On Sat, Mar 13, 2021 at 09:07:36PM +0200, Jarkko Sakkinen wrote:
> On Sat, Mar 13, 2021 at 09:05:36PM +0200, Jarkko Sakkinen wrote:
> > On Fri, Mar 12, 2021 at 01:44:58PM -0800, Sean Christopherson wrote:
> > > On Tue, Mar 09, 2021, 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@xxxxxxxxx>
> > > > Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>
> > > > ---
> > > > 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 44fe91a5bfb3..8c922e68274d 100644
> > > > --- a/arch/x86/kernel/cpu/sgx/main.c
> > > > +++ b/arch/x86/kernel/cpu/sgx/main.c
> > > > @@ -712,7 +712,15 @@ 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();
> > >
> > > I love this code.
> > >
> > > Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> >
> > I'm still wondering why this code let's go through when sgx_drv_init()
> > succeeds and sgx_vepc_init() fails.
> >
> > The inline comment explains only the mirrored case (which does make
> > sense).
>
> I.e. if sgx_drv_init() succeeds, I'd expect that sgx_vepc_init() must
> succeed. Why expect legitly anything else?
Apologies coming with these ideas at this point, but here is what this
led me.
I think that the all this complexity comes from a bad code structure.
So, what is essentially happening here:
- We essentially want to make EPC always work.
- Driver optionally.
So what this sums to is something like:
ret = sgx_epc_init();
if (ret) {
pr_err("EPC initialization failed.\n");
return ret;
}
ret = sgx_drv_init();
if (ret)
pr_info("Driver could not be initialized.\n");
/* continue */
I.e. I think there should be a single EPC init, which does both EPC
bootstrapping and vepc, and driver initialization comes after that.
/Jarkko
