i386: add hyperv-stub for CONFIG_HYPERV=n

This will allow to build slightly leaner QEMU that supports some HyperV
features of KVM (e.g. SynIC timers, PV spinlocks, APIC assists, etc.)
but nothing else on the QEMU side.

Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
Message-Id: <20180921082041.29380-6-rkagan@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

target/i386/Makefile.objs

@@ -3,17 +3,20 @@ obj-$(CONFIG_TCG) += translate.o
 obj-$(CONFIG_TCG) += bpt_helper.o cc_helper.o excp_helper.o fpu_helper.o
 obj-$(CONFIG_TCG) += int_helper.o mem_helper.o misc_helper.o mpx_helper.o
 obj-$(CONFIG_TCG) += seg_helper.o smm_helper.o svm_helper.o
-obj-$(CONFIG_SOFTMMU) += machine.o arch_memory_mapping.o arch_dump.o monitor.o
-obj-$(CONFIG_KVM) += kvm.o hyperv.o
-obj-$(CONFIG_SEV) += sev.o
+ifeq ($(CONFIG_SOFTMMU),y)
+obj-y += machine.o arch_memory_mapping.o arch_dump.o monitor.o
+obj-$(CONFIG_KVM) += kvm.o
 obj-$(call lnot,$(CONFIG_KVM)) += kvm-stub.o
-obj-$(call lnot,$(CONFIG_SEV)) += sev-stub.o
-# HAX support
-ifdef CONFIG_WIN32
+obj-$(CONFIG_HYPERV) += hyperv.o
+obj-$(call lnot,$(CONFIG_HYPERV)) += hyperv-stub.o
+ifeq ($(CONFIG_WIN32),y)
 obj-$(CONFIG_HAX) += hax-all.o hax-mem.o hax-windows.o
 endif
-ifdef CONFIG_DARWIN
+ifeq ($(CONFIG_DARWIN),y)
 obj-$(CONFIG_HAX) += hax-all.o hax-mem.o hax-darwin.o
 obj-$(CONFIG_HVF) += hvf/
 endif
 obj-$(CONFIG_WHPX) += whpx-all.o
+endif
+obj-$(CONFIG_SEV) += sev.o
+obj-$(call lnot,$(CONFIG_SEV)) += sev-stub.o

target/i386/hyperv-stub.c

@@ -0,0 +1,35 @@
+/*
+ * Stubs for CONFIG_HYPERV=n
+ *
+ * Copyright (c) 2015-2018 Virtuozzo International GmbH.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "hyperv.h"
+
+#ifdef CONFIG_KVM
+int kvm_hv_handle_exit(X86CPU *cpu, struct kvm_hyperv_exit *exit)
+{
+    switch (exit->type) {
+    case KVM_EXIT_HYPERV_SYNIC:
+        if (!cpu->hyperv_synic) {
+            return -1;
+        }
+
+        /*
+         * Tracking the changes in the MSRs is unnecessary as there are no
+         * users for them beside save/load, which is handled nicely by the
+         * generic MSR save/load code
+         */
+        return 0;
+    case KVM_EXIT_HYPERV_HCALL:
+        exit->u.hcall.result = HV_STATUS_INVALID_HYPERCALL_CODE;
+        return 0;
+    default:
+        return -1;
+    }
+}
+#endif

target/i386/hyperv.h

@@ -18,6 +18,8 @@
 #include "sysemu/kvm.h"
 #include "hw/hyperv/hyperv.h"
 
+#ifdef CONFIG_KVM
 int kvm_hv_handle_exit(X86CPU *cpu, struct kvm_hyperv_exit *exit);
+#endif
 
 #endif