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* [PATCH v3] vsock.7: add VMADDR_CID_LOCAL description
@ 2020-02-17 17:31 Stefano Garzarella
  2020-02-18  9:53 ` Stefan Hajnoczi
  0 siblings, 1 reply; 3+ messages in thread
From: Stefano Garzarella @ 2020-02-17 17:31 UTC (permalink / raw)
  To: mtk.manpages
  Cc: linux-man, Dexuan Cui, Stefan Hajnoczi, Jorgen Hansen, netdev

Linux 5.6 added the new well-known VMADDR_CID_LOCAL for
local communication.

This patch explains how to use it and remove the legacy
VMADDR_CID_RESERVED no longer available.

Reviewed-by: Jorgen Hansen <jhansen@vmware.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
v3:
    * rephrased "Previous versions" part [Jorgen]
v2:
    * rephrased "Local communication" description [Stefan]
    * added a mention of previous versions that supported
      loopback only in the guest [Stefan]
---
 man7/vsock.7 | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/man7/vsock.7 b/man7/vsock.7
index c5ffcf07d..219e3505f 100644
--- a/man7/vsock.7
+++ b/man7/vsock.7
@@ -127,8 +127,8 @@ There are several special addresses:
 means any address for binding;
 .B VMADDR_CID_HYPERVISOR
 (0) is reserved for services built into the hypervisor;
-.B VMADDR_CID_RESERVED
-(1) must not be used;
+.B VMADDR_CID_LOCAL
+(1) is the well-known address for local communication (loopback);
 .B VMADDR_CID_HOST
 (2)
 is the well-known address of the host.
@@ -164,6 +164,16 @@ Consider using
 .B VMADDR_CID_ANY
 when binding instead of getting the local CID with
 .BR IOCTL_VM_SOCKETS_GET_LOCAL_CID .
+.SS Local communication
+The
+.B VMADDR_CID_LOCAL
+(1) directs packets to the same host that generated them. This is useful
+for testing applications on a single host and for debugging.
+.PP
+The local CID obtained with
+.BR IOCTL_VM_SOCKETS_GET_LOCAL_CID
+can be used for the same purpose, but it is preferable to use
+.B VMADDR_CID_LOCAL .
 .SH ERRORS
 .TP
 .B EACCES
@@ -222,6 +232,11 @@ are valid.
 Support for VMware (VMCI) has been available since Linux 3.9.
 KVM (virtio) is supported since Linux 4.8.
 Hyper-V is supported since Linux 4.14.
+.PP
+VMADDR_CID_LOCAL is supported since Linux 5.6.
+Local communication in the guest and on the host is available since Linux 5.6.
+Previous versions only supported local communication within a guest
+(not on the host), and only with some transports (VMCI and virtio).
 .SH SEE ALSO
 .BR bind (2),
 .BR connect (2),
-- 
2.24.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH v3] vsock.7: add VMADDR_CID_LOCAL description
  2020-02-17 17:31 [PATCH v3] vsock.7: add VMADDR_CID_LOCAL description Stefano Garzarella
@ 2020-02-18  9:53 ` Stefan Hajnoczi
  2020-02-18  9:59   ` Stefano Garzarella
  0 siblings, 1 reply; 3+ messages in thread
From: Stefan Hajnoczi @ 2020-02-18  9:53 UTC (permalink / raw)
  To: Stefano Garzarella
  Cc: mtk.manpages, linux-man, Dexuan Cui, Jorgen Hansen, netdev

[-- Attachment #1: Type: text/plain, Size: 1664 bytes --]

