powerpc/papr_scm: Mark nvdimm as unarmed if needed during probe

In case an nvdimm is found to be unarmed during probe then set its
NDD_UNARMED flag before nvdimm_create(). This would enforce a
read-only access to the ndimm region. Presently even if an nvdimm is
unarmed its not marked as read-only on ppc64 guests.

The patch updates papr_scm_nvdimm_init() to force query of nvdimm
health via __drc_pmem_query_health() and if nvdimm is found to be
unarmed then set the nvdimm flag ND_UNARMED for nvdimm_create().
Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210329113103.476760-1-vaibhav@linux.ibm.com

arch/powerpc/platforms/pseries/papr_scm.c

@@ -947,6 +947,15 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
 	dimm_flags = 0;
 	set_bit(NDD_LABELING, &dimm_flags);
 
+	/*
+	 * Check if the nvdimm is unarmed. No locking needed as we are still
+	 * initializing. Ignore error encountered if any.
+	 */
+	__drc_pmem_query_health(p);
+
+	if (p->health_bitmap & PAPR_PMEM_UNARMED_MASK)
+		set_bit(NDD_UNARMED, &dimm_flags);
+
 	p->nvdimm = nvdimm_create(p->bus, p, papr_nd_attr_groups,
 				  dimm_flags, PAPR_SCM_DIMM_CMD_MASK, 0, NULL);
 	if (!p->nvdimm) {