Re: [PATCH v2 7/7] optee: add asynchronous notifications

From: Ard Biesheuvel
Date: Wed Jun 16 2021 - 10:08:56 EST

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In reply to: Jens Wiklander: "[PATCH v2 7/7] optee: add asynchronous notifications"
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On Wed, 16 Jun 2021 at 12:37, Jens Wiklander <jens.wiklander@xxxxxxxxxx> wrote:
>
> Adds support for asynchronous notifications from secure world to normal
> world. This allows a design with a top half and bottom half type of
> driver where the top half runs in secure interrupt context and a
> notifications tells normal world to schedule a yielding call to do the
> bottom half processing.
>
> The protocol is defined in optee_msg.h optee_rpc_cmd.h and optee_smc.h.
>
> A notification consists of a 32-bit value which normal world can
> retrieve using a fastcall into secure world. The value
> OPTEE_SMC_ASYNC_NOTIF_VALUE_DO_BOTTOM_HALF (0) has a special meaning.
> When this value is sent it means that normal world is supposed to make a
> yielding call OPTEE_MSG_CMD_DO_BOTTOM_HALF.
>
> Notification capability is negotiated while the driver is initialized.
> If both sides supports these notifications then they are enabled.
>
> An interrupt is used to notify the driver that there are asynchronous
> notifications pending. The maximum needed notification value is
> communicated at this stage. This allows scaling up when needed.
>
> Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>

Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx>

> ---
> drivers/tee/optee/call.c | 27 ++++++++
> drivers/tee/optee/core.c | 82 +++++++++++++++-------
> drivers/tee/optee/notif.c | 109 ++++++++++++++++++++++++++++--
> drivers/tee/optee/optee_msg.h | 9 +++
> drivers/tee/optee/optee_private.h | 6 +-
> drivers/tee/optee/optee_smc.h | 75 +++++++++++++++++++-
> 6 files changed, 276 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/tee/optee/call.c b/drivers/tee/optee/call.c
> index 6132cc8d014c..9da66acac828 100644
> --- a/drivers/tee/optee/call.c
> +++ b/drivers/tee/optee/call.c
> @@ -390,6 +390,33 @@ int optee_cancel_req(struct tee_context *ctx, u32 cancel_id, u32 session)
> return 0;
> }
>
> +static int simple_call_with_arg(struct tee_context *ctx, u32 cmd)
> +{
> + struct optee_msg_arg *msg_arg;
> + phys_addr_t msg_parg;
> + struct tee_shm *shm;
> +
> + shm = get_msg_arg(ctx, 0, &msg_arg, &msg_parg);
> + if (IS_ERR(shm))
> + return PTR_ERR(shm);
> +
> + msg_arg->cmd = cmd;
> + optee_do_call_with_arg(ctx, msg_parg);
> +
> + tee_shm_free(shm);
> + return 0;
> +}
> +
> +int optee_do_bottom_half(struct tee_context *ctx)
> +{
> + return simple_call_with_arg(ctx, OPTEE_MSG_CMD_DO_BOTTOM_HALF);
> +}
> +
> +int optee_stop_async_notif(struct tee_context *ctx)
> +{
> + return simple_call_with_arg(ctx, OPTEE_MSG_CMD_STOP_ASYNC_NOTIF);
> +}
> +
> /**
> * optee_enable_shm_cache() - Enables caching of some shared memory allocation
> * in OP-TEE
> diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
> index 2272696ac986..e3c80505cc88 100644
> --- a/drivers/tee/optee/core.c
> +++ b/drivers/tee/optee/core.c
> @@ -7,9 +7,12 @@
>
> #include <linux/arm-smccc.h>
> #include <linux/errno.h>
> +#include <linux/interrupt.h>
> #include <linux/io.h>
> +#include <linux/irqdomain.h>
> #include <linux/module.h>
> #include <linux/of.h>
> +#include <linux/of_irq.h>
> #include <linux/of_platform.h>
> #include <linux/platform_device.h>
> #include <linux/slab.h>
