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Message-ID: <20251008132758.784275-1-aneesh.kumar@kernel.org>
Date: Wed, 8 Oct 2025 18:57:58 +0530
From: "Aneesh Kumar K.V (Arm)" <aneesh.kumar@...nel.org>
To: linux-coco@...ts.linux.dev,
linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org
Cc: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Steven Price <steven.price@....com>,
Gavin Shan <gshan@...hat.com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Jeremy Linton <jeremy.linton@....com>,
Sami Mujawar <sami.mujawar@....com>,
"Aneesh Kumar K.V (Arm)" <aneesh.kumar@...nel.org>
Subject: [PATCH] coco: guest: arm64: Update ARM CCA guest driver
Make preparatory updates to the ARM CCA guest driver:
- Switch from using a platform device to a faux device (based on
feedback in [1])
- Rename the device from `arm-cca-dev` to `arm-rsi-dev`, so that the
host driver can register an equivalent `arm-rmi-dev`
These changes are purely structural and introduce no new functionality.
Subsequent patches will extend this driver to add guest device
assignment support.
[1] https://lore.kernel.org/all/2025073035-bulginess-rematch-b92e@gregkh
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@...nel.org>
---
NOTE:
This patch is sent early outside the patchseries to avoid userspace from
depending on the presence of the newly introduced platform device.
The platform device was added in v6.14-rc1.
arch/arm64/include/asm/rsi.h | 2 +-
arch/arm64/kernel/rsi.c | 15 -----
drivers/virt/coco/arm-cca-guest/Makefile | 3 +
.../{arm-cca-guest.c => arm-cca.c} | 65 +++++++++++--------
4 files changed, 41 insertions(+), 44 deletions(-)
rename drivers/virt/coco/arm-cca-guest/{arm-cca-guest.c => arm-cca.c} (85%)
diff --git a/arch/arm64/include/asm/rsi.h b/arch/arm64/include/asm/rsi.h
index b42aeac05340..26ef6143562b 100644
--- a/arch/arm64/include/asm/rsi.h
+++ b/arch/arm64/include/asm/rsi.h
@@ -10,7 +10,7 @@
#include <linux/jump_label.h>
#include <asm/rsi_cmds.h>
-#define RSI_PDEV_NAME "arm-cca-dev"
+#define RSI_DEV_NAME "arm-rsi-dev"
DECLARE_STATIC_KEY_FALSE(rsi_present);
diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
index ce4778141ec7..569ef08750e5 100644
--- a/arch/arm64/kernel/rsi.c
+++ b/arch/arm64/kernel/rsi.c
@@ -140,18 +140,3 @@ 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/Makefile b/drivers/virt/coco/arm-cca-guest/Makefile
index 69eeba08e98a..609462ea9438 100644
--- a/drivers/virt/coco/arm-cca-guest/Makefile
+++ b/drivers/virt/coco/arm-cca-guest/Makefile
@@ -1,2 +1,5 @@
# SPDX-License-Identifier: GPL-2.0-only
+#
obj-$(CONFIG_ARM_CCA_GUEST) += arm-cca-guest.o
+
+arm-cca-guest-$(CONFIG_TSM) += arm-cca.o
diff --git a/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c b/drivers/virt/coco/arm-cca-guest/arm-cca.c
similarity index 85%
rename from drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
rename to drivers/virt/coco/arm-cca-guest/arm-cca.c
index 0c9ea24a200c..89d9e7f8eb5d 100644
--- a/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
+++ b/drivers/virt/coco/arm-cca-guest/arm-cca.c
@@ -1,8 +1,9 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
- * Copyright (C) 2023 ARM Ltd.
+ * Copyright (C) 2025 ARM Ltd.
*/
+#include <linux/device/faux.h>
#include <linux/arm-smccc.h>
#include <linux/cc_platform.h>
#include <linux/kernel.h>
@@ -181,52 +182,60 @@ static int arm_cca_report_new(struct tsm_report *report, void *data)
return ret;
}
-static const struct tsm_report_ops arm_cca_tsm_ops = {
+static const struct tsm_report_ops arm_cca_tsm_report_ops = {
.name = KBUILD_MODNAME,
.report_new = arm_cca_report_new,
};
-/**
- * arm_cca_guest_init - Register with the Trusted Security Module (TSM)
- * interface.
- *
- * Return:
- * * %0 - Registered successfully with the TSM interface.
- * * %-ENODEV - The execution context is not an Arm Realm.
- * * %-EBUSY - Already registered.
- */
-static int __init arm_cca_guest_init(void)
+static void unregister_cca_tsm_report(void *data)
+{
+ tsm_report_unregister(&arm_cca_tsm_report_ops);
+}
+
+static int cca_tsm_probe(struct faux_device *fdev)
{
int ret;
if (!is_realm_world())
return -ENODEV;
- ret = tsm_report_register(&arm_cca_tsm_ops, NULL);
- if (ret < 0)
+ ret = tsm_report_register(&arm_cca_tsm_report_ops, NULL);
+ if (ret < 0) {
pr_err("Error %d registering with TSM\n", ret);
+ return ret;
+ }
+
+ ret = devm_add_action_or_reset(&fdev->dev, unregister_cca_tsm_report, NULL);
+ if (ret < 0) {
+ pr_err("Error %d registering devm action\n", ret);
+ unregister_cca_tsm_report(NULL);
+ return ret;
+ }
return ret;
}
-module_init(arm_cca_guest_init);
-/**
- * arm_cca_guest_exit - unregister with the Trusted Security Module (TSM)
- * interface.
- */
-static void __exit arm_cca_guest_exit(void)
+static struct faux_device *cca_tsm;
+
+static const struct faux_device_ops cca_device_ops = {
+ .probe = cca_tsm_probe,
+};
+
+static int __init cca_tsm_init(void)
{
- tsm_report_unregister(&arm_cca_tsm_ops);
+ cca_tsm = faux_device_create(RSI_DEV_NAME, NULL, &cca_device_ops);
+ if (!cca_tsm)
+ return -ENOMEM;
+ return 0;
}
-module_exit(arm_cca_guest_exit);
+module_init(cca_tsm_init);
-/* 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},
- { }
-};
+static void __exit cca_tsm_exit(void)
+{
+ faux_device_destroy(cca_tsm);
+}
+module_exit(cca_tsm_exit);
-MODULE_DEVICE_TABLE(platform, arm_cca_match);
MODULE_AUTHOR("Sami Mujawar <sami.mujawar@....com>");
MODULE_DESCRIPTION("Arm CCA Guest TSM Driver");
MODULE_LICENSE("GPL");
--
2.43.0
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