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From: Jason Andryuk <jandryuk@gmail.com>
To: "Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>
Cc: Anthony PERARD <anthony.perard@citrix.com>,
	xen-devel <xen-devel@lists.xenproject.org>,
	Ian Jackson <ian.jackson@eu.citrix.com>, Wei Liu <wl@xen.org>
Subject: Re: [Xen-devel] [PATCH v4 12/16] libxl: use vchan for QMP access with Linux stubdomain
Date: Fri, 24 Jan 2020 09:05:09 -0500
Message-ID: <CAKf6xpvzz39_OH6sEEq4QpumnyO12V23KHTGhBp7sx3GFoLJmQ@mail.gmail.com> (raw)
In-Reply-To: <20200121234611.GV1314@mail-itl>

On Tue, Jan 21, 2020 at 6:46 PM Marek Marczykowski-Górecki
<marmarek@invisiblethingslab.com> wrote:

<snip>

> > > +static void spawn_qmp_proxy(libxl__egc *egc,
> > > +                            libxl__stub_dm_spawn_state *sdss)
> > > +{
> > > +    STATE_AO_GC(sdss->qmp_proxy_spawn.ao);
> > > +    const uint32_t guest_domid = sdss->dm.guest_domid;
> > > +    const uint32_t dm_domid = sdss->pvqemu.guest_domid;
> > > +    const char *dom_path = libxl__xs_get_dompath(gc, dm_domid);
> > > +    char **args;
> > > +    int nr = 0;
> > > +    int rc, logfile_w, null;
> > > +
> > > +    if (access(STUBDOM_QMP_PROXY_PATH, X_OK) < 0) {
> > > +        LOGED(ERROR, guest_domid, "qmp proxy %s is not executable", STUBDOM_QMP_PROXY_PATH);
> > > +        rc = ERROR_FAIL;
> > > +        goto out;
> > > +    }
> > > +
> > > +    sdss->qmp_proxy_spawn.what = GCSPRINTF("domain %d device model qmp proxy", guest_domid);
> > > +    sdss->qmp_proxy_spawn.pidpath = GCSPRINTF("%s/image/qmp-proxy-pid", dom_path);
> > > +    sdss->qmp_proxy_spawn.xspath = GCSPRINTF("%s/image/qmp-proxy-state", dom_path);
> >
> > Since this is the vchan-socket-proxy in dom0, should it write to
> > "device-model/%u/qmp-proxy-state" underneath dom0?
>
> Yes, that would be more consistent. But pid should stay where it is
> (it's also where dom0 qemu pid is being written).

Hmm, that split between pids and device-model info is a little weird.
But it is specified in docs misc/xenstore-paths.pandoc

> > > +
> > > +    sdss->qmp_proxy_spawn.timeout_ms = LIBXL_DEVICE_MODEL_START_TIMEOUT * 1000;
> > > +    sdss->qmp_proxy_spawn.midproc_cb = libxl__spawn_record_pid;
> > > +    sdss->qmp_proxy_spawn.confirm_cb = qmp_proxy_confirm;
> > > +    sdss->qmp_proxy_spawn.failure_cb = qmp_proxy_startup_failed;
> > > +    sdss->qmp_proxy_spawn.detached_cb = qmp_proxy_detached;
> > > +
> > > +    const int arraysize = 6;
> > > +    GCNEW_ARRAY(args, arraysize);
> > > +    args[nr++] = STUBDOM_QMP_PROXY_PATH;
> > > +    args[nr++] = GCSPRINTF("--state-path=%s", sdss->qmp_proxy_spawn.xspath);
> > > +    args[nr++] = GCSPRINTF("%u", dm_domid);
> > > +    args[nr++] = GCSPRINTF("%s/device-model/%u/qmp-vchan", dom_path, guest_domid);
> >
> > Thinking of OpenXT"s qmp-helper, this path isn't useful.  But it is
> > for vchan-socket-proxy, so qmp-helper could just change to ignore it.
>
> For vchan we could use also a port number (and then it will encode it
> into a xenstore path). This is in fact how we use libvchan in Qubes. I
> opted for explicit path only because of lack of idea for some meaningful
> port number ;) But I'm open for suggestions.
> I guess that would be useful for Argo version then.

The argo version hard codes the port number, so it's not a command
line argument.  The port number would need to get passed to the
stubdom or it would need to be standardized.

I think the arguments for vchan-socket-proxy make sense.  Since it's
the one that's submitted upstream, it makes sense to use them.

