Re: [PATCH v3 07/25] x86/sgx: Initialize virtual EPC driver even when SGX driver is disabled

Borislav Petkov
2021-04-02T09:48:17Z

On Fri, Mar 19, 2021 at 08:23:02PM +1300, Kai Huang wrote:
> Modify sgx_init() to always try to initialize the virtual EPC driver,
> even if the SGX driver is disabled. The SGX driver might be disabled
> if SGX Launch Control is in locked mode, or not supported in the
> hardware at all. This allows (non-Linux) guests that support non-LC
> configurations to use SGX.
>
> Acked-by: Dave Hansen <dave.hansen@intel.com>
> Reviewed-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Kai Huang <kai.huang@intel.com>
> ---
> arch/x86/kernel/cpu/sgx/main.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index 6a734f484aa7..b73114150ff8 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -743,7 +743,15 @@ static int __init sgx_init(void)
> goto err_page_cache;
> }
>
> - ret = sgx_drv_init();
> + /*
> + * Always try to initialize the native *and* KVM drivers.
> + * The KVM driver is less picky than the native one and
> + * can function if the native one is not supported on the
> + * current system or fails to initialize.
> + *
> + * Error out only if both fail to initialize.
> + */
> + ret = !!sgx_drv_init() & !!sgx_vepc_init();

This is a silly way of writing:

if (sgx_drv_init() && sgx_vepc_init())
goto err_kthread;

methinks.

--
Regards/Gruss,
Boris.