ANDROID: KVM: arm64: Add .hyp.data section

The hypervisor has not needed its own .data section because all globals
were either .rodata or .bss. Linked lists are initialized with the head
pointing to itself. To avoid having to work around this by initializing
at runtime, add a .hyp.data section.

Bug: 190463801
Signed-off-by: David Brazdil <dbrazdil@google.com>
Change-Id: I7a56dc4c93e05bbef53c66837164d17c6103b6b8

arch/arm64/include/asm/sections.h

@@ -11,6 +11,7 @@ extern char __alt_instructions[], __alt_instructions_end[];
 extern char __hibernate_exit_text_start[], __hibernate_exit_text_end[];
 extern char __hyp_idmap_text_start[], __hyp_idmap_text_end[];
 extern char __hyp_text_start[], __hyp_text_end[];
+extern char __hyp_data_start[], __hyp_data_end[];
 extern char __hyp_rodata_start[], __hyp_rodata_end[];
 extern char __hyp_reloc_begin[], __hyp_reloc_end[];
 extern char __hyp_bss_start[], __hyp_bss_end[];

arch/arm64/kernel/image-vars.h

@@ -125,6 +125,8 @@ KVM_NVHE_ALIAS(__hyp_text_start);
 KVM_NVHE_ALIAS(__hyp_text_end);
 KVM_NVHE_ALIAS(__hyp_bss_start);
 KVM_NVHE_ALIAS(__hyp_bss_end);
+KVM_NVHE_ALIAS(__hyp_data_start);
+KVM_NVHE_ALIAS(__hyp_data_end);
 KVM_NVHE_ALIAS(__hyp_rodata_start);
 KVM_NVHE_ALIAS(__hyp_rodata_end);
 

arch/arm64/kernel/vmlinux.lds.S

@@ -13,7 +13,7 @@
 	*(__kvm_ex_table)					\
 	__stop___kvm_ex_table = .;
 
-#define HYPERVISOR_DATA_SECTIONS				\
+#define HYPERVISOR_RODATA_SECTIONS				\
 	HYP_SECTION_NAME(.rodata) : {				\
 		. = ALIGN(PAGE_SIZE);				\
 		__hyp_rodata_start = .;				\
@@ -23,6 +23,15 @@
 		__hyp_rodata_end = .;				\
 	}
 
+#define HYPERVISOR_DATA_SECTION					\
+	HYP_SECTION_NAME(.data) : {				\
+		. = ALIGN(PAGE_SIZE);				\
+		__hyp_data_start = .;				\
+		*(HYP_SECTION_NAME(.data))			\
+		. = ALIGN(PAGE_SIZE);				\
+		__hyp_data_end = .;				\
+	}
+
 #define HYPERVISOR_PERCPU_SECTION				\
 	. = ALIGN(PAGE_SIZE);					\
 	HYP_SECTION_NAME(.data..percpu) : {			\
@@ -51,7 +60,8 @@
 #define SBSS_ALIGN			PAGE_SIZE
 #else /* CONFIG_KVM */
 #define HYPERVISOR_EXTABLE
-#define HYPERVISOR_DATA_SECTIONS
+#define HYPERVISOR_RODATA_SECTIONS
+#define HYPERVISOR_DATA_SECTION
 #define HYPERVISOR_PERCPU_SECTION
 #define HYPERVISOR_RELOC_SECTION
 #define SBSS_ALIGN			0
@@ -181,7 +191,7 @@ SECTIONS
 	/* everything from this point to __init_begin will be marked RO NX */
 	RO_DATA(PAGE_SIZE)
 
-	HYPERVISOR_DATA_SECTIONS
+	HYPERVISOR_RODATA_SECTIONS
 
 	idmap_pg_dir = .;
 	. += IDMAP_DIR_SIZE;
@@ -262,6 +272,8 @@ SECTIONS
 	_sdata = .;
 	RW_DATA(L1_CACHE_BYTES, PAGE_SIZE, THREAD_ALIGN)
 
+	HYPERVISOR_DATA_SECTION
+
 	/*
 	 * Data written with the MMU off but read with the MMU on requires
 	 * cache lines to be invalidated, discarding up to a Cache Writeback

arch/arm64/kvm/arm.c

@@ -2061,6 +2061,13 @@ static int init_hyp_mode(void)
 		goto out_err;
 	}
 
+	err = create_hyp_mappings(kvm_ksym_ref(__hyp_data_start),
+				  kvm_ksym_ref(__hyp_data_end), PAGE_HYP);
+	if (err) {
+		kvm_err("Cannot map .hyp.data section\n");
+		goto out_err;
+	}
+
 	err = create_hyp_mappings(kvm_ksym_ref(__hyp_rodata_start),
 				  kvm_ksym_ref(__hyp_rodata_end), PAGE_HYP_RO);
 	if (err) {

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

@@ -25,5 +25,7 @@ SECTIONS {
 	BEGIN_HYP_SECTION(.data..percpu)
 		PERCPU_INPUT(L1_CACHE_BYTES)
 	END_HYP_SECTION
+
 	HYP_SECTION(.bss)
+	HYP_SECTION(.data)
 }

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

@@ -101,6 +101,10 @@ static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size,
 	if (ret)
 		return ret;
 
+	ret = pkvm_create_mappings(__hyp_data_start, __hyp_data_end, PAGE_HYP);
+	if (ret)
+		return ret;
+
 	ret = pkvm_create_mappings(__hyp_rodata_start, __hyp_rodata_end, PAGE_HYP_RO);
 	if (ret)
 		return ret;