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

 /*
  * Copyright (C) 2012,2013 - ARM Ltd
  * Author: Marc Zyngier <marc.zyngier@arm.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */

 #ifndef __ARM64_KVM_MMU_H__
 #define __ARM64_KVM_MMU_H__

 #include <asm/page.h>
 #include <asm/memory.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
  *
  * This of course assumes that the trampoline page exists within the
  * VA_BITS range. If it doesn't, then it means we're in the odd case
  * where the kernel idmap (as well as HYP) uses more levels than the
  * kernel runtime page tables (as seen when the kernel is configured
  * for 4k pages, 39bits VA, and yet memory lives just above that
  * limit, forcing the idmap to use 4 levels of page tables while the
  * kernel itself only uses 3). In this particular case, it doesn't
  * matter which side of VA_BITS we use, as we're guaranteed not to
  * conflict with anything.
  *
  * 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.
  */

 #define HYP_PAGE_OFFSET_HIGH_MASK	((UL(1) << VA_BITS) - 1)
 #define HYP_PAGE_OFFSET_LOW_MASK	((UL(1) << (VA_BITS - 1)) - 1)

 #ifdef __ASSEMBLY__

 #include <asm/alternative.h>
 #include <asm/cpufeature.h>

 /*
  * Convert a kernel VA into a HYP VA.
  * reg: VA to be converted.
  *
  * This generates the following sequences:
  * - High mask:
  *		and x0, x0, #HYP_PAGE_OFFSET_HIGH_MASK
  *		nop
  * - Low mask:
  *		and x0, x0, #HYP_PAGE_OFFSET_HIGH_MASK
  *		and x0, x0, #HYP_PAGE_OFFSET_LOW_MASK
  * - VHE:
  *		nop
  *		nop
  *
  * The "low mask" version works because the mask is a strict subset of
  * the "high mask", hence performing the first mask for nothing.
  * Should be completely invisible on any viable CPU.
  */
 .macro kern_hyp_va	reg
 alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
 	and     \reg, \reg, #HYP_PAGE_OFFSET_HIGH_MASK
 alternative_else_nop_endif
 alternative_if ARM64_HYP_OFFSET_LOW
 	and     \reg, \reg, #HYP_PAGE_OFFSET_LOW_MASK
 alternative_else_nop_endif
 .endm

 #else

 #include <asm/pgalloc.h>
 #include <asm/cache.h>
 #include <asm/cacheflush.h>
 #include <asm/mmu_context.h>
 #include <asm/pgtable.h>

 static inline unsigned long __kern_hyp_va(unsigned long v)
 {
 	asm volatile(ALTERNATIVE("and %0, %0, %1",
 				 "nop",
 				 ARM64_HAS_VIRT_HOST_EXTN)
 		     : "+r" (v)
 		     : "i" (HYP_PAGE_OFFSET_HIGH_MASK));
 	asm volatile(ALTERNATIVE("nop",
 				 "and %0, %0, %1",
 				 ARM64_HYP_OFFSET_LOW)
 		     : "+r" (v)
 		     : "i" (HYP_PAGE_OFFSET_LOW_MASK));
 	return v;
 }

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

 /*
  * We currently only support a 40bit IPA.
  */
 #define KVM_PHYS_SHIFT	(40)
 #define KVM_PHYS_SIZE	(1UL << KVM_PHYS_SHIFT)
 #define KVM_PHYS_MASK	(KVM_PHYS_SIZE - 1UL)

 #include <asm/stage2_pgtable.h>

 int create_hyp_mappings(void *from, void *to, pgprot_t prot);
 int create_hyp_io_mappings(void *from, void *to, phys_addr_t);
 void free_hyp_pgds(void);

 void stage2_unmap_vm(struct kvm *kvm);
 int kvm_alloc_stage2_pgd(struct kvm *kvm);
 void kvm_free_stage2_pgd(struct kvm *kvm);
 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, struct kvm_run *run);

 void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu);

 phys_addr_t kvm_mmu_get_httbr(void);
 phys_addr_t kvm_get_idmap_vector(void);
 int kvm_mmu_init(void);
 void kvm_clear_hyp_idmap(void);

