arch/arm64/include/asm/kvm_mmu.h - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * Copyright (C) 2012,2013 - ARM Ltd
  * Author: Marc Zyngier <marc.zyngier@arm.com>
  */

 #ifndef __ARM64_KVM_MMU_H__
 #define __ARM64_KVM_MMU_H__

 #include <asm/page.h>
 #include <asm/memory.h>
 #include <asm/mmu.h>
 #include <asm/cpufeature.h>

 /*
  * As ARMv8.0 only has the TTBR0_EL2 register, we cannot express
  * "negative" addresses. This makes it impossible to directly share
  * mappings with the kernel.
  *
  * Instead, give the HYP mode its own VA region at a fixed offset from
  * the kernel by just masking the top bits (which are all ones for a
  * kernel address). We need to find out how many bits to mask.
  *
  * We want to build a set of page tables that cover both parts of the
  * idmap (the trampoline page used to initialize EL2), and our normal
  * runtime VA space, at the same time.
  *
  * Given that the kernel uses VA_BITS for its entire address space,
  * and that half of that space (VA_BITS - 1) is used for the linear
  * mapping, we can also limit the EL2 space to (VA_BITS - 1).
  *
  * The main question is "Within the VA_BITS space, does EL2 use the
  * top or the bottom half of that space to shadow the kernel's linear
  * mapping?". As we need to idmap the trampoline page, this is
  * determined by the range in which this page lives.
  *
  * If the page is in the bottom half, we have to use the top half. If
  * the page is in the top half, we have to use the bottom half:
  *
  * T = __pa_symbol(__hyp_idmap_text_start)
  * if (T & BIT(VA_BITS - 1))
  *	HYP_VA_MIN = 0  //idmap in upper half
  * else
  *	HYP_VA_MIN = 1 << (VA_BITS - 1)
  * HYP_VA_MAX = HYP_VA_MIN + (1 << (VA_BITS - 1)) - 1
  *
  * When using VHE, there are no separate hyp mappings and all KVM
  * functionality is already mapped as part of the main kernel
  * mappings, and none of this applies in that case.
  */

 #ifdef __ASSEMBLY__

 #include <asm/alternative.h>

 /*
  * Convert a hypervisor VA to a PA
  * reg: hypervisor address to be converted in place
  * tmp: temporary register
  */
 .macro hyp_pa reg, tmp
 	ldr_l	\tmp, hyp_physvirt_offset
 	add	\reg, \reg, \tmp
 .endm

 /*
  * Convert a hypervisor VA to a kernel image address
  * reg: hypervisor address to be converted in place
  * tmp: temporary register
  *
  * The actual code generation takes place in kvm_get_kimage_voffset, and
  * the instructions below are only there to reserve the space and
  * perform the register allocation (kvm_get_kimage_voffset uses the
  * specific registers encoded in the instructions).
  */
 .macro hyp_kimg_va reg, tmp
 	/* Convert hyp VA -> PA. */
 	hyp_pa	\reg, \tmp

 	/* Load kimage_voffset. */
 alternative_cb ARM64_ALWAYS_SYSTEM, kvm_get_kimage_voffset
 	movz	\tmp, #0
 	movk	\tmp, #0, lsl #16
 	movk	\tmp, #0, lsl #32
 	movk	\tmp, #0, lsl #48
 alternative_cb_end

 	/* Convert PA -> kimg VA. */
 	add	\reg, \reg, \tmp
 .endm

 #else

 #include <linux/pgtable.h>
 #include <asm/pgalloc.h>
 #include <asm/cache.h>
 #include <asm/cacheflush.h>
 #include <asm/mmu_context.h>
 #include <asm/kvm_emulate.h>
 #include <asm/kvm_host.h>
 #include <asm/kvm_nested.h>

 void kvm_update_va_mask(struct alt_instr *alt,
 			__le32 *origptr, __le32 *updptr, int nr_inst);
 void kvm_compute_layout(void);
 void kvm_apply_hyp_relocations(void);

 #define __hyp_pa(x) (((phys_addr_t)(x)) + hyp_physvirt_offset)

 /*
  * Convert a kernel VA into a HYP VA.
  *
  * Can be called from hyp or non-hyp context.
  *
  * The actual code generation takes place in kvm_update_va_mask(), and
  * the instructions below are only there to reserve the space and
  * perform the register allocation (kvm_update_va_mask() uses the
  * specific registers encoded in the instructions).
  */
 static __always_inline unsigned long __kern_hyp_va(unsigned long v)
 {
 /*
  * This #ifndef is an optimisation for when this is called from VHE hyp
  * context.  When called from a VHE non-hyp context, kvm_update_va_mask() will
  * replace the instructions with `nop`s.
  */
 #ifndef __KVM_VHE_HYPERVISOR__
 	asm volatile(ALTERNATIVE_CB("and %0, %0, #1\n"         /* mask with va_mask */
 				    "ror %0, %0, #1\n"         /* rotate to the first tag bit */
 				    "add %0, %0, #0\n"         /* insert the low 12 bits of the tag */
 				    "add %0, %0, #0, lsl 12\n" /* insert the top 12 bits of the tag */
 				    "ror %0, %0, #63\n",       /* rotate back */
 				    ARM64_ALWAYS_SYSTEM,
 				    kvm_update_va_mask)
 		     : "+r" (v));
 #endif
 	return v;
 }

 #define kern_hyp_va(v) 	((typeof(v))(__kern_hyp_va((unsigned long)(v))))

 /*
  * We currently support using a VM-specified IPA size. For backward
  * compatibility, the default IPA size is fixed to 40bits.
  */
 #define KVM_PHYS_SHIFT	(40)

 #define kvm_phys_shift(mmu)		VTCR_EL2_IPA((mmu)->vtcr)
 #define kvm_phys_size(mmu)		(_AC(1, ULL) << kvm_phys_shift(mmu))
 #define kvm_phys_mask(mmu)		(kvm_phys_size(mmu) - _AC(1, ULL))

 #include <asm/kvm_pgtable.h>
 #include <asm/stage2_pgtable.h>

 int kvm_share_hyp(void *from, void *to);
 void kvm_unshare_hyp(void *from, void *to);
 int create_hyp_mappings(void *from, void *to, enum kvm_pgtable_prot prot);
 int __create_hyp_mappings(unsigned long start, unsigned long size,
 			  unsigned long phys, enum kvm_pgtable_prot prot);
 int hyp_alloc_private_va_range(size_t size, unsigned long *haddr);
 int create_hyp_io_mappings(phys_addr_t phys_addr, size_t size,
 			   void __iomem **kaddr,
 			   void __iomem **haddr);
 int create_hyp_exec_mappings(phys_addr_t phys_addr, size_t size,
 			     void **haddr);
 int create_hyp_stack(phys_addr_t phys_addr, unsigned long *haddr);
 void __init free_hyp_pgds(void);

 void kvm_stage2_unmap_range(struct kvm_s2_mmu *mmu, phys_addr_t start,
 			    u64 size, bool may_block);
 void kvm_stage2_flush_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end);
 void kvm_stage2_wp_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end);

 void stage2_unmap_vm(struct kvm *kvm);
 int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long type);
 void kvm_uninit_stage2_mmu(struct kvm *kvm);
 void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu);
 int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
 			  phys_addr_t pa, unsigned long size, bool writable);

 int kvm_handle_guest_abort(struct kvm_vcpu *vcpu);

 phys_addr_t kvm_mmu_get_httbr(void);
 phys_addr_t kvm_get_idmap_vector(void);
 int __init kvm_mmu_init(u32 *hyp_va_bits);

 static inline void *__kvm_vector_slot2addr(void *base,
 					   enum arm64_hyp_spectre_vector slot)
 {
 	int idx = slot - (slot != HYP_VECTOR_DIRECT);

 	return base + (idx * SZ_2K);
 }

 struct kvm;

