[PATCH v2 17/38] whpx: i386: unknown MSR configurability

[Mohamed Mediouni <mohamed@unpredictable.fr>]

Add an option to inject back a GPF for unknown MSRs.

Keep it on by default for now as Linux expects accesses to some
AMD-specific MSRs to always succeed when on an AMD host.

Signed-off-by: Mohamed Mediouni <mohamed@unpredictable.fr>
---
 accel/whpx/whpx-common.c       | 38 ++++++++++++++++++++++++++++++++++
 include/system/whpx-internal.h |  1 +
 target/i386/whpx/whpx-all.c    |  4 ++++
 3 files changed, 43 insertions(+)

diff --git a/accel/whpx/whpx-common.c b/accel/whpx/whpx-common.c
index 59be996aef..706871f138 100644
--- a/accel/whpx/whpx-common.c
+++ b/accel/whpx/whpx-common.c
@@ -505,6 +505,38 @@ static void whpx_set_hyperv(Object *obj, Visitor *v,
     }
 }
 
+static void whpx_set_unknown_msr(Object *obj, Visitor *v,
+                                   const char *name, void *opaque,
+                                   Error **errp)
+{
+    struct whpx_state *whpx = &whpx_global;
+    OnOffAuto mode;
+
+    if (!visit_type_OnOffAuto(v, name, &mode, errp)) {
+        return;
+    }
+
+    switch (mode) {
+    case ON_OFF_AUTO_ON:
+        whpx->ignore_unknown_msr = true;
+        break;
+
+    case ON_OFF_AUTO_OFF:
+        whpx->ignore_unknown_msr = false;
+        break;
+
+    case ON_OFF_AUTO_AUTO:
+        whpx->ignore_unknown_msr = true;
+        break;
+    default:
+        /*
+         * The value was checked in visit_type_OnOffAuto() above. If
+         * we get here, then something is wrong in QEMU.
+         */
+        abort();
+    }
+}
+
 static void whpx_cpu_accel_class_init(ObjectClass *oc, const void *data)
 {
     AccelCPUClass *acc = ACCEL_CPU_CLASS(oc);
@@ -538,6 +570,11 @@ static void whpx_accel_class_init(ObjectClass *oc, const void *data)
         NULL, NULL);
     object_class_property_set_description(oc, "hyperv",
         "Configure Hyper-V enlightenments");
+    object_class_property_add(oc, "ignore-unknown-msr", "OnOffAuto",
+        NULL, whpx_set_unknown_msr,
+        NULL, NULL);
+    object_class_property_set_description(oc, "ignore-unknown-msr",
+        "Configure unknown MSR behavior");
 }
 
 static void whpx_accel_instance_init(Object *obj)
@@ -552,6 +589,7 @@ static void whpx_accel_instance_init(Object *obj)
     whpx->hyperv_enlightenments_required = false;
     /* Value determined at whpx_accel_init */
     whpx->hyperv_enlightenments_enabled = false;
+    whpx->ignore_unknown_msr = true;
 }
 
 static const TypeInfo whpx_accel_type = {
diff --git a/include/system/whpx-internal.h b/include/system/whpx-internal.h
index cf782cf5f8..86639627b3 100644
--- a/include/system/whpx-internal.h
+++ b/include/system/whpx-internal.h
@@ -47,6 +47,7 @@ struct whpx_state {
     bool hyperv_enlightenments_required;
     bool hyperv_enlightenments_enabled;
 
+    bool ignore_unknown_msr;
 };
 
 extern struct whpx_state whpx_global;
diff --git a/target/i386/whpx/whpx-all.c b/target/i386/whpx/whpx-all.c
index 0d72e93621..550f30d50a 100644
--- a/target/i386/whpx/whpx-all.c
+++ b/target/i386/whpx/whpx-all.c
@@ -2048,6 +2048,10 @@ int whpx_vcpu_run(CPUState *cpu)
                     vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite);
             }
 
+            if (!is_known_msr && !whpx->ignore_unknown_msr) {
+                x86_emul_raise_exception(&X86_CPU(cpu)->env, EXCP0D_GPF, 0);
+            }
+
             hr = whp_dispatch.WHvSetVirtualProcessorRegisters(
                 whpx->partition,
                 cpu->cpu_index,
-- 
2.50.1 (Apple Git-155)