qapi/qom,target/i386: sev-guest: Introduce kernel-hashes=on|off option

Introduce new boolean 'kernel-hashes' option on the sev-guest object.
It will be used to to decide whether to add the hashes of
kernel/initrd/cmdline to SEV guest memory when booting with -kernel.
The default value is 'off'.

Signed-off-by: Dov Murik <dovmurik@linux.ibm.com>
Acked-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
diff --git a/qemu-options.hx b/qemu-options.hx
index 7749f59..ae2c6db 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -5189,7 +5189,7 @@
                  -object secret,id=sec0,keyid=secmaster0,format=base64,\\
                      data=$SECRET,iv=$(<iv.b64)
 
-    ``-object sev-guest,id=id,cbitpos=cbitpos,reduced-phys-bits=val,[sev-device=string,policy=policy,handle=handle,dh-cert-file=file,session-file=file]``
+    ``-object sev-guest,id=id,cbitpos=cbitpos,reduced-phys-bits=val,[sev-device=string,policy=policy,handle=handle,dh-cert-file=file,session-file=file,kernel-hashes=on|off]``
         Create a Secure Encrypted Virtualization (SEV) guest object,
         which can be used to provide the guest memory encryption support
         on AMD processors.
@@ -5229,6 +5229,10 @@
         session with the guest owner to negotiate keys used for
         attestation. The file must be encoded in base64.
 
+        The ``kernel-hashes`` adds the hashes of given kernel/initrd/
+        cmdline to a designated guest firmware page for measured Linux
+        boot with -kernel. The default is off. (Since 6.2)
+
         e.g to launch a SEV guest
 
         .. parsed-literal::