 #define kvm_flush_dcache_to_poc(a,l)	\
 	dcache_clean_inval_poc((unsigned long)(a), (unsigned long)(a)+(l))

 static inline bool vcpu_has_cache_enabled(struct kvm_vcpu *vcpu)
 {
 	u64 cache_bits = SCTLR_ELx_M | SCTLR_ELx_C;
 	int reg;

 	if (vcpu_is_el2(vcpu))
 		reg = SCTLR_EL2;
 	else
 		reg = SCTLR_EL1;

 	return (vcpu_read_sys_reg(vcpu, reg) & cache_bits) == cache_bits;
 }

 static inline void __clean_dcache_guest_page(void *va, size_t size)
 {
 	/*
 	 * With FWB, we ensure that the guest always accesses memory using
 	 * cacheable attributes, and we don't have to clean to PoC when
 	 * faulting in pages. Furthermore, FWB implies IDC, so cleaning to
 	 * PoU is not required either in this case.
 	 */
 	if (cpus_have_final_cap(ARM64_HAS_STAGE2_FWB))
 		return;

 	kvm_flush_dcache_to_poc(va, size);
 }

 static inline size_t __invalidate_icache_max_range(void)
 {
 	u8 iminline;
 	u64 ctr;

 	asm volatile(ALTERNATIVE_CB("movz %0, #0\n"
 				    "movk %0, #0, lsl #16\n"
 				    "movk %0, #0, lsl #32\n"
 				    "movk %0, #0, lsl #48\n",
 				    ARM64_ALWAYS_SYSTEM,
 				    kvm_compute_final_ctr_el0)
 		     : "=r" (ctr));

 	iminline = SYS_FIELD_GET(CTR_EL0, IminLine, ctr) + 2;
 	return MAX_DVM_OPS << iminline;
 }

 static inline void __invalidate_icache_guest_page(void *va, size_t size)
 {
 	/*
 	 * Blow the whole I-cache if it is aliasing (i.e. VIPT) or the
 	 * invalidation range exceeds our arbitrary limit on invadations by
 	 * cache line.
 	 */
 	if (icache_is_aliasing() || size > __invalidate_icache_max_range())
 		icache_inval_all_pou();
 	else
 		icache_inval_pou((unsigned long)va, (unsigned long)va + size);
 }

 void kvm_set_way_flush(struct kvm_vcpu *vcpu);
 void kvm_toggle_cache(struct kvm_vcpu *vcpu, bool was_enabled);

 static inline unsigned int kvm_get_vmid_bits(void)
 {
 	int reg = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);

 	return get_vmid_bits(reg);
 }

 /*
  * We are not in the kvm->srcu critical section most of the time, so we take
  * the SRCU read lock here. Since we copy the data from the user page, we
  * can immediately drop the lock again.
  */
 static inline int kvm_read_guest_lock(struct kvm *kvm,
 				      gpa_t gpa, void *data, unsigned long len)
 {
 	int srcu_idx = srcu_read_lock(&kvm->srcu);
 	int ret = kvm_read_guest(kvm, gpa, data, len);

 	srcu_read_unlock(&kvm->srcu, srcu_idx);

 	return ret;
 }

 static inline int kvm_write_guest_lock(struct kvm *kvm, gpa_t gpa,
 				       const void *data, unsigned long len)
 {
 	int srcu_idx = srcu_read_lock(&kvm->srcu);
 	int ret = kvm_write_guest(kvm, gpa, data, len);

 	srcu_read_unlock(&kvm->srcu, srcu_idx);

 	return ret;
 }

 #define kvm_phys_to_vttbr(addr)		phys_to_ttbr(addr)

 /*
  * When this is (directly or indirectly) used on the TLB invalidation
  * path, we rely on a previously issued DSB so that page table updates
  * and VMID reads are correctly ordered.
  */
 static __always_inline u64 kvm_get_vttbr(struct kvm_s2_mmu *mmu)
 {
 	struct kvm_vmid *vmid = &mmu->vmid;
 	u64 vmid_field, baddr;
 	u64 cnp = system_supports_cnp() ? VTTBR_CNP_BIT : 0;

 	baddr = mmu->pgd_phys;
 	vmid_field = atomic64_read(&vmid->id) << VTTBR_VMID_SHIFT;
 	vmid_field &= VTTBR_VMID_MASK(kvm_arm_vmid_bits);
 	return kvm_phys_to_vttbr(baddr) | vmid_field | cnp;
 }