 #define	kvm_set_pte(ptep, pte)		set_pte(ptep, pte)
 #define	kvm_set_pmd(pmdp, pmd)		set_pmd(pmdp, pmd)

 static inline pte_t kvm_s2pte_mkwrite(pte_t pte)
 {
 	pte_val(pte) |= PTE_S2_RDWR;
 	return pte;
 }

 static inline pmd_t kvm_s2pmd_mkwrite(pmd_t pmd)
 {
 	pmd_val(pmd) |= PMD_S2_RDWR;
 	return pmd;
 }

 static inline void kvm_set_s2pte_readonly(pte_t *pte)
 {
 	pteval_t old_pteval, pteval;

 	pteval = READ_ONCE(pte_val(*pte));
 	do {
 		old_pteval = pteval;
 		pteval &= ~PTE_S2_RDWR;
 		pteval |= PTE_S2_RDONLY;
 		pteval = cmpxchg_relaxed(&pte_val(*pte), old_pteval, pteval);
 	} while (pteval != old_pteval);
 }

 static inline bool kvm_s2pte_readonly(pte_t *pte)
 {
 	return (pte_val(*pte) & PTE_S2_RDWR) == PTE_S2_RDONLY;
 }

 static inline void kvm_set_s2pmd_readonly(pmd_t *pmd)
 {
 	kvm_set_s2pte_readonly((pte_t *)pmd);
 }

 static inline bool kvm_s2pmd_readonly(pmd_t *pmd)
 {
 	return kvm_s2pte_readonly((pte_t *)pmd);
 }

 static inline bool kvm_page_empty(void *ptr)
 {
 	struct page *ptr_page = virt_to_page(ptr);
 	return page_count(ptr_page) == 1;
 }

 #define hyp_pte_table_empty(ptep) kvm_page_empty(ptep)

 #ifdef __PAGETABLE_PMD_FOLDED
 #define hyp_pmd_table_empty(pmdp) (0)
 #else
 #define hyp_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
 #endif

 #ifdef __PAGETABLE_PUD_FOLDED
 #define hyp_pud_table_empty(pudp) (0)
 #else
 #define hyp_pud_table_empty(pudp) kvm_page_empty(pudp)
 #endif

 struct kvm;

 #define kvm_flush_dcache_to_poc(a,l)	__flush_dcache_area((a), (l))

 static inline bool vcpu_has_cache_enabled(struct kvm_vcpu *vcpu)
 {
 	return (vcpu_sys_reg(vcpu, SCTLR_EL1) & 0b101) == 0b101;
 }

 static inline void __coherent_cache_guest_page(struct kvm_vcpu *vcpu,
 					       kvm_pfn_t pfn,
 					       unsigned long size)
 {
 	void *va = page_address(pfn_to_page(pfn));

 	kvm_flush_dcache_to_poc(va, size);

 	if (icache_is_aliasing()) {
 		/* any kind of VIPT cache */
 		__flush_icache_all();
 	} else if (is_kernel_in_hyp_mode() || !icache_is_vpipt()) {
 		/* PIPT or VPIPT at EL2 (see comment in __kvm_tlb_flush_vmid_ipa) */
 		flush_icache_range((unsigned long)va,
 				   (unsigned long)va + size);
 	}
 }

 static inline void __kvm_flush_dcache_pte(pte_t pte)
 {
 	struct page *page = pte_page(pte);
 	kvm_flush_dcache_to_poc(page_address(page), PAGE_SIZE);
 }

 static inline void __kvm_flush_dcache_pmd(pmd_t pmd)
 {
 	struct page *page = pmd_page(pmd);
 	kvm_flush_dcache_to_poc(page_address(page), PMD_SIZE);
 }

 static inline void __kvm_flush_dcache_pud(pud_t pud)
 {
 	struct page *page = pud_page(pud);
 	kvm_flush_dcache_to_poc(page_address(page), PUD_SIZE);
 }

 #define kvm_virt_to_phys(x)		__pa_symbol(x)

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

 static inline bool __kvm_cpu_uses_extended_idmap(void)
 {
 	return __cpu_uses_extended_idmap();
 }

 static inline void __kvm_extend_hypmap(pgd_t *boot_hyp_pgd,
 				       pgd_t *hyp_pgd,
 				       pgd_t *merged_hyp_pgd,
 				       unsigned long hyp_idmap_start)
 {
 	int idmap_idx;

 	/*
 	 * Use the first entry to access the HYP mappings. It is
 	 * guaranteed to be free, otherwise we wouldn't use an
 	 * extended idmap.
 	 */
 	VM_BUG_ON(pgd_val(merged_hyp_pgd[0]));
 	merged_hyp_pgd[0] = __pgd(__pa(hyp_pgd) | PMD_TYPE_TABLE);

 	/*
 	 * Create another extended level entry that points to the boot HYP map,
 	 * which contains an ID mapping of the HYP init code. We essentially
 	 * merge the boot and runtime HYP maps by doing so, but they don't
 	 * overlap anyway, so this is fine.
 	 */
 	idmap_idx = hyp_idmap_start >> VA_BITS;
 	VM_BUG_ON(pgd_val(merged_hyp_pgd[idmap_idx]));
 	merged_hyp_pgd[idmap_idx] = __pgd(__pa(boot_hyp_pgd) | PMD_TYPE_TABLE);
 }

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

 	return (cpuid_feature_extract_unsigned_field(reg, ID_AA64MMFR1_VMIDBITS_SHIFT) == 2) ? 16 : 8;
 }

