kvm: i386: halt poll control MSR support

Add support for halt poll control MSR: save/restore, migration
and new feature name.

The purpose of this MSR is to allow the guest to disable
host halt poll.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Message-Id: <20190603230408.GA7938@amt.cnet>
[Do not enable by default, as pointed out by Mark Kanda. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/target/i386/machine.c b/target/i386/machine.c
index ce55755f0f..2767b3096d 100644
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -437,6 +437,14 @@ static const VMStateDescription vmstate_exception_info = {
     }
 };
 
+/* Poll control MSR enabled by default */
+static bool poll_control_msr_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+
+    return cpu->env.poll_control_msr != 1;
+}
+
 static const VMStateDescription vmstate_steal_time_msr = {
     .name = "cpu/steal_time_msr",
     .version_id = 1,
@@ -470,6 +478,17 @@ static const VMStateDescription vmstate_pv_eoi_msr = {
     }
 };
 
+static const VMStateDescription vmstate_poll_control_msr = {
+    .name = "cpu/poll_control_msr",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = poll_control_msr_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(env.poll_control_msr, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static bool fpop_ip_dp_needed(void *opaque)
 {
     X86CPU *cpu = opaque;
@@ -1354,6 +1373,7 @@ VMStateDescription vmstate_x86_cpu = {
         &vmstate_async_pf_msr,
         &vmstate_pv_eoi_msr,
         &vmstate_steal_time_msr,
+        &vmstate_poll_control_msr,
         &vmstate_fpop_ip_dp,
         &vmstate_msr_tsc_adjust,
         &vmstate_msr_tscdeadline,