> @@ -353,6 +356,17 @@ static const struct tee_desc optee_supp_desc = {
> .flags = TEE_DESC_PRIVILEGED,
> };
>
> +static int enable_async_notif(optee_invoke_fn *invoke_fn)
> +{
> + struct arm_smccc_res res;
> +
> + invoke_fn(OPTEE_SMC_ENABLE_ASYNC_NOTIF, 0, 0, 0, 0, 0, 0, 0, &res);
> +
> + if (res.a0)
> + return -EINVAL;
> + return 0;
> +}
> +
> static bool optee_msg_api_uid_is_optee_api(optee_invoke_fn *invoke_fn)
> {
> struct arm_smccc_res res;
> @@ -402,7 +416,7 @@ 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 *sec_caps, u32 *max_notif_value)
> {
> union {
> struct arm_smccc_res smccc;
> @@ -425,6 +439,7 @@ static bool optee_msg_exchange_capabilities(optee_invoke_fn *invoke_fn,
> return false;
>
> *sec_caps = res.result.capabilities;
> + *max_notif_value = res.result.max_notif_value;
> return true;
> }
>
> @@ -609,6 +624,7 @@ static int optee_probe(struct platform_device *pdev)
> struct optee *optee = NULL;
> void *memremaped_shm = NULL;
> struct tee_device *teedev;
> + u32 max_notif_value;
> u32 sec_caps;
> int rc;
>
> @@ -628,7 +644,8 @@ static int optee_probe(struct platform_device *pdev)
> return -EINVAL;
> }
>
> - if (!optee_msg_exchange_capabilities(invoke_fn, &sec_caps)) {
> + if (!optee_msg_exchange_capabilities(invoke_fn, &sec_caps,
> + &max_notif_value)) {
> pr_warn("capabilities mismatch\n");
> return -EINVAL;
> }
> @@ -651,7 +668,7 @@ static int optee_probe(struct platform_device *pdev)
> optee = kzalloc(sizeof(*optee), GFP_KERNEL);
> if (!optee) {
> rc = -ENOMEM;
> - goto err;
> + goto err_free_pool;
> }
>
> optee->invoke_fn = invoke_fn;
> @@ -660,24 +677,24 @@ static int optee_probe(struct platform_device *pdev)
> teedev = tee_device_alloc(&optee_desc, NULL, pool, optee);
> if (IS_ERR(teedev)) {
> rc = PTR_ERR(teedev);
> - goto err;
> + goto err_free_optee;
> }
> optee->teedev = teedev;
>
> teedev = tee_device_alloc(&optee_supp_desc, NULL, pool, optee);
> if (IS_ERR(teedev)) {
> rc = PTR_ERR(teedev);
> - goto err;
> + goto err_unreg_teedev;
> }
> optee->supp_teedev = teedev;
>
> rc = tee_device_register(optee->teedev);
> if (rc)
> - goto err;
> + goto err_unreg_supp_teedev;
>
> rc = tee_device_register(optee->supp_teedev);
> if (rc)
> - goto err;
> + goto err_unreg_supp_teedev;
>
> mutex_init(&optee->call_queue.mutex);
> INIT_LIST_HEAD(&optee->call_queue.waiters);
> @@ -687,10 +704,30 @@ static int optee_probe(struct platform_device *pdev)
>
> platform_set_drvdata(pdev, optee);
>
> - rc = optee_notif_init(optee, 255);
> - if (rc) {
> - optee_remove(pdev);
> - return rc;
> + if (sec_caps & OPTEE_SMC_SEC_CAP_ASYNC_NOTIF) {
> + unsigned int irq;
> +
> + rc = platform_get_irq(pdev, 0);
> + if (rc < 0) {
> + pr_err("platform_get_irq: ret %d\n", rc);
> + goto err_unreg_supp_teedev;
> + }
> + irq = rc;
> +
> + rc = optee_notif_init(optee, max_notif_value, irq);
> + if (rc) {
> + irq_dispose_mapping(irq);
> + optee_remove(pdev);
> + return rc;
> + }
> + enable_async_notif(optee->invoke_fn);
> + pr_info("Asynchronous notifications enabled\n");
> + } else {
> + rc = optee_notif_init(optee, 255, 0);
> + if (rc) {
> + optee_remove(pdev);
> + return rc;
> + }
> }
>
> optee_enable_shm_cache(optee);
> @@ -706,20 +743,15 @@ static int optee_probe(struct platform_device *pdev)
>
> pr_info("initialized driver\n");
> return 0;
> -err:
> - if (optee) {
> - /*
> - * tee_device_unregister() is safe to call even if the
> - * devices hasn't been registered with
> - * tee_device_register() yet.
