Re: [PATCH v2 2/4] optee: add OPTEE_SMC_CALL_WITH_RPC_ARG and OPTEE_SMC_CALL_WITH_REGD_ARG

From: Sumit Garg
Date: Mon Apr 11 2022 - 09:19:04 EST

On Mon, 21 Mar 2022 at 18:33, Jens Wiklander <jens.wiklander@xxxxxxxxxx> wrote:
>
> Adds OPTEE_SMC_CALL_WITH_RPC_ARG and OPTEE_SMC_CALL_WITH_REGD_ARG where
> the struct optee_msg_arg to be used for RPC is appended in the memory
> following the normal argument struct optee_msg_arg. This is an
> optimization to avoid caching the RPC argument struct while still
> maintaining similar performance as if it was cached.
>
> OPTEE_SMC_CALL_WITH_REGD_ARG optimized one step further by using a
> registered shared memory object instead. It's in other aspects identical
> to OPTEE_SMC_CALL_WITH_RPC_ARG.
>
> The presence of OPTEE_SMC_CALL_WITH_RPC_ARG and
> OPTEE_SMC_CALL_WITH_REGD_ARG is indicated by the new
> OPTEE_SMC_SEC_CAP_RPC_ARG bit returned by
> OPTEE_SMC_EXCHANGE_CAPABILITIES. OPTEE_SMC_EXCHANGE_CAPABILITIES also
> reports the number of arguments that the RPC argument struct must have
> room for.
>
> OPTEE_SMC_CALL_WITH_RPC_ARG and OPTEE_SMC_CALL_WITH_ARG can be used
> interleaved with difference that when OPTEE_SMC_CALL_WITH_RPC_ARG is
> used the RPC argument struct to be used is the one appended to the
> normal argument struct. The same is true for
> OPTEE_SMC_CALL_WITH_REGD_ARG.
>
> Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
> ---
> drivers/tee/optee/call.c | 2 +-
> drivers/tee/optee/optee_smc.h | 47 ++++++++++++++---
> drivers/tee/optee/smc_abi.c | 99 ++++++++++++++++++++++++++---------
> 3 files changed, 116 insertions(+), 32 deletions(-)
>

Apart from minor nits below, feel free to add:

Reviewed-by: Sumit Garg <sumit.garg@xxxxxxxxxx>

> diff --git a/drivers/tee/optee/call.c b/drivers/tee/optee/call.c
> index a9a237d20c61..58ac15c02818 100644
> --- a/drivers/tee/optee/call.c
> +++ b/drivers/tee/optee/call.c
> @@ -130,7 +130,7 @@ struct tee_shm *optee_get_msg_arg(struct tee_context *ctx, size_t num_params,
> return (void *)ma;
> }
>
> - memset(ma, 0, OPTEE_MSG_GET_ARG_SIZE(num_params));
> + memset(ma, 0, sz);
> ma->num_params = num_params;
> *msg_arg = ma;
>
> diff --git a/drivers/tee/optee/optee_smc.h b/drivers/tee/optee/optee_smc.h
> index d44a6ae994f8..378741a459b6 100644
> --- a/drivers/tee/optee/optee_smc.h
> +++ b/drivers/tee/optee/optee_smc.h
> @@ -107,14 +107,22 @@ struct optee_smc_call_get_os_revision_result {
> /*
> * Call with struct optee_msg_arg as argument
> *
> - * When calling this function normal world has a few responsibilities:
> + * 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
> + * 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.
> + *
> + * When calling these functions normal world has a few responsibilities:

