[PATCH v3 0/1] arm64: CCA TSM module autoloading

[PATCH v3 0/1] arm64: CCA TSM module autoloading

[Jeremy Linton]

Provide module tables and a platform device so that the
CCA TSM module will autoload when needed.

v2->v3:
	Fix __maybe_used placement, it does fix CLANG builds now.
	Add reviewed-by tag, Thanks Gavin!
	Ugly commit message cleanup.
v1->v2:
	Various comment updates/variable renames
	Add missing __maybe_unused to the platform_device_id

Jeremy Linton (1):
  arm64: rsi: Add automatic arm-cca-guest module loading

 arch/arm64/include/asm/rsi.h                    |  2 ++
 arch/arm64/kernel/rsi.c                         | 15 +++++++++++++++
 drivers/virt/coco/arm-cca-guest/arm-cca-guest.c |  8 ++++++++
 3 files changed, 25 insertions(+)

-- 
2.46.0

[PATCH v3 1/1] arm64: rsi: Add automatic arm-cca-guest module loading

[Jeremy Linton]

The TSM module provides guest identification and attestation when a
guest runs in CCA mode. By creating a dummy platform device, let's
ensure the module is automatically loaded. The udev daemon loads the
TSM module after it receives a device addition event. Once that
happens, it can be used earlier in the boot process to decrypt the
rootfs.

Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
---
 arch/arm64/include/asm/rsi.h                    |  2 ++
 arch/arm64/kernel/rsi.c                         | 15 +++++++++++++++
 drivers/virt/coco/arm-cca-guest/arm-cca-guest.c |  8 ++++++++
 3 files changed, 25 insertions(+)

diff --git a/arch/arm64/include/asm/rsi.h b/arch/arm64/include/asm/rsi.h
index 188cbb9b23f5..b42aeac05340 100644
--- a/arch/arm64/include/asm/rsi.h
+++ b/arch/arm64/include/asm/rsi.h
@@ -10,6 +10,8 @@
 #include <linux/jump_label.h>
 #include <asm/rsi_cmds.h>
 
+#define RSI_PDEV_NAME "arm-cca-dev"
+
 DECLARE_STATIC_KEY_FALSE(rsi_present);
 
 void __init arm64_rsi_init(void);
diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
index 3031f25c32ef..5434e5496ac2 100644
--- a/arch/arm64/kernel/rsi.c
+++ b/arch/arm64/kernel/rsi.c
@@ -8,6 +8,7 @@
 #include <linux/psci.h>
 #include <linux/swiotlb.h>
 #include <linux/cc_platform.h>
+#include <linux/platform_device.h>
 
 #include <asm/io.h>
 #include <asm/mem_encrypt.h>
@@ -140,3 +141,17 @@ void __init arm64_rsi_init(void)
 	static_branch_enable(&rsi_present);
 }
 
+static struct platform_device rsi_dev = {
+	.name = RSI_PDEV_NAME,
+	.id = PLATFORM_DEVID_NONE
+};
+
+static int __init rsi_init(void)
+{
+	if (is_realm_world() &&
+	    platform_device_register(&rsi_dev))
+		pr_err("failed to register rsi platform device\n");
+	return 0;
+}
+
+arch_initcall(rsi_init)
diff --git a/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c b/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
index 488153879ec9..87f162736b2e 100644
--- a/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
+++ b/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
@@ -6,6 +6,7 @@
 #include <linux/arm-smccc.h>
 #include <linux/cc_platform.h>
 #include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/smp.h>
 #include <linux/tsm.h>
@@ -219,6 +220,13 @@ static void __exit arm_cca_guest_exit(void)
 }
 module_exit(arm_cca_guest_exit);
 
+/* modalias, so userspace can autoload this module when RSI is available */
+static const struct platform_device_id arm_cca_match[] __maybe_unused = {
+	{ RSI_PDEV_NAME, 0},
+	{ }
+};
+
+MODULE_DEVICE_TABLE(platform, arm_cca_match);
 MODULE_AUTHOR("Sami Mujawar <sami.mujawar@arm.com>");
 MODULE_DESCRIPTION("Arm CCA Guest TSM Driver");
 MODULE_LICENSE("GPL");
-- 
2.46.0

Re: [PATCH v3 1/1] arm64: rsi: Add automatic arm-cca-guest module loading

[Itaru Kitayama]

Hi Jeremy,

On Fri, Dec 06, 2024 at 07:21:28PM -0600, Jeremy Linton wrote:
> The TSM module provides guest identification and attestation when a
> guest runs in CCA mode. By creating a dummy platform device, let's

Perhaps could you spell out like; a guest runs in the Realm state?

Thanks,
Itaru.
 
