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Message-ID: <CAFA6WYMoWn6MgoRp8hD89PwmLeHaO+X1sGB0QOMQDLJtuseP3g@mail.gmail.com>
Date: Fri, 13 Oct 2023 13:29:34 +0530
From: Sumit Garg <sumit.garg@...aro.org>
To: Masahisa Kojima <masahisa.kojima@...aro.org>
Cc: Ard Biesheuvel <ardb@...nel.org>,
Jens Wiklander <jens.wiklander@...aro.org>,
Jan Kiszka <jan.kiszka@...mens.com>,
linux-kernel@...r.kernel.org, op-tee@...ts.trustedfirmware.org,
Ilias Apalodimas <ilias.apalodimas@...aro.org>,
Johan Hovold <johan+linaro@...nel.org>,
Randy Dunlap <rdunlap@...radead.org>,
Heinrich Schuchardt <heinrich.schuchardt@...onical.com>,
Jonathan Cameron <Jonathan.Cameron@...wei.com>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
Alexandre Torgue <alexandre.torgue@...s.st.com>,
linux-efi@...r.kernel.org,
linux-stm32@...md-mailman.stormreply.com,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v9 6/6] tee: optee: restore efivars ops when
tee-supplicant stops
Hi Kojima-san,
On Fri, 13 Oct 2023 at 13:18, Masahisa Kojima
<masahisa.kojima@...aro.org> 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].
[1] https://lore.kernel.org/all/20230728134832.326467-1-sumit.garg@linaro.org/
-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@...aro.org>
> ---
> 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
>
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