s/functions normal/functions, the normal/

> * 1. It must be able to handle eventual RPCs
> * 2. Non-secure interrupts should not be masked
> * 3. If asynchronous notifications has been negotiated successfully, then
> - * asynchronous notifications should be unmasked during this call.
> + * the interrupt for asynchronous notifications should be unmasked
> + * during this call.
> *
> - * Call register usage:
> - * a0 SMC Function ID, OPTEE_SMC*CALL_WITH_ARG
> + * Call register usage, OPTEE_SMC_CALL_WITH_ARG and
> + * OPTEE_SMC_CALL_WITH_RPC_ARG:
> + * a0 SMC Function ID, OPTEE_SMC_CALL_WITH_ARG or OPTEE_SMC_CALL_WITH_RPC_ARG
> * a1 Upper 32 bits of a 64-bit physical pointer to a struct optee_msg_arg
> * a2 Lower 32 bits of a 64-bit physical pointer to a struct optee_msg_arg
> * a3 Cache settings, not used if physical pointer is in a predefined shared
> @@ -122,6 +130,15 @@ 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
> + * 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
> + * supplied cookie
> + * a4-6 Not used
> + * a7 Hypervisor Client ID register
> + *
> * Normal return register usage:
> * a0 Return value, OPTEE_SMC_RETURN_*
> * a1-3 Not used
> @@ -154,6 +171,10 @@ struct optee_smc_call_get_os_revision_result {
> #define OPTEE_SMC_FUNCID_CALL_WITH_ARG OPTEE_MSG_FUNCID_CALL_WITH_ARG
> #define OPTEE_SMC_CALL_WITH_ARG \
> OPTEE_SMC_STD_CALL_VAL(OPTEE_SMC_FUNCID_CALL_WITH_ARG)
> +#define OPTEE_SMC_CALL_WITH_RPC_ARG \
> + 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)
>
> /*
> * Get Shared Memory Config
> @@ -202,6 +223,10 @@ struct optee_smc_get_shm_config_result {
> * a0 OPTEE_SMC_RETURN_OK
> * a1 bitfield of secure world capabilities OPTEE_SMC_SEC_CAP_*
> * a2 The maximum secure world notification number
> + * a3 Bit[7:0]: Number of parameters needed for RPC to be supplied
> + * as the second MSG arg struct for
> + * OPTEE_SMC_CALL_WITH_ARG
> + * Bit[31:8]: Reserved (MBZ)
> * a3-7 Preserved

s/a3-7/a4-7/

> *
> * Error return register usage:
> @@ -215,7 +240,6 @@ struct optee_smc_get_shm_config_result {
> #define OPTEE_SMC_SEC_CAP_HAVE_RESERVED_SHM BIT(0)
> /* Secure world can communicate via previously unregistered shared memory */
> #define OPTEE_SMC_SEC_CAP_UNREGISTERED_SHM BIT(1)
> -

nit: blank line shouldn't be removed.