 #endif /* __ASSEMBLY__ */
 #endif /* __ARM64_KVM_MMU_H__ */
	/*
	* Copyright (C) 2012,2013 - ARM Ltd
	* Author: Marc Zyngier <marc.zyngier@arm.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program. If not, see <http://www.gnu.org/licenses/>.
	*/

	#ifndef __ARM64_KVM_MMU_H__
	#define __ARM64_KVM_MMU_H__

	#include <asm/page.h>
	#include <asm/memory.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
	*
	* This of course assumes that the trampoline page exists within the
	* VA_BITS range. If it doesn't, then it means we're in the odd case
	* where the kernel idmap (as well as HYP) uses more levels than the
	* kernel runtime page tables (as seen when the kernel is configured
	* for 4k pages, 39bits VA, and yet memory lives just above that
	* limit, forcing the idmap to use 4 levels of page tables while the
	* kernel itself only uses 3). In this particular case, it doesn't
	* matter which side of VA_BITS we use, as we're guaranteed not to
	* conflict with anything.
	*
	* 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.
	*/

	#define HYP_PAGE_OFFSET_HIGH_MASK ((UL(1) << VA_BITS) - 1)
	#define HYP_PAGE_OFFSET_LOW_MASK ((UL(1) << (VA_BITS - 1)) - 1)

	#ifdef __ASSEMBLY__

	#include <asm/alternative.h>
	#include <asm/cpufeature.h>

	/*
	* Convert a kernel VA into a HYP VA.
	* reg: VA to be converted.
	*
	* This generates the following sequences:
	* - High mask:
	* and x0, x0, #HYP_PAGE_OFFSET_HIGH_MASK
	* nop
	* - Low mask:
	* and x0, x0, #HYP_PAGE_OFFSET_HIGH_MASK
	* and x0, x0, #HYP_PAGE_OFFSET_LOW_MASK
	* - VHE:
	* nop
	* nop
	*
	* The "low mask" version works because the mask is a strict subset of
	* the "high mask", hence performing the first mask for nothing.
	* Should be completely invisible on any viable CPU.
	*/
	.macro kern_hyp_va reg
	alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
	and \reg, \reg, #HYP_PAGE_OFFSET_HIGH_MASK
	alternative_else_nop_endif
	alternative_if ARM64_HYP_OFFSET_LOW
	and \reg, \reg, #HYP_PAGE_OFFSET_LOW_MASK
	alternative_else_nop_endif
	.endm

	#else

	#include <asm/pgalloc.h>
	#include <asm/cache.h>
	#include <asm/cacheflush.h>
	#include <asm/mmu_context.h>
	#include <asm/pgtable.h>

	static inline unsigned long __kern_hyp_va(unsigned long v)
	{
	asm volatile(ALTERNATIVE("and %0, %0, %1",
	"nop",
	ARM64_HAS_VIRT_HOST_EXTN)
	: "+r" (v)
	: "i" (HYP_PAGE_OFFSET_HIGH_MASK));
	asm volatile(ALTERNATIVE("nop",
	"and %0, %0, %1",
	ARM64_HYP_OFFSET_LOW)
	: "+r" (v)
	: "i" (HYP_PAGE_OFFSET_LOW_MASK));
	return v;
	}

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

	/*
	* We currently only support a 40bit IPA.
	*/
	#define KVM_PHYS_SHIFT (40)
	#define KVM_PHYS_SIZE (1UL << KVM_PHYS_SHIFT)
	#define KVM_PHYS_MASK (KVM_PHYS_SIZE - 1UL)

	#include <asm/stage2_pgtable.h>

	int create_hyp_mappings(void from, void to, pgprot_t prot);
	int create_hyp_io_mappings(void from, void to, phys_addr_t);
	void free_hyp_pgds(void);

	void stage2_unmap_vm(struct kvm *kvm);
	int kvm_alloc_stage2_pgd(struct kvm *kvm);
	void kvm_free_stage2_pgd(struct kvm *kvm);
	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, struct kvm_run run);

	void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu);

	phys_addr_t kvm_mmu_get_httbr(void);
	phys_addr_t kvm_get_idmap_vector(void);
	int kvm_mmu_init(void);
	void kvm_clear_hyp_idmap(void);

