From 6ea427bbbd4078297bb1dbd6c5cb83f3f48aac46 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Tue, 8 Mar 2016 11:55:04 +0100 Subject: [PATCH] s390/mm: add reference counter to gmap structure Let's use a reference counter mechanism to control the lifetime of gmap structures. This will be needed for further changes related to gmap shadows. Reviewed-by: David Hildenbrand Signed-off-by: Martin Schwidefsky Signed-off-by: Christian Borntraeger --- arch/s390/include/asm/gmap.h | 9 ++++- arch/s390/kvm/kvm-s390.c | 16 ++++---- arch/s390/mm/gmap.c | 90 ++++++++++++++++++++++++++++++++++---------- 3 files changed, 85 insertions(+), 30 deletions(-) diff --git a/arch/s390/include/asm/gmap.h b/arch/s390/include/asm/gmap.h index 6897a09..e69853c 100644 --- a/arch/s390/include/asm/gmap.h +++ b/arch/s390/include/asm/gmap.h @@ -15,6 +15,7 @@ * @guest_to_host: radix tree with guest to host address translation * @host_to_guest: radix tree with pointer to segment table entries * @guest_table_lock: spinlock to protect all entries in the guest page table + * @ref_count: reference counter for the gmap structure * @table: pointer to the page directory * @asce: address space control element for gmap page table * @pfault_enabled: defines if pfaults are applicable for the guest @@ -26,6 +27,7 @@ struct gmap { struct radix_tree_root guest_to_host; struct radix_tree_root host_to_guest; spinlock_t guest_table_lock; + atomic_t ref_count; unsigned long *table; unsigned long asce; unsigned long asce_end; @@ -44,8 +46,11 @@ struct gmap_notifier { unsigned long end); }; -struct gmap *gmap_alloc(struct mm_struct *mm, unsigned long limit); -void gmap_free(struct gmap *gmap); +struct gmap *gmap_create(struct mm_struct *mm, unsigned long limit); +void gmap_remove(struct gmap *gmap); +struct gmap *gmap_get(struct gmap *gmap); +void gmap_put(struct gmap *gmap); + void gmap_enable(struct gmap *gmap); void gmap_disable(struct gmap *gmap); int gmap_map_segment(struct gmap *gmap, unsigned long from, diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index b6e7f66..9dd5298 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -532,20 +532,20 @@ static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *att if (!new_limit) return -EINVAL; - /* gmap_alloc takes last usable address */ + /* gmap_create takes last usable address */ if (new_limit != KVM_S390_NO_MEM_LIMIT) new_limit -= 1; ret = -EBUSY; mutex_lock(&kvm->lock); if (!kvm->created_vcpus) { - /* gmap_alloc will round the limit up */ - struct gmap *new = gmap_alloc(current->mm, new_limit); + /* gmap_create will round the limit up */ + struct gmap *new = gmap_create(current->mm, new_limit); if (!new) { ret = -ENOMEM; } else { - gmap_free(kvm->arch.gmap); + gmap_remove(kvm->arch.gmap); new->private = kvm; kvm->arch.gmap = new; ret = 0; @@ -1394,7 +1394,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) else kvm->arch.mem_limit = min_t(unsigned long, TASK_MAX_SIZE, sclp.hamax + 1); - kvm->arch.gmap = gmap_alloc(current->mm, kvm->arch.mem_limit - 1); + kvm->arch.gmap = gmap_create(current->mm, kvm->arch.mem_limit - 1); if (!kvm->arch.gmap) goto out_err; kvm->arch.gmap->private = kvm; @@ -1427,7 +1427,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu) sca_del_vcpu(vcpu); if (kvm_is_ucontrol(vcpu->kvm)) - gmap_free(vcpu->arch.gmap); + gmap_remove(vcpu->arch.gmap); if (vcpu->kvm->arch.use_cmma) kvm_s390_vcpu_unsetup_cmma(vcpu); @@ -1460,7 +1460,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm) debug_unregister(kvm->arch.dbf); free_page((unsigned long)kvm->arch.sie_page2); if (!kvm_is_ucontrol(kvm)) - gmap_free(kvm->arch.gmap); + gmap_remove(kvm->arch.gmap); kvm_s390_destroy_adapters(kvm); kvm_s390_clear_float_irqs(kvm); KVM_EVENT(3, "vm 0x%pK destroyed", kvm); @@ -1469,7 +1469,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm) /* Section: vcpu related */ static int __kvm_ucontrol_vcpu_init(struct kvm_vcpu *vcpu) { - vcpu->arch.gmap = gmap_alloc(current->mm, -1UL); + vcpu->arch.gmap = gmap_create(current->mm, -1UL); if (!vcpu->arch.gmap) return -ENOMEM; vcpu->arch.gmap->private = vcpu->kvm; diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c index 480c076..fe25f19 100644 --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -21,13 +21,13 @@ #include /** - * gmap_alloc - allocate a guest address space + * gmap_alloc - allocate and initialize a guest address space * @mm: pointer to the parent mm_struct * @limit: maximum address of the gmap address space * * Returns a guest address space structure. */ -struct gmap *gmap_alloc(struct mm_struct *mm, unsigned long limit) +static struct gmap *gmap_alloc(unsigned long limit) { struct gmap *gmap; struct page *page; @@ -58,7 +58,7 @@ struct gmap *gmap_alloc(struct mm_struct *mm, unsigned long limit) INIT_RADIX_TREE(&gmap->guest_to_host, GFP_KERNEL); INIT_RADIX_TREE(&gmap->host_to_guest, GFP_ATOMIC); spin_lock_init(&gmap->guest_table_lock); - gmap->mm = mm; + atomic_set(&gmap->ref_count, 1); page = alloc_pages(GFP_KERNEL, 2); if (!page) goto out_free; @@ -70,9 +70,6 @@ struct gmap *gmap_alloc(struct mm_struct *mm, unsigned long limit) gmap->asce = atype | _ASCE_TABLE_LENGTH | _ASCE_USER_BITS | __pa(table); gmap->asce_end = limit; - spin_lock(&mm->context.gmap_lock); - list_add_rcu(&gmap->list, &mm->context.gmap_list); - spin_unlock(&mm->context.gmap_lock); return gmap; out_free: @@ -80,7 +77,28 @@ out_free: out: return NULL; } -EXPORT_SYMBOL_GPL(gmap_alloc); + +/** + * gmap_create - create a guest address space + * @mm: pointer to the parent mm_struct + * @limit: maximum size of the gmap address space + * + * Returns a guest address space structure. + */ +struct gmap *gmap_create(struct mm_struct *mm, unsigned long limit) +{ + struct gmap *gmap; + + gmap = gmap_alloc(limit); + if (!gmap) + return NULL; + gmap->mm = mm; + spin_lock(&mm->context.gmap_lock); + list_add_rcu(&gmap->list, &mm->context.gmap_list); + spin_unlock(&mm->context.gmap_lock); + return gmap; +} +EXPORT_SYMBOL_GPL(gmap_create); static void gmap_flush_tlb(struct gmap *gmap) { @@ -118,21 +136,10 @@ static void gmap_radix_tree_free(struct radix_tree_root *root) * gmap_free - free a guest address space * @gmap: pointer to the guest address space structure */ -void gmap_free(struct gmap *gmap) +static void gmap_free(struct gmap *gmap) { struct page *page, *next; - /* Flush tlb. */ - if (MACHINE_HAS_IDTE) - __tlb_flush_asce(gmap->mm, gmap->asce); - else - __tlb_flush_global(); - - spin_lock(&gmap->mm->context.gmap_lock); - list_del_rcu(&gmap->list); - spin_unlock(&gmap->mm->context.gmap_lock); - synchronize_rcu(); - /* Free all segment & region tables. */ list_for_each_entry_safe(page, next, &gmap->crst_list, lru) __free_pages(page, 2); @@ -140,7 +147,50 @@ void gmap_free(struct gmap *gmap) gmap_radix_tree_free(&gmap->host_to_guest); kfree(gmap); } -EXPORT_SYMBOL_GPL(gmap_free); + +/** + * gmap_get - increase reference counter for guest address space + * @gmap: pointer to the guest address space structure + * + * Returns the gmap pointer + */ +struct gmap *gmap_get(struct gmap *gmap) +{ + atomic_inc(&gmap->ref_count); + return gmap; +} +EXPORT_SYMBOL_GPL(gmap_get); + +/** + * gmap_put - decrease reference counter for guest address space + * @gmap: pointer to the guest address space structure + * + * If the reference counter reaches zero the guest address space is freed. + */ +void gmap_put(struct gmap *gmap) +{ + if (atomic_dec_return(&gmap->ref_count) == 0) + gmap_free(gmap); +} +EXPORT_SYMBOL_GPL(gmap_put); + +/** + * gmap_remove - remove a guest address space but do not free it yet + * @gmap: pointer to the guest address space structure + */ +void gmap_remove(struct gmap *gmap) +{ + /* Flush tlb. */ + gmap_flush_tlb(gmap); + /* Remove gmap from the pre-mm list */ + spin_lock(&gmap->mm->context.gmap_lock); + list_del_rcu(&gmap->list); + spin_unlock(&gmap->mm->context.gmap_lock); + synchronize_rcu(); + /* Put reference */ + gmap_put(gmap); +} +EXPORT_SYMBOL_GPL(gmap_remove); /** * gmap_enable - switch primary space to the guest address space -- 2.7.4