arch/x86/kvm/mmu.h - third_party/linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __KVM_X86_MMU_H
 #define __KVM_X86_MMU_H

 #include <linux/kvm_host.h>
 #include "kvm_cache_regs.h"

 #define PT64_PT_BITS 9
 #define PT64_ENT_PER_PAGE (1 << PT64_PT_BITS)
 #define PT32_PT_BITS 10
 #define PT32_ENT_PER_PAGE (1 << PT32_PT_BITS)

 #define PT_WRITABLE_SHIFT 1
 #define PT_USER_SHIFT 2

 #define PT_PRESENT_MASK (1ULL << 0)
 #define PT_WRITABLE_MASK (1ULL << PT_WRITABLE_SHIFT)
 #define PT_USER_MASK (1ULL << PT_USER_SHIFT)
 #define PT_PWT_MASK (1ULL << 3)
 #define PT_PCD_MASK (1ULL << 4)
 #define PT_ACCESSED_SHIFT 5
 #define PT_ACCESSED_MASK (1ULL << PT_ACCESSED_SHIFT)
 #define PT_DIRTY_SHIFT 6
 #define PT_DIRTY_MASK (1ULL << PT_DIRTY_SHIFT)
 #define PT_PAGE_SIZE_SHIFT 7
 #define PT_PAGE_SIZE_MASK (1ULL << PT_PAGE_SIZE_SHIFT)
 #define PT_PAT_MASK (1ULL << 7)
 #define PT_GLOBAL_MASK (1ULL << 8)
 #define PT64_NX_SHIFT 63
 #define PT64_NX_MASK (1ULL << PT64_NX_SHIFT)

 #define PT_PAT_SHIFT 7
 #define PT_DIR_PAT_SHIFT 12
 #define PT_DIR_PAT_MASK (1ULL << PT_DIR_PAT_SHIFT)

 #define PT32_DIR_PSE36_SIZE 4
 #define PT32_DIR_PSE36_SHIFT 13
 #define PT32_DIR_PSE36_MASK \
 	(((1ULL << PT32_DIR_PSE36_SIZE) - 1) << PT32_DIR_PSE36_SHIFT)

 #define PT64_ROOT_5LEVEL 5
 #define PT64_ROOT_4LEVEL 4
 #define PT32_ROOT_LEVEL 2
 #define PT32E_ROOT_LEVEL 3

 #define PT_PDPE_LEVEL 3
 #define PT_DIRECTORY_LEVEL 2
 #define PT_PAGE_TABLE_LEVEL 1
 #define PT_MAX_HUGEPAGE_LEVEL (PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES - 1)

 static inline u64 rsvd_bits(int s, int e)
 {
 	if (e < s)
 		return 0;

 	return ((1ULL << (e - s + 1)) - 1) << s;
 }

 void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask, u64 mmio_value);

 void
 reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context);

 void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu);
 void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
 			     bool accessed_dirty);
 bool kvm_can_do_async_pf(struct kvm_vcpu *vcpu);
 int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code,
 				u64 fault_address, char *insn, int insn_len);

 static inline unsigned int kvm_mmu_available_pages(struct kvm *kvm)
 {
 	if (kvm->arch.n_max_mmu_pages > kvm->arch.n_used_mmu_pages)
 		return kvm->arch.n_max_mmu_pages -
 			kvm->arch.n_used_mmu_pages;

 	return 0;
 }

 static inline int kvm_mmu_reload(struct kvm_vcpu *vcpu)
 {
 	if (likely(vcpu->arch.mmu.root_hpa != INVALID_PAGE))
 		return 0;

