diff mbox series

[v4] ACPI: Add acpi=nospcr to disable ACPI SPCR as default console on ARM64

Message ID 20240625030504.58025-1-liuwei09@cestc.cn (mailing list archive)
State New, archived
Headers show
Series [v4] ACPI: Add acpi=nospcr to disable ACPI SPCR as default console on ARM64 | expand

Commit Message

Liu Wei June 25, 2024, 3:05 a.m. UTC
For varying privacy and security reasons, sometimes we would like to
completely silence the _serial_ console, and only enable it when needed.

But there are many existing systems that depend on this _serial_ console,
so add acpi=nospcr to disable console in ACPI SPCR table as default
_serial_ console.

Signed-off-by: Liu Wei <liuwei09@cestc.cn>
Suggested-by: Prarit Bhargava <prarit@redhat.com>
Suggested-by: Will Deacon <will@kernel.org>
Suggested-by: Andrew Lunn <andrew@lunn.ch>
---

v2: Add a config option suggested by Prarit

v3: Use cmdline acpi=nospcr instead of config

v4: Some description in comment or document
---
 .../admin-guide/kernel-parameters.txt          | 10 +++++++---
 arch/arm64/kernel/acpi.c                       | 18 +++++++++++++++++-
 2 files changed, 24 insertions(+), 4 deletions(-)

Comments

Prarit Bhargava June 25, 2024, 12:58 p.m. UTC | #1
On 6/24/24 23:05, Liu Wei wrote:
> For varying privacy and security reasons, sometimes we would like to
> completely silence the _serial_ console, and only enable it when needed.
> 
> But there are many existing systems that depend on this _serial_ console,
> so add acpi=nospcr to disable console in ACPI SPCR table as default
> _serial_ console.
> 
> Signed-off-by: Liu Wei <liuwei09@cestc.cn>
> Suggested-by: Prarit Bhargava <prarit@redhat.com>
> Suggested-by: Will Deacon <will@kernel.org>
> Suggested-by: Andrew Lunn <andrew@lunn.ch>
> ---
> 
> v2: Add a config option suggested by Prarit
> 
> v3: Use cmdline acpi=nospcr instead of config
> 
> v4: Some description in comment or document
> ---
>   .../admin-guide/kernel-parameters.txt          | 10 +++++++---
>   arch/arm64/kernel/acpi.c                       | 18 +++++++++++++++++-
>   2 files changed, 24 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 11e57ba2985c..6814ff7ae446 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -12,7 +12,7 @@
>   	acpi=		[HW,ACPI,X86,ARM64,RISCV64,EARLY]
>   			Advanced Configuration and Power Interface
>   			Format: { force | on | off | strict | noirq | rsdt |
> -				  copy_dsdt }
> +				  copy_dsdt | nospcr }
>   			force -- enable ACPI if default was off
>   			on -- enable ACPI but allow fallback to DT [arm64,riscv64]
>   			off -- disable ACPI if default was on
> @@ -21,8 +21,12 @@
>   				strictly ACPI specification compliant.
>   			rsdt -- prefer RSDT over (default) XSDT
>   			copy_dsdt -- copy DSDT to memory
> -			For ARM64 and RISCV64, ONLY "acpi=off", "acpi=on" or
> -			"acpi=force" are available
> +			nospcr -- disable console in ACPI SPCR table as
> +				default _serial_ console on ARM64
> +			For ARM64, ONLY "acpi=off", "acpi=on", "acpi=force" or
> +			"acpi=nospcr" are available
> +			For RISCV64, ONLY "acpi=off", "acpi=on" or "acpi=force"
> +			are available
>   
>   			See also Documentation/power/runtime_pm.rst, pci=noacpi
>   
> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> index e0e7b93c16cc..55757d8884d4 100644
> --- a/arch/arm64/kernel/acpi.c
> +++ b/arch/arm64/kernel/acpi.c
> @@ -45,6 +45,7 @@ EXPORT_SYMBOL(acpi_pci_disabled);
>   static bool param_acpi_off __initdata;
>   static bool param_acpi_on __initdata;
>   static bool param_acpi_force __initdata;
> +static bool param_acpi_nospcr __initdata;
>   
>   static int __init parse_acpi(char *arg)
>   {
> @@ -58,6 +59,8 @@ static int __init parse_acpi(char *arg)
>   		param_acpi_on = true;
>   	else if (strcmp(arg, "force") == 0) /* force ACPI to be enabled */
>   		param_acpi_force = true;
> +	else if (strcmp(arg, "nospcr") == 0) /* disable SPCR as default console */
> +		param_acpi_nospcr = true;
>   	else
>   		return -EINVAL;	/* Core will print when we return error */
>   
> @@ -237,7 +240,20 @@ void __init acpi_boot_table_init(void)
>   			acpi_put_table(facs);
>   		}
>   #endif
> -		acpi_parse_spcr(earlycon_acpi_spcr_enable, true);
> +
> +		/*
> +		 * For varying privacy and security reasons, sometimes need
> +		 * to completely silence the serial console output, and only
> +		 * enable it when needed.
> +		 * But there are many existing systems that depend on this
> +		 * behavior, use acpi=nospcr to disable console in ACPI SPCR
> +		 * table as default serial console.
> +		 */
> +		acpi_parse_spcr(earlycon_acpi_spcr_enable,
> +			!param_acpi_nospcr);
> +		pr_info("Use ACPI SPCR as default console: %s\n",
> +				param_acpi_nospcr ? "No" : "Yes");
> +
>   		if (IS_ENABLED(CONFIG_ACPI_BGRT))
>   			acpi_table_parse(ACPI_SIG_BGRT, acpi_parse_bgrt);
>   	}

