Re: [PATCH v9 6/6] tee: optee: restore efivars ops when tee-supplicant stops

[Masahisa Kojima]

Hi Sumit,

On Fri, 13 Oct 2023 at 16:59, Sumit Garg <sumit.garg@xxxxxxxxxx> wrote:
>
> Hi Kojima-san,
>
> On Fri, 13 Oct 2023 at 13:18, Masahisa Kojima
> <masahisa.kojima@xxxxxxxxxx> wrote:
> >
> > When tee-supplicant stops, tee-based EFI variable service
> > is no longer available. Restore the efivars generic ops at the
> > moment when tee-supplicant stops.
>
> This is a layering violation as evident from below linking error. The
> tee-supplicant is internal to how OP-TEE is implemented. I have
> already shared a unified way to handle shutdown of supplicant
> dependent devices here [1].

I will drop this patch, and send the next version.

Thanks,
Masahisa Kojima

>
> [1] https://lore.kernel.org/all/20230728134832.326467-1-sumit.garg@xxxxxxxxxx/
>
> -Sumit
>
> >
> > Linking error occurs if we set CONFIG_OPTEE=y and
> > CONFIG_TEE_STMM_EFI=m. Use IS_REACHABLE() guard to call
> > tee_stmm_restore_efivars_generic_ops() function.
> >
> > Signed-off-by: Masahisa Kojima <masahisa.kojima@xxxxxxxxxx>
> > ---
> >  drivers/firmware/efi/stmm/tee_stmm_efi.c | 8 +++++++-
> >  drivers/tee/optee/supp.c                 | 4 ++++
> >  include/linux/efi.h                      | 1 +
> >  3 files changed, 12 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/firmware/efi/stmm/tee_stmm_efi.c b/drivers/firmware/efi/stmm/tee_stmm_efi.c
> > index edc165bc1bb0..e804b260edaa 100644
> > --- a/drivers/firmware/efi/stmm/tee_stmm_efi.c
> > +++ b/drivers/firmware/efi/stmm/tee_stmm_efi.c
> > @@ -572,10 +572,16 @@ static int tee_stmm_efi_probe(struct device *dev)
> >         return 0;
> >  }
> >
> > -static int tee_stmm_efi_remove(struct device *dev)
> > +void tee_stmm_restore_efivars_generic_ops(void)
> >  {
> >         efivars_unregister(&tee_efivars);
> >         efivars_generic_ops_register();
> > +}
> > +EXPORT_SYMBOL_GPL(tee_stmm_restore_efivars_generic_ops);
> > +
> > +static int tee_stmm_efi_remove(struct device *dev)
> > +{
> > +       tee_stmm_restore_efivars_generic_ops();
> >
> >         return 0;
> >  }
> > diff --git a/drivers/tee/optee/supp.c b/drivers/tee/optee/supp.c
> > index 322a543b8c27..d07d4fc4e72e 100644
> > --- a/drivers/tee/optee/supp.c
> > +++ b/drivers/tee/optee/supp.c
> > @@ -3,6 +3,7 @@
> >   * Copyright (c) 2015, Linaro Limited
> >   */
> >  #include <linux/device.h>
> > +#include <linux/efi.h>
> >  #include <linux/slab.h>
> >  #include <linux/uaccess.h>
> >  #include "optee_private.h"
> > @@ -58,6 +59,9 @@ void optee_supp_release(struct optee_supp *supp)
> >                 complete(&req->c);
> >         }
> >
> > +       if (IS_REACHABLE(CONFIG_TEE_STMM_EFI))
> > +               tee_stmm_restore_efivars_generic_ops();
> > +
> >         supp->ctx = NULL;
> >         supp->req_id = -1;
> >
> > diff --git a/include/linux/efi.h b/include/linux/efi.h
> > index 489707b9b0b0..9b60893d6299 100644
> > --- a/include/linux/efi.h
> > +++ b/include/linux/efi.h
> > @@ -1365,5 +1365,6 @@ extern struct blocking_notifier_head efivar_ops_nh;
> >
> >  void efivars_generic_ops_register(void);
> >  void efivars_generic_ops_unregister(void);
> > +void tee_stmm_restore_efivars_generic_ops(void);
> >
> >  #endif /* _LINUX_EFI_H */
> > --
> > 2.30.2
> >