> On 21 May 2025, at 18:53, Jens Wiklander <jens.wiklan...@linaro.org> wrote:
>
> Hi Bertrand,
>
> On Wed, Apr 16, 2025 at 9:40 AM 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>
>> ---
>> 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 | 115 ++++++++++++++++++++++++++++++++-----
>> 1 file changed, 101 insertions(+), 14 deletions(-)
>>
>> diff --git a/xen/arch/arm/tee/ffa_msg.c b/xen/arch/arm/tee/ffa_msg.c
>> index ee594e737fc7..35de260c013a 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,
>> + 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);
>
> Please align with the opening '(' at the row above.
Will do.
>
> Other than that:
> Reviewed-by: Jens Wiklander <jens.wiklan...@linaro.org>
>
Thanks
Bertrand
> Cheers,
> Jens
>
>> + }
>> + 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
>>