This looks good to me.  Sorry that this took so long Liu.

Reviewed-by: Prarit Bhargava <prarit@redhat.com>

P.
Liu Wei June 26, 2024, 3:07 a.m. UTC | #2
From: Prarit Bhargava <prarit@redhat.com>

> On 6/24/24 23:05, Liu Wei wrote:
> > For varying privacy and security reasons, sometimes we would like to
> > completely silence the _serial_ console, and only enable it when needed.
> > 
> > But there are many existing systems that depend on this _serial_ console,
> > so add acpi=nospcr to disable console in ACPI SPCR table as default
> > _serial_ console.
> > 
> > Signed-off-by: Liu Wei <liuwei09@cestc.cn>
> > Suggested-by: Prarit Bhargava <prarit@redhat.com>
> > Suggested-by: Will Deacon <will@kernel.org>
> > Suggested-by: Andrew Lunn <andrew@lunn.ch>
> > ---
> > 
> > v2: Add a config option suggested by Prarit
> > 
> > v3: Use cmdline acpi=nospcr instead of config
> > 
> > v4: Some description in comment or document
> > ---
> >   .../admin-guide/kernel-parameters.txt          | 10 +++++++---
> >   arch/arm64/kernel/acpi.c                       | 18 +++++++++++++++++-
> >   2 files changed, 24 insertions(+), 4 deletions(-)
> > 
> >  ... 
> > 
> 
> This looks good to me.  Sorry that this took so long Liu.
> 
> Reviewed-by: Prarit Bhargava <prarit@redhat.com>
> 

Thanks, my pleasure.

Liu Wei
 
> 
> P.
Hanjun Guo June 26, 2024, 7:54 a.m. UTC | #3
On 2024/6/25 11:05, Liu Wei wrote:
> For varying privacy and security reasons, sometimes we would like to
> completely silence the _serial_ console, and only enable it when needed.
> 
> But there are many existing systems that depend on this _serial_ console,
> so add acpi=nospcr to disable console in ACPI SPCR table as default
> _serial_ console.

I think this is reasonable, with ACPI SPCR on in default is compatible
with old systems.

