ANDROID: KVM: arm64: Allow skipping module page donation

__pkvm_map_module_page() currently goes through a full host-to-hyp
donation for every module page being mapped. However, in order to allow
mapping protected pages as modules, let's make this behaviour optional.

Bug: 278749606
Bug: 264070847
Change-Id: Ic3b1b68f11283c215bc8c6e1352f91bcf52a3935
Signed-off-by: Quentin Perret <[email protected]>

Author: Quentin Perret

arch/arm64/include/asm/kvm_pkvm_module.h

@@ -20,7 +20,7 @@ struct pkvm_module_ops {
 				      enum kvm_pgtable_prot prot,
 				      unsigned long *haddr);
 	void *(*alloc_module_va)(u64 nr_pages);
-	int (*map_module_page)(u64 pfn, void *va, enum kvm_pgtable_prot prot);
+	int (*map_module_page)(u64 pfn, void *va, enum kvm_pgtable_prot prot, bool is_protected);
 	int (*register_serial_driver)(void (*hyp_putc_cb)(char));
 	void (*putc)(char c);
 	void (*puts)(const char *s);

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

@@ -32,7 +32,7 @@ int pkvm_create_stack(phys_addr_t phys, unsigned long *haddr);
 int pkvm_alloc_private_va_range(size_t size, unsigned long *haddr);
 void pkvm_remove_mappings(void *from, void *to);
 
-int __pkvm_map_module_page(u64 pfn, void *va, enum kvm_pgtable_prot prot);
+int __pkvm_map_module_page(u64 pfn, void *va, enum kvm_pgtable_prot prot, bool is_protected);
 void __pkvm_unmap_module_page(u64 pfn, void *va);
 void *__pkvm_alloc_module_va(u64 nr_pages);
 #ifdef CONFIG_NVHE_EL2_DEBUG

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

@@ -1232,7 +1232,7 @@ static void handle___pkvm_map_module_page(struct kvm_cpu_context *host_ctxt)
 	DECLARE_REG(void *, va, host_ctxt, 2);
 	DECLARE_REG(enum kvm_pgtable_prot, prot, host_ctxt, 3);
 
-	cpu_reg(host_ctxt, 1) = (u64)__pkvm_map_module_page(pfn, va, prot);
+	cpu_reg(host_ctxt, 1) = (u64)__pkvm_map_module_page(pfn, va, prot, false);
 }
 
 static void handle___pkvm_unmap_module_page(struct kvm_cpu_context *host_ctxt)

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

@@ -150,24 +150,24 @@ void *__pkvm_alloc_module_va(u64 nr_pages)
 	return (void *)addr;
 }
 
-int __pkvm_map_module_page(u64 pfn, void *va, enum kvm_pgtable_prot prot)
+int __pkvm_map_module_page(u64 pfn, void *va, enum kvm_pgtable_prot prot, bool is_protected)
 {
 	unsigned long addr = (unsigned long)va;
 	int ret;
 
 	assert_in_mod_range(addr);
 
-	ret = __pkvm_host_donate_hyp(pfn, 1);
-	if (ret)
-		return ret;
+	if (!is_protected) {
+		ret = __pkvm_host_donate_hyp(pfn, 1);
+		if (ret)
+			return ret;
+	}
 
 	ret = __pkvm_create_mappings(addr, PAGE_SIZE, hyp_pfn_to_phys(pfn), prot);
-	if (ret) {
+	if (ret && !is_protected)
 		WARN_ON(__pkvm_hyp_donate_host(pfn, 1));
-		return ret;
-	}
 
-	return 0;
+	return ret;
 }
 
 void __pkvm_unmap_module_page(u64 pfn, void *va)