> ensure the module is automatically loaded. The udev daemon loads the
> TSM module after it receives a device addition event. Once that
> happens, it can be used earlier in the boot process to decrypt the
> rootfs.
> 
> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> ---
>  arch/arm64/include/asm/rsi.h                    |  2 ++
>  arch/arm64/kernel/rsi.c                         | 15 +++++++++++++++
>  drivers/virt/coco/arm-cca-guest/arm-cca-guest.c |  8 ++++++++
>  3 files changed, 25 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/rsi.h b/arch/arm64/include/asm/rsi.h
> index 188cbb9b23f5..b42aeac05340 100644
> --- a/arch/arm64/include/asm/rsi.h
> +++ b/arch/arm64/include/asm/rsi.h
> @@ -10,6 +10,8 @@
>  #include <linux/jump_label.h>
>  #include <asm/rsi_cmds.h>
>  
> +#define RSI_PDEV_NAME "arm-cca-dev"
> +
>  DECLARE_STATIC_KEY_FALSE(rsi_present);
>  
>  void __init arm64_rsi_init(void);
> diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
> index 3031f25c32ef..5434e5496ac2 100644
> --- a/arch/arm64/kernel/rsi.c
> +++ b/arch/arm64/kernel/rsi.c
> @@ -8,6 +8,7 @@
>  #include <linux/psci.h>
>  #include <linux/swiotlb.h>
>  #include <linux/cc_platform.h>
> +#include <linux/platform_device.h>
>  
>  #include <asm/io.h>
>  #include <asm/mem_encrypt.h>
> @@ -140,3 +141,17 @@ void __init arm64_rsi_init(void)
>  	static_branch_enable(&rsi_present);
>  }
>  
> +static struct platform_device rsi_dev = {
> +	.name = RSI_PDEV_NAME,
> +	.id = PLATFORM_DEVID_NONE
> +};
> +
> +static int __init rsi_init(void)
> +{
> +	if (is_realm_world() &&
> +	    platform_device_register(&rsi_dev))
> +		pr_err("failed to register rsi platform device\n");
> +	return 0;
> +}
> +
> +arch_initcall(rsi_init)
> diff --git a/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c b/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
> index 488153879ec9..87f162736b2e 100644
> --- a/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
> +++ b/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
> @@ -6,6 +6,7 @@
>  #include <linux/arm-smccc.h>
>  #include <linux/cc_platform.h>
>  #include <linux/kernel.h>
> +#include <linux/mod_devicetable.h>
>  #include <linux/module.h>
>  #include <linux/smp.h>
>  #include <linux/tsm.h>
> @@ -219,6 +220,13 @@ static void __exit arm_cca_guest_exit(void)
>  }
>  module_exit(arm_cca_guest_exit);
>  
> +/* modalias, so userspace can autoload this module when RSI is available */
> +static const struct platform_device_id arm_cca_match[] __maybe_unused = {
> +	{ RSI_PDEV_NAME, 0},
> +	{ }
> +};
> +
> +MODULE_DEVICE_TABLE(platform, arm_cca_match);
>  MODULE_AUTHOR("Sami Mujawar <sami.mujawar@arm.com>");
>  MODULE_DESCRIPTION("Arm CCA Guest TSM Driver");
>  MODULE_LICENSE("GPL");
> -- 
> 2.46.0
> 

Re: [PATCH v3 1/1] arm64: rsi: Add automatic arm-cca-guest module loading

[Will Deacon]

On Fri, Dec 06, 2024 at 07:21:28PM -0600, Jeremy Linton wrote:
> The TSM module provides guest identification and attestation when a
> guest runs in CCA mode. By creating a dummy platform device, let's
> ensure the module is automatically loaded. The udev daemon loads the
> TSM module after it receives a device addition event. Once that
> happens, it can be used earlier in the boot process to decrypt the
> rootfs.
> 
> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> ---
>  arch/arm64/include/asm/rsi.h                    |  2 ++
>  arch/arm64/kernel/rsi.c                         | 15 +++++++++++++++
>  drivers/virt/coco/arm-cca-guest/arm-cca-guest.c |  8 ++++++++
>  3 files changed, 25 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/rsi.h b/arch/arm64/include/asm/rsi.h
> index 188cbb9b23f5..b42aeac05340 100644
> --- a/arch/arm64/include/asm/rsi.h
> +++ b/arch/arm64/include/asm/rsi.h
> @@ -10,6 +10,8 @@
>  #include <linux/jump_label.h>
>  #include <asm/rsi_cmds.h>
>  
> +#define RSI_PDEV_NAME "arm-cca-dev"
> +
>  DECLARE_STATIC_KEY_FALSE(rsi_present);
>  
>  void __init arm64_rsi_init(void);
> diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
> index 3031f25c32ef..5434e5496ac2 100644
> --- a/arch/arm64/kernel/rsi.c
> +++ b/arch/arm64/kernel/rsi.c
> @@ -8,6 +8,7 @@
>  #include <linux/psci.h>
>  #include <linux/swiotlb.h>
>  #include <linux/cc_platform.h>
> +#include <linux/platform_device.h>
>  
>  #include <asm/io.h>
>  #include <asm/mem_encrypt.h>
> @@ -140,3 +141,17 @@ void __init arm64_rsi_init(void)
>  	static_branch_enable(&rsi_present);
>  }
>  
> +static struct platform_device rsi_dev = {
> +	.name = RSI_PDEV_NAME,
> +	.id = PLATFORM_DEVID_NONE
> +};
> +
> +static int __init rsi_init(void)
> +{
> +	if (is_realm_world() &&
> +	    platform_device_register(&rsi_dev))
> +		pr_err("failed to register rsi platform device\n");
> +	return 0;
> +}
> +
> +arch_initcall(rsi_init)

This file already has an arm64_rsi_init()... Ideally, we'd hang this
off the end of that instead of the initcall but I suspect you're going
to tell me that platform_device_register() doesn't like being called
that early?