> /*
> * Secure world supports commands "register/unregister shared memory",
> * secure world accepts command buffers located in any parts of non-secure RAM
> @@ -227,6 +251,8 @@ struct optee_smc_get_shm_config_result {
> #define OPTEE_SMC_SEC_CAP_MEMREF_NULL BIT(4)
> /* Secure world supports asynchronous notification of normal world */
> #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)
>
> #define OPTEE_SMC_FUNCID_EXCHANGE_CAPABILITIES 9
> #define OPTEE_SMC_EXCHANGE_CAPABILITIES \
> @@ -236,7 +262,7 @@ struct optee_smc_exchange_capabilities_result {
> unsigned long status;
> unsigned long capabilities;
> unsigned long max_notif_value;
> - unsigned long reserved0;
> + unsigned long data;
> };
>
> /*
> @@ -358,6 +384,9 @@ struct optee_smc_disable_shm_cache_result {
> * should be called until all pended values have been retrieved. When a
> * value is retrieved, it's cleared from the record in secure world.
> *
> + * It is expected that this function is called from an interrupt handler
> + * in normal world.
> + *
> * Call requests usage:
> * a0 SMC Function ID, OPTEE_SMC_GET_ASYNC_NOTIF_VALUE
> * a1-6 Not used
> @@ -390,6 +419,12 @@ struct optee_smc_disable_shm_cache_result {
> #define OPTEE_SMC_GET_ASYNC_NOTIF_VALUE \
> OPTEE_SMC_FAST_CALL_VAL(OPTEE_SMC_FUNCID_GET_ASYNC_NOTIF_VALUE)
>
> +/* See OPTEE_SMC_CALL_WITH_RPC_ARG above */
> +#define OPTEE_SMC_FUNCID_CALL_WITH_RPC_ARG 18
> +
> +/* See OPTEE_SMC_CALL_WITH_REGD_ARG above */
> +#define OPTEE_SMC_FUNCID_CALL_WITH_REGD_ARG 19
> +
> /*
> * 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 67b7f7d2ff27..b258d7306042 100644
> --- a/drivers/tee/optee/smc_abi.c
> +++ b/drivers/tee/optee/smc_abi.c
> @@ -732,16 +732,9 @@ static void optee_rpc_finalize_call(struct optee_call_ctx *call_ctx)
> }
>
> static void handle_rpc_func_cmd(struct tee_context *ctx, struct optee *optee,
> - struct tee_shm *shm,
> + struct optee_msg_arg *arg,
> struct optee_call_ctx *call_ctx)
> {
> - struct optee_msg_arg *arg;
> -
> - arg = tee_shm_get_va(shm, 0);
> - if (IS_ERR(arg)) {
> - pr_err("%s: tee_shm_get_va %p failed\n", __func__, shm);
> - return;
> - }
>
> switch (arg->cmd) {
> case OPTEE_RPC_CMD_SHM_ALLOC:
> @@ -765,11 +758,13 @@ static void handle_rpc_func_cmd(struct tee_context *ctx, struct optee *optee,
> * Result of RPC is written back into @param.
> */
> static void optee_handle_rpc(struct tee_context *ctx,
> + struct optee_msg_arg *rpc_arg,
> struct optee_rpc_param *param,
> struct optee_call_ctx *call_ctx)
> {
> struct tee_device *teedev = ctx->teedev;
> struct optee *optee = tee_get_drvdata(teedev);
> + struct optee_msg_arg *arg;
> struct tee_shm *shm;
> phys_addr_t pa;
>
> @@ -801,8 +796,19 @@ static void optee_handle_rpc(struct tee_context *ctx,
> */
> break;
> case OPTEE_SMC_RPC_FUNC_CMD:
> - shm = reg_pair_to_ptr(param->a1, param->a2);
> - handle_rpc_func_cmd(ctx, optee, shm, call_ctx);
> + if (rpc_arg) {
> + arg = rpc_arg;
> + } else {
> + shm = reg_pair_to_ptr(param->a1, param->a2);
> + arg = tee_shm_get_va(shm, 0);
> + if (IS_ERR(arg)) {
> + pr_err("%s: tee_shm_get_va %p failed\n",
> + __func__, shm);
> + break;
> + }
> + }
> +
> + handle_rpc_func_cmd(ctx, optee, arg, call_ctx);
> break;
> default:
> pr_warn("Unknown RPC func 0x%x\n",
> @@ -816,7 +822,7 @@ static void optee_handle_rpc(struct tee_context *ctx,
> /**
> * optee_smc_do_call_with_arg() - Do an SMC to OP-TEE in secure world
> * @ctx: calling context
> - * @arg: shared memory holding the message to pass to secure world
> + * @shm: shared memory holding the message to pass to secure world
> *
> * Does and SMC to OP-TEE in secure world and handles eventual resulting
> * Remote Procedure Calls (RPC) from OP-TEE.
> @@ -824,21 +830,46 @@ static void optee_handle_rpc(struct tee_context *ctx,
> * Returns return code from secure world, 0 is OK
> */
> static int optee_smc_do_call_with_arg(struct tee_context *ctx,
> - struct tee_shm *arg)
> + struct tee_shm *shm)
> {
> struct optee *optee = tee_get_drvdata(ctx->teedev);
> struct optee_call_waiter w;
> struct optee_rpc_param param = { };
> struct optee_call_ctx call_ctx = { };
> - phys_addr_t parg;
> + struct optee_msg_arg *rpc_arg = NULL;
> int rc;
>
> - rc = tee_shm_get_pa(arg, 0, &parg);
> - if (rc)
> - return rc;
> + if (optee->rpc_param_count) {
> + struct optee_msg_arg *arg;
