linux-kernel - Re: [PATCH net-next v1 3/3] af_vsock: Assign the vsock transport considering the vsock address flag

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Date:   Tue, 1 Dec 2020 21:06:39 +0200
From:   "Paraschiv, Andra-Irina" <andraprs@...zon.com>
To:     Stefano Garzarella <sgarzare@...hat.com>
CC:     netdev <netdev@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "David S . Miller" <davem@...emloft.net>,
        David Duncan <davdunc@...zon.com>,
        Dexuan Cui <decui@...rosoft.com>,
        Alexander Graf <graf@...zon.de>,
        Jorgen Hansen <jhansen@...are.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>
Subject: Re: [PATCH net-next v1 3/3] af_vsock: Assign the vsock transport
 considering the vsock address flag



On 01/12/2020 18:23, Stefano Garzarella wrote:
>
> On Tue, Dec 01, 2020 at 05:25:05PM +0200, Andra Paraschiv wrote:
>> The vsock flag has been set in the connect and (listen) receive paths.
>>
>> When the vsock transport is assigned, the remote CID is used to
>> distinguish between types of connection.
>>
>> Use the vsock flag (in addition to the CID) from the remote address to
>> decide which vsock transport to assign. For the sibling VMs use case,
>> all the vsock packets need to be forwarded to the host, so always assign
>> the guest->host transport if the vsock flag is set. For the other use
>> cases, the vsock transport assignment logic is not changed.
>>
>> Signed-off-by: Andra Paraschiv <andraprs@...zon.com>
>> ---
>> net/vmw_vsock/af_vsock.c | 15 +++++++++++----
>> 1 file changed, 11 insertions(+), 4 deletions(-)
>>
>> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>> index d10916ab45267..bafc1cb20abd4 100644
>> --- a/net/vmw_vsock/af_vsock.c
>> +++ b/net/vmw_vsock/af_vsock.c
>> @@ -419,16 +419,21 @@ static void vsock_deassign_transport(struct 
>> vsock_sock *vsk)
>>  * (e.g. during the connect() or when a connection request on a listener
>>  * socket is received).
>>  * The vsk->remote_addr is used to decide which transport to use:
>> - *  - remote CID == VMADDR_CID_LOCAL or g2h->local_cid or 
>> VMADDR_CID_HOST if
>> - *    g2h is not loaded, will use local transport;
>> - *  - remote CID <= VMADDR_CID_HOST will use guest->host transport;
>> - *  - remote CID > VMADDR_CID_HOST will use host->guest transport;
>> + *  - remote flag == VMADDR_FLAG_SIBLING_VMS_COMMUNICATION, will always
>> + *    forward the vsock packets to the host and use guest->host 
>> transport;
>> + *  - otherwise, going forward with the remote flag default value:
>> + *    - remote CID == VMADDR_CID_LOCAL or g2h->local_cid or 
>> VMADDR_CID_HOST
>> + *      if g2h is not loaded, will use local transport;
>> + *    - remote CID <= VMADDR_CID_HOST or h2g is not loaded, will use
>> + *      guest->host transport;
>> + *    - remote CID > VMADDR_CID_HOST will use host->guest transport;
>>  */
>> int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock 
>> *psk)
>> {
>>       const struct vsock_transport *new_transport;
>>       struct sock *sk = sk_vsock(vsk);
>>       unsigned int remote_cid = vsk->remote_addr.svm_cid;
>> +      unsigned short remote_flag = vsk->remote_addr.svm_flag;
>>       int ret;
>>
>>       switch (sk->sk_type) {
>> @@ -438,6 +443,8 @@ int vsock_assign_transport(struct vsock_sock 
>> *vsk, struct vsock_sock *psk)
>>       case SOCK_STREAM:
>>               if (vsock_use_local_transport(remote_cid))
>>                       new_transport = transport_local;
>> +              else if (remote_flag == 
>> VMADDR_FLAG_SIBLING_VMS_COMMUNICATION)
>
> Others flags can be added, so here we should use the bitwise AND
> operator to check if this flag is set.
>
> And what about merging with the next if clause?
>

Indeed, I'll update the codebase to use the bitwise operator. Then I can 
also merge all the checks corresponding to the g2h transport in a single 
if block.

Thanks,
Andra

>
>> +                      new_transport = transport_g2h;
>>               else if (remote_cid <= VMADDR_CID_HOST ||
>>               !transport_h2g)
>>                       new_transport = transport_g2h;
>>               else
>> -- 
>> 2.20.1 (Apple Git-117)
>>
>




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