[PATCH v4 0/1] arm64: CCA TSM module autoloading

[PATCH v4 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.

v3->v4:
	More comment/function name tweaking

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 v4 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 realm 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..ce4778141ec7 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 arm64_create_dummy_rsi_dev(void)
+{
+	if (is_realm_world() &&
+	    platform_device_register(&rsi_dev))
+		pr_err("failed to register rsi platform device\n");
+	return 0;
+}
+
+arch_initcall(arm64_create_dummy_rsi_dev)
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 v4 1/1] arm64: rsi: Add automatic arm-cca-guest module loading

[Steven Price]

On 20/12/2024 18:12, Jeremy Linton wrote:
> The TSM module provides guest identification and attestation when a
> guest runs in CCA realm 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>

LGTM

Reviewed-by: Steven Price <steven.price@arm.com>

Thanks,
Steve

> ---
>  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..ce4778141ec7 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 arm64_create_dummy_rsi_dev(void)
> +{
> +	if (is_realm_world() &&
> +	    platform_device_register(&rsi_dev))
> +		pr_err("failed to register rsi platform device\n");
> +	return 0;
> +}
> +
> +arch_initcall(arm64_create_dummy_rsi_dev)
> 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");

Re: [PATCH v4 0/1] arm64: CCA TSM module autoloading

[Will Deacon]

On Fri, 20 Dec 2024 12:12:35 -0600, Jeremy Linton wrote:
> Provide module tables and a platform device so that the
> CCA TSM module will autoload when needed.
> 
> v3->v4:
> 	More comment/function name tweaking
> 
> 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
> 
> [...]

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

[1/1] arm64: rsi: Add automatic arm-cca-guest module loading
      https://git.kernel.org/arm64/c/a1edec22457e

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev