Re: [PATCH v2 1/2] tee: system invocation

From: Etienne Carriere
Date: Wed Feb 15 2023 - 11:03:35 EST

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In reply to: Jens Wiklander: "Re: [PATCH v2 1/2] tee: system invocation"
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Hi Jens,

On Wed, 15 Feb 2023 at 12:50, Jens Wiklander <jens.wiklander@xxxxxxxxxx> wrote:
>
> On Tue, Feb 14, 2023 at 04:20:46PM +0100, Etienne Carriere wrote:
> > Adds TEE system invocation context provisioning for a Linux driver
> > to provision execution contexts for invocation of system service
> > hosted in TEE. OP-TEE SMC ABI implements such invocation context
> > provisioning.
> >
> > This feature is needed when a TEE invocation cannot afford to wait for
> > a free TEE thread when all TEE threads context are used and suspended
> > as these may be suspended waiting for a system service, as an SCMI clock
> > or voltage regulator, to be enabled. An example is when OP-TEE invokes
> > a Linux OS remote service (RPC) to access an eMMC RPMB partition and
> > the eMMC device is supplied by an OP-TEE SCMI regulator.
> >
> > Signed-off-by: Etienne Carriere <etienne.carriere@xxxxxxxxxx>
> > ---
> > Change since v1
> > - Addressed comment on Linux client to claim reservation on TEE context.
> > This brings 2 new operations from client to TEE to request and release
> > system thread contexts: 2 new tee_drv.h API functions, 2 new ops
> > functions in struct tee_driver_ops. The OP-TEE implement shall implement
> > 2 new fastcall SMC funcIDs.
> > - Fixed typos in commit message.
> > ---
> > drivers/tee/optee/optee_smc.h | 60 +++++++++++++++++++++++++++++++++--
> > drivers/tee/optee/smc_abi.c | 34 +++++++++++++++++++-
> > drivers/tee/tee_core.c | 30 ++++++++++++++++++
> > include/linux/tee_drv.h | 21 ++++++++++++
> > 4 files changed, 141 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/tee/optee/optee_smc.h b/drivers/tee/optee/optee_smc.h
> > index 73b5e7760d10..75b19e1bd185 100644
> > --- a/drivers/tee/optee/optee_smc.h
> > +++ b/drivers/tee/optee/optee_smc.h
> > @@ -108,7 +108,8 @@ struct optee_smc_call_get_os_revision_result {
> > * Call with struct optee_msg_arg as argument
> > *
> > * When called with OPTEE_SMC_CALL_WITH_RPC_ARG or
> > - * OPTEE_SMC_CALL_WITH_REGD_ARG in a0 there is one RPC struct optee_msg_arg
> > + * OPTEE_SMC_CALL_WITH_REGD_ARG or OPTEE_SMC_FUNCID_CALL_SYSTEM_WITH_REGD_ARG
> > + * in a0 there is one RPC struct optee_msg_arg
> > * following after the first struct optee_msg_arg. The RPC struct
> > * optee_msg_arg has reserved space for the number of RPC parameters as
> > * returned by OPTEE_SMC_EXCHANGE_CAPABILITIES.
> > @@ -130,8 +131,8 @@ struct optee_smc_call_get_os_revision_result {
> > * a4-6 Not used
> > * a7 Hypervisor Client ID register
> > *
> > - * Call register usage, OPTEE_SMC_CALL_WITH_REGD_ARG:
> > - * a0 SMC Function ID, OPTEE_SMC_CALL_WITH_REGD_ARG
> > + * Call register usage, OPTEE_SMC_CALL_WITH_REGD_ARG and OPTEE_SMC_FUNCID_CALL_SYSTEM_WITH_REGD_ARG:
> > + * a0 SMC Function ID, OPTEE_SMC_CALL_WITH_REGD_ARG or OPTEE_SMC_FUNCID_CALL_SYSTEM_WITH_REGD_ARG
> > * a1 Upper 32 bits of a 64-bit shared memory cookie
> > * a2 Lower 32 bits of a 64-bit shared memory cookie
> > * a3 Offset of the struct optee_msg_arg in the shared memory with the
> > @@ -175,6 +176,8 @@ struct optee_smc_call_get_os_revision_result {
> > OPTEE_SMC_STD_CALL_VAL(OPTEE_SMC_FUNCID_CALL_WITH_RPC_ARG)
> > #define OPTEE_SMC_CALL_WITH_REGD_ARG \
> > OPTEE_SMC_STD_CALL_VAL(OPTEE_SMC_FUNCID_CALL_WITH_REGD_ARG)
