1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Guest memory management for KVM/s390 nested VMs. 4 * 5 * Copyright IBM Corp. 2008, 2020, 2024 6 * 7 * Author(s): Claudio Imbrenda <imbrenda@linux.ibm.com> 8 * Martin Schwidefsky <schwidefsky@de.ibm.com> 9 * David Hildenbrand <david@redhat.com> 10 * Janosch Frank <frankja@linux.vnet.ibm.com> 11 */ 12 13 #include <linux/compiler.h> 14 #include <linux/kvm.h> 15 #include <linux/kvm_host.h> 16 #include <linux/pgtable.h> 17 #include <linux/pagemap.h> 18 #include <linux/mman.h> 19 20 #include <asm/lowcore.h> 21 #include <asm/gmap.h> 22 #include <asm/uv.h> 23 24 #include "kvm-s390.h" 25 26 /** 27 * gmap_find_shadow - find a specific asce in the list of shadow tables 28 * @parent: pointer to the parent gmap 29 * @asce: ASCE for which the shadow table is created 30 * @edat_level: edat level to be used for the shadow translation 31 * 32 * Returns the pointer to a gmap if a shadow table with the given asce is 33 * already available, ERR_PTR(-EAGAIN) if another one is just being created, 34 * otherwise NULL 35 * 36 * Context: Called with parent->shadow_lock held 37 */ 38 static struct gmap *gmap_find_shadow(struct gmap *parent, unsigned long asce, int edat_level) 39 { 40 struct gmap *sg; 41 42 lockdep_assert_held(&parent->shadow_lock); 43 list_for_each_entry(sg, &parent->children, list) { 44 if (!gmap_shadow_valid(sg, asce, edat_level)) 45 continue; 46 if (!sg->initialized) 47 return ERR_PTR(-EAGAIN); 48 refcount_inc(&sg->ref_count); 49 return sg; 50 } 51 return NULL; 52 } 53 54 /** 55 * gmap_shadow - create/find a shadow guest address space 56 * @parent: pointer to the parent gmap 57 * @asce: ASCE for which the shadow table is created 58 * @edat_level: edat level to be used for the shadow translation 59 * 60 * The pages of the top level page table referred by the asce parameter 61 * will be set to read-only and marked in the PGSTEs of the kvm process. 62 * The shadow table will be removed automatically on any change to the 63 * PTE mapping for the source table. 64 * 65 * Returns a guest address space structure, ERR_PTR(-ENOMEM) if out of memory, 66 * ERR_PTR(-EAGAIN) if the caller has to retry and ERR_PTR(-EFAULT) if the 67 * parent gmap table could not be protected. 68 */ 69 struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce, int edat_level) 70 { 71 struct gmap *sg, *new; 72 unsigned long limit; 73 int rc; 74 75 if (KVM_BUG_ON(parent->mm->context.allow_gmap_hpage_1m, (struct kvm *)parent->private) || 76 KVM_BUG_ON(gmap_is_shadow(parent), (struct kvm *)parent->private)) 77 return ERR_PTR(-EFAULT); 78 spin_lock(&parent->shadow_lock); 79 sg = gmap_find_shadow(parent, asce, edat_level); 80 spin_unlock(&parent->shadow_lock); 81 if (sg) 82 return sg; 83 /* Create a new shadow gmap */ 84 limit = -1UL >> (33 - (((asce & _ASCE_TYPE_MASK) >> 2) * 11)); 85 if (asce & _ASCE_REAL_SPACE) 86 limit = -1UL; 87 new = gmap_alloc(limit); 88 if (!new) 89 return ERR_PTR(-ENOMEM); 90 new->mm = parent->mm; 91 new->parent = gmap_get(parent); 92 new->private = parent->private; 93 new->orig_asce = asce; 94 new->edat_level = edat_level; 95 new->initialized = false; 96 spin_lock(&parent->shadow_lock); 97 /* Recheck if another CPU created the same shadow */ 98 sg = gmap_find_shadow(parent, asce, edat_level); 99 if (sg) { 100 spin_unlock(&parent->shadow_lock); 101 gmap_free(new); 102 return sg; 103 } 104 if (asce & _ASCE_REAL_SPACE) { 105 /* only allow one real-space gmap shadow */ 106 list_for_each_entry(sg, &parent->children, list) { 107 if (sg->orig_asce & _ASCE_REAL_SPACE) { 108 spin_lock(&sg->guest_table_lock); 109 gmap_unshadow(sg); 110 spin_unlock(&sg->guest_table_lock); 111 list_del(&sg->list); 112 gmap_put(sg); 113 break; 114 } 115 } 116 } 117 refcount_set(&new->ref_count, 2); 118 list_add(&new->list, &parent->children); 119 if (asce & _ASCE_REAL_SPACE) { 120 /* nothing to protect, return right away */ 121 new->initialized = true; 122 spin_unlock(&parent->shadow_lock); 123 return new; 124 } 125 spin_unlock(&parent->shadow_lock); 126 /* protect after insertion, so it will get properly invalidated */ 127 mmap_read_lock(parent->mm); 128 rc = __kvm_s390_mprotect_many(parent, asce & _ASCE_ORIGIN, 129 ((asce & _ASCE_TABLE_LENGTH) + 1), 130 PROT_READ, GMAP_NOTIFY_SHADOW); 131 mmap_read_unlock(parent->mm); 132 spin_lock(&parent->shadow_lock); 133 new->initialized = true; 134 if (rc) { 135 list_del(&new->list); 136 gmap_free(new); 137 new = ERR_PTR(rc); 138 } 139 spin_unlock(&parent->shadow_lock); 140 return new; 141 } 142