 /*
  * Must be called from hyp code running at EL2 with an updated VTTBR
  * and interrupts disabled.
  */
 static __always_inline void __load_stage2(struct kvm_s2_mmu *mmu,
 					  struct kvm_arch *arch)
 {
 	write_sysreg(mmu->vtcr, vtcr_el2);
 	write_sysreg(kvm_get_vttbr(mmu), vttbr_el2);

 	/*
 	 * ARM errata 1165522 and 1530923 require the actual execution of the
 	 * above before we can switch to the EL1/EL0 translation regime used by
 	 * the guest.
 	 */
 	asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_SPECULATIVE_AT));
 }

 static inline struct kvm *kvm_s2_mmu_to_kvm(struct kvm_s2_mmu *mmu)
 {
 	return container_of(mmu->arch, struct kvm, arch);
 }

 static inline u64 get_vmid(u64 vttbr)
 {
 	return (vttbr & VTTBR_VMID_MASK(kvm_get_vmid_bits())) >>
 		VTTBR_VMID_SHIFT;
 }

 static inline bool kvm_s2_mmu_valid(struct kvm_s2_mmu *mmu)
 {
 	return !(mmu->tlb_vttbr & VTTBR_CNP_BIT);
 }

 static inline bool kvm_is_nested_s2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu)
 {
 	/*
 	 * Be careful, mmu may not be fully initialised so do look at
 	 * *any* of its fields.
 	 */
 	return &kvm->arch.mmu != mmu;
 }

 #ifdef CONFIG_PTDUMP_STAGE2_DEBUGFS
 void kvm_s2_ptdump_create_debugfs(struct kvm *kvm);
 #else
 static inline void kvm_s2_ptdump_create_debugfs(struct kvm *kvm) {}
 #endif /* CONFIG_PTDUMP_STAGE2_DEBUGFS */

 #endif /* __ASSEMBLY__ */
 #endif /* __ARM64_KVM_MMU_H__ */
	/* SPDX-License-Identifier: GPL-2.0-only */
	/*
	* Copyright (C) 2012,2013 - ARM Ltd
	* Author: Marc Zyngier <marc.zyngier@arm.com>
	*/

	#ifndef __ARM64_KVM_MMU_H__
	#define __ARM64_KVM_MMU_H__

	#include <asm/page.h>
	#include <asm/memory.h>
	#include <asm/mmu.h>
	#include <asm/cpufeature.h>

	/*
	* As ARMv8.0 only has the TTBR0_EL2 register, we cannot express
	* "negative" addresses. This makes it impossible to directly share
	* mappings with the kernel.
	*
	* Instead, give the HYP mode its own VA region at a fixed offset from
	* the kernel by just masking the top bits (which are all ones for a
	* kernel address). We need to find out how many bits to mask.
	*
	* We want to build a set of page tables that cover both parts of the
	* idmap (the trampoline page used to initialize EL2), and our normal
	* runtime VA space, at the same time.
	*
	* Given that the kernel uses VA_BITS for its entire address space,
	* and that half of that space (VA_BITS - 1) is used for the linear
	* mapping, we can also limit the EL2 space to (VA_BITS - 1).
	*
	* The main question is "Within the VA_BITS space, does EL2 use the
	* top or the bottom half of that space to shadow the kernel's linear
	* mapping?". As we need to idmap the trampoline page, this is
	* determined by the range in which this page lives.
	*
	* If the page is in the bottom half, we have to use the top half. If
	* the page is in the top half, we have to use the bottom half:
	*
	* T = __pa_symbol(__hyp_idmap_text_start)
	* if (T & BIT(VA_BITS - 1))
	* HYP_VA_MIN = 0 //idmap in upper half
	* else
	* HYP_VA_MIN = 1 << (VA_BITS - 1)
	* HYP_VA_MAX = HYP_VA_MIN + (1 << (VA_BITS - 1)) - 1
	*
	* When using VHE, there are no separate hyp mappings and all KVM
	* functionality is already mapped as part of the main kernel
	* mappings, and none of this applies in that case.
	*/

