diff --git a/docs/manpages/virt-qemu-sev-validate.rst b/docs/manpages/virt-qemu-sev-validate.rst
index 34ef328fe8..eef8a0281c 100644
--- a/docs/manpages/virt-qemu-sev-validate.rst
+++ b/docs/manpages/virt-qemu-sev-validate.rst
@@ -358,7 +358,6 @@ Validate the measurement of a SEV-ES SMP guest booting from disk:
 
    # virt-dom-sev-validate \
        --insecure \
-       --num-cpus 2 \
        --vmsa-cpu0 vmsa0.bin \
        --vmsa-cpu1 vmsa1.bin \
        --tk this-guest-tk.bin \
@@ -371,9 +370,6 @@ automatically constructed VMSA:
 
    # virt-dom-sev-validate \
        --insecure \
-       --cpu-family 23 \
-       --cpu-model 49 \
-       --cpu-stepping 0 \
        --tk this-guest-tk.bin \
        --domain fedora34x86_64
 
diff --git a/tools/virt-qemu-sev-validate b/tools/virt-qemu-sev-validate
index ef8fa6fa27..37f6f65bac 100755
--- a/tools/virt-qemu-sev-validate
+++ b/tools/virt-qemu-sev-validate
@@ -873,6 +873,14 @@ class LibvirtConfidentialVM(ConfidentialVM):
         if self.policy is None:
             self.policy = sevinfo["sev-policy"]
 
+        if self.is_sev_es() and self.num_cpus is None:
+            if secure:
+                raise InsecureUsageException(
+                    "Using CPU count from guest is not secure")
+
+            info = self.dom.info()
+            self.num_cpus = info[3]
+
         if self.firmware is None:
             if remote:
                 raise UnsupportedUsageException(
@@ -918,6 +926,24 @@ class LibvirtConfidentialVM(ConfidentialVM):
                         "Using cmdline string from XML is not secure")
                 self.kernel_table.load_cmdline(cmdlinenodes[0].text)
 
+        capsxml = self.conn.getCapabilities()
+        capsdoc = etree.fromstring(capsxml)
+
+        if self.is_sev_es() and self.vmsa_cpu0 is None:
+            if secure:
+                raise InsecureUsageException(
+                    "Using CPU SKU from capabilities is not secure")
+
+            sig = capsdoc.xpath("/capabilities/host/cpu/signature")
+            if len(sig) != 1:
+                raise UnsupportedUsageException(
+                    "Libvirt is too old to report host CPU signature")
+
+            cpu_family = int(sig[0].get("family"))
+            cpu_model = int(sig[0].get("model"))
+            cpu_stepping = int(sig[0].get("stepping"))
+            self.build_vmsas(cpu_family, cpu_model, cpu_stepping)
+
 
 def parse_command_line():
     parser = argparse.ArgumentParser(