On Mon, Feb 17, 2020 at 06:31:21PM +0100, Stefano Garzarella wrote:
> Linux 5.6 added the new well-known VMADDR_CID_LOCAL for
> local communication.
> 
> This patch explains how to use it and remove the legacy
> VMADDR_CID_RESERVED no longer available.
> 
> Reviewed-by: Jorgen Hansen <jhansen@vmware.com>
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
> v3:
>     * rephrased "Previous versions" part [Jorgen]
> v2:
>     * rephrased "Local communication" description [Stefan]
>     * added a mention of previous versions that supported
>       loopback only in the guest [Stefan]
> ---
>  man7/vsock.7 | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/man7/vsock.7 b/man7/vsock.7
> index c5ffcf07d..219e3505f 100644
> --- a/man7/vsock.7
> +++ b/man7/vsock.7
> @@ -127,8 +127,8 @@ There are several special addresses:
>  means any address for binding;
>  .B VMADDR_CID_HYPERVISOR
>  (0) is reserved for services built into the hypervisor;
> -.B VMADDR_CID_RESERVED
> -(1) must not be used;
> +.B VMADDR_CID_LOCAL
> +(1) is the well-known address for local communication (loopback);
>  .B VMADDR_CID_HOST
>  (2)
>  is the well-known address of the host.
> @@ -164,6 +164,16 @@ Consider using
>  .B VMADDR_CID_ANY
>  when binding instead of getting the local CID with
>  .BR IOCTL_VM_SOCKETS_GET_LOCAL_CID .
> +.SS Local communication
> +The
> +.B VMADDR_CID_LOCAL
> +(1) directs packets to the same host that generated them. This is useful

Please see my comment on v2.  "The VMADDR_CID_LOCAL (1) directs packets
..." sounds unnatural.  Please drop "The".

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^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH v3] vsock.7: add VMADDR_CID_LOCAL description
  2020-02-18  9:53 ` Stefan Hajnoczi
@ 2020-02-18  9:59   ` Stefano Garzarella
  0 siblings, 0 replies; 3+ messages in thread
From: Stefano Garzarella @ 2020-02-18  9:59 UTC (permalink / raw)
  To: Stefan Hajnoczi
  Cc: mtk.manpages, linux-man, Dexuan Cui, Jorgen Hansen, netdev

On Tue, Feb 18, 2020 at 09:53:19AM +0000, Stefan Hajnoczi wrote:
> On Mon, Feb 17, 2020 at 06:31:21PM +0100, Stefano Garzarella wrote:
> > Linux 5.6 added the new well-known VMADDR_CID_LOCAL for
> > local communication.
> > 
> > This patch explains how to use it and remove the legacy
> > VMADDR_CID_RESERVED no longer available.
> > 
> > Reviewed-by: Jorgen Hansen <jhansen@vmware.com>
> > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> > ---
> > v3:
> >     * rephrased "Previous versions" part [Jorgen]
> > v2:
> >     * rephrased "Local communication" description [Stefan]
> >     * added a mention of previous versions that supported
> >       loopback only in the guest [Stefan]
> > ---
> >  man7/vsock.7 | 19 +++++++++++++++++--
> >  1 file changed, 17 insertions(+), 2 deletions(-)
> > 
> > diff --git a/man7/vsock.7 b/man7/vsock.7
> > index c5ffcf07d..219e3505f 100644
> > --- a/man7/vsock.7
> > +++ b/man7/vsock.7
> > @@ -127,8 +127,8 @@ There are several special addresses:
> >  means any address for binding;
> >  .B VMADDR_CID_HYPERVISOR
> >  (0) is reserved for services built into the hypervisor;
> > -.B VMADDR_CID_RESERVED
> > -(1) must not be used;
> > +.B VMADDR_CID_LOCAL
> > +(1) is the well-known address for local communication (loopback);
> >  .B VMADDR_CID_HOST
> >  (2)
> >  is the well-known address of the host.
> > @@ -164,6 +164,16 @@ Consider using
> >  .B VMADDR_CID_ANY
> >  when binding instead of getting the local CID with
> >  .BR IOCTL_VM_SOCKETS_GET_LOCAL_CID .
> > +.SS Local communication
> > +The
> > +.B VMADDR_CID_LOCAL
> > +(1) directs packets to the same host that generated them. This is useful
> 
> Please see my comment on v2.  "The VMADDR_CID_LOCAL (1) directs packets
> ..." sounds unnatural.  Please drop "The".

I received it just now :O but you sent it 4 days ago!
Sorry for that!

I'll send v4 dropping "The".

Thanks,
Stefano


^ permalink raw reply	[flat|nested] 3+ messages in thread

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2020-02-17 17:31 [PATCH v3] vsock.7: add VMADDR_CID_LOCAL description Stefano Garzarella
2020-02-18  9:53 ` Stefan Hajnoczi
2020-02-18  9:59   ` Stefano Garzarella

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