1 // SPDX-License-Identifier: GPL-2.0
3  *  Helper functions for KVM guest address space mapping code
21  * ptep_zap_softleaf_entry() - discard a software leaf entry.
23  * @entry: the software leaf entry that needs to be zapped
25  * Discards the given software leaf entry. If the leaf entry was an actual
26  * swap entry (and not a migration entry, for example), the actual swapped
29 static void ptep_zap_softleaf_entry(struct mm_struct *mm, softleaf_t entry)  in ptep_zap_softleaf_entry()  argument
31 	if (softleaf_is_swap(entry))  in ptep_zap_softleaf_entry()
33 	else if (softleaf_is_migration(entry))  in ptep_zap_softleaf_entry()
34 		dec_mm_counter(mm, mm_counter(softleaf_to_folio(entry)));  in ptep_zap_softleaf_entry()
35 	free_swap_and_cache(entry);  in ptep_zap_softleaf_entry()
39  * gmap_helper_zap_one_page() - discard a page if it was swapped.
41  * @vmaddr: the userspace virtual address that needs to be discarded
43  * If the given address maps to a swap entry, discard it.
56 	/* Find the vm address for the guest address */  in gmap_helper_zap_one_page()
61 	/* Get pointer to the page table entry */  in gmap_helper_zap_one_page()
80  * gmap_helper_discard() - discard user pages in the given range
82  * @vmaddr: starting userspace address
83  * @end: end address (first address outside the range)
100 			zap_page_range_single(vma, vmaddr, min(end, vma->vm_end) - vmaddr, NULL);  in gmap_helper_discard()
101 		vmaddr = vma->vm_end;  in gmap_helper_discard()
109 	unsigned long *found_addr = walk->private;  in find_zeropage_pte_entry()
119 		if (!is_cow_mapping(walk->vma->vm_flags))  in find_zeropage_pte_entry()
120 			return -EFAULT;  in find_zeropage_pte_entry()
133 /** __gmap_helper_unshare_zeropages() - unshare all shared zeropages
140  * This must be called after mm->context.allow_cow_sharing was
147  * mm->context.allow_cow_sharing is set to 0.
163 		if ((vma->vm_flags & VM_PFNMAP) || is_vm_hugetlb_page(vma))  in __gmap_helper_unshare_zeropages()
165 		addr = vma->vm_start;  in __gmap_helper_unshare_zeropages()
168 		rc = walk_page_range_vma(vma, addr, vma->vm_end,  in __gmap_helper_unshare_zeropages()
180 			return -ENOMEM;  in __gmap_helper_unshare_zeropages()
183 		 * must start the lookup from the current address, because  in __gmap_helper_unshare_zeropages()
199  * gmap_helper_disable_cow_sharing() - disable all COW sharing
201  * Disable most COW-sharing of memory pages for the whole process:
205  * Not that we currently don't bother with COW-shared pages that are shared
210 	struct mm_struct *mm = current->mm;  in gmap_helper_disable_cow_sharing()
215 	if (!mm->context.allow_cow_sharing)  in gmap_helper_disable_cow_sharing()
218 	mm->context.allow_cow_sharing = 0;  in gmap_helper_disable_cow_sharing()
225 	 * from re-enabling it.  in gmap_helper_disable_cow_sharing()
230 		mm->context.allow_cow_sharing = 1;  in gmap_helper_disable_cow_sharing()