> 
> Signed-off-by: Liu Wei <liuwei09@cestc.cn>
> Suggested-by: Prarit Bhargava <prarit@redhat.com>
> Suggested-by: Will Deacon <will@kernel.org>
> Suggested-by: Andrew Lunn <andrew@lunn.ch>
> ---
> 
> v2: Add a config option suggested by Prarit
> 
> v3: Use cmdline acpi=nospcr instead of config
> 
> v4: Some description in comment or document
> ---
>   .../admin-guide/kernel-parameters.txt          | 10 +++++++---
>   arch/arm64/kernel/acpi.c                       | 18 +++++++++++++++++-
>   2 files changed, 24 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 11e57ba2985c..6814ff7ae446 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -12,7 +12,7 @@
>   	acpi=		[HW,ACPI,X86,ARM64,RISCV64,EARLY]
>   			Advanced Configuration and Power Interface
>   			Format: { force | on | off | strict | noirq | rsdt |
> -				  copy_dsdt }
> +				  copy_dsdt | nospcr }
>   			force -- enable ACPI if default was off
>   			on -- enable ACPI but allow fallback to DT [arm64,riscv64]
>   			off -- disable ACPI if default was on
> @@ -21,8 +21,12 @@
>   				strictly ACPI specification compliant.
>   			rsdt -- prefer RSDT over (default) XSDT
>   			copy_dsdt -- copy DSDT to memory
> -			For ARM64 and RISCV64, ONLY "acpi=off", "acpi=on" or
> -			"acpi=force" are available
> +			nospcr -- disable console in ACPI SPCR table as
> +				default _serial_ console on ARM64
> +			For ARM64, ONLY "acpi=off", "acpi=on", "acpi=force" or
> +			"acpi=nospcr" are available
> +			For RISCV64, ONLY "acpi=off", "acpi=on" or "acpi=force"
> +			are available
>   
>   			See also Documentation/power/runtime_pm.rst, pci=noacpi
>   
> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> index e0e7b93c16cc..55757d8884d4 100644
> --- a/arch/arm64/kernel/acpi.c
> +++ b/arch/arm64/kernel/acpi.c
> @@ -45,6 +45,7 @@ EXPORT_SYMBOL(acpi_pci_disabled);
>   static bool param_acpi_off __initdata;
>   static bool param_acpi_on __initdata;
>   static bool param_acpi_force __initdata;
> +static bool param_acpi_nospcr __initdata;
>   
>   static int __init parse_acpi(char *arg)
>   {
> @@ -58,6 +59,8 @@ static int __init parse_acpi(char *arg)
>   		param_acpi_on = true;
>   	else if (strcmp(arg, "force") == 0) /* force ACPI to be enabled */
>   		param_acpi_force = true;
> +	else if (strcmp(arg, "nospcr") == 0) /* disable SPCR as default console */
> +		param_acpi_nospcr = true;
>   	else
>   		return -EINVAL;	/* Core will print when we return error */
>   
> @@ -237,7 +240,20 @@ void __init acpi_boot_table_init(void)
>   			acpi_put_table(facs);
>   		}
>   #endif
> -		acpi_parse_spcr(earlycon_acpi_spcr_enable, true);
> +
> +		/*
> +		 * For varying privacy and security reasons, sometimes need
> +		 * to completely silence the serial console output, and only
> +		 * enable it when needed.
> +		 * But there are many existing systems that depend on this
> +		 * behavior, use acpi=nospcr to disable console in ACPI SPCR

Nit: s/behavior/behaviour

> +		 * table as default serial console.
> +		 */
> +		acpi_parse_spcr(earlycon_acpi_spcr_enable,
> +			!param_acpi_nospcr);
> +		pr_info("Use ACPI SPCR as default console: %s\n",
> +				param_acpi_nospcr ? "No" : "Yes");
> +
>   		if (IS_ENABLED(CONFIG_ACPI_BGRT))
>   			acpi_table_parse(ACPI_SIG_BGRT, acpi_parse_bgrt);
>   	}

