This is just a draft, or a request for comments if you will.

This patch sets drafts the support of sending events by QEMU Guest Agent.
Events can plan important role in monitoring of the guest OS behaviour. The
range of use cases ranges from events important for scheduling, e.g. memory and
CPU usage statistics, to things like changes to IP addresses on network
interfaces to for example changes in the list of active users.

For now the patch set adds single periodic callback function to the GA main
loop that can perform checks and trigger events that have occured since
previous run of the callback.

We can of course take it one step further and add a general framwork for
periodically running any of the already implemented commands. Add a function
that would maintain a list of registered checks. Client would use some command
(register-monitor-command) passing it a command name and timeout in seconds and
the monitoring handler would then run the specified command and report the
result... or report only if the return value changed since previous invocation.
This feature would remove part of the communication overhead between client and
GA.

So before I invest any more time in either of these approaches, tell me. Would
somethign like this be wanted or is that too controversial? Any other thoughts
and ideas?

Tomáš Golembiovský (3):
  qemu-ga: add support for events
  qemu-ga: add simple event reporting memory statistics
  qemu-ga: add support for periodic command runner

 Makefile               |  7 +++-
 qga/Makefile.objs      |  2 +-
 qga/channel-posix.c    |  8 +++++
 qga/channel-win32.c    |  6 ++++
 qga/channel.h          |  1 +
 qga/guest-agent-core.h |  1 +
 qga/main.c             | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++
 qga/qapi-event.json    | 35 ++++++++++++++++++
 qga/qapi-schema.json   |  2 ++
 9 files changed, 158 insertions(+), 2 deletions(-)
 create mode 100644 qga/qapi-event.json

-- 
2.13.1

On 06/23/2017 08:02 AM, Tomáš Golembiovský wrote:
> This is just a draft, or a request for comments if you will.
> 
> This patch sets drafts the support of sending events by QEMU Guest Agent.
> Events can plan important role in monitoring of the guest OS behaviour. The
> range of use cases ranges from events important for scheduling, e.g. memory and
> CPU usage statistics, to things like changes to IP addresses on network
> interfaces to for example changes in the list of active users.
> 
> For now the patch set adds single periodic callback function to the GA main
> loop that can perform checks and trigger events that have occured since
> previous run of the callback.

How do we guarantee that the guest cannot flood qemu with too many events?

Obviously, qga is already used where we (in general) trust the guest to
not be malicious, but we still have to assume that a guest can be
compromised, and will try to abuse qga to escape to an attack against qemu.

> 
> We can of course take it one step further and add a general framwork for
> periodically running any of the already implemented commands. Add a function
> that would maintain a list of registered checks. Client would use some command
> (register-monitor-command) passing it a command name and timeout in seconds and
> the monitoring handler would then run the specified command and report the
> result... or report only if the return value changed since previous invocation.
> This feature would remove part of the communication overhead between client and
> GA.
> 
> So before I invest any more time in either of these approaches, tell me. Would
> somethign like this be wanted or is that too controversial? Any other thoughts
> and ideas?
> 
-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

On Fri, 7 Jul 2017 15:55:31 -0500
Eric Blake <eblake@redhat.com> wrote:

> On 06/23/2017 08:02 AM, Tomáš Golembiovský wrote:
> > This is just a draft, or a request for comments if you will.
> > 
> > This patch sets drafts the support of sending events by QEMU Guest Agent.
> > Events can plan important role in monitoring of the guest OS behaviour. The
> > range of use cases ranges from events important for scheduling, e.g. memory and
> > CPU usage statistics, to things like changes to IP addresses on network
> > interfaces to for example changes in the list of active users.
> > 
> > For now the patch set adds single periodic callback function to the GA main
> > loop that can perform checks and trigger events that have occured since
> > previous run of the callback.  
> 
> How do we guarantee that the guest cannot flood qemu with too many events?
> 
> Obviously, qga is already used where we (in general) trust the guest to
> not be malicious, but we still have to assume that a guest can be
> compromised, and will try to abuse qga to escape to an attack against qemu.
> 

If you mean situation where something in guest will be triggering events
that qga will be sending then we can implement some throttling in qga. I
belive qemu does something similar for QMP events.

But if you're considering situation where something kills qga and will
attach itself to the serial channel then this is of course more
complex issue.

