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Commit 6ea427bb authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Christian Borntraeger
Browse files

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: default avatarDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
parent b2d73b2a

arch/s390/include/asm/gmap.h

+7 −2
Original line number Diff line number Diff line
@@ -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,

arch/s390/kvm/kvm-s390.c

+8 −8
Original line number Diff line number Diff line
@@ -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;

arch/s390/mm/gmap.c

+70 −20
Original line number Diff line number Diff line
@@ -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 @@ struct gmap *gmap_alloc(struct mm_struct *mm, unsigned long limit) 
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