 	return kvm_mmu_load(vcpu);
 }

 /*
  * Currently, we have two sorts of write-protection, a) the first one
  * write-protects guest page to sync the guest modification, b) another one is
  * used to sync dirty bitmap when we do KVM_GET_DIRTY_LOG. The differences
  * between these two sorts are:
  * 1) the first case clears SPTE_MMU_WRITEABLE bit.
  * 2) the first case requires flushing tlb immediately avoiding corrupting
  *    shadow page table between all vcpus so it should be in the protection of
  *    mmu-lock. And the another case does not need to flush tlb until returning
  *    the dirty bitmap to userspace since it only write-protects the page
  *    logged in the bitmap, that means the page in the dirty bitmap is not
  *    missed, so it can flush tlb out of mmu-lock.
  *
  * So, there is the problem: the first case can meet the corrupted tlb caused
  * by another case which write-protects pages but without flush tlb
  * immediately. In order to making the first case be aware this problem we let
  * it flush tlb if we try to write-protect a spte whose SPTE_MMU_WRITEABLE bit
  * is set, it works since another case never touches SPTE_MMU_WRITEABLE bit.
  *
  * Anyway, whenever a spte is updated (only permission and status bits are
  * changed) we need to check whether the spte with SPTE_MMU_WRITEABLE becomes
  * readonly, if that happens, we need to flush tlb. Fortunately,
  * mmu_spte_update() has already handled it perfectly.
  *
  * The rules to use SPTE_MMU_WRITEABLE and PT_WRITABLE_MASK:
  * - if we want to see if it has writable tlb entry or if the spte can be
  *   writable on the mmu mapping, check SPTE_MMU_WRITEABLE, this is the most
  *   case, otherwise
  * - if we fix page fault on the spte or do write-protection by dirty logging,
  *   check PT_WRITABLE_MASK.
  *
  * TODO: introduce APIs to split these two cases.
  */
 static inline int is_writable_pte(unsigned long pte)
 {
 	return pte & PT_WRITABLE_MASK;
 }

 static inline bool is_write_protection(struct kvm_vcpu *vcpu)
 {
 	return kvm_read_cr0_bits(vcpu, X86_CR0_WP);
 }

 /*
  * Check if a given access (described through the I/D, W/R and U/S bits of a
  * page fault error code pfec) causes a permission fault with the given PTE
  * access rights (in ACC_* format).
  *
  * Return zero if the access does not fault; return the page fault error code
  * if the access faults.
  */
 static inline u8 permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 				  unsigned pte_access, unsigned pte_pkey,
 				  unsigned pfec)
 {
 	int cpl = kvm_x86_ops->get_cpl(vcpu);
 	unsigned long rflags = kvm_x86_ops->get_rflags(vcpu);

 	/*
 	 * If CPL < 3, SMAP prevention are disabled if EFLAGS.AC = 1.
 	 *
 	 * If CPL = 3, SMAP applies to all supervisor-mode data accesses
 	 * (these are implicit supervisor accesses) regardless of the value
 	 * of EFLAGS.AC.
 	 *
 	 * This computes (cpl < 3) && (rflags & X86_EFLAGS_AC), leaving
 	 * the result in X86_EFLAGS_AC. We then insert it in place of
 	 * the PFERR_RSVD_MASK bit; this bit will always be zero in pfec,
 	 * but it will be one in index if SMAP checks are being overridden.
 	 * It is important to keep this branchless.
 	 */
 	unsigned long smap = (cpl - 3) & (rflags & X86_EFLAGS_AC);
 	int index = (pfec >> 1) +
 		    (smap >> (X86_EFLAGS_AC_BIT - PFERR_RSVD_BIT + 1));
 	bool fault = (mmu->permissions[index] >> pte_access) & 1;
 	u32 errcode = PFERR_PRESENT_MASK;

 	WARN_ON(pfec & (PFERR_PK_MASK | PFERR_RSVD_MASK));
 	if (unlikely(mmu->pkru_mask)) {
 		u32 pkru_bits, offset;

 		/*
 		* PKRU defines 32 bits, there are 16 domains and 2
 		* attribute bits per domain in pkru.  pte_pkey is the
 		* index of the protection domain, so pte_pkey * 2 is
 		* is the index of the first bit for the domain.
 		*/
 		pkru_bits = (vcpu->arch.pkru >> (pte_pkey * 2)) & 3;

 		/* clear present bit, replace PFEC.RSVD with ACC_USER_MASK. */
 		offset = (pfec & ~1) +
 			((pte_access & PT_USER_MASK) << (PFERR_RSVD_BIT - PT_USER_SHIFT));

 		pkru_bits &= mmu->pkru_mask >> offset;
 		errcode |= -pkru_bits & PFERR_PK_MASK;
 		fault |= (pkru_bits != 0);
 	}

 	return -(u32)fault & errcode;
 }

 void kvm_mmu_invalidate_zap_all_pages(struct kvm *kvm);
 void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end);

 void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
 void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
 bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
 				    struct kvm_memory_slot *slot, u64 gfn);
 int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu);
 #endif
	/* SPDX-License-Identifier: GPL-2.0 */
	#ifndef __KVM_X86_MMU_H
	#define __KVM_X86_MMU_H