> - */
> - tee_device_unregister(optee->supp_teedev);
> - tee_device_unregister(optee->teedev);
> - kfree(optee);
> - }
> - if (pool)
> - tee_shm_pool_free(pool);
> - if (memremaped_shm)
> +err_unreg_supp_teedev:
> + tee_device_unregister(optee->supp_teedev);
> +err_unreg_teedev:
> + tee_device_unregister(optee->teedev);
> +err_free_optee:
> + kfree(optee);
> +err_free_pool:
> + tee_shm_pool_free(pool);
> + if (optee->memremaped_shm)
> memunmap(memremaped_shm);
> return rc;
> }
> diff --git a/drivers/tee/optee/notif.c b/drivers/tee/optee/notif.c
> index a28fa03dcd0e..ecfa82797695 100644
> --- a/drivers/tee/optee/notif.c
> +++ b/drivers/tee/optee/notif.c
> @@ -7,10 +7,14 @@
>
> #include <linux/arm-smccc.h>
> #include <linux/errno.h>
> +#include <linux/interrupt.h>
> +#include <linux/irqdomain.h>
> #include <linux/slab.h>
> #include <linux/spinlock.h>
> #include <linux/tee_drv.h>
> #include "optee_private.h"
> +#include "optee_smc.h"
> +#include "optee_rpc_cmd.h"
>
> struct notif_entry {
> struct list_head link;
> @@ -18,6 +22,54 @@ struct notif_entry {
> u_int key;
> };
>
> +static u32 get_async_notif_value(optee_invoke_fn *invoke_fn, bool *value_valid,
> + bool *value_pending)
> +{
> + struct arm_smccc_res res;
> +
> + invoke_fn(OPTEE_SMC_GET_ASYNC_NOTIF_VALUE, 0, 0, 0, 0, 0, 0, 0, &res);
> +
> + if (res.a0)
> + return 0;
> + *value_valid = (res.a2 & OPTEE_SMC_ASYNC_NOTIF_VALUE_VALID);
> + *value_pending = (res.a2 & OPTEE_SMC_ASYNC_NOTIF_VALUE_PENDING);
> + return res.a1;
> +}
> +
> +static irqreturn_t notif_irq_handler(int irq, void *dev_id)
> +{
> + struct optee *optee = dev_id;
> + bool do_bottom_half = false;
> + bool value_valid;
> + bool value_pending;
> + u32 value;
> +
> + do {
> + value = get_async_notif_value(optee->invoke_fn, &value_valid,
> + &value_pending);
> + if (!value_valid)
> + break;
> +
> + if (value == OPTEE_SMC_ASYNC_NOTIF_VALUE_DO_BOTTOM_HALF)
> + do_bottom_half = true;
> + else
> + optee_notif_send(optee, value);
> + } while (value_pending);
> +
> + if (do_bottom_half)
> + return IRQ_WAKE_THREAD;
> + return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t notif_irq_thread_fn(int irq, void *dev_id)
> +{
> + struct optee *optee = dev_id;
> +
> + optee_do_bottom_half(optee->notif.ctx);
> +
> + return IRQ_HANDLED;
> +}
> +
> static bool have_key(struct optee *optee, u_int key)
> {
> struct notif_entry *entry;
