[PATCH 4/4] firmware: arm_ffa: Add support for FFA_MSG_SEND2

[Jens Wiklander]

On Mon, Apr 15, 2024 at 6:05 PM Sudeep Holla <sudeep.holla at arm.com> wrote:
>
> The FFA_MSG_SEND2 can be  used to transmit a partition message from
> the Tx buffer of the sender(the driver in this case) endpoint to the Rx
> buffer of the receiver endpoint.
>
> An invocation of the FFA_MSG_SEND2 transfers the ownership to the

ownership of the TX buffer to the

> receiver endpoint(or any intermediate consumer). Completion of an
> FFA_MSG_SEND2 invocation transfers the ownership back to the sender

ownership of the buffer back

> endpoint.
>
> The framework defines the FFA_MSG_SEND2 interface to transmit a partition
> message from the Tx buffer of the sender to the Rx buffer of a receiver
> and inform the scheduler that the receiver must be run.
>
> Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
> ---
>  drivers/firmware/arm_ffa/driver.c | 40 +++++++++++++++++++++++++++++++++++++++
>  include/linux/arm_ffa.h           |  9 +++++++++
>  2 files changed, 49 insertions(+)
>
> diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
> index d5087e4f6d35..6c2602f7e7cc 100644
> --- a/drivers/firmware/arm_ffa/driver.c
> +++ b/drivers/firmware/arm_ffa/driver.c
> @@ -344,6 +344,34 @@ static int ffa_msg_send_direct_req(u16 src_id, u16 dst_id, bool mode_32bit,
>         return -EINVAL;
>  }
>
> +static int ffa_msg_send2(u16 src_id, u16 dst_id, void *buf, size_t sz)
> +{
> +       u32 src_dst_ids = PACK_TARGET_INFO(src_id, dst_id);
> +       struct ffa_indirect_msg_hdr *msg;
> +       ffa_value_t ret;
> +
> +       mutex_lock(&drv_info->tx_lock);
> +
> +       msg = drv_info->tx_buffer;
> +       msg->flags = 0;
> +       msg->res0 = 0;
> +       msg->offset = sizeof(*msg);
> +       msg->send_recv_id = src_dst_ids;
> +       msg->size = sz;
> +       memcpy(msg + msg->offset, buf, sz);
> +
> +       /* flags = 0, sender VMID = 0 works for both physical/virtual NS */
> +       invoke_ffa_fn((ffa_value_t){
> +                     .a0 = FFA_MSG_SEND2, .a1 = 0, .a2 = 0
> +                     }, &ret);
> +
> +       if (ret.a0 == FFA_ERROR)
> +               return ffa_to_linux_errno((int)ret.a2);
> +
> +       mutex_lock(&drv_info->tx_lock);

mutex_unlock(), before the potential return above?

> +       return 0;
> +}
> +
>  static int ffa_mem_first_frag(u32 func_id, phys_addr_t buf, u32 buf_sz,
>                               u32 frag_len, u32 len, u64 *handle)
>  {
> @@ -888,6 +916,17 @@ static int ffa_sync_send_receive(struct ffa_device *dev,
>                                        dev->mode_32bit, data);
>  }
>
> +#define ffa_partition_supports_indirect_msg(dev)       \
> +       ffa_partition_check_property(dev, FFA_PARTITION_INDIRECT_MSG)
> +
> +static int ffa_indirect_msg_send(struct ffa_device *dev, void *buf, size_t sz)
> +{
> +       if (!ffa_partition_supports_direct_recv(dev))

ffa_partition_supports_indirect_msg(), but I'm not sure we should do
this check at all. The client could do this in advance. Unexpected
FFA_MSG_SEND2 calls are caught in other layers.

Cheers,
Jens

> +               return -EOPNOTSUPP;
> +
> +       return ffa_msg_send2(drv_info->vm_id, dev->vm_id, buf, sz);
> +}
> +
>  static int ffa_memory_share(struct ffa_mem_ops_args *args)
>  {
>         if (drv_info->mem_ops_native)
> @@ -1167,6 +1206,7 @@ static const struct ffa_info_ops ffa_drv_info_ops = {
>  static const struct ffa_msg_ops ffa_drv_msg_ops = {
>         .mode_32bit_set = ffa_mode_32bit_set,
>         .sync_send_receive = ffa_sync_send_receive,
> +       .indirect_send = ffa_indirect_msg_send,
>  };
>
>  static const struct ffa_mem_ops ffa_drv_mem_ops = {
> diff --git a/include/linux/arm_ffa.h b/include/linux/arm_ffa.h
> index 13830be5851d..d61a6df397f6 100644
> --- a/include/linux/arm_ffa.h
> +++ b/include/linux/arm_ffa.h
> @@ -238,6 +238,14 @@ struct ffa_send_direct_data {
>         unsigned long data4; /* w7/x7 */
>  };
>
> +struct ffa_indirect_msg_hdr {
> +       u32 flags;
> +       u32 res0;
> +       u32 offset;
> +       u32 send_recv_id;
> +       u32 size;
> +};
> +
>  struct ffa_mem_region_addr_range {
>         /* The base IPA of the constituent memory region, aligned to 4 kiB */
>         u64 address;
> @@ -398,6 +406,7 @@ struct ffa_msg_ops {
>         void (*mode_32bit_set)(struct ffa_device *dev);
>         int (*sync_send_receive)(struct ffa_device *dev,
>                                  struct ffa_send_direct_data *data);
> +       int (*indirect_send)(struct ffa_device *dev, void *buf, size_t sz);
>  };
>
>  struct ffa_mem_ops {
>
> --
> 2.43.2
>