	#include <linux/kvm_host.h>
	#include "kvm_cache_regs.h"

	#define PT64_PT_BITS 9
	#define PT64_ENT_PER_PAGE (1 << PT64_PT_BITS)
	#define PT32_PT_BITS 10
	#define PT32_ENT_PER_PAGE (1 << PT32_PT_BITS)

	#define PT_WRITABLE_SHIFT 1
	#define PT_USER_SHIFT 2

	#define PT_PRESENT_MASK (1ULL << 0)
	#define PT_WRITABLE_MASK (1ULL << PT_WRITABLE_SHIFT)
	#define PT_USER_MASK (1ULL << PT_USER_SHIFT)
	#define PT_PWT_MASK (1ULL << 3)
	#define PT_PCD_MASK (1ULL << 4)
	#define PT_ACCESSED_SHIFT 5
	#define PT_ACCESSED_MASK (1ULL << PT_ACCESSED_SHIFT)
	#define PT_DIRTY_SHIFT 6
	#define PT_DIRTY_MASK (1ULL << PT_DIRTY_SHIFT)
	#define PT_PAGE_SIZE_SHIFT 7
	#define PT_PAGE_SIZE_MASK (1ULL << PT_PAGE_SIZE_SHIFT)
	#define PT_PAT_MASK (1ULL << 7)
	#define PT_GLOBAL_MASK (1ULL << 8)
	#define PT64_NX_SHIFT 63
	#define PT64_NX_MASK (1ULL << PT64_NX_SHIFT)

	#define PT_PAT_SHIFT 7
	#define PT_DIR_PAT_SHIFT 12
	#define PT_DIR_PAT_MASK (1ULL << PT_DIR_PAT_SHIFT)

	#define PT32_DIR_PSE36_SIZE 4
	#define PT32_DIR_PSE36_SHIFT 13
	#define PT32_DIR_PSE36_MASK \
	(((1ULL << PT32_DIR_PSE36_SIZE) - 1) << PT32_DIR_PSE36_SHIFT)

	#define PT64_ROOT_5LEVEL 5
	#define PT64_ROOT_4LEVEL 4
	#define PT32_ROOT_LEVEL 2
	#define PT32E_ROOT_LEVEL 3

	#define PT_PDPE_LEVEL 3
	#define PT_DIRECTORY_LEVEL 2
	#define PT_PAGE_TABLE_LEVEL 1
	#define PT_MAX_HUGEPAGE_LEVEL (PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES - 1)

	static inline u64 rsvd_bits(int s, int e)
	{
	if (e < s)
	return 0;

	return ((1ULL << (e - s + 1)) - 1) << s;
	}

	void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask, u64 mmio_value);

	void
	reset_shadow_zero_bits_mask(struct kvm_vcpu vcpu, struct kvm_mmu context);

	void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu);
	void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
	bool accessed_dirty);
	bool kvm_can_do_async_pf(struct kvm_vcpu *vcpu);
	int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code,
	u64 fault_address, char *insn, int insn_len);

	static inline unsigned int kvm_mmu_available_pages(struct kvm *kvm)
	{
	if (kvm->arch.n_max_mmu_pages > kvm->arch.n_used_mmu_pages)
	return kvm->arch.n_max_mmu_pages -
	kvm->arch.n_used_mmu_pages;

	return 0;
	}

	static inline int kvm_mmu_reload(struct kvm_vcpu *vcpu)
	{
	if (likely(vcpu->arch.mmu.root_hpa != INVALID_PAGE))
	return 0;

