ANDROID: KVM: arm64: Pass pkvm_el2_module struct to hypervisor

When a pKVM module is initialized, only a pointer to the init function
is give to the hypervisor. With the growing set of features the pKVM
modules are supporting, more and more initialization is necessary in the
hypervisor. Give access to the pkvm_el2_module containing the
addresses of ELF sections to facilitate that job.

Bug: 357781595
Bug: 244543039
Bug: 244373730
Change-Id: Id1595719acfddeb0ae04fe6387f47ee15cc2e64f
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

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

@@ -13,7 +13,7 @@ enum pkvm_psci_notification;
 int __pkvm_register_psci_notifier(void (*cb)(enum pkvm_psci_notification, struct user_pt_regs *));
 
 #ifdef CONFIG_MODULES
-int __pkvm_init_module(void *module_init);
+int __pkvm_init_module(void *host_mod);
 int __pkvm_register_hcall(unsigned long hfn_hyp_va);
 int handle_host_dynamic_hcall(struct user_pt_regs *regs, int id);
 void __pkvm_close_module_registration(void);

arch/arm64/kvm/hyp/nvhe/hyp-main.c

@@ -1571,9 +1571,9 @@ static void handle___pkvm_unmap_module_page(struct kvm_cpu_context *host_ctxt)
 
 static void handle___pkvm_init_module(struct kvm_cpu_context *host_ctxt)
 {
-	DECLARE_REG(void *, ptr, host_ctxt, 1);
+	DECLARE_REG(void *, host_mod, host_ctxt, 1);
 
-	cpu_reg(host_ctxt, 1) = __pkvm_init_module(ptr);
+	cpu_reg(host_ctxt, 1) = __pkvm_init_module(host_mod);
 }
 
 static void handle___pkvm_register_hcall(struct kvm_cpu_context *host_ctxt)

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

@@ -5,6 +5,7 @@
 #include <asm/kvm_host.h>
 #include <asm/kvm_pkvm_module.h>
 #include <asm/kvm_hypevents.h>
+#include <asm/module.h>
 
 #include <nvhe/alloc.h>
 #include <nvhe/iommu.h>
@@ -267,9 +268,17 @@ const struct pkvm_module_ops module_ops = {
 	.hyp_smp_processor_id = __hyp_smp_processor_id,
 };
 
-int __pkvm_init_module(void *module_init)
+static void *pkvm_module_hyp_va(struct pkvm_el2_module *mod, void *kern_va)
 {
-	int (*do_module_init)(const struct pkvm_module_ops *ops) = module_init;
+	return kern_va - mod->sections.start + mod->hyp_va;
+}
+
+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);
+
+	do_module_init = pkvm_module_hyp_va(mod, (void *)mod->init);
 
 	return do_module_init(&module_ops);
 }

arch/arm64/kvm/pkvm.c

@@ -1015,6 +1015,7 @@ static int pkvm_map_module_sections(struct pkvm_mod_sec_mapping *secs_map,
 
 	return 0;
 }
+
 static int __pkvm_cmp_mod_sec(const void *p1, const void *p2)
 {
 	struct pkvm_mod_sec_mapping const *s1 = p1;
@@ -1023,6 +1024,33 @@ static int __pkvm_cmp_mod_sec(const void *p1, const void *p2)
 	return s1->sec->start < s2->sec->start ? -1 : s1->sec->start > s2->sec->start;
 }
 
+static void *pkvm_map_module_struct(struct pkvm_el2_module *mod)
+{
+	void *addr = (void *)__get_free_page(GFP_KERNEL);
+
+	if (!addr)
+		return NULL;
+
+	if (kvm_share_hyp(addr, addr + PAGE_SIZE)) {
+		free_page((unsigned long)addr);
+		return NULL;
+	}
+
+	/*
+	 * pkvm_el2_module being stored in vmalloc we can't guarantee a
+	 * linear map for the hypervisor to rely on. Copy the struct instead.
+	 */
+	memcpy(addr, mod, sizeof(*mod));
+
+	return addr;
+}
+
+static void pkvm_unmap_module_struct(void *addr)
+{
+	kvm_unshare_hyp(addr, addr + PAGE_SIZE);
+	free_page((unsigned long)addr);
+}
+
 int __pkvm_load_el2_module(struct module *this, unsigned long *token)
 {
 	struct pkvm_el2_module *mod = &this->arch.hyp;
@@ -1033,11 +1061,11 @@ int __pkvm_load_el2_module(struct module *this, unsigned long *token)
 		{ &mod->event_ids, KVM_PGTABLE_PROT_R },
 		{ &mod->data, KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W },
 	};
-	void *start, *end, *hyp_va;
+	void *start, *end, *hyp_va, *mod_remap;
 	struct arm_smccc_res res;
 	kvm_nvhe_reloc_t *endrel;
 	int ret, i, secs_first;
-	size_t offset, size;
+	size_t size;
 
 	/* The pKVM hyp only allows loading before it is fully initialized */
 	if (!is_protected_kvm_enabled() || is_pkvm_initialized())
@@ -1115,18 +1143,25 @@ int __pkvm_load_el2_module(struct module *this, unsigned long *token)
 	if (ret)
 		kvm_err("Failed to init module events: %d\n", ret);
 
+	mod_remap = pkvm_map_module_struct(mod);
+	if (!mod_remap) {
+		module_put(this);
+		return -ENOMEM;
+	}
+
 	ret = pkvm_map_module_sections(secs_map + secs_first, hyp_va,
 				       ARRAY_SIZE(secs_map) - secs_first);
 	if (ret) {
 		kvm_err("Failed to map EL2 module page: %d\n", ret);
+		pkvm_unmap_module_struct(mod_remap);
 		module_put(this);
 		return ret;
 	}
 
 	pkvm_el2_mod_add(mod);
 
-	offset = (size_t)((void *)mod->init - start);
-	ret = kvm_call_hyp_nvhe(__pkvm_init_module, hyp_va + offset);
+	ret = kvm_call_hyp_nvhe(__pkvm_init_module, mod_remap);
+	pkvm_unmap_module_struct(mod_remap);
 	if (ret) {
 		kvm_err("Failed to init EL2 module: %d\n", ret);
 		list_del(&mod->node);