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

Sean Christopherson
2021-04-02T19:30:33Z

On Fri, Apr 02, 2021, Borislav Petkov wrote:
> On Fri, Apr 02, 2021 at 03:42:51PM +0000, Sean Christopherson wrote:
> > Nope! That's wrong, as sgx_epc_init() will not be called if sgx_drv_init()
> > succeeds. And writing it as "if (sgx_drv_init() || sgx_vepc_init())" is also
> > wrong since that would kill SGX when one of the drivers is alive and well.
>
> Bah, right you are.
>
> How about:
>
> /* Error out only if both fail to initialize. */
> ret = sgx_drv_init();
>
> if (sgx_vepc_init() && ret)
> goto err_kthread;

Heh, that's what I had originally and used for literally years. IIRC, I
suggested the "!! & !!" abomination after internal review complained about the
oddness of the above.

FWIW, I think the above is far less likely to be misread, even though I love the
cleverness of the bitwise AND.

>
> And yah, this looks strange so it needs the comment to explain what's
> going on here.
>
> Thx.
>
> --
> Regards/Gruss,
> Boris.
>
> https://people.kernel.org/tglx/notes-about-netiquette