[PATCH v4 2/6] firmware: smccc: Detect hypervisor via RSI host call in CCA Realms
WARM3d
REVIEWED: 1 (0M)
From: Kameron Carr <hidden>
Date: 2026-10-01 22:07:00
Also in:
linux-arch, linux-hyperv, lkml
Subsystem:
secure monitor call(smc) calling convention (smccc), the rest · Maintainers:
Mark Rutland, Lorenzo Pieralisi, Sudeep Holla, Linus Torvalds
Revision v4 of 5 in this series; 1 review trailer.
Revisions (5)
Modify arm_smccc_hypervisor_has_uuid() to check is_realm_world() and use rsi_host_call() to query the hypervisor vendor UUID when inside a Realm. The realm path is factored into a helper, arm_smccc_realm_get_hypervisor_uuid(), that owns a file-static rsi_host_call buffer (uuid_hc) serialized by a spinlock. The RSI-specific includes, file-static state and helper are guarded with CONFIG_ARM64 because <asm/rsi.h> does not exist on 32-bit ARM. For non-Realm environments, the existing arm_smccc_1_1_invoke() path is unchanged. Reviewed-by: Michael Kelley <redacted> Signed-off-by: Kameron Carr <redacted> --- drivers/firmware/smccc/smccc.c | 41 +++++++++++++++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/smccc/smccc.c b/drivers/firmware/smccc/smccc.c
index afc2e4d..7e77170 100644
--- a/drivers/firmware/smccc/smccc.c
+++ b/drivers/firmware/smccc/smccc.c@@ -14,6 +14,12 @@ #include <asm/archrandom.h> +#ifdef CONFIG_ARM64 +#include <linux/arm-rsi-cmds.h> +#include <linux/cleanup.h> +#include <linux/spinlock.h> +#endif + static u32 smccc_version = ARM_SMCCC_VERSION_1_0; static enum arm_smccc_conduit smccc_conduit = SMCCC_CONDUIT_NONE;
@@ -69,12 +75,45 @@ s32 arm_smccc_get_soc_id_revision(void) } EXPORT_SYMBOL_GPL(arm_smccc_get_soc_id_revision); +#ifdef CONFIG_ARM64 +static struct rsi_host_call uuid_hc; +static DEFINE_SPINLOCK(uuid_hc_lock); + +/* + * Helper function to get the hypervisor UUID via an RsiHostCall. + */ +static void arm_smccc_realm_get_hypervisor_uuid(struct arm_smccc_res *res) +{ + guard(spinlock_irqsave)(&uuid_hc_lock); + + memset(&uuid_hc, 0, sizeof(uuid_hc)); + uuid_hc.gprs[0] = ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID; + + if (rsi_host_call(__pa_symbol(&uuid_hc)) != RSI_SUCCESS) { + res->a0 = SMCCC_RET_NOT_SUPPORTED; + return; + } + + res->a0 = uuid_hc.gprs[0]; + res->a1 = uuid_hc.gprs[1]; + res->a2 = uuid_hc.gprs[2]; + res->a3 = uuid_hc.gprs[3]; +} +#endif + bool arm_smccc_hypervisor_has_uuid(const uuid_t *hyp_uuid) { struct arm_smccc_res res = {}; uuid_t uuid; - arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, &res); +#ifdef CONFIG_ARM64 + if (is_realm_world()) + arm_smccc_realm_get_hypervisor_uuid(&res); + else +#endif + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, + &res); + if (res.a0 == SMCCC_RET_NOT_SUPPORTED) return false;
--
2.45.4