	#define kvm_set_pte(ptep, pte) set_pte(ptep, pte)
	#define kvm_set_pmd(pmdp, pmd) set_pmd(pmdp, pmd)

	static inline pte_t kvm_s2pte_mkwrite(pte_t pte)
	{
	pte_val(pte) \|= PTE_S2_RDWR;
	return pte;
	}

	static inline pmd_t kvm_s2pmd_mkwrite(pmd_t pmd)
	{
	pmd_val(pmd) \|= PMD_S2_RDWR;
	return pmd;
	}

	static inline void kvm_set_s2pte_readonly(pte_t *pte)
	{
	pteval_t old_pteval, pteval;

	pteval = READ_ONCE(pte_val(*pte));
	do {
	old_pteval = pteval;
	pteval &= ~PTE_S2_RDWR;
	pteval \|= PTE_S2_RDONLY;
	pteval = cmpxchg_relaxed(&pte_val(*pte), old_pteval, pteval);
	} while (pteval != old_pteval);
	}

	static inline bool kvm_s2pte_readonly(pte_t *pte)
	{
	return (pte_val(*pte) & PTE_S2_RDWR) == PTE_S2_RDONLY;
	}

	static inline void kvm_set_s2pmd_readonly(pmd_t *pmd)
	{
	kvm_set_s2pte_readonly((pte_t *)pmd);
	}

	static inline bool kvm_s2pmd_readonly(pmd_t *pmd)
	{
	return kvm_s2pte_readonly((pte_t *)pmd);
	}

	static inline bool kvm_page_empty(void *ptr)
	{
	struct page *ptr_page = virt_to_page(ptr);
	return page_count(ptr_page) == 1;
	}

	#define hyp_pte_table_empty(ptep) kvm_page_empty(ptep)

	#ifdef __PAGETABLE_PMD_FOLDED
	#define hyp_pmd_table_empty(pmdp) (0)
	#else
	#define hyp_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
	#endif

	#ifdef __PAGETABLE_PUD_FOLDED
	#define hyp_pud_table_empty(pudp) (0)
	#else
	#define hyp_pud_table_empty(pudp) kvm_page_empty(pudp)
	#endif

	struct kvm;

	#define kvm_flush_dcache_to_poc(a,l) __flush_dcache_area((a), (l))

	static inline bool vcpu_has_cache_enabled(struct kvm_vcpu *vcpu)
	{
	return (vcpu_sys_reg(vcpu, SCTLR_EL1) & 0b101) == 0b101;
	}

	static inline void __coherent_cache_guest_page(struct kvm_vcpu *vcpu,
	kvm_pfn_t pfn,
	unsigned long size)
	{
	void *va = page_address(pfn_to_page(pfn));

	kvm_flush_dcache_to_poc(va, size);

	if (icache_is_aliasing()) {
	/* any kind of VIPT cache */
	__flush_icache_all();
	} else if (is_kernel_in_hyp_mode() \|\| !icache_is_vpipt()) {
	/* PIPT or VPIPT at EL2 (see comment in __kvm_tlb_flush_vmid_ipa) */
	flush_icache_range((unsigned long)va,
	(unsigned long)va + size);
	}
	}

	static inline void __kvm_flush_dcache_pte(pte_t pte)
	{
	struct page *page = pte_page(pte);
	kvm_flush_dcache_to_poc(page_address(page), PAGE_SIZE);
	}

	static inline void __kvm_flush_dcache_pmd(pmd_t pmd)
	{
	struct page *page = pmd_page(pmd);
	kvm_flush_dcache_to_poc(page_address(page), PMD_SIZE);
	}

	static inline void __kvm_flush_dcache_pud(pud_t pud)
	{
	struct page *page = pud_page(pud);
	kvm_flush_dcache_to_poc(page_address(page), PUD_SIZE);
	}

	#define kvm_virt_to_phys(x) __pa_symbol(x)

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

	static inline bool __kvm_cpu_uses_extended_idmap(void)
	{
	return __cpu_uses_extended_idmap();
	}

	static inline void __kvm_extend_hypmap(pgd_t *boot_hyp_pgd,
	pgd_t *hyp_pgd,
	pgd_t *merged_hyp_pgd,
	unsigned long hyp_idmap_start)
	{
	int idmap_idx;

	/*
	* Use the first entry to access the HYP mappings. It is
	* guaranteed to be free, otherwise we wouldn't use an
	* extended idmap.
	*/
	VM_BUG_ON(pgd_val(merged_hyp_pgd[0]));
	merged_hyp_pgd[0] = __pgd(__pa(hyp_pgd) \| PMD_TYPE_TABLE);

	/*
	* Create another extended level entry that points to the boot HYP map,
	* which contains an ID mapping of the HYP init code. We essentially
	* merge the boot and runtime HYP maps by doing so, but they don't
	* overlap anyway, so this is fine.
	*/
	idmap_idx = hyp_idmap_start >> VA_BITS;
	VM_BUG_ON(pgd_val(merged_hyp_pgd[idmap_idx]));
	merged_hyp_pgd[idmap_idx] = __pgd(__pa(boot_hyp_pgd) \| PMD_TYPE_TABLE);
	}

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

	return (cpuid_feature_extract_unsigned_field(reg, ID_AA64MMFR1_VMIDBITS_SHIFT) == 2) ? 16 : 8;
	}

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