0611-tools-libxl-enable-in-band-reconnect-marker-for-stub.patch

From 3af534eeacc8c2369c0a1c92137cb854ec1bd3a2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
 <marmarek@invisiblethingslab.com>
Date: Sat, 3 Sep 2022 04:31:34 +0200
Subject: [PATCH] tools/libxl: enable in-band reconnect marker for stubdom QMP
 proxy
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This enables stubdom reliably detect when it needs to reconnect QMP
socket. It is critical, as otherwise QEMU will not send its handshake,
and so libxl will timeout while waiting on one. When it happens during
domain startup, it can result in error like this:

libxl: libxl_pci.c:1772:device_pci_add_done: Domain 3:libxl__device_pci_add failed for PCI device 0:0:14.0 (rc -9)
libxl: libxl_create.c:1904:domcreate_attach_devices: Domain 3:unable to add pci devices

See vchan-socket-proxy commit message for details about this reconnect
corner case.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
---
 tools/libs/light/libxl_dm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/libs/light/libxl_dm.c b/tools/libs/light/libxl_dm.c
index 160d4e065d08..d3df66786c45 100644
--- a/tools/libs/light/libxl_dm.c
+++ b/tools/libs/light/libxl_dm.c
@@ -2646,10 +2646,11 @@ static void spawn_qmp_proxy(libxl__egc *egc,
     sdss->qmp_proxy_spawn.failure_cb = qmp_proxy_startup_failed;
     sdss->qmp_proxy_spawn.detached_cb = qmp_proxy_detached;
 
-    const int arraysize = 6;
+    const int arraysize = 7;
     GCNEW_ARRAY(args, arraysize);
     args[nr++] = STUBDOM_QMP_PROXY_PATH;
     args[nr++] = GCSPRINTF("--state-path=%s", sdss->qmp_proxy_spawn.xspath);
+    args[nr++] = "--reconnect-marker=1";
     args[nr++] = GCSPRINTF("%u", dm_domid);
     args[nr++] = GCSPRINTF("%s/device-model/%u/qmp-vchan", dom_path, guest_domid);
     args[nr++] = (char*)libxl__qemu_qmp_path(gc, guest_domid);
-- 
2.44.0