diff options
| -rw-r--r-- | arch/s390/include/asm/gmap.h | 2 | ||||
| -rw-r--r-- | arch/s390/kvm/pv.c | 9 | ||||
| -rw-r--r-- | arch/s390/mm/gmap.c | 86 |
3 files changed, 94 insertions, 3 deletions
diff --git a/arch/s390/include/asm/gmap.h b/arch/s390/include/asm/gmap.h index 40264f60b0da..f4073106e1f3 100644 --- a/arch/s390/include/asm/gmap.h +++ b/arch/s390/include/asm/gmap.h @@ -148,4 +148,6 @@ void gmap_sync_dirty_log_pmd(struct gmap *gmap, unsigned long dirty_bitmap[4], unsigned long gaddr, unsigned long vmaddr); int gmap_mark_unmergeable(void); void s390_reset_acc(struct mm_struct *mm); +void s390_unlist_old_asce(struct gmap *gmap); +int s390_replace_asce(struct gmap *gmap); #endif /* _ASM_S390_GMAP_H */ diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c index b4a499b10b67..f1733812a263 100644 --- a/arch/s390/kvm/pv.c +++ b/arch/s390/kvm/pv.c @@ -162,10 +162,13 @@ int kvm_s390_pv_deinit_vm(struct kvm *kvm, u16 *rc, u16 *rrc) atomic_set(&kvm->mm->context.is_protected, 0); KVM_UV_EVENT(kvm, 3, "PROTVIRT DESTROY VM: rc %x rrc %x", *rc, *rrc); WARN_ONCE(cc, "protvirt destroy vm failed rc %x rrc %x", *rc, *rrc); - /* Inteded memory leak on "impossible" error */ - if (!cc) + /* Intended memory leak on "impossible" error */ + if (!cc) { kvm_s390_pv_dealloc_vm(kvm); - return cc ? -EIO : 0; + return 0; + } + s390_replace_asce(kvm->arch.gmap); + return -EIO; } int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc) diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c index b8ae4a4aa2ba..85cab61d87a9 100644 --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -2735,3 +2735,89 @@ void s390_reset_acc(struct mm_struct *mm) mmput(mm); } EXPORT_SYMBOL_GPL(s390_reset_acc); + +/** + * s390_unlist_old_asce - Remove the topmost level of page tables from the + * list of page tables of the gmap. + * @gmap: the gmap whose table is to be removed + * + * On s390x, KVM keeps a list of all pages containing the page tables of the + * gmap (the CRST list). This list is used at tear down time to free all + * pages that are now not needed anymore. + * + * This function removes the topmost page of the tree (the one pointed to by + * the ASCE) from the CRST list. + * + * This means that it will not be freed when the VM is torn down, and needs + * to be handled separately by the caller, unless a leak is actually + * intended. Notice that this function will only remove the page from the + * list, the page will still be used as a top level page table (and ASCE). + */ +void s390_unlist_old_asce(struct gmap *gmap) +{ + struct page *old; + + old = virt_to_page(gmap->table); + spin_lock(&gmap->guest_table_lock); + list_del(&old->lru); + /* + * Sometimes the topmost page might need to be "removed" multiple + * times, for example if the VM is rebooted into secure mode several + * times concurrently, or if s390_replace_asce fails after calling + * s390_remove_old_asce and is attempted again later. In that case + * the old asce has been removed from the list, and therefore it + * will not be freed when the VM terminates, but the ASCE is still + * in use and still pointed to. + * A subsequent call to replace_asce will follow the pointer and try + * to remove the same page from the list again. + * Therefore it's necessary that the page of the ASCE has valid + * pointers, so list_del can work (and do nothing) without + * dereferencing stale or invalid pointers. + */ + INIT_LIST_HEAD(&old->lru); + spin_unlock(&gmap->guest_table_lock); +} +EXPORT_SYMBOL_GPL(s390_unlist_old_asce); + +/** + * s390_replace_asce - Try to replace the current ASCE of a gmap with a copy + * @gmap: the gmap whose ASCE needs to be replaced + * + * If the allocation of the new top level page table fails, the ASCE is not + * replaced. + * In any case, the old ASCE is always removed from the gmap CRST list. + * Therefore the caller has to make sure to save a pointer to it + * beforehand, unless a leak is actually intended. + */ +int s390_replace_asce(struct gmap *gmap) +{ + unsigned long asce; + struct page *page; + void *table; + + s390_unlist_old_asce(gmap); + + page = alloc_pages(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER); + if (!page) + return -ENOMEM; + table = page_to_virt(page); + memcpy(table, gmap->table, 1UL << (CRST_ALLOC_ORDER + PAGE_SHIFT)); + + /* + * The caller has to deal with the old ASCE, but here we make sure + * the new one is properly added to the CRST list, so that + * it will be freed when the VM is torn down. + */ + spin_lock(&gmap->guest_table_lock); + list_add(&page->lru, &gmap->crst_list); + spin_unlock(&gmap->guest_table_lock); + + /* Set new table origin while preserving existing ASCE control bits */ + asce = (gmap->asce & ~_ASCE_ORIGIN) | __pa(table); + WRITE_ONCE(gmap->asce, asce); + WRITE_ONCE(gmap->mm->context.gmap_asce, asce); + WRITE_ONCE(gmap->table, table); + + return 0; +} +EXPORT_SYMBOL_GPL(s390_replace_asce); |