	#ifdef __ASSEMBLY__

	#include <asm/alternative.h>

	/*
	* Convert a hypervisor VA to a PA
	* reg: hypervisor address to be converted in place
	* tmp: temporary register
	*/
	.macro hyp_pa reg, tmp
	ldr_l \tmp, hyp_physvirt_offset
	add \reg, \reg, \tmp
	.endm

	/*
	* Convert a hypervisor VA to a kernel image address
	* reg: hypervisor address to be converted in place
	* tmp: temporary register
	*
	* The actual code generation takes place in kvm_get_kimage_voffset, and
	* the instructions below are only there to reserve the space and
	* perform the register allocation (kvm_get_kimage_voffset uses the
	* specific registers encoded in the instructions).
	*/
	.macro hyp_kimg_va reg, tmp
	/* Convert hyp VA -> PA. */
	hyp_pa \reg, \tmp

	/* Load kimage_voffset. */
	alternative_cb ARM64_ALWAYS_SYSTEM, kvm_get_kimage_voffset
	movz \tmp, #0
	movk \tmp, #0, lsl #16
	movk \tmp, #0, lsl #32
	movk \tmp, #0, lsl #48
	alternative_cb_end

	/* Convert PA -> kimg VA. */
	add \reg, \reg, \tmp
	.endm

	#else

	#include <linux/pgtable.h>
	#include <asm/pgalloc.h>
	#include <asm/cache.h>
	#include <asm/cacheflush.h>
	#include <asm/mmu_context.h>
	#include <asm/kvm_emulate.h>
	#include <asm/kvm_host.h>
	#include <asm/kvm_nested.h>

	void kvm_update_va_mask(struct alt_instr *alt,
	__le32 origptr, __le32 updptr, int nr_inst);
	void kvm_compute_layout(void);
	void kvm_apply_hyp_relocations(void);

	#define __hyp_pa(x) (((phys_addr_t)(x)) + hyp_physvirt_offset)

	/*
	* Convert a kernel VA into a HYP VA.
	*
	* Can be called from hyp or non-hyp context.
	*
	* The actual code generation takes place in kvm_update_va_mask(), and
	* the instructions below are only there to reserve the space and
	* perform the register allocation (kvm_update_va_mask() uses the
	* specific registers encoded in the instructions).
	*/
	static __always_inline unsigned long __kern_hyp_va(unsigned long v)
	{
	/*
	* This #ifndef is an optimisation for when this is called from VHE hyp
	* context. When called from a VHE non-hyp context, kvm_update_va_mask() will
	* replace the instructions with `nop`s.
	*/
	#ifndef __KVM_VHE_HYPERVISOR__
	asm volatile(ALTERNATIVE_CB("and %0, %0, #1\n" /* mask with va_mask */
	"ror %0, %0, #1\n" /* rotate to the first tag bit */
	"add %0, %0, #0\n" /* insert the low 12 bits of the tag */
	"add %0, %0, #0, lsl 12\n" /* insert the top 12 bits of the tag */
	"ror %0, %0, #63\n", /* rotate back */
	ARM64_ALWAYS_SYSTEM,
	kvm_update_va_mask)
	: "+r" (v));
	#endif
	return v;
	}

	#define kern_hyp_va(v) ((typeof(v))(__kern_hyp_va((unsigned long)(v))))

	/*
	* We currently support using a VM-specified IPA size. For backward
	* compatibility, the default IPA size is fixed to 40bits.
	*/
	#define KVM_PHYS_SHIFT (40)

	#define kvm_phys_shift(mmu) VTCR_EL2_IPA((mmu)->vtcr)
	#define kvm_phys_size(mmu) (_AC(1, ULL) << kvm_phys_shift(mmu))
	#define kvm_phys_mask(mmu) (kvm_phys_size(mmu) - _AC(1, ULL))

