Re: [PATCH v3 10/10] xen/arm: ffa: Add indirect message support

[Jens Wiklander <jens.wiklander@xxxxxxxxxx>]

Hi Bertrand,

On Wed, Nov 27, 2024 at 5:08 PM Bertrand Marquis
<bertrand.marquis@xxxxxxx> wrote:
>
> Add support for FFA_MSG_SEND2 to send indirect messages from a VM to a
> secure partition.
>
> Signed-off-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
> ---
> Changes in v3:
> - in ffa_handle_msg_send2 use ffa_get_vm_id instead of a local variable
>   to make sure that we use the right VM ID as source without having a
>   potential solution for the VM to give a wrong identity.
> Changes in v2:
> - rebase
> ---
>  xen/arch/arm/tee/ffa.c         |  5 ++++
>  xen/arch/arm/tee/ffa_msg.c     | 50 ++++++++++++++++++++++++++++++++++
>  xen/arch/arm/tee/ffa_private.h |  1 +
>  3 files changed, 56 insertions(+)

Looks good.
Reviewed-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>

Cheers,
Jens

>
> diff --git a/xen/arch/arm/tee/ffa.c b/xen/arch/arm/tee/ffa.c
> index 04d2403415fe..87775ed88ffd 100644
> --- a/xen/arch/arm/tee/ffa.c
> +++ b/xen/arch/arm/tee/ffa.c
> @@ -101,6 +101,7 @@ static const struct ffa_fw_abi ffa_fw_abi_needed[] = {
>      FW_ABI(FFA_MEM_RECLAIM),
>      FW_ABI(FFA_MSG_SEND_DIRECT_REQ_32),
>      FW_ABI(FFA_MSG_SEND_DIRECT_REQ_64),
> +    FW_ABI(FFA_MSG_SEND2),
>  };
>
>  /*
> @@ -195,6 +196,7 @@ static void handle_features(struct cpu_user_regs *regs)
>      case FFA_PARTITION_INFO_GET:
>      case FFA_MSG_SEND_DIRECT_REQ_32:
>      case FFA_MSG_SEND_DIRECT_REQ_64:
> +    case FFA_MSG_SEND2:
>          ffa_set_regs_success(regs, 0, 0);
>          break;
>      case FFA_MEM_SHARE_64:
> @@ -275,6 +277,9 @@ static bool ffa_handle_call(struct cpu_user_regs *regs)
>      case FFA_MSG_SEND_DIRECT_REQ_64:
>          ffa_handle_msg_send_direct_req(regs, fid);
>          return true;
> +    case FFA_MSG_SEND2:
> +        e = ffa_handle_msg_send2(regs);
> +        break;
>      case FFA_MEM_SHARE_32:
>      case FFA_MEM_SHARE_64:
>          ffa_handle_mem_share(regs);
> diff --git a/xen/arch/arm/tee/ffa_msg.c b/xen/arch/arm/tee/ffa_msg.c
> index ae263e54890e..ee594e737fc7 100644
> --- a/xen/arch/arm/tee/ffa_msg.c
> +++ b/xen/arch/arm/tee/ffa_msg.c
> @@ -12,6 +12,15 @@
>
>  #include "ffa_private.h"
>
> +/* Encoding of partition message in RX/TX buffer */
> +struct ffa_part_msg_rxtx {
> +    uint32_t flags;
> +    uint32_t reserved;
> +    uint32_t msg_offset;
> +    uint32_t send_recv_id;
> +    uint32_t msg_size;
> +};
> +
>  void ffa_handle_msg_send_direct_req(struct cpu_user_regs *regs, uint32_t fid)
>  {
>      struct arm_smccc_1_2_regs arg = { .a0 = fid, };
> @@ -78,3 +87,44 @@ out:
>                   resp.a4 & mask, resp.a5 & mask, resp.a6 & mask,
>                   resp.a7 & mask);
>  }
> +
> +int32_t ffa_handle_msg_send2(struct cpu_user_regs *regs)
> +{
> +    struct domain *src_d = current->domain;
> +    struct ffa_ctx *src_ctx = src_d->arch.tee;
> +    const struct ffa_part_msg_rxtx *src_msg;
> +    uint16_t dst_id, src_id;
> +    int32_t ret;
> +
> +    if ( !ffa_fw_supports_fid(FFA_MSG_SEND2) )
> +        return FFA_RET_NOT_SUPPORTED;
> +
> +    if ( !spin_trylock(&src_ctx->tx_lock) )
> +        return FFA_RET_BUSY;
> +
> +    src_msg = src_ctx->tx;
> +    src_id = src_msg->send_recv_id >> 16;
> +    dst_id = src_msg->send_recv_id & GENMASK(15,0);
> +
> +    if ( src_id != ffa_get_vm_id(src_d) || !FFA_ID_IS_SECURE(dst_id) )
> +    {
> +        ret = FFA_RET_INVALID_PARAMETERS;
> +        goto out_unlock_tx;
> +    }
> +
> +    /* check source message fits in buffer */
> +    if ( src_ctx->page_count * FFA_PAGE_SIZE <
> +         src_msg->msg_offset + src_msg->msg_size ||
> +         src_msg->msg_offset < sizeof(struct ffa_part_msg_rxtx) )
> +    {
> +        ret = FFA_RET_INVALID_PARAMETERS;
> +        goto out_unlock_tx;
> +    }
> +
> +    ret = ffa_simple_call(FFA_MSG_SEND2,
> +                          ((uint32_t)ffa_get_vm_id(src_d)) << 16, 0, 0, 0);
> +
> +out_unlock_tx:
> +    spin_unlock(&src_ctx->tx_lock);
> +    return ret;
> +}
> diff --git a/xen/arch/arm/tee/ffa_private.h b/xen/arch/arm/tee/ffa_private.h
> index 973ee55be09b..d441c0ca5598 100644
> --- a/xen/arch/arm/tee/ffa_private.h
> +++ b/xen/arch/arm/tee/ffa_private.h
> @@ -359,6 +359,7 @@ void ffa_handle_notification_get(struct cpu_user_regs 
> *regs);
>  int ffa_handle_notification_set(struct cpu_user_regs *regs);
>
>  void ffa_handle_msg_send_direct_req(struct cpu_user_regs *regs, uint32_t 
> fid);
> +int32_t ffa_handle_msg_send2(struct cpu_user_regs *regs);
>
>  static inline uint16_t ffa_get_vm_id(const struct domain *d)
>  {
> --
> 2.47.0
>