Reviewed-by: Hanjun Guo <guohanjun@huawei.com>

Thanks
Hanjun
Catalin Marinas July 4, 2024, 4:22 p.m. UTC | #4
On Tue, 25 Jun 2024 11:05:04 +0800, Liu Wei wrote:
> For varying privacy and security reasons, sometimes we would like to
> completely silence the _serial_ console, and only enable it when needed.
> 
> But there are many existing systems that depend on this _serial_ console,
> so add acpi=nospcr to disable console in ACPI SPCR table as default
> _serial_ console.
> 
> [...]

Applied to arm64 (for-next/acpi), thanks!

[1/1] ACPI: Add acpi=nospcr to disable ACPI SPCR as default console on ARM64
      https://git.kernel.org/arm64/c/f5a4af3c7527
diff mbox series

Patch

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 11e57ba2985c..6814ff7ae446 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -12,7 +12,7 @@ 
 	acpi=		[HW,ACPI,X86,ARM64,RISCV64,EARLY]
 			Advanced Configuration and Power Interface
 			Format: { force | on | off | strict | noirq | rsdt |
-				  copy_dsdt }
+				  copy_dsdt | nospcr }
 			force -- enable ACPI if default was off
 			on -- enable ACPI but allow fallback to DT [arm64,riscv64]
 			off -- disable ACPI if default was on
@@ -21,8 +21,12 @@ 
 				strictly ACPI specification compliant.
 			rsdt -- prefer RSDT over (default) XSDT
 			copy_dsdt -- copy DSDT to memory
-			For ARM64 and RISCV64, ONLY "acpi=off", "acpi=on" or
-			"acpi=force" are available
+			nospcr -- disable console in ACPI SPCR table as
+				default _serial_ console on ARM64
+			For ARM64, ONLY "acpi=off", "acpi=on", "acpi=force" or
+			"acpi=nospcr" are available
+			For RISCV64, ONLY "acpi=off", "acpi=on" or "acpi=force"
+			are available
 
 			See also Documentation/power/runtime_pm.rst, pci=noacpi
 
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index e0e7b93c16cc..55757d8884d4 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -45,6 +45,7 @@  EXPORT_SYMBOL(acpi_pci_disabled);
 static bool param_acpi_off __initdata;
 static bool param_acpi_on __initdata;
 static bool param_acpi_force __initdata;
+static bool param_acpi_nospcr __initdata;
 
 static int __init parse_acpi(char *arg)
 {
@@ -58,6 +59,8 @@  static int __init parse_acpi(char *arg)
 		param_acpi_on = true;
 	else if (strcmp(arg, "force") == 0) /* force ACPI to be enabled */
 		param_acpi_force = true;
+	else if (strcmp(arg, "nospcr") == 0) /* disable SPCR as default console */
+		param_acpi_nospcr = true;
 	else
 		return -EINVAL;	/* Core will print when we return error */
 
@@ -237,7 +240,20 @@  void __init acpi_boot_table_init(void)
 			acpi_put_table(facs);
 		}
 #endif
-		acpi_parse_spcr(earlycon_acpi_spcr_enable, true);
+
+		/*
+		 * For varying privacy and security reasons, sometimes need
+		 * to completely silence the serial console output, and only
+		 * enable it when needed.
+		 * But there are many existing systems that depend on this
+		 * behavior, use acpi=nospcr to disable console in ACPI SPCR
+		 * table as default serial console.
+		 */
+		acpi_parse_spcr(earlycon_acpi_spcr_enable,
+			!param_acpi_nospcr);
+		pr_info("Use ACPI SPCR as default console: %s\n",
+				param_acpi_nospcr ? "No" : "Yes");
+
 		if (IS_ENABLED(CONFIG_ACPI_BGRT))
 			acpi_table_parse(ACPI_SIG_BGRT, acpi_parse_bgrt);
 	}