From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
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 <dahi@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
---
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 <asm/tlb.h>
/**
- * 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
--
2.5.5
--
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