Re: [PATCH v4 13/18] migration/rdma: Add the function for dynamic page registration

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Chuan Zheng (zhengchuan@huawei.com) wrote:
> Add the 'qemu_rdma_registration' function, multifd send threads
> call it to register memory.

This function is a copy of the code out of qemu_rdma_registration_stop;
with some of the comments removed.
It's OK to split this code out so you can use it as well; but then why
not make qemu_rdma_registration_stop use this function as well to stop
having two copies ?  And keep the comments!

> Signed-off-by: Zhimin Feng <fengzhimin1@huawei.com>
> Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
> ---
>  migration/rdma.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 51 insertions(+)
> 
> diff --git a/migration/rdma.c b/migration/rdma.c
> index cff9446..1095a8f 100644
> --- a/migration/rdma.c
> +++ b/migration/rdma.c
> @@ -3739,6 +3739,57 @@ out:
>      return ret;
>  }
>  
> +/*
> + * Dynamic page registrations for multifd RDMA threads.
> + */
> +static int qemu_rdma_registration(void *opaque)
> +{
> +    RDMAContext *rdma = opaque;

Can't you keep that as qemu_rdma_registration(RDMAContext *rdma) ?

> +    RDMAControlHeader resp = {.type = RDMA_CONTROL_RAM_BLOCKS_RESULT };
> +    RDMALocalBlocks *local = &rdma->local_ram_blocks;
> +    int reg_result_idx, i, nb_dest_blocks;
> +    RDMAControlHeader head = { .len = 0, .repeat = 1 };
> +    int ret = 0;
> +
> +    head.type = RDMA_CONTROL_RAM_BLOCKS_REQUEST;
> +
> +    ret = qemu_rdma_exchange_send(rdma, &head, NULL, &resp,
> +            &reg_result_idx, rdma->pin_all ?
> +            qemu_rdma_reg_whole_ram_blocks : NULL);
> +    if (ret < 0) {
> +        goto out;
> +    }
> +
> +    nb_dest_blocks = resp.len / sizeof(RDMADestBlock);
> +
> +    if (local->nb_blocks != nb_dest_blocks) {
> +        rdma->error_state = -EINVAL;
> +        ret = -1;
> +        goto out;
> +    }
> +
> +    qemu_rdma_move_header(rdma, reg_result_idx, &resp);
> +    memcpy(rdma->dest_blocks,
> +           rdma->wr_data[reg_result_idx].control_curr, resp.len);
> +
> +    for (i = 0; i < nb_dest_blocks; i++) {
> +        network_to_dest_block(&rdma->dest_blocks[i]);
> +
> +        /* We require that the blocks are in the same order */
> +        if (rdma->dest_blocks[i].length != local->block[i].length) {
> +            rdma->error_state = -EINVAL;
> +            ret = -1;
> +            goto out;
> +        }
> +        local->block[i].remote_host_addr =
> +            rdma->dest_blocks[i].remote_host_addr;
> +        local->block[i].remote_rkey = rdma->dest_blocks[i].remote_rkey;
> +    }
> +
> +out:
> +    return ret;
> +}
> +
>  /* Destination:
>   * Called via a ram_control_load_hook during the initial RAM load section which
>   * lists the RAMBlocks by name.  This lets us know the order of the RAMBlocks
> -- 
> 1.8.3.1
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK