diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 902dd58112..cd344716a3 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -2491,7 +2491,9 @@ struct _virDomainSEVDef {
     char *dh_cert;
     char *session;
     unsigned int policy;
+    bool haveCbitpos;
     unsigned int cbitpos;
+    bool haveReducedPhysBits;
     unsigned int reduced_phys_bits;
 };
 
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 16d6f54f66..6422881a33 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -6233,6 +6233,33 @@ qemuProcessPrepareAllowReboot(virDomainObjPtr vm)
 }
 
 
+static int
+qemuProcessUpdateSEVInfo(virDomainObjPtr vm)
+{
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    virQEMUCapsPtr qemuCaps = priv->qemuCaps;
+    virDomainSEVDefPtr sev = vm->def->sev;
+    virSEVCapabilityPtr sevCaps = NULL;
+
+    /* if platform specific info like 'cbitpos' and 'reducedPhysBits' have
+     * not been supplied, we need to autofill them from caps now as both are
+     * mandatory on QEMU cmdline
+     */
+    sevCaps = virQEMUCapsGetSEVCapabilities(qemuCaps);
+    if (!sev->haveCbitpos) {
+        sev->cbitpos = sevCaps->cbitpos;
+        sev->haveCbitpos = true;
+    }
+
+    if (!sev->haveReducedPhysBits) {
+        sev->reduced_phys_bits = sevCaps->reduced_phys_bits;
+        sev->haveReducedPhysBits = true;
+    }
+
+    return 0;
+}
+
+
 /**
  * qemuProcessPrepareDomain:
  * @driver: qemu driver
@@ -6361,6 +6388,12 @@ qemuProcessPrepareDomain(virQEMUDriverPtr driver,
     for (i = 0; i < vm->def->nshmems; i++)
         qemuDomainPrepareShmemChardev(vm->def->shmems[i]);
 
+    if (vm->def->sev) {
+        VIR_DEBUG("Updating SEV platform info");
+        if (qemuProcessUpdateSEVInfo(vm) < 0)
+            return -1;
+    }
+
     return 0;
 }