> > +#define OPTEE_SMC_CALL_SYSTEM_WITH_REGD_ARG \
> > + OPTEE_SMC_STD_CALL_VAL(OPTEE_SMC_FUNCID_CALL_SYSTEM_WITH_REGD_ARG)
> >
> > /*
> > * Get Shared Memory Config
> > @@ -254,6 +257,8 @@ struct optee_smc_get_shm_config_result {
> > #define OPTEE_SMC_SEC_CAP_ASYNC_NOTIF BIT(5)
> > /* Secure world supports pre-allocating RPC arg struct */
> > #define OPTEE_SMC_SEC_CAP_RPC_ARG BIT(6)
> > +/* Secure world provisions thread for system service invocation */
> > +#define OPTEE_SMC_SEC_CAP_SYSTEM_THREAD BIT(7)
> >
> > #define OPTEE_SMC_FUNCID_EXCHANGE_CAPABILITIES 9
> > #define OPTEE_SMC_EXCHANGE_CAPABILITIES \
> > @@ -426,6 +431,55 @@ struct optee_smc_disable_shm_cache_result {
> > /* See OPTEE_SMC_CALL_WITH_REGD_ARG above */
> > #define OPTEE_SMC_FUNCID_CALL_WITH_REGD_ARG 19
> >
> > +/* See OPTEE_SMC_CALL_SYSTEM_WITH_REGD_ARG above */
> > +#define OPTEE_SMC_FUNCID_CALL_SYSTEM_WITH_REGD_ARG 20
> > +
> > +/*
> > + * Request reservation of a system invocation thread context in OP-TEE
> > + *
> > + * Call register usage:
> > + * a0 SMC Function ID: OPTEE_SMC_CALL_RESERVE_SYS_THREAD
> > + * a1-6 Not used
> > + * a7 Hypervisor Client ID register
> > + *
> > + * Normal return register usage:
> > + * a0 Return value, OPTEE_SMC_RETURN_*
> > + * a1-3 Not used
> > + * a4-7 Preserved
> > + *
> > + * Possible return values:
> > + * OPTEE_SMC_RETURN_UNKNOWN_FUNCTION Trusted OS does not recognize this
> > + * function.
> > + * OPTEE_SMC_RETURN_OK Call successfully completed.
> > + * OPTEE_SMC_RETURN_ETHREAD_LIMIT Number of Trusted OS threads exceeded
> > + * for the request.
> > + */
> > +#define OPTEE_SMC_FUNCID_CALL_RESERVE_SYS_THREAD 21
> > +#define OPTEE_SMC_CALL_RESERVE_SYS_THREAD \
> > + OPTEE_SMC_STD_CALL_VAL(OPTEE_SMC_FUNCID_CALL_RESERVE_SYS_THREAD)
> > +
> > +/*
> > + * Unregister reservation of a system invocation thread context in OP-TEE
> > + *
> > + * Call register usage:
> > + * a0 SMC Function ID: OPTEE_SMC_CALL_UNRESERVE_SYS_THREAD
> > + * a1-6 Not used
> > + * a7 Hypervisor Client ID register
> > + *
> > + * Normal return register usage:
> > + * a0 Return value, OPTEE_SMC_RETURN_*
> > + * a1-3 Not used
> > + * a4-7 Preserved
> > + *
> > + * Possible return values:
> > + * OPTEE_SMC_RETURN_UNKNOWN_FUNCTION Trusted OS does not recognize this
> > + * function.
> > + * OPTEE_SMC_RETURN_OK Call successfully completed.
> > + */
> > +#define OPTEE_SMC_FUNCID_CALL_UNRESERVE_SYS_THREAD 22
> > +#define OPTEE_SMC_CALL_UNRESERVE_SYS_THREAD \
> > + OPTEE_SMC_STD_CALL_VAL(OPTEE_SMC_FUNCID_CALL_UNRESERVE_SYS_THREAD)
> > +
> > /*
> > * Resume from RPC (for example after processing a foreign interrupt)
> > *
> > diff --git a/drivers/tee/optee/smc_abi.c b/drivers/tee/optee/smc_abi.c
> > index a1c1fa1a9c28..013b5ae31c0e 100644
> > --- a/drivers/tee/optee/smc_abi.c
> > +++ b/drivers/tee/optee/smc_abi.c
> > @@ -889,7 +889,10 @@ static int optee_smc_do_call_with_arg(struct tee_context *ctx,
> > }
> >
> > if (rpc_arg && tee_shm_is_dynamic(shm)) {
> > - param.a0 = OPTEE_SMC_CALL_WITH_REGD_ARG;
> > + if (ctx->system_ctx_count)
> > + param.a0 = OPTEE_SMC_CALL_SYSTEM_WITH_REGD_ARG;
> > + else
> > + param.a0 = OPTEE_SMC_CALL_WITH_REGD_ARG;
> > reg_pair_from_64(&param.a1, &param.a2, (u_long)shm);
> > param.a3 = offs;
> > } else {
> > @@ -1085,6 +1088,33 @@ static int optee_smc_open(struct tee_context *ctx)
> > return optee_open(ctx, sec_caps & OPTEE_SMC_SEC_CAP_MEMREF_NULL);
> > }
> >
> > +static int optee_request_sys_ctx(struct tee_context *ctx)
> > +{
> > + struct optee *optee = tee_get_drvdata(ctx->teedev);
> > + struct arm_smccc_res res;
> > +
> > + if (!(optee->smc.sec_caps & OPTEE_SMC_SEC_CAP_SYSTEM_THREAD))
> > + return -EINVAL;
> > +
> > + optee->smc.invoke_fn(OPTEE_SMC_CALL_RESERVE_SYS_THREAD,
> > + 0, 0, 0, 0, 0, 0, 0, &res);
> > +
> > + if (res.a0 != OPTEE_SMC_RETURN_OK)
> > + return -EINVAL;
> > +
> > + return 0;
> > +}
> > +
> > +static void optee_release_sys_ctx(struct tee_context *ctx)
> > +{
> > + struct optee *optee = tee_get_drvdata(ctx->teedev);
> > + struct arm_smccc_res res;
> > +
> > + if (optee->smc.sec_caps & OPTEE_SMC_SEC_CAP_SYSTEM_THREAD)
> > + optee->smc.invoke_fn(OPTEE_SMC_CALL_UNRESERVE_SYS_THREAD,
> > + 0, 0, 0, 0, 0, 0, 0, &res);
> > +}
> > +
> > static const struct tee_driver_ops optee_clnt_ops = {
> > .get_version = optee_get_version,
> > .open = optee_smc_open,
> > @@ -1095,6 +1125,8 @@ static const struct tee_driver_ops optee_clnt_ops = {
> > .cancel_req = optee_cancel_req,
> > .shm_register = optee_shm_register,
> > .shm_unregister = optee_shm_unregister,
> > + .system_ctx_request = optee_request_sys_ctx,
> > + .system_ctx_release = optee_release_sys_ctx,
> > };
> >
> > static const struct tee_desc optee_clnt_desc = {
> > diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
> > index 98da206cd761..a7dfdea5d85b 100644
> > --- a/drivers/tee/tee_core.c
> > +++ b/drivers/tee/tee_core.c
> > @@ -5,6 +5,7 @@
> >
> > #define pr_fmt(fmt) "%s: " fmt, __func__
> >
> > +#include <linux/bug.h>
> > #include <linux/cdev.h>
> > #include <linux/cred.h>
> > #include <linux/fs.h>
> > @@ -1141,10 +1142,39 @@ EXPORT_SYMBOL_GPL(tee_client_open_context);
> >
> > void tee_client_close_context(struct tee_context *ctx)
> > {
> > + while (ctx->system_ctx_count)
> > + tee_client_release_system_context(ctx);
> > +
> > teedev_close_context(ctx);
> > }
> > EXPORT_SYMBOL_GPL(tee_client_close_context);
> >
> > +int tee_client_request_system_context(struct tee_context *ctx)
> > +{
> > + int ret;
> > +
> > + if (!ctx->teedev->desc->ops->system_ctx_request ||
> > + !ctx->teedev->desc->ops->system_ctx_release)
> > + return -EINVAL;
> > +
> > + ret = ctx->teedev->desc->ops->system_ctx_request(ctx);
> > + if (!ret)
> > + ctx->system_ctx_count++;
> > +
> > + return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(tee_client_request_system_context);
> > +
> > +void tee_client_release_system_context(struct tee_context *ctx)
> > +{
> > + if (ctx->system_ctx_count &&
> > + ctx->teedev->desc->ops->system_ctx_release) {
> > + ctx->teedev->desc->ops->system_ctx_release(ctx);
> > + ctx->system_ctx_count--;
> > + }
> > +}
> > +EXPORT_SYMBOL_GPL(tee_client_release_system_context);
> > +
> > void tee_client_get_version(struct tee_context *ctx,
> > struct tee_ioctl_version_data *vers)
> > {
> > diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
> > index 17eb1c5205d3..45577256bb71 100644
> > --- a/include/linux/tee_drv.h
> > +++ b/include/linux/tee_drv.h
> > @@ -47,6 +47,8 @@ struct tee_shm_pool;
> > * non-blocking in nature.
> > * @cap_memref_null: flag indicating if the TEE Client support shared
> > * memory buffer with a NULL pointer.
> > + * @system_ctx_count: Number of system invocation contexts provisioned for
> > + * this TEE client or 0.
> > */
> > struct tee_context {
> > struct tee_device *teedev;
> > @@ -55,6 +57,7 @@ struct tee_context {
> > bool releasing;
> > bool supp_nowait;
> > bool cap_memref_null;
> > + unsigned int system_ctx_count;
>
> Does it make sense for a tee_context to reserve more than one system
> context/thread?

A single Linux driver optee context (opened from
tee_client_open_context()) can be used for concurrent invocations of
TEE hence the implementation here supporting a linux context to
reserve several OP-TEE thread contexts.

> I wonder if keeping track on this shouldn't be done in a
> driver specific struct, perhaps struct optee_context_data for OP-TEE.

Yes, I can move that to optee private data since how TEE drivers
handle this are specific to their TEE.

>
> > };
> >
> > struct tee_param_memref {
> > @@ -90,6 +93,8 @@ struct tee_param {
> > * @supp_send: called for supplicant to send a response
> > * @shm_register: register shared memory buffer in TEE
> > * @shm_unregister: unregister shared memory buffer in TEE
> > + * @system_ctx_request: Request provisioning of a new system context in TEE
> > + * @system_ctx_release: Release a provisioned system context in TEE
> > */
> > struct tee_driver_ops {
> > void (*get_version)(struct tee_device *teedev,
> > @@ -112,6 +117,8 @@ struct tee_driver_ops {
> > struct page **pages, size_t num_pages,
> > unsigned long start);
> > int (*shm_unregister)(struct tee_context *ctx, struct tee_shm *shm);
> > + int (*system_ctx_request)(struct tee_context *ctx);
> > + void (*system_ctx_release)(struct tee_context *ctx);
> > };
> >
> > /**
> > @@ -397,6 +404,20 @@ tee_client_open_context(struct tee_context *start,
> > */
> > void tee_client_close_context(struct tee_context *ctx);
> >
> > +/**
> > + * tee_client_request_system_context() - Close a TEE context
>
> Copy & paste error
>
> > + * @ctx: TEE context to close
> > + *
> > + * @return 0 on success else an error code
> > + */
> > +int tee_client_request_system_context(struct tee_context *ctx);
> > +
> > +/**
> > + * tee_client_release_system_context() - Release a reserved system exec context
>
> Please drop "exec", it's not mentioned anywhere else.

Ok.

Etienne

>
> Thanks,
> Jens
>
> > + * @ctx: TEE context reference
> > + */
> > +void tee_client_release_system_context(struct tee_context *ctx);
> > +
> > /**
> > * tee_client_get_version() - Query version of TEE
> > * @ctx: TEE context to TEE to query
> > --
> > 2.25.1
> >

Next message: Guenter Roeck: "Re: [PATCH] ASoC: da7219: Improve the IRQ process to increase the stability"
Previous message: Sebastian Andrzej Siewior: "Re: [PATCH v4] locking/rwbase: Mitigate indefinite writer starvation"
In reply to: Jens Wiklander: "Re: [PATCH v2 1/2] tee: system invocation"
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