[PULL 4/4] hw/xen: Set suppress-vmdesc for Xen machines

[Anthony PERARD via <qemu-devel@nongnu.org>]

From: Jason Andryuk <jandryuk@gmail.com>

xen-save-devices-state doesn't currently generate a vmdesc, so restore
always triggers "Expected vmdescription section, but got 0".  This is
not a problem when restore comes from a file.  However, when QEMU runs
in a linux stubdom and comes over a console, EOF is not received.  This
causes a delay restoring - though it does restore.

Setting suppress-vmdesc skips looking for the vmdesc during restore and
avoids the wait.

The other approach would be generate a vmdesc in qemu_save_device_state.
Since COLO shared that function, and the vmdesc is just discarded on
restore, we choose to skip it.

Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: <20201013190506.3325-1-jandryuk@gmail.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
---
 hw/i386/pc_piix.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 3c2ae0612b23..0cf22a57ad14 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -987,7 +987,7 @@ static void xenfv_4_2_machine_options(MachineClass *m)
     pc_i440fx_4_2_machine_options(m);
     m->desc = "Xen Fully-virtualized PC";
     m->max_cpus = HVM_MAX_VCPUS;
-    m->default_machine_opts = "accel=xen";
+    m->default_machine_opts = "accel=xen,suppress-vmdesc=on";
 }
 
 DEFINE_PC_MACHINE(xenfv_4_2, "xenfv-4.2", pc_xen_hvm_init,
@@ -999,7 +999,7 @@ static void xenfv_3_1_machine_options(MachineClass *m)
     m->desc = "Xen Fully-virtualized PC";
     m->alias = "xenfv";
     m->max_cpus = HVM_MAX_VCPUS;
-    m->default_machine_opts = "accel=xen";
+    m->default_machine_opts = "accel=xen,suppress-vmdesc=on";
 }
 
 DEFINE_PC_MACHINE(xenfv, "xenfv-3.1", pc_xen_hvm_init,
-- 
Anthony PERARD