Put another way, do we want this to support alternate implementations
for a qmp proxy?  Should the arguments be generic for that case?
Since the existing arguments have enough information for either proxy,
I think it's fine to leave it as is.  While you could have a wrapper
generate all the above from just the domid & stub_domid, that's kinda
hacky.

Thanks,
Jason

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Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-15  2:39 [Xen-devel] [PATCH v4 00/16] Add support for qemu-xen runnning in a Linux-based stubdomain Marek Marczykowski-Górecki
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 01/16] Document ioemu MiniOS stubdomain protocol Marek Marczykowski-Górecki
2020-01-20 18:30   ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 02/16] Document ioemu Linux " Marek Marczykowski-Górecki
2020-01-20 18:54   ` Jason Andryuk
2020-01-21 21:08     ` Marek Marczykowski-Górecki
2020-01-22 14:04       ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 03/16] libxl: fix qemu-trad cmdline for no sdl/vnc case Marek Marczykowski-Górecki
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 04/16] libxl: Allow running qemu-xen in stubdomain Marek Marczykowski-Górecki
2020-01-20 18:56   ` Jason Andryuk
2020-01-21 21:12     ` Marek Marczykowski-Górecki
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 05/16] libxl: Handle Linux stubdomain specific QEMU options Marek Marczykowski-Górecki
2020-01-20 19:24   ` Jason Andryuk
2020-01-21 21:18     ` Marek Marczykowski-Górecki
2020-01-22 14:25       ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 06/16] libxl: write qemu arguments into separate xenstore keys Marek Marczykowski-Górecki
2020-01-20 19:36   ` Jason Andryuk
2020-01-21 21:19     ` Marek Marczykowski-Górecki
2020-01-22 14:39       ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 07/16] xl: add stubdomain related options to xl config parser Marek Marczykowski-Górecki
2020-01-20 19:41   ` Jason Andryuk
2020-01-21 21:22     ` Marek Marczykowski-Górecki
2020-01-22 14:39       ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 08/16] tools/libvchan: notify server when client is connected Marek Marczykowski-Górecki
2020-01-20 19:44   ` Jason Andryuk
2020-01-21 21:28     ` Marek Marczykowski-Górecki
2020-01-22 14:43       ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 09/16] libxl: add save/restore support for qemu-xen in stubdomain Marek Marczykowski-Górecki
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 10/16] tools: add missing libxenvchan cflags Marek Marczykowski-Górecki
2020-01-20 19:58   ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 11/16] tools: add simple vchan-socket-proxy Marek Marczykowski-Górecki
2020-01-15 11:02   ` Jan Beulich
2020-01-16 17:11     ` Marek Marczykowski-Górecki
2020-01-17  8:13       ` Jan Beulich
2020-01-17 18:44   ` Rich Persaud
2020-01-17 18:56     ` Marek Marczykowski-Górecki
2020-01-21 19:43   ` Jason Andryuk
2020-01-21 23:09     ` Marek Marczykowski-Górecki
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 12/16] libxl: use vchan for QMP access with Linux stubdomain Marek Marczykowski-Górecki
2020-01-21 20:17   ` Jason Andryuk
2020-01-21 23:46     ` Marek Marczykowski-Górecki
2020-01-24 14:05       ` Jason Andryuk [this message]
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 13/16] Regenerate autotools files Marek Marczykowski-Górecki
2020-01-15 21:57   ` Rich Persaud
2020-01-21 20:56     ` Marek Marczykowski-Górecki
2020-01-21 21:28       ` Rich Persaud
2020-01-22  8:57         ` Lars Kurth
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 14/16] libxl: require qemu in dom0 even if stubdomain is in use Marek Marczykowski-Górecki
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 15/16] libxl: ignore emulated IDE disks beyond the first 4 Marek Marczykowski-Górecki
2020-01-21 20:24   ` Jason Andryuk
2020-01-15  2:39 ` [Xen-devel] [PATCH v4 16/16] libxl: consider also qemu in stubdomain in libxl__dm_active check Marek Marczykowski-Górecki
2020-01-21 20:25   ` Jason Andryuk
2020-01-22 16:50 ` [Xen-devel] [PATCH v4 00/16] Add support for qemu-xen runnning in a Linux-based stubdomain Jason Andryuk
2020-01-24 19:58 [Xen-devel] [PATCH v4 12/16] libxl: use vchan for QMP access with Linux stubdomain Rich Persaud
2020-01-24 20:22 ` Marek Marczykowski-Górecki

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