> + unsigned int rpc_arg_offs;
> +
> + arg = tee_shm_get_va(shm, 0);
> + if (IS_ERR(arg))
> + return PTR_ERR(arg);
>
> - param.a0 = OPTEE_SMC_CALL_WITH_ARG;
> - reg_pair_from_64(&param.a1, &param.a2, parg);
> + rpc_arg_offs = OPTEE_MSG_GET_ARG_SIZE(arg->num_params);
> + rpc_arg = tee_shm_get_va(shm, rpc_arg_offs);
> + if (IS_ERR(arg))
> + return PTR_ERR(arg);
> + }
> +
> + if (rpc_arg && tee_shm_is_dynamic(shm)) {
> + param.a0 = OPTEE_SMC_CALL_WITH_REGD_ARG;
> + reg_pair_from_64(&param.a1, &param.a2, (u_long)shm);
> + param.a3 = 0;
> + } else {
> + phys_addr_t parg;
> +
> + rc = tee_shm_get_pa(shm, 0, &parg);
> + if (rc)
> + return rc;
> +
> + if (rpc_arg)
> + param.a0 = OPTEE_SMC_CALL_WITH_RPC_ARG;
> + else
> + param.a0 = OPTEE_SMC_CALL_WITH_ARG;
> + reg_pair_from_64(&param.a1, &param.a2, parg);
> + }
> /* Initialize waiter */
> optee_cq_wait_init(&optee->call_queue, &w);
> while (true) {
> @@ -862,7 +893,7 @@ static int optee_smc_do_call_with_arg(struct tee_context *ctx,
> param.a1 = res.a1;
> param.a2 = res.a2;
> param.a3 = res.a3;
> - optee_handle_rpc(ctx, &param, &call_ctx);
> + optee_handle_rpc(ctx, rpc_arg, &param, &call_ctx);
> } else {
> rc = res.a0;
> break;
> @@ -1118,7 +1149,8 @@ static bool optee_msg_api_revision_is_compatible(optee_invoke_fn *invoke_fn)
> }
>
> static bool optee_msg_exchange_capabilities(optee_invoke_fn *invoke_fn,
> - u32 *sec_caps, u32 *max_notif_value)
> + u32 *sec_caps, u32 *max_notif_value,
> + unsigned int *rpc_param_count)
> {
> union {
> struct arm_smccc_res smccc;
> @@ -1145,6 +1177,10 @@ static bool optee_msg_exchange_capabilities(optee_invoke_fn *invoke_fn,
> *max_notif_value = res.result.max_notif_value;
> else
> *max_notif_value = OPTEE_DEFAULT_MAX_NOTIF_VALUE;
> + if (*sec_caps & OPTEE_SMC_SEC_CAP_RPC_ARG)
> + *rpc_param_count = (u8)res.result.data;
> + else
> + *rpc_param_count = 0;
>
> return true;
> }
> @@ -1251,7 +1287,8 @@ static int optee_smc_remove(struct platform_device *pdev)
> * reference counters and also avoid wild pointers in secure world
> * into the old shared memory range.
> */
> - optee_disable_shm_cache(optee);
> + if (!optee->rpc_param_count)
> + optee_disable_shm_cache(optee);
>
> optee_smc_notif_uninit_irq(optee);
>
> @@ -1274,7 +1311,10 @@ static int optee_smc_remove(struct platform_device *pdev)
> */
> static void optee_shutdown(struct platform_device *pdev)
> {
> - optee_disable_shm_cache(platform_get_drvdata(pdev));
> + struct optee *optee = platform_get_drvdata(pdev);
> +
> + if (!optee->rpc_param_count)
> + optee_disable_shm_cache(optee);
> }
>
> static int optee_probe(struct platform_device *pdev)
> @@ -1283,6 +1323,7 @@ static int optee_probe(struct platform_device *pdev)
> struct tee_shm_pool *pool = ERR_PTR(-EINVAL);
> struct optee *optee = NULL;
> void *memremaped_shm = NULL;
> + unsigned int rpc_param_count;
> struct tee_device *teedev;
> struct tee_context *ctx;
> u32 max_notif_value;
> @@ -1306,7 +1347,8 @@ static int optee_probe(struct platform_device *pdev)
> }
>
> if (!optee_msg_exchange_capabilities(invoke_fn, &sec_caps,
> - &max_notif_value)) {
> + &max_notif_value,
> + &rpc_param_count)) {
> pr_warn("capabilities mismatch\n");
> return -EINVAL;
> }
> @@ -1335,6 +1377,7 @@ static int optee_probe(struct platform_device *pdev)
> optee->ops = &optee_ops;
> optee->smc.invoke_fn = invoke_fn;
> optee->smc.sec_caps = sec_caps;
> + optee->rpc_param_count = rpc_param_count;
>
> teedev = tee_device_alloc(&optee_clnt_desc, NULL, pool, optee);
> if (IS_ERR(teedev)) {
> @@ -1403,7 +1446,12 @@ static int optee_probe(struct platform_device *pdev)
> */
> optee_disable_unmapped_shm_cache(optee);
>
> - optee_enable_shm_cache(optee);
> + /*
> + * Only enable the shm cache in case we're not able to pass the RPC
> + * arg struct right after the normal arg struct.
> + */
> + if (!optee->rpc_param_count)
> + optee_enable_shm_cache(optee);
>
> if (optee->smc.sec_caps & OPTEE_SMC_SEC_CAP_DYNAMIC_SHM)
> pr_info("dynamic shared memory is enabled\n");
> @@ -1416,7 +1464,8 @@ static int optee_probe(struct platform_device *pdev)
> return 0;
>
> err_disable_shm_cache:
> - optee_disable_shm_cache(optee);
> + if (!optee->rpc_param_count)
> + optee_disable_shm_cache(optee);
> optee_smc_notif_uninit_irq(optee);
> optee_unregister_devices();
> err_notif_uninit:
> --
> 2.31.1
>