Re: [PATCH for-8.1] hw/rdma/vmw/pvrdma_cmd: Use correct struct in query_port()

[Thomas Huth <thuth@redhat.com>]

On 25/07/2023 13.36, Peter Maydell wrote:
> In query_port() we pass the address of a local pvrdma_port_attr
> struct to the rdma_query_backend_port() function.  Unfortunately,
> rdma_backend_query_port() wants a pointer to a struct ibv_port_attr,
> and the two are not the same length.
> 
> Coverity spotted this (CID 1507146): pvrdma_port_attr is 48 bytes
> long, and ibv_port_attr is 52 bytes, because it has a few extra
> fields at the end.
> 
> Fortunately, all we do with the attrs struct after the call is to
> read a few specific fields out of it which are all at the same
> offsets in both structs, so we can simply make the local variable the
> correct type.  This also lets us drop the cast (which should have
> been a bit of a warning flag that we were doing something wrong
> here).
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> I don't know anything about the rdma code so this fix is based
> purely on looking at the code, and is untested beyond just
> make check/make check-avocado.
> ---
>   hw/rdma/vmw/pvrdma_cmd.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/rdma/vmw/pvrdma_cmd.c b/hw/rdma/vmw/pvrdma_cmd.c
> index c6ed0259821..d31c1875938 100644
> --- a/hw/rdma/vmw/pvrdma_cmd.c
> +++ b/hw/rdma/vmw/pvrdma_cmd.c
> @@ -129,14 +129,13 @@ static int query_port(PVRDMADev *dev, union pvrdma_cmd_req *req,
>   {
>       struct pvrdma_cmd_query_port *cmd = &req->query_port;
>       struct pvrdma_cmd_query_port_resp *resp = &rsp->query_port_resp;
> -    struct pvrdma_port_attr attrs = {};
> +    struct ibv_port_attr attrs = {};
>   
>       if (cmd->port_num > MAX_PORTS) {
>           return -EINVAL;
>       }
>   
> -    if (rdma_backend_query_port(&dev->backend_dev,
> -                                (struct ibv_port_attr *)&attrs)) {
> +    if (rdma_backend_query_port(&dev->backend_dev, &attrs)) {
>           return -ENOMEM;
>       }
>   

  Hi Peter,

this seems to fail with Clang:

../../devel/qemu/hw/rdma/vmw/pvrdma_cmd.c:144:59: error: implicit conversion 
from enumeration type 'enum ibv_port_state' to different enumeration type 
'enum pvrdma_port_state' [-Werror,-Wenum-conversion]
     resp->attrs.state = dev->func0->device_active ? attrs.state :
                       ~                             ~~~~~~^~~~~
../../devel/qemu/hw/rdma/vmw/pvrdma_cmd.c:146:33: error: implicit conversion 
from enumeration type 'enum ibv_mtu' to different enumeration type 'enum 
pvrdma_mtu' [-Werror,-Wenum-conversion]
     resp->attrs.max_mtu = attrs.max_mtu;
                         ~ ~~~~~~^~~~~~~
../../devel/qemu/hw/rdma/vmw/pvrdma_cmd.c:147:36: error: implicit conversion 
from enumeration type 'enum ibv_mtu' to different enumeration type 'enum 
pvrdma_mtu' [-Werror,-Wenum-conversion]
     resp->attrs.active_mtu = attrs.active_mtu;
                            ~ ~~~~~~^~~~~~~~~~
3 errors generated.

Could you please have a look ?

  Thomas