If so, perhaps arm64_create_dummy_rsi_dev() might be better?

Will

Re: [PATCH v3 1/1] arm64: rsi: Add automatic arm-cca-guest module loading

[Jeremy Linton]

Hi,

On 12/7/24 10:38 PM, Itaru Kitayama wrote:
> Hi Jeremy,
> 
> On Fri, Dec 06, 2024 at 07:21:28PM -0600, Jeremy Linton wrote:
>> The TSM module provides guest identification and attestation when a
>> guest runs in CCA mode. By creating a dummy platform device, let's
> 
> Perhaps could you spell out like; a guest runs in the Realm state?

Thanks for looking at this.

I thought that was evident from the rest of the commits here, but sure.

Thanks again.


> 
> Thanks,
> Itaru.
>   
>> ensure the module is automatically loaded. The udev daemon loads the
>> TSM module after it receives a device addition event. Once that
>> happens, it can be used earlier in the boot process to decrypt the
>> rootfs.
>>
>> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
>> Reviewed-by: Gavin Shan <gshan@redhat.com>
>> ---
>>   arch/arm64/include/asm/rsi.h                    |  2 ++
>>   arch/arm64/kernel/rsi.c                         | 15 +++++++++++++++
>>   drivers/virt/coco/arm-cca-guest/arm-cca-guest.c |  8 ++++++++
>>   3 files changed, 25 insertions(+)
>>
>> diff --git a/arch/arm64/include/asm/rsi.h b/arch/arm64/include/asm/rsi.h
>> index 188cbb9b23f5..b42aeac05340 100644
>> --- a/arch/arm64/include/asm/rsi.h
>> +++ b/arch/arm64/include/asm/rsi.h
>> @@ -10,6 +10,8 @@
>>   #include <linux/jump_label.h>
>>   #include <asm/rsi_cmds.h>
>>   
>> +#define RSI_PDEV_NAME "arm-cca-dev"
>> +
>>   DECLARE_STATIC_KEY_FALSE(rsi_present);
>>   
>>   void __init arm64_rsi_init(void);
>> diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
>> index 3031f25c32ef..5434e5496ac2 100644
>> --- a/arch/arm64/kernel/rsi.c
>> +++ b/arch/arm64/kernel/rsi.c
>> @@ -8,6 +8,7 @@
>>   #include <linux/psci.h>
>>   #include <linux/swiotlb.h>
>>   #include <linux/cc_platform.h>
>> +#include <linux/platform_device.h>
>>   
>>   #include <asm/io.h>
>>   #include <asm/mem_encrypt.h>
>> @@ -140,3 +141,17 @@ void __init arm64_rsi_init(void)
>>   	static_branch_enable(&rsi_present);
>>   }
>>   
>> +static struct platform_device rsi_dev = {
>> +	.name = RSI_PDEV_NAME,
>> +	.id = PLATFORM_DEVID_NONE
>> +};
>> +
>> +static int __init rsi_init(void)
>> +{
>> +	if (is_realm_world() &&
>> +	    platform_device_register(&rsi_dev))
>> +		pr_err("failed to register rsi platform device\n");
>> +	return 0;
>> +}
>> +
>> +arch_initcall(rsi_init)
>> diff --git a/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c b/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
>> index 488153879ec9..87f162736b2e 100644
>> --- a/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
>> +++ b/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
>> @@ -6,6 +6,7 @@
>>   #include <linux/arm-smccc.h>
>>   #include <linux/cc_platform.h>
>>   #include <linux/kernel.h>
>> +#include <linux/mod_devicetable.h>
>>   #include <linux/module.h>
>>   #include <linux/smp.h>
>>   #include <linux/tsm.h>
>> @@ -219,6 +220,13 @@ static void __exit arm_cca_guest_exit(void)
>>   }
>>   module_exit(arm_cca_guest_exit);
>>   
>> +/* modalias, so userspace can autoload this module when RSI is available */
>> +static const struct platform_device_id arm_cca_match[] __maybe_unused = {
>> +	{ RSI_PDEV_NAME, 0},
>> +	{ }
>> +};
>> +
>> +MODULE_DEVICE_TABLE(platform, arm_cca_match);
>>   MODULE_AUTHOR("Sami Mujawar <sami.mujawar@arm.com>");
>>   MODULE_DESCRIPTION("Arm CCA Guest TSM Driver");
>>   MODULE_LICENSE("GPL");
>> -- 
>> 2.46.0
>>