> @@ -106,20 +158,69 @@ int optee_notif_send(struct optee *optee, u_int key)
> return 0;
> }
>
> -int optee_notif_init(struct optee *optee, u_int max_key)
> +int optee_notif_init(struct optee *optee, u_int max_key, u_int irq)
> {
> + struct tee_context *ctx;
> + int rc;
> +
> + if (irq) {
> + ctx = tee_dev_open_helper(optee->teedev);
> + if (IS_ERR(ctx))
> + return PTR_ERR(ctx);
> +
> + optee->notif.ctx = ctx;
> + }
> +
> spin_lock_init(&optee->notif.lock);
> INIT_LIST_HEAD(&optee->notif.db);
> optee->notif.bitmap = bitmap_zalloc(max_key, GFP_KERNEL);
> - if (!optee->notif.bitmap)
> - return -ENOMEM;
> -
> + if (!optee->notif.bitmap) {
> + rc = -ENOMEM;
> + goto err_put_ctx;
> + }
> optee->notif.max_key = max_key;
>
> + if (irq) {
> + rc = request_threaded_irq(irq, notif_irq_handler,
> + notif_irq_thread_fn,
> + 0, "optee_notification", optee);
> + if (rc)
> + goto err_free_bitmap;
> +
> + optee->notif.irq = irq;
> + }
> +
> return 0;
> +
> +err_free_bitmap:
> + kfree(optee->notif.bitmap);
> +err_put_ctx:
> + tee_dev_ctx_put(optee->notif.ctx);
> + optee->notif.ctx = NULL;
> +
> + return rc;
> }
>
> void optee_notif_uninit(struct optee *optee)
> {
> + if (optee->notif.ctx) {
> + optee_stop_async_notif(optee->notif.ctx);
> + if (optee->notif.irq) {
> + free_irq(optee->notif.irq, optee);
> + irq_dispose_mapping(optee->notif.irq);
> + }
> +
> + /*
> + * The thread normally working with optee->notif.ctx was
> + * stopped with free_irq() above.
> + *
> + * Note we're not using teedev_close_context() or
> + * tee_client_close_context() since we have already called
> + * tee_device_put() while initializing to avoid a circular
> + * reference counting.
> + */
> + tee_dev_ctx_put(optee->notif.ctx);
> + }
> +
> kfree(optee->notif.bitmap);
> }
> diff --git a/drivers/tee/optee/optee_msg.h b/drivers/tee/optee/optee_msg.h
> index 81ff593ac4ec..35970932de34 100644
> --- a/drivers/tee/optee/optee_msg.h
> +++ b/drivers/tee/optee/optee_msg.h
> @@ -291,6 +291,13 @@ struct optee_msg_arg {
> * [in] param[0].u.rmem.shm_ref holds shared memory reference
> * [in] param[0].u.rmem.offs 0
> * [in] param[0].u.rmem.size 0
> + *
> + * OPTEE_MSG_CMD_DO_BOTTOM_HALF does the scheduled bottom half processing
> + * of a driver.
> + *
> + * OPTEE_MSG_CMD_STOP_ASYNC_NOTIF informs secure world that from now is
> + * normal world unable to process asynchronous notifications. Typically
> + * used when the driver is shut down.
