linux/arch/x86/kvm/mmu/tdp_iter.h

// SPDX-License-Identifier: GPL-2.0

#ifndef __KVM_X86_MMU_TDP_ITER_H
#define __KVM_X86_MMU_TDP_ITER_H

#include <linux/kvm_host.h>

#include "mmu.h"
#include "spte.h"

/*
 * TDP MMU SPTEs are RCU protected to allow paging structures (non-leaf SPTEs)
 * to be zapped while holding mmu_lock for read, and to allow TLB flushes to be
 * batched without having to collect the list of zapped SPs.  Flows that can
 * remove SPs must service pending TLB flushes prior to dropping RCU protection.
 */
static inline u64 kvm_tdp_mmu_read_spte(tdp_ptep_t sptep)
{ … }

static inline u64 kvm_tdp_mmu_write_spte_atomic(tdp_ptep_t sptep, u64 new_spte)
{ … }

static inline void __kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 new_spte)
{ … }

/*
 * SPTEs must be modified atomically if they are shadow-present, leaf
 * SPTEs, and have volatile bits, i.e. has bits that can be set outside
 * of mmu_lock.  The Writable bit can be set by KVM's fast page fault
 * handler, and Accessed and Dirty bits can be set by the CPU.
 *
 * Note, non-leaf SPTEs do have Accessed bits and those bits are
 * technically volatile, but KVM doesn't consume the Accessed bit of
 * non-leaf SPTEs, i.e. KVM doesn't care if it clobbers the bit.  This
 * logic needs to be reassessed if KVM were to use non-leaf Accessed
 * bits, e.g. to skip stepping down into child SPTEs when aging SPTEs.
 */
static inline bool kvm_tdp_mmu_spte_need_atomic_write(u64 old_spte, int level)
{ … }

static inline u64 kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 old_spte,
					 u64 new_spte, int level)
{ … }

static inline u64 tdp_mmu_clear_spte_bits(tdp_ptep_t sptep, u64 old_spte,
					  u64 mask, int level)
{ … }

/*
 * A TDP iterator performs a pre-order walk over a TDP paging structure.
 */
struct tdp_iter { … };

/*
 * Iterates over every SPTE mapping the GFN range [start, end) in a
 * preorder traversal.
 */
#define for_each_tdp_pte_min_level(iter, root, min_level, start, end) …

#define for_each_tdp_pte(iter, root, start, end) …

tdp_ptep_t spte_to_child_pt(u64 pte, int level);

void tdp_iter_start(struct tdp_iter *iter, struct kvm_mmu_page *root,
		    int min_level, gfn_t next_last_level_gfn);
void tdp_iter_next(struct tdp_iter *iter);
void tdp_iter_restart(struct tdp_iter *iter);

#endif /* __KVM_X86_MMU_TDP_ITER_H */