Commit 3ee16c81 authored by Izik Eidus's avatar Izik Eidus Committed by Avi Kivity
Browse files

KVM: MMU: allow the vm to shrink the kvm mmu shadow caches 



Allow the Linux memory manager to reclaim memory in the kvm shadow cache.

Signed-off-by: default avatarIzik Eidus <izike@qumranet.com>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 3200f405

arch/x86/kvm/mmu.c

+56 −2
Original line number Diff line number Diff line
@@ -1966,7 +1966,53 @@ void kvm_mmu_zap_all(struct kvm *kvm) 
	kvm_flush_remote_tlbs(kvm);

}



void kvm_mmu_module_exit(void)

void kvm_mmu_remove_one_alloc_mmu_page(struct kvm *kvm)

{

	struct kvm_mmu_page *page;



	page = container_of(kvm->arch.active_mmu_pages.prev,

			    struct kvm_mmu_page, link);

	kvm_mmu_zap_page(kvm, page);

}



static int mmu_shrink(int nr_to_scan, gfp_t gfp_mask)

{

	struct kvm *kvm;

	struct kvm *kvm_freed = NULL;

	int cache_count = 0;



	spin_lock(&kvm_lock);



	list_for_each_entry(kvm, &vm_list, vm_list) {

		int npages;



		spin_lock(&kvm->mmu_lock);

		npages = kvm->arch.n_alloc_mmu_pages -

			 kvm->arch.n_free_mmu_pages;

		cache_count += npages;

		if (!kvm_freed && nr_to_scan > 0 && npages > 0) {

			kvm_mmu_remove_one_alloc_mmu_page(kvm);

			cache_count--;

			kvm_freed = kvm;

		}

		nr_to_scan--;



		spin_unlock(&kvm->mmu_lock);

	}

	if (kvm_freed)

		list_move_tail(&kvm_freed->vm_list, &vm_list);



	spin_unlock(&kvm_lock);



	return cache_count;

}



static struct shrinker mmu_shrinker = {

	.shrink = mmu_shrink,

	.seeks = DEFAULT_SEEKS * 10,

};



void mmu_destroy_caches(void)

{

	if (pte_chain_cache)

		kmem_cache_destroy(pte_chain_cache);
@@ -1976,6 +2022,12 @@ void kvm_mmu_module_exit(void) 
		kmem_cache_destroy(mmu_page_header_cache);

}



void kvm_mmu_module_exit(void)

{

	mmu_destroy_caches();

	unregister_shrinker(&mmu_shrinker);

}



int kvm_mmu_module_init(void)

{

	pte_chain_cache = kmem_cache_create("kvm_pte_chain",
@@ -1995,10 +2047,12 @@ int kvm_mmu_module_init(void) 
	if (!mmu_page_header_cache)

		goto nomem;



	register_shrinker(&mmu_shrinker);



	return 0;



nomem:

	kvm_mmu_module_exit();

	mmu_destroy_caches();

	return -ENOMEM;

}