[PATCH 2/2] target/i386: defer the Hyper-V SynIC post_load

["Denis V. Lunev" <den@openvz.org>]

From: Denis V. Lunev <den@openvz.org>

hyperv_synic_post_load() maps the SynIC message and event pages, and a
guest which has programmed the SynIC carries the subsection on every
vCPU, so restoring one rebuilds the flatview per vCPU rather than once.

The hook cannot fail and does not read guest memory, so it can run with
the rest of the deferred hooks once the stream has been consumed. The
saving scales with vCPU count.

CC: Peter Xu <peterx@redhat.com>
CC: Fabiano Rosas <farosas@suse.de>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Denis V. Lunev <den@virtuozzo.com>
---
 target/i386/machine.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/target/i386/machine.c b/target/i386/machine.c
index 8d69d7e25e..eae74e33de 100644
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -873,6 +873,7 @@ static const VMStateDescription vmstate_msr_hyperv_synic = {
     .minimum_version_id = 1,
     .needed = hyperv_synic_enable_needed,
     .post_load = hyperv_synic_post_load,
+    .post_load_deferrable = true,
     .fields = (const VMStateField[]) {
         VMSTATE_UINT64(env.msr_hv_synic_control, X86CPU),
         VMSTATE_UINT64(env.msr_hv_synic_evt_page, X86CPU),
-- 
2.53.0