> */
> #define OPTEE_MSG_CMD_OPEN_SESSION 0
> #define OPTEE_MSG_CMD_INVOKE_COMMAND 1
> @@ -298,6 +305,8 @@ struct optee_msg_arg {
> #define OPTEE_MSG_CMD_CANCEL 3
> #define OPTEE_MSG_CMD_REGISTER_SHM 4
> #define OPTEE_MSG_CMD_UNREGISTER_SHM 5
> +#define OPTEE_MSG_CMD_DO_BOTTOM_HALF 6
> +#define OPTEE_MSG_CMD_STOP_ASYNC_NOTIF 7
> #define OPTEE_MSG_FUNCID_CALL_WITH_ARG 0x0004
>
> #endif /* _OPTEE_MSG_H */
> diff --git a/drivers/tee/optee/optee_private.h b/drivers/tee/optee/optee_private.h
> index 7dc058d008b2..62365912a70b 100644
> --- a/drivers/tee/optee/optee_private.h
> +++ b/drivers/tee/optee/optee_private.h
> @@ -37,6 +37,8 @@ struct optee_call_queue {
>
> struct optee_notif {
> u_int max_key;
> + unsigned int irq;
> + struct tee_context *ctx;
> /* Serializes access to the elements below in this struct */
> spinlock_t lock;
> struct list_head db;
> @@ -132,7 +134,7 @@ void optee_handle_rpc(struct tee_context *ctx, struct optee_rpc_param *param,
> struct optee_call_ctx *call_ctx);
> void optee_rpc_finalize_call(struct optee_call_ctx *call_ctx);
>
> -int optee_notif_init(struct optee *optee, u_int max_key);
> +int optee_notif_init(struct optee *optee, u_int max_key, u_int irq);
> void optee_notif_uninit(struct optee *optee);
> int optee_notif_wait(struct optee *optee, u_int key);
> int optee_notif_send(struct optee *optee, u_int key);
> @@ -159,6 +161,8 @@ int optee_close_session(struct tee_context *ctx, u32 session);
> int optee_invoke_func(struct tee_context *ctx, struct tee_ioctl_invoke_arg *arg,
> struct tee_param *param);
> int optee_cancel_req(struct tee_context *ctx, u32 cancel_id, u32 session);
> +int optee_do_bottom_half(struct tee_context *ctx);
> +int optee_stop_async_notif(struct tee_context *ctx);
>
> void optee_enable_shm_cache(struct optee *optee);
> void optee_disable_shm_cache(struct optee *optee);
> diff --git a/drivers/tee/optee/optee_smc.h b/drivers/tee/optee/optee_smc.h
> index 80eb763a8a80..c6eec6b6febf 100644
> --- a/drivers/tee/optee/optee_smc.h
> +++ b/drivers/tee/optee/optee_smc.h
> @@ -107,6 +107,12 @@ 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:
> + * 1. It must be able to handle eventual RPCs
> + * 2. Non-secure interrupts should not be masked
> + * 3. If asynchronous notifications has be negotiated successfully, then
> + * asynchronous notifications should be unmasked during this call.
> + *
> * Call register usage:
> * a0 SMC Function ID, OPTEE_SMC*CALL_WITH_ARG
> * a1 Upper 32 bits of a 64-bit physical pointer to a struct optee_msg_arg
> @@ -195,7 +201,8 @@ struct optee_smc_get_shm_config_result {
> * Normal return register usage:
> * a0 OPTEE_SMC_RETURN_OK
> * a1 bitfield of secure world capabilities OPTEE_SMC_SEC_CAP_*
> - * a2-7 Preserved
> + * a2 The maximum secure world notification number
> + * a3-7 Preserved
> *
> * Error return register usage:
> * a0 OPTEE_SMC_RETURN_ENOTAVAIL, can't use the capabilities from normal world
> @@ -218,6 +225,8 @@ struct optee_smc_get_shm_config_result {
> #define OPTEE_SMC_SEC_CAP_VIRTUALIZATION BIT(3)
> /* Secure world supports Shared Memory with a NULL reference */
> #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)
>
> #define OPTEE_SMC_FUNCID_EXCHANGE_CAPABILITIES 9
> #define OPTEE_SMC_EXCHANGE_CAPABILITIES \
> @@ -226,8 +235,8 @@ struct optee_smc_get_shm_config_result {
> struct optee_smc_exchange_capabilities_result {
> unsigned long status;
> unsigned long capabilities;
> + unsigned long max_notif_value;
> unsigned long reserved0;
> - unsigned long reserved1;
> };
>
> /*
> @@ -319,6 +328,68 @@ struct optee_smc_disable_shm_cache_result {
> #define OPTEE_SMC_GET_THREAD_COUNT \
> OPTEE_SMC_FAST_CALL_VAL(OPTEE_SMC_FUNCID_GET_THREAD_COUNT)
>
> +/*
> + * Inform OP-TEE that normal world is able to receive asynchronous
> + * notifications.
