[Xen-devel] [PATCH v7 4/5] xen/arm: optee: check if OP-TEE is virtualization-aware

[Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>]

This is workaround for OP-TEE 3.5. This is the first OP-TEE release
which supports virtualization, but there is no way to tell if
OP-TEE was built with that support enabled. We can probe for it
by calling SMC that is available only when OP-TEE is built with
virtualization support.

Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
---
 xen/arch/arm/tee/optee.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/xen/arch/arm/tee/optee.c b/xen/arch/arm/tee/optee.c
index 28d34360fc..14381d6b2d 100644
--- a/xen/arch/arm/tee/optee.c
+++ b/xen/arch/arm/tee/optee.c
@@ -172,6 +172,16 @@ static bool optee_probe(void)
         return false;
     }
 
+    /*
+     * Workaround: OP-TEE 3.5 have no way to tell if it is build with
+     * virtualization support. But we can probe for OPTEE_SMC_VM_DESTROYED
+     * call. It will return OPTEE_SMC_RETURN_UNKNOWN_FUNCTION if
+     * OP-TEE have no virtualization support enabled.
+     */
+    arm_smccc_smc(OPTEE_SMC_VM_DESTROYED, 0, 0, 0, 0, 0, 0, 0, &resp);
+    if ( resp.a0 == OPTEE_SMC_RETURN_UNKNOWN_FUNCTION )
+        return false;
+
     return true;
 }
 
-- 
2.21.0

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