6 files changed, 72 insertions, 0 deletions

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 50d5553991..83a444472b 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1999,6 +1999,11 @@ static void pc_cpu_pre_plug(HotplugHandler *hotplug_dev,
     }
     cpu->thread_id = topo.smt_id;
 
+    if (cpu->hyperv_vpindex && !kvm_hv_vpindex_settable()) {
+        error_setg(errp, "kernel doesn't allow setting HyperV VP_INDEX");
+        return;
+    }
+
     cs = CPU(cpu);
     cs->cpu_index = idx;
 
diff --git a/target/i386/hyperv.c b/target/i386/hyperv.c
index 7cc0fbb272..3065d765ed 100644
--- a/target/i386/hyperv.c
+++ b/target/i386/hyperv.c
@@ -16,6 +16,16 @@
 #include "hyperv.h"
 #include "hyperv-proto.h"
 
+uint32_t hyperv_vp_index(X86CPU *cpu)
+{
+    return CPU(cpu)->cpu_index;
+}
+
+X86CPU *hyperv_find_vcpu(uint32_t vp_index)
+{
+    return X86_CPU(qemu_get_cpu(vp_index));
+}
+
 int kvm_hv_handle_exit(X86CPU *cpu, struct kvm_hyperv_exit *exit)
 {
     CPUX86State *env = &cpu->env;
diff --git a/target/i386/hyperv.h b/target/i386/hyperv.h
index eaf3df34b0..00c9b454bb 100644
--- a/target/i386/hyperv.h
+++ b/target/i386/hyperv.h
@@ -39,4 +39,7 @@ void kvm_hv_sint_route_destroy(HvSintRoute *sint_route);
 
 int kvm_hv_sint_route_set_sint(HvSintRoute *sint_route);
 
+uint32_t hyperv_vp_index(X86CPU *cpu);
+X86CPU *hyperv_find_vcpu(uint32_t vp_index);
+
 #endif
diff --git a/target/i386/kvm-stub.c b/target/i386/kvm-stub.c
index bda4dc2f0c..e7a673e5db 100644
--- a/target/i386/kvm-stub.c
+++ b/target/i386/kvm-stub.c
@@ -40,3 +40,8 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *env, uint32_t function,
     abort();
 }
 #endif
+
+bool kvm_hv_vpindex_settable(void)
+{
+    return false;
+}
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index ebb2d23aa4..9313602d3d 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -85,6 +85,7 @@ static bool has_msr_hv_hypercall;
 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 has_msr_hv_runtime;
 static bool has_msr_hv_synic;
 static bool has_msr_hv_stimer;
@@ -162,6 +163,11 @@ bool kvm_enable_x2apic(void)
              has_x2apic_api);
 }
 
+bool kvm_hv_vpindex_settable(void)
+{
+    return hv_vpindex_settable;
+}
+
 static int kvm_get_tsc(CPUState *cs)
 {
     X86CPU *cpu = X86_CPU(cs);
@@ -745,6 +751,37 @@ static int hyperv_handle_properties(CPUState *cs)
     return 0;
 }
 
+static int hyperv_init_vcpu(X86CPU *cpu)
+{
+    if (cpu->hyperv_vpindex && !hv_vpindex_settable) {
+        /*
+         * the kernel doesn't support setting vp_index; assert that its value
+         * is in sync
+         */
+        int ret;
+        struct {
+            struct kvm_msrs info;
+            struct kvm_msr_entry entries[1];
+        } msr_data = {
+            .info.nmsrs = 1,
+            .entries[0].index = HV_X64_MSR_VP_INDEX,
+        };
+
+        ret = kvm_vcpu_ioctl(CPU(cpu), KVM_GET_MSRS, &msr_data);
+        if (ret < 0) {
+            return ret;
+        }
+        assert(ret == 1);
+
+        if (msr_data.entries[0].data != hyperv_vp_index(cpu)) {
+            error_report("kernel's vp_index != QEMU's vp_index");
+            return -ENXIO;
+        }
+    }
+
+    return 0;
+}
+
 static Error *invtsc_mig_blocker;
 
 #define KVM_MAX_CPUID_ENTRIES  100
@@ -1160,6 +1197,11 @@ int kvm_arch_init_vcpu(CPUState *cs)
         has_msr_tsc_aux = false;
     }
 
+    r = hyperv_init_vcpu(cpu);
+    if (r) {
+        goto fail;
+    }
+
     return 0;
 
  fail:
@@ -1351,6 +1393,8 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
     has_pit_state2 = kvm_check_extension(s, KVM_CAP_PIT_STATE2);
 #endif
 
+    hv_vpindex_settable = kvm_check_extension(s, KVM_CAP_HYPERV_VP_INDEX);
+
     ret = kvm_get_supported_msrs(s);
     if (ret < 0) {
         return ret;
@@ -1900,6 +1944,9 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
         if (has_msr_hv_runtime) {
             kvm_msr_entry_add(cpu, HV_X64_MSR_VP_RUNTIME, env->msr_hv_runtime);
         }
+        if (cpu->hyperv_vpindex && hv_vpindex_settable) {
+            kvm_msr_entry_add(cpu, HV_X64_MSR_VP_INDEX, hyperv_vp_index(cpu));
+        }
         if (cpu->hyperv_synic) {
             int j;
 
diff --git a/target/i386/kvm_i386.h b/target/i386/kvm_i386.h
index e5df24cad1..3057ba4f7d 100644
--- a/target/i386/kvm_i386.h
+++ b/target/i386/kvm_i386.h
@@ -63,4 +63,6 @@ void kvm_put_apicbase(X86CPU *cpu, uint64_t value);
 
 bool kvm_enable_x2apic(void);
 bool kvm_has_x2apic_api(void);
+
+bool kvm_hv_vpindex_settable(void);
 #endif