| Message ID | 20200217173121.159132-1-sgarzare@redhat.com |
|---|---|
| State | Not Applicable |
| Delegated to: | David Miller |
| Headers | show |
| Series | [v3] vsock.7: add VMADDR_CID_LOCAL description | expand |
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".
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
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),