[PATCH v2 07/18] whpx: i386: allow migration for restricted scenarios

[Mohamed Mediouni <mohamed@unpredictable.fr>]

Currently, nested virtualisation state is not saved/restored and
neither is Hyper-V enlightenment state.

Also, not debug register state nor MTRRs but still usable.

Signed-off-by: Mohamed Mediouni <mohamed@unpredictable.fr>
---
 target/i386/whpx/whpx-all.c | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/target/i386/whpx/whpx-all.c b/target/i386/whpx/whpx-all.c
index d13513985c..5f14564f10 100644
--- a/target/i386/whpx/whpx-all.c
+++ b/target/i386/whpx/whpx-all.c
@@ -2828,6 +2828,22 @@ static void whpx_cpu_update_state(void *opaque, bool running, RunState state)
     }
 }
 
+static bool whpx_is_migration_allowed(CPUState *cpu) {
+    struct whpx_state *whpx = &whpx_global;
+    X86CPU *x86_cpu = X86_CPU(cpu);
+    CPUX86State *env = &x86_cpu->env;
+
+    if (whpx->hyperv_enlightenments_enabled == true) {
+        return false;
+    }
+
+    if (cpu_has_vmx(env) || cpu_has_svm(env)) {
+        return false;
+    }
+
+    return true;
+}
+
 int whpx_init_vcpu(CPUState *cpu)
 {
     HRESULT hr;
@@ -2845,10 +2861,11 @@ int whpx_init_vcpu(CPUState *cpu)
     /* Add migration blockers for all unsupported features of the
      * Windows Hypervisor Platform
      */
-    if (whpx_migration_blocker == NULL) {
+    if (whpx_migration_blocker == NULL
+        && !whpx_is_migration_allowed(cpu)) {
         error_setg(&whpx_migration_blocker,
-               "State blocked due to missing dirty memory tracking support,"
-               "And some system register/state save-restore ");
+               "State blocked due to missing Hyper-V enlightenments,"
+               "save-restore and/or nested virtualisation");
 
         if (migrate_add_blocker(&whpx_migration_blocker, &local_error) < 0) {
             error_report_err(local_error);
-- 
2.54.0 (Apple Git-157)