ANDROID: KVM: arm64: Automate pKVM module event registration

Previously, modules had to register themselves the .event_ids ELF
section. This is now on done on their behalf before jumping into the
module init function.

Bug: 357781595
Bug: 268495982
Change-Id: Iebe839dc096d3020921e2c97a75a5284c518dee7
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

arch/arm64/include/asm/kvm_pkvm_module.h

@@ -210,7 +210,6 @@ struct pkvm_module_ops {
 	phys_addr_t (*hyp_pa)(void *x);
 	void* (*hyp_va)(phys_addr_t phys);
 	unsigned long (*kern_hyp_va)(unsigned long x);
-	int (*register_hyp_event_ids)(unsigned long start, unsigned long end);
 	void* (*tracing_reserve_entry)(unsigned long length);
 	void (*tracing_commit_entry)(void);
 	void (*tracing_mod_hyp_printk)(u8 fmt_id, u64 a, u64 b, u64 c, u64 d);

arch/arm64/kvm/hyp/include/nvhe/trace/trace.h

@@ -7,7 +7,7 @@
 #ifdef CONFIG_TRACING
 void *tracing_reserve_entry(unsigned long length);
 void tracing_commit_entry(void);
-int register_hyp_event_ids(unsigned long start, unsigned long end);
+int register_hyp_event_ids(void *event_ids, size_t nr_events);
 
 #define HYP_EVENT(__name, __proto, __struct, __assign, __printk)		\
 	HYP_EVENT_FORMAT(__name, __struct);					\
@@ -80,7 +80,7 @@ do {							\
 #else
 static inline void *tracing_reserve_entry(unsigned long length) { return NULL; }
 static inline void tracing_commit_entry(void) { }
-static inline int register_hyp_event_ids(unsigned long start, unsigned long end)
+static inline int register_hyp_event_ids(void *event_ids, size_t nr_events)
 {
 	return -ENODEV;
 }

arch/arm64/kvm/hyp/nvhe/events.c

@@ -72,7 +72,7 @@ static bool try_set_mod_event(unsigned short id, bool enable)
 	return false;
 }
 
-int register_hyp_event_ids(unsigned long start, unsigned long end)
+int register_hyp_event_ids(void *event_ids, size_t nr_events)
 {
 	int mod, ret = -ENOMEM;
 
@@ -80,8 +80,8 @@ int register_hyp_event_ids(unsigned long start, unsigned long end)
 
 	mod = atomic_read(&num_event_id_mod);
 	if (mod < MAX_EVENT_ID_MOD) {
-		event_id_mod[mod].start = (struct hyp_event_id *)start;
-		event_id_mod[mod].end = (struct hyp_event_id *)end;
+		event_id_mod[mod].start = (struct hyp_event_id *)event_ids;
+		event_id_mod[mod].end = (struct hyp_event_id *)event_ids + nr_events;
 		/*
 		 * Order access between num_event_id_mod and event_id_mod.
 		 * Paired with try_set_mod_event()

arch/arm64/kvm/hyp/nvhe/module.lds.S

@@ -21,9 +21,7 @@ SECTIONS {
 
 	.hyp.event_ids : {
 		HYP_SECTION_SYMBOL_NAME(.event_ids) = .;
-		__hyp_event_ids_start = .;
 		*(HYP_SECTION_NAME(.event_ids))
-		__hyp_event_ids_end = .;
 		*(HYP_SECTION_NAME(.printk_fmt_offset))
 	}
 

arch/arm64/kvm/hyp/nvhe/modules.c

@@ -244,7 +244,6 @@ const struct pkvm_module_ops module_ops = {
 	.hyp_pa = hyp_virt_to_phys,
 	.hyp_va = hyp_phys_to_virt,
 	.kern_hyp_va = __kern_hyp_va,
-	.register_hyp_event_ids = register_hyp_event_ids,
 	.tracing_reserve_entry = tracing_reserve_entry,
 	.tracing_commit_entry = tracing_commit_entry,
 	.tracing_mod_hyp_printk = tracing_mod_hyp_printk,
@@ -277,6 +276,12 @@ int __pkvm_init_module(void *host_mod)
 {
 	int (*do_module_init)(const struct pkvm_module_ops *ops);
 	struct pkvm_el2_module *mod = kern_hyp_va(host_mod);
+	void *event_ids;
+
+	event_ids = pkvm_module_hyp_va(mod, mod->event_ids.start);
+
+	if (mod->nr_hyp_events)
+		register_hyp_event_ids(event_ids, mod->nr_hyp_events);
 
 	do_module_init = pkvm_module_hyp_va(mod, (void *)mod->init);
 

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

@@ -134,10 +134,6 @@ bool filter_smc(struct user_pt_regs *regs)
 
 int pkvm_smc_filter_hyp_init(const struct pkvm_module_ops *ops)
 {
-#ifdef CONFIG_TRACING
-	ops->register_hyp_event_ids((unsigned long)__hyp_event_ids_start,
-				    (unsigned long)__hyp_event_ids_end);
-#endif
 	pkvm_ops = ops;
 	return ops->register_host_smc_handler(filter_smc);
 }