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

[Julien Grall <julien.grall@xxxxxxx>]

Hi Volodymyr,

On 6/19/19 6:54 PM, Volodymyr Babchuk wrote:
> 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>
Acked-by: Julien Grall <julien.grall@xxxxxxx>

Cheers,

> ---
>   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;
>   }
>   
--
Julien Grall

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