	return kvm_mmu_load(vcpu);
	}

	/*
	* Currently, we have two sorts of write-protection, a) the first one
	* write-protects guest page to sync the guest modification, b) another one is
	* used to sync dirty bitmap when we do KVM_GET_DIRTY_LOG. The differences
	* between these two sorts are:
	* 1) the first case clears SPTE_MMU_WRITEABLE bit.
	* 2) the first case requires flushing tlb immediately avoiding corrupting
	* shadow page table between all vcpus so it should be in the protection of
	* mmu-lock. And the another case does not need to flush tlb until returning
	* the dirty bitmap to userspace since it only write-protects the page
	* logged in the bitmap, that means the page in the dirty bitmap is not
	* missed, so it can flush tlb out of mmu-lock.
	*
	* So, there is the problem: the first case can meet the corrupted tlb caused
	* by another case which write-protects pages but without flush tlb
	* immediately. In order to making the first case be aware this problem we let
	* it flush tlb if we try to write-protect a spte whose SPTE_MMU_WRITEABLE bit
	* is set, it works since another case never touches SPTE_MMU_WRITEABLE bit.
	*
	* Anyway, whenever a spte is updated (only permission and status bits are
	* changed) we need to check whether the spte with SPTE_MMU_WRITEABLE becomes
	* readonly, if that happens, we need to flush tlb. Fortunately,
	* mmu_spte_update() has already handled it perfectly.
	*
	* The rules to use SPTE_MMU_WRITEABLE and PT_WRITABLE_MASK:
	* - if we want to see if it has writable tlb entry or if the spte can be
	* writable on the mmu mapping, check SPTE_MMU_WRITEABLE, this is the most
	* case, otherwise
	* - if we fix page fault on the spte or do write-protection by dirty logging,
	* check PT_WRITABLE_MASK.
	*
	* TODO: introduce APIs to split these two cases.
	*/
	static inline int is_writable_pte(unsigned long pte)
	{
	return pte & PT_WRITABLE_MASK;
	}

	static inline bool is_write_protection(struct kvm_vcpu *vcpu)
	{
	return kvm_read_cr0_bits(vcpu, X86_CR0_WP);
	}

	/*
	* Check if a given access (described through the I/D, W/R and U/S bits of a
	* page fault error code pfec) causes a permission fault with the given PTE
	* access rights (in ACC_* format).
	*
	* Return zero if the access does not fault; return the page fault error code
	* if the access faults.
	*/
	static inline u8 permission_fault(struct kvm_vcpu vcpu, struct kvm_mmu mmu,
	unsigned pte_access, unsigned pte_pkey,
	unsigned pfec)
	{
	int cpl = kvm_x86_ops->get_cpl(vcpu);
	unsigned long rflags = kvm_x86_ops->get_rflags(vcpu);

	/*
	* If CPL < 3, SMAP prevention are disabled if EFLAGS.AC = 1.
	*
	* If CPL = 3, SMAP applies to all supervisor-mode data accesses
	* (these are implicit supervisor accesses) regardless of the value
	* of EFLAGS.AC.
	*
	* This computes (cpl < 3) && (rflags & X86_EFLAGS_AC), leaving
	* the result in X86_EFLAGS_AC. We then insert it in place of
	* the PFERR_RSVD_MASK bit; this bit will always be zero in pfec,
	* but it will be one in index if SMAP checks are being overridden.
	* It is important to keep this branchless.
	*/
	unsigned long smap = (cpl - 3) & (rflags & X86_EFLAGS_AC);
	int index = (pfec >> 1) +
	(smap >> (X86_EFLAGS_AC_BIT - PFERR_RSVD_BIT + 1));
	bool fault = (mmu->permissions[index] >> pte_access) & 1;
	u32 errcode = PFERR_PRESENT_MASK;

	WARN_ON(pfec & (PFERR_PK_MASK \| PFERR_RSVD_MASK));
	if (unlikely(mmu->pkru_mask)) {
	u32 pkru_bits, offset;

	/*
	* PKRU defines 32 bits, there are 16 domains and 2
	* attribute bits per domain in pkru. pte_pkey is the
	* index of the protection domain, so pte_pkey * 2 is
	* is the index of the first bit for the domain.
	*/
	pkru_bits = (vcpu->arch.pkru >> (pte_pkey * 2)) & 3;

	/* clear present bit, replace PFEC.RSVD with ACC_USER_MASK. */
	offset = (pfec & ~1) +
	((pte_access & PT_USER_MASK) << (PFERR_RSVD_BIT - PT_USER_SHIFT));

	pkru_bits &= mmu->pkru_mask >> offset;
	errcode \|= -pkru_bits & PFERR_PK_MASK;
	fault \|= (pkru_bits != 0);
	}

	return -(u32)fault & errcode;
	}

	void kvm_mmu_invalidate_zap_all_pages(struct kvm *kvm);
	void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end);

	void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
	void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
	bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
	struct kvm_memory_slot *slot, u64 gfn);
	int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu);
	#endif