Commit a1edec22 authored by Jeremy Linton's avatar Jeremy Linton Committed by Will Deacon
Browse files

arm64: rsi: Add automatic arm-cca-guest module loading 



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: default avatarJeremy Linton <jeremy.linton@arm.com>
Reviewed-by: default avatarGavin Shan <gshan@redhat.com>
Reviewed-by: default avatarSteven Price <steven.price@arm.com>
Link: https://lore.kernel.org/r/20241220181236.172060-2-jeremy.linton@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent fac04efc

arch/arm64/include/asm/rsi.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

arch/arm64/kernel/rsi.c

+15 −0
Original line number Diff line number Diff line
@@ -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)

drivers/virt/coco/arm-cca-guest/arm-cca-guest.c

+8 −0
Original line number Diff line number Diff line
@@ -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");