linux-kernel - Re: [PATCH net-next v2 4/4] af_vsock: Assign the vsock transport considering the vsock address flags

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Date:   Mon, 7 Dec 2020 21:51:55 +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 v2 4/4] af_vsock: Assign the vsock transport
 considering the vsock address flags



On 07/12/2020 12:00, Stefano Garzarella wrote:
>
> On Fri, Dec 04, 2020 at 07:02:35PM +0200, Andra Paraschiv wrote:
>> The vsock flags field can be 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 flags value (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 VMADDR_FLAG_TO_HOST flag
>> is set. For the other use cases, the vsock transport assignment logic is
>> not changed.
>>
>> Changelog
>>
>> v1 -> v2
>>
>> * Use bitwise operator to check the vsock flag.
>> * Use the updated "VMADDR_FLAG_TO_HOST" flag naming.
>> * Merge the checks for the g2h transport assignment in one "if" block.
>>
>> Signed-off-by: Andra Paraschiv <andraprs@...zon.com>
>> ---
>> net/vmw_vsock/af_vsock.c | 9 +++++++--
>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>> index 83d035eab0b05..66e643c3b5f85 100644
>> --- a/net/vmw_vsock/af_vsock.c
>> +++ b/net/vmw_vsock/af_vsock.c
>> @@ -421,7 +421,8 @@ static void vsock_deassign_transport(struct 
>> vsock_sock *vsk)
>>  * 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 or h2g is not loaded or remote 
>> flags field
>> + *    includes VMADDR_FLAG_TO_HOST flag value, 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)
>> @@ -429,6 +430,7 @@ 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_flags;
>>       int ret;
>>
>>       /* If the packet is coming with the source and destination CIDs 
>> higher
>> @@ -443,6 +445,8 @@ int vsock_assign_transport(struct vsock_sock 
>> *vsk, struct vsock_sock *psk)
>>           vsk->remote_addr.svm_cid > VMADDR_CID_HOST)
>>               vsk->remote_addr.svm_flags |= VMADDR_FLAG_TO_HOST;
>>
>> +      remote_flags = vsk->remote_addr.svm_flags;
>> +
>>       switch (sk->sk_type) {
>>       case SOCK_DGRAM:
>>               new_transport = transport_dgram;
>> @@ -450,7 +454,8 @@ 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_cid <= VMADDR_CID_HOST || !transport_h2g)
>> +              else if (remote_cid <= VMADDR_CID_HOST || 
>> !transport_h2g ||
>> +                       (remote_flags & VMADDR_FLAG_TO_HOST) == 
>> VMADDR_FLAG_TO_HOST)
>
> Maybe "remote_flags & VMADDR_FLAG_TO_HOST" should be enough, but the
> patch is okay:
>
> Reviewed-by: Stefano Garzarella <sgarzare@...hat.com>

Done, updated to have only the bitwise logic, without the comparison.

Thanks,
Andra

>
>>                       new_transport = transport_g2h;
>>               else
>>                       new_transport = transport_h2g;
>> -- 
>> 2.20.1 (Apple Git-117)
>>
>>
>>
>>
>> Amazon Development Center (Romania) S.R.L. registered office: 27A Sf. 
>> Lazar Street, UBC5, floor 2, Iasi, Iasi County, 700045, Romania. 
>> Registered in Romania. Registration number J22/2621/2005.
>>
>




Amazon Development Center (Romania) S.R.L. registered office: 27A Sf. Lazar Street, UBC5, floor 2, Iasi, Iasi County, 700045, Romania. Registered in Romania. Registration number J22/2621/2005.