diff --git a/docs/hyperv.txt b/docs/hyperv.txt
index 8fdf25c829..6518b716a9 100644
--- a/docs/hyperv.txt
+++ b/docs/hyperv.txt
@@ -184,6 +184,19 @@ enabled.
 
 Requires: hv-vpindex, hv-synic, hv-time, hv-stimer
 
+3.17. hv-no-nonarch-coresharing=on/off/auto
+===========================================
+This enlightenment tells guest OS that virtual processors will never share a
+physical core unless they are reported as sibling SMT threads. This information
+is required by Windows and Hyper-V guests to properly mitigate SMT related CPU
+vulnerabilities.
+When the option is set to 'auto' QEMU will enable the feature only when KVM
+reports that non-architectural coresharing is impossible, this means that
+hyper-threading is not supported or completely disabled on the host. This
+setting also prevents migration as SMT settings on the destination may differ.
+When the option is set to 'on' QEMU will always enable the feature, regardless
+of host setup. To keep guests secure, this can only be used in conjunction with
+exposing correct vCPU topology and vCPU pinning.
 
 4. Development features
 ========================
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 47200b40c1..6c87c99487 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6174,6 +6174,8 @@ static Property x86_cpu_properties[] = {
                       HYPERV_FEAT_IPI, 0),
     DEFINE_PROP_BIT64("hv-stimer-direct", X86CPU, hyperv_features,
                       HYPERV_FEAT_STIMER_DIRECT, 0),
+    DEFINE_PROP_ON_OFF_AUTO("hv-no-nonarch-coresharing", X86CPU,
+                            hyperv_no_nonarch_cs, ON_OFF_AUTO_OFF),
     DEFINE_PROP_BOOL("hv-passthrough", X86CPU, hyperv_passthrough, false),
 
     DEFINE_PROP_BOOL("check", X86CPU, check_cpuid, true),
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index cedb5bc205..c50a9c7257 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -24,6 +24,7 @@
 #include "cpu-qom.h"
 #include "hyperv-proto.h"
 #include "exec/cpu-defs.h"
+#include "qapi/qapi-types-common.h"
 
 /* The x86 has a strong memory model with some store-after-load re-ordering */
 #define TCG_GUEST_DEFAULT_MO      (TCG_MO_ALL & ~TCG_MO_ST_LD)
@@ -1614,6 +1615,7 @@ struct X86CPU {
     bool hyperv_synic_kvm_only;
     uint64_t hyperv_features;
     bool hyperv_passthrough;
+    OnOffAuto hyperv_no_nonarch_cs;
 
     bool check_cpuid;
     bool enforce_cpuid;
diff --git a/target/i386/hyperv-proto.h b/target/i386/hyperv-proto.h
index cffac10b45..056a305be3 100644
--- a/target/i386/hyperv-proto.h
+++ b/target/i386/hyperv-proto.h
@@ -63,6 +63,7 @@
 #define HV_CLUSTER_IPI_RECOMMENDED          (1u << 10)
 #define HV_EX_PROCESSOR_MASKS_RECOMMENDED   (1u << 11)
 #define HV_ENLIGHTENED_VMCS_RECOMMENDED     (1u << 14)
+#define HV_NO_NONARCH_CORESHARING           (1u << 18)
 
 /*
  * Basic virtualized MSRs
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 0e3da998d1..49a301190a 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -1227,6 +1227,16 @@ static int hyperv_handle_properties(CPUState *cs,
         }
     }
 
+    if (cpu->hyperv_no_nonarch_cs == ON_OFF_AUTO_ON) {
+        env->features[FEAT_HV_RECOMM_EAX] |= HV_NO_NONARCH_CORESHARING;
+    } else if (cpu->hyperv_no_nonarch_cs == ON_OFF_AUTO_AUTO) {
+        c = cpuid_find_entry(cpuid, HV_CPUID_ENLIGHTMENT_INFO, 0);
+        if (c) {
+            env->features[FEAT_HV_RECOMM_EAX] |=
+                c->eax & HV_NO_NONARCH_CORESHARING;
+        }
+    }
+
     /* Features */
     r = hv_cpuid_check_and_set(cs, cpuid, HYPERV_FEAT_RELAXED);
     r |= hv_cpuid_check_and_set(cs, cpuid, HYPERV_FEAT_VAPIC);
@@ -1340,6 +1350,7 @@ free:
 }
 
 static Error *hv_passthrough_mig_blocker;
+static Error *hv_no_nonarch_cs_mig_blocker;
 
 static int hyperv_init_vcpu(X86CPU *cpu)
 {
@@ -1359,6 +1370,21 @@ static int hyperv_init_vcpu(X86CPU *cpu)
         }
     }
 
+    if (cpu->hyperv_no_nonarch_cs == ON_OFF_AUTO_AUTO &&
+        hv_no_nonarch_cs_mig_blocker == NULL) {
+        error_setg(&hv_no_nonarch_cs_mig_blocker,
+                   "'hv-no-nonarch-coresharing=auto' CPU flag prevents migration"
+                   " use explicit 'hv-no-nonarch-coresharing=on' instead (but"
+                   " make sure SMT is disabled and/or that vCPUs are properly"
+                   " pinned)");
+        ret = migrate_add_blocker(hv_no_nonarch_cs_mig_blocker, &local_err);
+        if (local_err) {
+            error_report_err(local_err);
+            error_free(hv_no_nonarch_cs_mig_blocker);
+            return ret;
+        }
+    }
+
     if (hyperv_feat_enabled(cpu, HYPERV_FEAT_VPINDEX) && !hv_vpindex_settable) {
         /*
          * the kernel doesn't support setting vp_index; assert that its value