[QEMU PATCH] i386/kvm: add support for Direct Mode for Hyper-V synthetic timers

[Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>]

Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
 linux-headers/linux/kvm.h  |  1 +
 target/i386/cpu.c          |  1 +
 target/i386/cpu.h          |  1 +
 target/i386/hyperv-proto.h |  1 +
 target/i386/kvm.c          | 11 +++++++++++
 5 files changed, 15 insertions(+)

diff --git a/linux-headers/linux/kvm.h b/linux-headers/linux/kvm.h
index f11a7eb49c..43fb240b60 100644
--- a/linux-headers/linux/kvm.h
+++ b/linux-headers/linux/kvm.h
@@ -965,6 +965,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_COALESCED_PIO 162
 #define KVM_CAP_HYPERV_ENLIGHTENED_VMCS 163
 #define KVM_CAP_EXCEPTION_PAYLOAD 164
+#define KVM_CAP_HYPERV_STIMER_DIRECT 166
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index af7e9f09cc..cd42fb81dd 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -5733,6 +5733,7 @@ static Property x86_cpu_properties[] = {
     DEFINE_PROP_BOOL("hv-reenlightenment", X86CPU, hyperv_reenlightenment, false),
     DEFINE_PROP_BOOL("hv-tlbflush", X86CPU, hyperv_tlbflush, false),
     DEFINE_PROP_BOOL("hv-ipi", X86CPU, hyperv_ipi, false),
+    DEFINE_PROP_BOOL("hv-stimer-direct", X86CPU, hyperv_stimer_direct, false),
     DEFINE_PROP_BOOL("check", X86CPU, check_cpuid, true),
     DEFINE_PROP_BOOL("enforce", X86CPU, enforce_cpuid, false),
     DEFINE_PROP_BOOL("kvm", X86CPU, expose_kvm, true),
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index ad0e0b4534..a3d7cac8be 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1392,6 +1392,7 @@ struct X86CPU {
     bool hyperv_reenlightenment;
     bool hyperv_tlbflush;
     bool hyperv_ipi;
+    bool hyperv_stimer_direct;
     bool check_cpuid;
     bool enforce_cpuid;
     bool expose_kvm;
diff --git a/target/i386/hyperv-proto.h b/target/i386/hyperv-proto.h
index 8c572cd7c2..4543112cf5 100644
--- a/target/i386/hyperv-proto.h
+++ b/target/i386/hyperv-proto.h
@@ -48,6 +48,7 @@
 #define HV_GUEST_IDLE_STATE_AVAILABLE           (1u << 5)
 #define HV_FREQUENCY_MSRS_AVAILABLE             (1u << 8)
 #define HV_GUEST_CRASH_MSR_AVAILABLE            (1u << 10)
+#define HV_STIMER_DIRECT_MODE_AVAILABLE		(1u << 19)
 
 /*
  * HV_CPUID_ENLIGHTMENT_INFO.EAX bits
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 796a049a0d..f12321e0f7 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -797,6 +797,17 @@ static int hyperv_handle_properties(CPUState *cs)
         }
         env->features[FEAT_HYPERV_EAX] |= HV_SYNTIMERS_AVAILABLE;
     }
+    if (cpu->hyperv_stimer_direct) {
+        if (kvm_check_extension(cs->kvm_state,
+                                KVM_CAP_HYPERV_STIMER_DIRECT) <= 0) {
+            fprintf(stderr, "Hyper-V timers direct mode "
+                        "(requested by 'hv-stimer-direct' cpu flag) "
+                        " is not supported by kernel\n");
+                return -ENOSYS;
+        }
+        env->features[FEAT_HYPERV_EDX] |= HV_STIMER_DIRECT_MODE_AVAILABLE;
+    }
+
     return 0;
 }
 
-- 
2.17.2