	#include <asm/kvm_pgtable.h>
	#include <asm/stage2_pgtable.h>

	int kvm_share_hyp(void from, void to);
	void kvm_unshare_hyp(void from, void to);
	int create_hyp_mappings(void from, void to, enum kvm_pgtable_prot prot);
	int __create_hyp_mappings(unsigned long start, unsigned long size,
	unsigned long phys, enum kvm_pgtable_prot prot);
	int hyp_alloc_private_va_range(size_t size, unsigned long *haddr);
	int create_hyp_io_mappings(phys_addr_t phys_addr, size_t size,
	void __iomem **kaddr,
	void __iomem **haddr);
	int create_hyp_exec_mappings(phys_addr_t phys_addr, size_t size,
	void **haddr);
	int create_hyp_stack(phys_addr_t phys_addr, unsigned long *haddr);
	void __init free_hyp_pgds(void);

	void kvm_stage2_unmap_range(struct kvm_s2_mmu *mmu, phys_addr_t start,
	u64 size, bool may_block);
	void kvm_stage2_flush_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end);
	void kvm_stage2_wp_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end);

	void stage2_unmap_vm(struct kvm *kvm);
	int kvm_init_stage2_mmu(struct kvm kvm, struct kvm_s2_mmu mmu, unsigned long type);
	void kvm_uninit_stage2_mmu(struct kvm *kvm);
	void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu);
	int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
	phys_addr_t pa, unsigned long size, bool writable);

	int kvm_handle_guest_abort(struct kvm_vcpu *vcpu);

	phys_addr_t kvm_mmu_get_httbr(void);
	phys_addr_t kvm_get_idmap_vector(void);
	int __init kvm_mmu_init(u32 *hyp_va_bits);

	static inline void __kvm_vector_slot2addr(void base,
	enum arm64_hyp_spectre_vector slot)
	{
	int idx = slot - (slot != HYP_VECTOR_DIRECT);

	return base + (idx * SZ_2K);
	}

	struct kvm;

	#define kvm_flush_dcache_to_poc(a,l) \
	dcache_clean_inval_poc((unsigned long)(a), (unsigned long)(a)+(l))

	static inline bool vcpu_has_cache_enabled(struct kvm_vcpu *vcpu)
	{
	u64 cache_bits = SCTLR_ELx_M \| SCTLR_ELx_C;
	int reg;

	if (vcpu_is_el2(vcpu))
	reg = SCTLR_EL2;
	else
	reg = SCTLR_EL1;

	return (vcpu_read_sys_reg(vcpu, reg) & cache_bits) == cache_bits;
	}

	static inline void __clean_dcache_guest_page(void *va, size_t size)
	{
	/*
	* With FWB, we ensure that the guest always accesses memory using
	* cacheable attributes, and we don't have to clean to PoC when
	* faulting in pages. Furthermore, FWB implies IDC, so cleaning to
	* PoU is not required either in this case.
	*/
	if (cpus_have_final_cap(ARM64_HAS_STAGE2_FWB))
	return;

	kvm_flush_dcache_to_poc(va, size);
	}

	static inline size_t __invalidate_icache_max_range(void)
	{
	u8 iminline;
	u64 ctr;

	asm volatile(ALTERNATIVE_CB("movz %0, #0\n"
	"movk %0, #0, lsl #16\n"
	"movk %0, #0, lsl #32\n"
	"movk %0, #0, lsl #48\n",
	ARM64_ALWAYS_SYSTEM,
	kvm_compute_final_ctr_el0)
	: "=r" (ctr));

	iminline = SYS_FIELD_GET(CTR_EL0, IminLine, ctr) + 2;
	return MAX_DVM_OPS << iminline;
	}

	static inline void __invalidate_icache_guest_page(void *va, size_t size)
	{
	/*
	* Blow the whole I-cache if it is aliasing (i.e. VIPT) or the
	* invalidation range exceeds our arbitrary limit on invadations by
	* cache line.
	*/
	if (icache_is_aliasing() \|\| size > __invalidate_icache_max_range())
	icache_inval_all_pou();
	else
	icache_inval_pou((unsigned long)va, (unsigned long)va + size);
	}

