acpi.c |    7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> Index: linux-pm/drivers/acpi/cppc_acpi.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/cppc_acpi.c
> +++ linux-pm/drivers/acpi/cppc_acpi.c
> @@ -915,14 +915,13 @@ int __weak cpc_write_ffh(int cpunum, str
>  
>  static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
>  {
> -	int ret_val = 0;
>  	void __iomem *vaddr = NULL;
>  	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
>  	struct cpc_reg *reg = &reg_res->cpc_entry.reg;
>  
>  	if (reg_res->type == ACPI_TYPE_INTEGER) {
>  		*val = reg_res->cpc_entry.int_value;
> -		return ret_val;
> +		return 0;
>  	}
>  
>  	*val = 0;
> @@ -968,10 +967,10 @@ static int cpc_read(int cpu, struct cpc_
>  	default:
>  		pr_debug("Error: Cannot read %u bit width from PCC for ss: %d\n",
>  			 reg->bit_width, pcc_ss_id);
> -		ret_val = -EFAULT;
> +		return -EFAULT;
>  	}
>  
> -	return ret_val;
> +	return 0;
>  }
>  
>  static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
> 
> 
> 

Re: [PATCH v1 1/2] ACPI: CPPC: Fix up I/O port access in cpc_read()

[Huang Rui]

On Wed, Jan 12, 2022 at 07:26:32PM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> The code as currently implemented does not work on big endian systems,
> so fix it up.
> 
> Fixes: a2c8f92bea5f ("ACPI: CPPC: Implement support for SystemIO registers")
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
> Link: https://lore.kernel.org/linux-acpi/20220111092928.GA24968@kili/
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Acked-by: Huang Rui <ray.huang@amd.com>

> ---
>  drivers/acpi/cppc_acpi.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> Index: linux-pm/drivers/acpi/cppc_acpi.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/cppc_acpi.c
> +++ linux-pm/drivers/acpi/cppc_acpi.c
> @@ -929,16 +929,18 @@ static int cpc_read(int cpu, struct cpc_
>  
>  	if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
>  		u32 width = 8 << (reg->access_width - 1);
> +		u32 val_u32;
>  		acpi_status status;
>  
>  		status = acpi_os_read_port((acpi_io_address)reg->address,
> -					   (u32 *)val, width);
> +					   &val_u32, width);
>  		if (ACPI_FAILURE(status)) {
>  			pr_debug("Error: Failed to read SystemIO port %llx\n",
>  				 reg->address);
>  			return -EFAULT;
>  		}
>  
> +		*val = val_u32;
>  		return 0;
>  	} else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
>  		vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);
> 
> 
>