Hi,
A gentle ping for someone to review this :-)
Thanks
Bertrand
> On 17 Jul 2025, at 14:11, Bertrand Marquis <bertrand.marq...@arm.com> wrote:
>
> Add support for indirect messages between VMs.
> This is only enabled if CONFIG_FFA_VM_TO_VM is selected.
>
> Signed-off-by: Bertrand Marquis <bertrand.marq...@arm.com>
> Reviewed-by: Jens Wiklander <jens.wiklan...@linaro.org>
> ---
> Changes in v6:
> - fix code alignment (Jens)
> - add Jens R-b
> Changes in v5:
> - Prevent potential overflow in send2 handling (Julien)
> - Only use page_count with rx lock acquired
> - Fix an issue where send2 between VMs was not doing the copy from the
> tx buffer but from a wrong location in the stack. This bug was
> introduced in v4 when switching to a local copy for the header.
> Changes in v4:
> - Use a local copy of the message header to prevent a TOC/TOU possible
> issue when using the payload size
> Changes in v3:
> - Move vm to vm indirect message handling in a sub function to simplify
> lock handling and make implementation easier to read
> Changes in v2:
> - Switch ifdef to IS_ENABLED
> ---
> xen/arch/arm/tee/ffa_msg.c | 117 ++++++++++++++++++++++++++++++++-----
> 1 file changed, 102 insertions(+), 15 deletions(-)
>
> diff --git a/xen/arch/arm/tee/ffa_msg.c b/xen/arch/arm/tee/ffa_msg.c
> index ee594e737fc7..c20c5bec0f76 100644
> --- a/xen/arch/arm/tee/ffa_msg.c
> +++ b/xen/arch/arm/tee/ffa_msg.c
> @@ -88,43 +88,130 @@ out:
> resp.a7 & mask);
> }
>
> +static int32_t ffa_msg_send2_vm(uint16_t dst_id, const void *src_buf,
> + struct ffa_part_msg_rxtx *src_msg)
> +{
> + struct domain *dst_d;
> + struct ffa_ctx *dst_ctx;
> + struct ffa_part_msg_rxtx *dst_msg;
> + int err;
> + int32_t ret;
> +
> + if ( dst_id == 0 )
> + /* FF-A ID 0 is the hypervisor, this is not valid */
> + return FFA_RET_INVALID_PARAMETERS;
> +
> + /* This is also checking that dest is not src */
> + err = rcu_lock_live_remote_domain_by_id(dst_id - 1, &dst_d);
> + if ( err )
> + return FFA_RET_INVALID_PARAMETERS;
> +
> + if ( dst_d->arch.tee == NULL )
> + {
> + ret = FFA_RET_INVALID_PARAMETERS;
> + goto out_unlock;
> + }
> +
> + dst_ctx = dst_d->arch.tee;
> + if ( !dst_ctx->guest_vers )
> + {
> + ret = FFA_RET_INVALID_PARAMETERS;
> + goto out_unlock;
> + }
> +
> + /* This also checks that destination has set a Rx buffer */
> + ret = ffa_rx_acquire(dst_d);
> + if ( ret )
> + goto out_unlock;
> +
> + /* we need to have enough space in the destination buffer */
> + if ( (dst_ctx->page_count * FFA_PAGE_SIZE -
> + sizeof(struct ffa_part_msg_rxtx)) < src_msg->msg_size )
> + {
> + ret = FFA_RET_NO_MEMORY;
> + ffa_rx_release(dst_d);
> + goto out_unlock;
> + }
> +
> + dst_msg = dst_ctx->rx;
> +
> + /* prepare destination header */
> + dst_msg->flags = 0;
> + dst_msg->reserved = 0;
> + dst_msg->msg_offset = sizeof(struct ffa_part_msg_rxtx);
> + dst_msg->send_recv_id = src_msg->send_recv_id;
> + dst_msg->msg_size = src_msg->msg_size;
> +
> + memcpy(dst_ctx->rx + sizeof(struct ffa_part_msg_rxtx),
> + src_buf + src_msg->msg_offset, src_msg->msg_size);
> +
> + /* receiver rx buffer will be released by the receiver*/
> +
> +out_unlock:
> + rcu_unlock_domain(dst_d);
> + if ( !ret )
> + ffa_raise_rx_buffer_full(dst_d);
> +
> + return ret;
> +}
> +
> 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;
> + 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;
> + BUILD_BUG_ON(sizeof(struct ffa_part_msg_rxtx) >= FFA_PAGE_SIZE);
>
> 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);
> + /* create a copy of the message header */
> + memcpy(&src_msg, src_ctx->tx, sizeof(src_msg));
>
> - if ( src_id != ffa_get_vm_id(src_d) || !FFA_ID_IS_SECURE(dst_id) )
> + 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) )
> {
> ret = FFA_RET_INVALID_PARAMETERS;
> - goto out_unlock_tx;
> + goto out;
> }
>
> /* 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) )
> + if ( src_msg.msg_offset < sizeof(struct ffa_part_msg_rxtx) ||
> + src_msg.msg_size == 0 ||
> + src_msg.msg_offset > src_ctx->page_count * FFA_PAGE_SIZE ||
> + src_msg.msg_size > (src_ctx->page_count * FFA_PAGE_SIZE -
> + src_msg.msg_offset) )
> {
> ret = FFA_RET_INVALID_PARAMETERS;
> - goto out_unlock_tx;
> + goto out;
> }
>
> - ret = ffa_simple_call(FFA_MSG_SEND2,
> - ((uint32_t)ffa_get_vm_id(src_d)) << 16, 0, 0, 0);
> + if ( FFA_ID_IS_SECURE(dst_id) )
> + {
> + /* Message for a secure partition */
> + if ( !ffa_fw_supports_fid(FFA_MSG_SEND2) )
> + {
> + ret = FFA_RET_NOT_SUPPORTED;
> + goto out;
> + }
> +
> + ret = ffa_simple_call(FFA_MSG_SEND2,
> + ((uint32_t)ffa_get_vm_id(src_d)) << 16, 0, 0,
> 0);
> + }
> + else if ( IS_ENABLED(CONFIG_FFA_VM_TO_VM) )
> + {
> + /* Message for a VM */
> + ret = ffa_msg_send2_vm(dst_id, src_ctx->tx, &src_msg);
> + }
> + else
> + ret = FFA_RET_INVALID_PARAMETERS;
>
> -out_unlock_tx:
> +out:
> spin_unlock(&src_ctx->tx_lock);
> return ret;
> }
> --
> 2.47.1
>
>