> > 
> > We can of course take it one step further and add a general framwork for
> > periodically running any of the already implemented commands. Add a function
> > that would maintain a list of registered checks. Client would use some command
> > (register-monitor-command) passing it a command name and timeout in seconds and
> > the monitoring handler would then run the specified command and report the
> > result... or report only if the return value changed since previous invocation.
> > This feature would remove part of the communication overhead between client and
> > GA.
> > 
> > So before I invest any more time in either of these approaches, tell me. Would
> > somethign like this be wanted or is that too controversial? Any other thoughts
> > and ideas?
> >   
> -- 
> Eric Blake, Principal Software Engineer
> Red Hat, Inc.           +1-919-301-3266
> Virtualization:  qemu.org | libvirt.org
> 


-- 
Tomáš Golembiovský <tgolembi@redhat.com>

Hi

On Fri, Jun 23, 2017 at 3:03 PM Tomáš Golembiovský <tgolembi@redhat.com>
wrote:

> This is just a draft, or a request for comments if you will.
>
> This patch sets drafts the support of sending events by QEMU Guest Agent.
> Events can plan important role in monitoring of the guest OS behaviour. The
> range of use cases ranges from events important for scheduling, e.g.
> memory and
> CPU usage statistics, to things like changes to IP addresses on network
> interfaces to for example changes in the list of active users.
>
> For now the patch set adds single periodic callback function to the GA main
> loop that can perform checks and trigger events that have occured since
> previous run of the callback.
>
> We can of course take it one step further and add a general framwork for
> periodically running any of the already implemented commands. Add a
> function
> that would maintain a list of registered checks. Client would use some
> command
> (register-monitor-command) passing it a command name and timeout in
> seconds and
> the monitoring handler would then run the specified command and report the
> result... or report only if the return value changed since previous
> invocation.
> This feature would remove part of the communication overhead between
> client and
> GA.
>
> So before I invest any more time in either of these approaches, tell me.
> Would
> somethign like this be wanted or is that too controversial? Any other
> thoughts
> and ideas?
>
>
It doesn't feel wrong, but Is there really too much overhead and/or latency
if a request is periodic from the client? ie did you do some measurements
before coming to this proposal?

Tomáš Golembiovský (3):
>   qemu-ga: add support for events
>   qemu-ga: add simple event reporting memory statistics
>   qemu-ga: add support for periodic command runner
>
>  Makefile               |  7 +++-
>  qga/Makefile.objs      |  2 +-
>  qga/channel-posix.c    |  8 +++++
>  qga/channel-win32.c    |  6 ++++
>  qga/channel.h          |  1 +
>  qga/guest-agent-core.h |  1 +
>  qga/main.c             | 98
> ++++++++++++++++++++++++++++++++++++++++++++++++++
>  qga/qapi-event.json    | 35 ++++++++++++++++++
>  qga/qapi-schema.json   |  2 ++
>  9 files changed, 158 insertions(+), 2 deletions(-)
>  create mode 100644 qga/qapi-event.json
>
> --
> 2.13.1
>
>
> --
Marc-André Lureau

Hi,

On Fri, 23 Jun 2017 13:25:34 +0000
Marc-André Lureau <marcandre.lureau@gmail.com> wrote:

> Hi
> 
> On Fri, Jun 23, 2017 at 3:03 PM Tomáš Golembiovský <tgolembi@redhat.com>
> wrote:
> 
> > This is just a draft, or a request for comments if you will.
> >
> > This patch sets drafts the support of sending events by QEMU Guest Agent.
> > Events can plan important role in monitoring of the guest OS behaviour. The
> > range of use cases ranges from events important for scheduling, e.g.
> > memory and
> > CPU usage statistics, to things like changes to IP addresses on network
> > interfaces to for example changes in the list of active users.
> >
> > For now the patch set adds single periodic callback function to the GA main
> > loop that can perform checks and trigger events that have occured since
> > previous run of the callback.
> >
> > We can of course take it one step further and add a general framwork for
> > periodically running any of the already implemented commands. Add a
> > function
> > that would maintain a list of registered checks. Client would use some
> > command
> > (register-monitor-command) passing it a command name and timeout in
> > seconds and
> > the monitoring handler would then run the specified command and report the
> > result... or report only if the return value changed since previous
> > invocation.
> > This feature would remove part of the communication overhead between
> > client and
> > GA.
> >
> > So before I invest any more time in either of these approaches, tell me.
> > Would
> > somethign like this be wanted or is that too controversial? Any other
> > thoughts
> > and ideas?
> >
> >  
> It doesn't feel wrong, but Is there really too much overhead and/or latency
> if a request is periodic from the client? ie did you do some measurements
> before coming to this proposal?

No, I didn't do any measurements. And it may be even true that in the
grand scheme of things the overhead/latency may be insignificant, if we
imagine a client that repeatedly calls about 5 to 10 commands every 5 or
10 seconds. Still, it just feels like a more correct approach to me. But
that may be just my feeling, that's why I brought this to the list to
get the opinion of others.