	void kvm_set_way_flush(struct kvm_vcpu *vcpu);
	void kvm_toggle_cache(struct kvm_vcpu *vcpu, bool was_enabled);

	static inline unsigned int kvm_get_vmid_bits(void)
	{
	int reg = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);

	return get_vmid_bits(reg);
	}

	/*
	* We are not in the kvm->srcu critical section most of the time, so we take
	* the SRCU read lock here. Since we copy the data from the user page, we
	* can immediately drop the lock again.
	*/
	static inline int kvm_read_guest_lock(struct kvm *kvm,
	gpa_t gpa, void *data, unsigned long len)
	{
	int srcu_idx = srcu_read_lock(&kvm->srcu);
	int ret = kvm_read_guest(kvm, gpa, data, len);

	srcu_read_unlock(&kvm->srcu, srcu_idx);

	return ret;
	}

	static inline int kvm_write_guest_lock(struct kvm *kvm, gpa_t gpa,
	const void *data, unsigned long len)
	{
	int srcu_idx = srcu_read_lock(&kvm->srcu);
	int ret = kvm_write_guest(kvm, gpa, data, len);

	srcu_read_unlock(&kvm->srcu, srcu_idx);

	return ret;
	}

	#define kvm_phys_to_vttbr(addr) phys_to_ttbr(addr)

	/*
	* When this is (directly or indirectly) used on the TLB invalidation
	* path, we rely on a previously issued DSB so that page table updates
	* and VMID reads are correctly ordered.
	*/
	static __always_inline u64 kvm_get_vttbr(struct kvm_s2_mmu *mmu)
	{
	struct kvm_vmid *vmid = &mmu->vmid;
	u64 vmid_field, baddr;
	u64 cnp = system_supports_cnp() ? VTTBR_CNP_BIT : 0;

	baddr = mmu->pgd_phys;
	vmid_field = atomic64_read(&vmid->id) << VTTBR_VMID_SHIFT;
	vmid_field &= VTTBR_VMID_MASK(kvm_arm_vmid_bits);
	return kvm_phys_to_vttbr(baddr) \| vmid_field \| cnp;
	}

	/*
	* Must be called from hyp code running at EL2 with an updated VTTBR
	* and interrupts disabled.
	*/
	static __always_inline void __load_stage2(struct kvm_s2_mmu *mmu,
	struct kvm_arch *arch)
	{
	write_sysreg(mmu->vtcr, vtcr_el2);
	write_sysreg(kvm_get_vttbr(mmu), vttbr_el2);

	/*
	* ARM errata 1165522 and 1530923 require the actual execution of the
	* above before we can switch to the EL1/EL0 translation regime used by
	* the guest.
	*/
	asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_SPECULATIVE_AT));
	}

	static inline struct kvm kvm_s2_mmu_to_kvm(struct kvm_s2_mmu mmu)
	{
	return container_of(mmu->arch, struct kvm, arch);
	}

	static inline u64 get_vmid(u64 vttbr)
	{
	return (vttbr & VTTBR_VMID_MASK(kvm_get_vmid_bits())) >>
	VTTBR_VMID_SHIFT;
	}

	static inline bool kvm_s2_mmu_valid(struct kvm_s2_mmu *mmu)
	{
	return !(mmu->tlb_vttbr & VTTBR_CNP_BIT);
	}

	static inline bool kvm_is_nested_s2_mmu(struct kvm kvm, struct kvm_s2_mmu mmu)
	{
	/*
	* Be careful, mmu may not be fully initialised so do look at
	* any of its fields.
	*/
	return &kvm->arch.mmu != mmu;
	}

	#ifdef CONFIG_PTDUMP_STAGE2_DEBUGFS
	void kvm_s2_ptdump_create_debugfs(struct kvm *kvm);
	#else
	static inline void kvm_s2_ptdump_create_debugfs(struct kvm *kvm) {}
	#endif /* CONFIG_PTDUMP_STAGE2_DEBUGFS */

	#endif /* __ASSEMBLY__ */
	#endif /* __ARM64_KVM_MMU_H__ */