KVM: PPC: Use RCU for arch.spapr_tce_tables

[mirror_ubuntu-bionic-kernel.git] / arch / powerpc / kvm / book3s_64_vio.c

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright 2010 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
 * Copyright 2011 David Gibson, IBM Corporation <dwg@au1.ibm.com>
 */

#include <linux/types.h>
#include <linux/string.h>
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/highmem.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/hugetlb.h>
#include <linux/list.h>
#include <linux/anon_inodes.h>

#include <asm/tlbflush.h>
#include <asm/kvm_ppc.h>
#include <asm/kvm_book3s.h>
#include <asm/mmu-hash64.h>
#include <asm/hvcall.h>
#include <asm/synch.h>
#include <asm/ppc-opcode.h>
#include <asm/kvm_host.h>
#include <asm/udbg.h>

#define TCES_PER_PAGE	(PAGE_SIZE / sizeof(u64))

static long kvmppc_stt_npages(unsigned long window_size)
{
	return ALIGN((window_size >> SPAPR_TCE_SHIFT)
		     * sizeof(u64), PAGE_SIZE) / PAGE_SIZE;
}

static void release_spapr_tce_table(struct rcu_head *head)
{
	struct kvmppc_spapr_tce_table *stt = container_of(head,
			struct kvmppc_spapr_tce_table, rcu);
	int i;

	for (i = 0; i < kvmppc_stt_npages(stt->window_size); i++)
		__free_page(stt->pages[i]);

	kfree(stt);
}

static int kvm_spapr_tce_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
	struct kvmppc_spapr_tce_table *stt = vma->vm_file->private_data;
	struct page *page;

	if (vmf->pgoff >= kvmppc_stt_npages(stt->window_size))
		return VM_FAULT_SIGBUS;

	page = stt->pages[vmf->pgoff];
	get_page(page);
	vmf->page = page;
	return 0;
}

static const struct vm_operations_struct kvm_spapr_tce_vm_ops = {
	.fault = kvm_spapr_tce_fault,
};

static int kvm_spapr_tce_mmap(struct file *file, struct vm_area_struct *vma)
{
	vma->vm_ops = &kvm_spapr_tce_vm_ops;
	return 0;
}

static int kvm_spapr_tce_release(struct inode *inode, struct file *filp)
{
	struct kvmppc_spapr_tce_table *stt = filp->private_data;

	list_del_rcu(&stt->list);

	kvm_put_kvm(stt->kvm);

	call_rcu(&stt->rcu, release_spapr_tce_table);

	return 0;
}

static const struct file_operations kvm_spapr_tce_fops = {
	.mmap           = kvm_spapr_tce_mmap,
	.release	= kvm_spapr_tce_release,
};

long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
				   struct kvm_create_spapr_tce *args)
{
	struct kvmppc_spapr_tce_table *stt = NULL;
	long npages;
	int ret = -ENOMEM;
	int i;

	/* Check this LIOBN hasn't been previously allocated */
	list_for_each_entry(stt, &kvm->arch.spapr_tce_tables, list) {
		if (stt->liobn == args->liobn)
			return -EBUSY;
	}

	npages = kvmppc_stt_npages(args->window_size);

	stt = kzalloc(sizeof(*stt) + npages * sizeof(struct page *),
		      GFP_KERNEL);
	if (!stt)
		goto fail;

	stt->liobn = args->liobn;
	stt->window_size = args->window_size;
	stt->kvm = kvm;

	for (i = 0; i < npages; i++) {
		stt->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO);
		if (!stt->pages[i])
			goto fail;
	}

	kvm_get_kvm(kvm);

	mutex_lock(&kvm->lock);
	list_add_rcu(&stt->list, &kvm->arch.spapr_tce_tables);

	mutex_unlock(&kvm->lock);

	return anon_inode_getfd("kvm-spapr-tce", &kvm_spapr_tce_fops,
				stt, O_RDWR | O_CLOEXEC);

fail:
	if (stt) {
		for (i = 0; i < npages; i++)
			if (stt->pages[i])
				__free_page(stt->pages[i]);

		kfree(stt);
	}
	return ret;
}