[PATCH v2 1/2] i386: introduce kvm_hv_evmcs_available()

[Vitaly Kuznetsov <vkuznets@redhat.com>]

Enlightened VMCS feature is hardware specific, it is only supported on
Intel CPUs. Introduce a simple kvm_hv_evmcs_available() helper, it will
be used to filter out 'hv_evmcs' when 'hyperv=on' option is added to
X86MachineClass.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 target/i386/kvm-stub.c | 5 +++++
 target/i386/kvm.c      | 8 ++++++++
 target/i386/kvm_i386.h | 1 +
 3 files changed, 14 insertions(+)

diff --git a/target/i386/kvm-stub.c b/target/i386/kvm-stub.c
index 92f49121b8fa..0a163ae207c5 100644
--- a/target/i386/kvm-stub.c
+++ b/target/i386/kvm-stub.c
@@ -39,3 +39,8 @@ bool kvm_hv_vpindex_settable(void)
 {
     return false;
 }
+
+bool kvm_hv_evmcs_available(void)
+{
+    return false;
+}
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index bcfa4b03e077..96395d499729 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -95,6 +95,7 @@ static bool has_msr_hv_crash;
 static bool has_msr_hv_reset;
 static bool has_msr_hv_vpindex;
 static bool hv_vpindex_settable;
+static bool hv_evmcs_available;
 static bool has_msr_hv_runtime;
 static bool has_msr_hv_synic;
 static bool has_msr_hv_stimer;
@@ -192,6 +193,11 @@ bool kvm_hv_vpindex_settable(void)
     return hv_vpindex_settable;
 }
 
+bool kvm_hv_evmcs_available(void)
+{
+    return hv_evmcs_available;
+}
+
 static int kvm_get_tsc(CPUState *cs)
 {
     X86CPU *cpu = X86_CPU(cs);
@@ -2124,6 +2130,8 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
     has_pit_state2 = kvm_check_extension(s, KVM_CAP_PIT_STATE2);
 
     hv_vpindex_settable = kvm_check_extension(s, KVM_CAP_HYPERV_VP_INDEX);
+    hv_evmcs_available =
+        kvm_check_extension(s, KVM_CAP_HYPERV_ENLIGHTENED_VMCS);
 
     has_exception_payload = kvm_check_extension(s, KVM_CAP_EXCEPTION_PAYLOAD);
     if (has_exception_payload) {
diff --git a/target/i386/kvm_i386.h b/target/i386/kvm_i386.h
index dc725083891c..08968cfb33f1 100644
--- a/target/i386/kvm_i386.h
+++ b/target/i386/kvm_i386.h
@@ -47,6 +47,7 @@ bool kvm_has_x2apic_api(void);
 bool kvm_has_waitpkg(void);
 
 bool kvm_hv_vpindex_settable(void);
+bool kvm_hv_evmcs_available(void);
 
 uint64_t kvm_swizzle_msi_ext_dest_id(uint64_t address);
 
-- 
2.29.2