> + *
> + * Call requests usage:
> + * a0 SMC Function ID, OPTEE_SMC_ENABLE_ASYNC_NOTIF
> + * a1-6 Not used
> + * a7 Hypervisor Client ID register
> + *
> + * Normal return register usage:
> + * a0 OPTEE_SMC_RETURN_OK
> + * a1-7 Preserved
> + *
> + * Not supported return register usage:
> + * a0 OPTEE_SMC_RETURN_ENOTAVAIL
> + * a1-7 Preserved
> + */
> +#define OPTEE_SMC_FUNCID_ENABLE_ASYNC_NOTIF 16
> +#define OPTEE_SMC_ENABLE_ASYNC_NOTIF \
> + OPTEE_SMC_FAST_CALL_VAL(OPTEE_SMC_FUNCID_ENABLE_ASYNC_NOTIF)
> +
> +/*
> + * Retrieve a value of notifications pended since the last call of this
> + * function.
> + *
> + * OP-TEE keeps a records of all posted values. When an interrupts is
> + * received which indicates that there are posed values this function
> + * should be called until all pended values has been retrieved. When a
> + * value is retrieved it's cleared from the record in secure world.
> + *
> + * Call requests usage:
> + * a0 SMC Function ID, OPTEE_SMC_GET_ASYNC_NOTIF_VALUE
> + * a1-6 Not used
> + * a7 Hypervisor Client ID register
> + *
> + * Normal return register usage:
> + * a0 OPTEE_SMC_RETURN_OK
> + * a1 value
> + * a2 Bit[0]: OPTEE_SMC_ASYNC_NOTIF_VALUE_VALID if the value in a1 is
> + * valid, else 0 if no values where pending
> + * a2 Bit[1]: OPTEE_SMC_ASYNC_NOTIF_VALUE_PENDING if another value is
> + * pending, else 0.
> + * Bit[31:2]: MBZ
> + * a3-7 Preserved
> + *
> + * Not supported return register usage:
> + * a0 OPTEE_SMC_RETURN_ENOTAVAIL
> + * a1-7 Preserved
> + */
> +#define OPTEE_SMC_ASYNC_NOTIF_VALUE_VALID BIT(0)
> +#define OPTEE_SMC_ASYNC_NOTIF_VALUE_PENDING BIT(1)
> +
> +/*
> + * Notification that OP-TEE expects a yielding call to do some bottom half
> + * work in a driver.
> + */
> +#define OPTEE_SMC_ASYNC_NOTIF_VALUE_DO_BOTTOM_HALF 0
> +
> +#define OPTEE_SMC_FUNCID_GET_ASYNC_NOTIF_VALUE 17
> +#define OPTEE_SMC_GET_ASYNC_NOTIF_VALUE \
> + OPTEE_SMC_FAST_CALL_VAL(OPTEE_SMC_FUNCID_GET_ASYNC_NOTIF_VALUE)
> +
> /*
> * Resume from RPC (for example after processing a foreign interrupt)
> *
> --
> 2.31.1
>

Next message: Robert Foss: "[RFC v1 00/11] Qcom SM8350 DispCC & VideoCC"
Previous message: Jonathan Cameron: "Re: [PATCH v2 05/10] iio: Remove a cast in iio-test-format which is no longer required"
In reply to: Jens Wiklander: "[PATCH v2 7/7] optee: add asynchronous notifications"
Next in thread: Sumit Garg: "Re: [PATCH v2 0/7] Asynchronous notifications from secure world"
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