    Tomas

> 
> Tomáš Golembiovský (3):
> >   qemu-ga: add support for events
> >   qemu-ga: add simple event reporting memory statistics
> >   qemu-ga: add support for periodic command runner
> >
> >  Makefile               |  7 +++-
> >  qga/Makefile.objs      |  2 +-
> >  qga/channel-posix.c    |  8 +++++
> >  qga/channel-win32.c    |  6 ++++
> >  qga/channel.h          |  1 +
> >  qga/guest-agent-core.h |  1 +
> >  qga/main.c             | 98
> > ++++++++++++++++++++++++++++++++++++++++++++++++++
> >  qga/qapi-event.json    | 35 ++++++++++++++++++
> >  qga/qapi-schema.json   |  2 ++
> >  9 files changed, 158 insertions(+), 2 deletions(-)
> >  create mode 100644 qga/qapi-event.json
> >
> > --
> > 2.13.1
> >
> >
> > --  
> Marc-André Lureau


-- 
Tomáš Golembiovský <tgolembi@redhat.com>

Hi,

On Sun, 25 Jun 2017 23:25:17 +0200
Tomáš Golembiovský <tgolembi@redhat.com> wrote:

> Hi,
> 
> On Fri, 23 Jun 2017 13:25:34 +0000
> Marc-André Lureau <marcandre.lureau@gmail.com> wrote:
> 
> > Hi
> > 
> > On Fri, Jun 23, 2017 at 3:03 PM Tomáš Golembiovský <tgolembi@redhat.com>
> > wrote:
> >   
> > > This is just a draft, or a request for comments if you will.
> > >
> > > This patch sets drafts the support of sending events by QEMU Guest Agent.
> > > Events can plan important role in monitoring of the guest OS behaviour. The
> > > range of use cases ranges from events important for scheduling, e.g.
> > > memory and
> > > CPU usage statistics, to things like changes to IP addresses on network
> > > interfaces to for example changes in the list of active users.
> > >
> > > For now the patch set adds single periodic callback function to the GA main
> > > loop that can perform checks and trigger events that have occured since
> > > previous run of the callback.
> > >
> > > We can of course take it one step further and add a general framwork for
> > > periodically running any of the already implemented commands. Add a
> > > function
> > > that would maintain a list of registered checks. Client would use some
> > > command
> > > (register-monitor-command) passing it a command name and timeout in
> > > seconds and
> > > the monitoring handler would then run the specified command and report the
> > > result... or report only if the return value changed since previous
> > > invocation.
> > > This feature would remove part of the communication overhead between
> > > client and
> > > GA.
> > >
> > > So before I invest any more time in either of these approaches, tell me.
> > > Would
> > > somethign like this be wanted or is that too controversial? Any other
> > > thoughts
> > > and ideas?
> > >
> > >    
> > It doesn't feel wrong, but Is there really too much overhead and/or latency
> > if a request is periodic from the client? ie did you do some measurements
> > before coming to this proposal?  
> 
> No, I didn't do any measurements. And it may be even true that in the
> grand scheme of things the overhead/latency may be insignificant, if we
> imagine a client that repeatedly calls about 5 to 10 commands every 5 or
> 10 seconds. Still, it just feels like a more correct approach to me. But
> that may be just my feeling, that's why I brought this to the list to
> get the opinion of others.
> 

This is not really a wild discussion I have anticipated. Or does the
silence mean I should drop the idea?

If some measurements are necessary can you suggest how to construct the
benchmark? What numbers would be convincing to support the idea?

Still, let me restate that I see it more as an architectural decision
rather than something where latency or overhead would be the main
factor.


    Tomas

> 
> > 
> > Tomáš Golembiovský (3):  
> > >   qemu-ga: add support for events
> > >   qemu-ga: add simple event reporting memory statistics
> > >   qemu-ga: add support for periodic command runner
> > >
> > >  Makefile               |  7 +++-
> > >  qga/Makefile.objs      |  2 +-
> > >  qga/channel-posix.c    |  8 +++++
> > >  qga/channel-win32.c    |  6 ++++
> > >  qga/channel.h          |  1 +
> > >  qga/guest-agent-core.h |  1 +
> > >  qga/main.c             | 98
> > > ++++++++++++++++++++++++++++++++++++++++++++++++++
> > >  qga/qapi-event.json    | 35 ++++++++++++++++++
> > >  qga/qapi-schema.json   |  2 ++
> > >  9 files changed, 158 insertions(+), 2 deletions(-)
> > >  create mode 100644 qga/qapi-event.json
> > >
> > > --
> > > 2.13.1
> > >
> > >
> > > --    
> > Marc-André Lureau  
> 
> 
> -- 
> Tomáš Golembiovský <tgolembi@redhat.com>


-- 
Tomáš Golembiovský <tgolembi@redhat.com>