[RFC PATCH 4/4] firmware: arm_ffa: check pkvm initailised when initailise ffa driver

[Yeoreum Yun <yeoreum.yun@arm.com>]

When pKVM is enabled, the FF-A driver must be initialized after pKVM.
Otherwise, pKVM cannot negotiate the FF-A version or
obtain RX/TX buffer information, leading to failures in FF-A calls.

During FF-A driver initialization, check whether pKVM has been initialized.
If not, defer probing of the FF-A driver.

Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
---
 arch/arm64/kvm/arm.c              |  1 +
 drivers/firmware/arm_ffa/driver.c | 12 ++++++++++++
 2 files changed, 13 insertions(+)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 410ffd41fd73..0f517b1c05cd 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -119,6 +119,7 @@ bool is_kvm_arm_initialised(void)
 {
 	return kvm_arm_initialised;
 }
+EXPORT_SYMBOL(is_kvm_arm_initialised);

 int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
 {
diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
index 02c76ac1570b..2647d6554afd 100644
--- a/drivers/firmware/arm_ffa/driver.c
+++ b/drivers/firmware/arm_ffa/driver.c
@@ -42,6 +42,8 @@
 #include <linux/uuid.h>
 #include <linux/xarray.h>

+#include <asm/virt.h>
+
 #include "common.h"

 #define FFA_DRIVER_VERSION	FFA_VERSION_1_2
@@ -2035,6 +2037,16 @@ static int __init ffa_init(void)
 	u32 buf_sz;
 	size_t rxtx_bufsz = SZ_4K;

+	/*
+	 * When pKVM is enabled, the FF-A driver must be initialized
+	 * after pKVM initialization. Otherwise, pKVM cannot negotiate
+	 * the FF-A version or obtain RX/TX buffer information,
+	 * which leads to failures in FF-A calls.
+	 */
+	if (IS_ENABLED(CONFIG_KVM) && is_protected_kvm_enabled() &&
+	    !is_kvm_arm_initialised())
+		return -EPROBE_DEFER;
+
 	ret = ffa_transport_init(&invoke_ffa_fn);
 	if (ret)
 		return ret;
--
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}