linux-kernel - [PATCH 1/2] KVM: arm64: fix FF-A call failure when ff-a driver is built-in

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Message-Id: <20251027191729.1704744-2-yeoreum.yun@arm.com>
Date: Mon, 27 Oct 2025 19:17:28 +0000
From: Yeoreum Yun <yeoreum.yun@....com>
To: maz@...nel.org,
	oliver.upton@...ux.dev,
	joey.gouly@....com,
	suzuki.poulose@....com,
	yuzenghui@...wei.com,
	catalin.marinas@....com,
	will@...nel.org,
	perlarsen@...gle.com,
	ayrton@...gle.com
Cc: linux-arm-kernel@...ts.infradead.org,
	kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Yeoreum Yun <yeoreum.yun@....com>
Subject: [PATCH 1/2] KVM: arm64: fix FF-A call failure when ff-a driver is built-in

Until has_version_negotiated is set to true,
all FF-A function calls fail except FFA_VERSION.
The has_version_negotiated flag is set to true when
the first FFA_VERSION call is made after init_hyp_mode().

This works fine when the FF-A driver is built as a module,
since ffa_init() is invoked after kvm_arm_init(), allowing do_ffa_version()
to set has_version_negotiated to true.

However, when the FF-A driver is built-in (CONFIG_ARM_FFA_TRANSPORT=y),
all FF-A calls fail. This happens because ffa_init() runs before
kvm_arm_init() — the init level of ffa_init() is rootfs_initcall.
As a result, the hypervisor cannot set has_version_negotiated,
since the FFA_VERSION call made in ffa_init() does not trap to the hypervisor
(HCR_EL2.TSC is cleared before kvm_arm_init()).

Consequently, this causes failures when using EFI variable services
with secure partitions that rely on FFA_SEND_DIRECT_MSG.

To fix this, call hyp_ffa_post_init() and set has_version_negotiated
during hyp_ffa_init() when the FF-A driver is built-in (CONFIG_ARM_FFA_TRANSPORT=y).

Signed-off-by: Yeoreum Yun <yeoreum.yun@....com>
---
 arch/arm64/kvm/hyp/nvhe/ffa.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index 4e16f9b96f63..0ae87ff61758 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -984,5 +984,17 @@ int hyp_ffa_init(void *pages)
 	};

 	version_lock = __HYP_SPIN_LOCK_UNLOCKED;
+
+	if (IS_BUILTIN(CONFIG_ARM_FFA_TRANSPORT)) {
+		hyp_spin_lock(&version_lock);
+		if (hyp_ffa_post_init()) {
+			hyp_spin_unlock(&version_lock);
+			return -EOPNOTSUPP;
+		}
+
+		smp_store_release(&has_version_negotiated, true);
+		hyp_spin_unlock(&version_lock);
+	}
+
 	return 0;
 }
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}