ANDROID: misc: pkvm_smc: Add permissive option

Add module param "permissive", that only logs the violations, that
can be useful for bring-up.

Bug: 278009271
Bug: 357781595
Change-Id: I07fd4e8e043fdcc0017350a43da434e965a17de3
Signed-off-by: Mostafa Saleh <smostafa@google.com>

drivers/misc/pkvm-smc/pkvm-smc.c

@@ -14,17 +14,24 @@
 
 static unsigned long pkvm_module_token;
 int kvm_nvhe_sym(pkvm_smc_filter_hyp_init)(const struct pkvm_module_ops *ops);
+extern int kvm_nvhe_sym(permissive);
+
+static bool permissive;
+module_param(permissive, bool, 0444);
+MODULE_PARM_DESC(permissive, "Only log SMC filter violations.");
 
 static int __init smc_filter_init(void)
 {
 	int ret;
 
+	kvm_nvhe_sym(permissive) = permissive;
 	ret = pkvm_load_el2_module(kvm_nvhe_sym(pkvm_smc_filter_hyp_init),
 				   &pkvm_module_token);
 	if (ret)
 		pr_err("Failed to register pKVM SMC filter: %d\n", ret);
 	else
-		pr_info("pKVM SMC filter registered successfully\n");
+		pr_info("pKVM SMC filter registered successfully with permissive = %s\n",
+			permissive ? "true" : "false");
 
 	return ret;
 }

drivers/misc/pkvm-smc/pkvm/pkvm-smc.c

@@ -14,6 +14,7 @@
 #include <define_events.h>
 
 const struct pkvm_module_ops *pkvm_ops;
+bool permissive;
 
 #ifdef CONFIG_TRACING
 extern char __hyp_event_ids_start[];
@@ -38,6 +39,10 @@ struct pkvm_smc_filter {
 static bool deny_smc(struct user_pt_regs *regs)
 {
 	trace_filtered_smc(regs->regs[0]);
+
+	if (permissive)
+		return false;
+
 	regs->regs[0] = SMCCC_RET_NOT_SUPPORTED;
 	return true;
 }