path: root/arch/x86/kernel/cpu/sgx/main.c

// SPDX-License-Identifier: GPL-2.0
/*  Copyright(c) 2016-20 Intel Corporation. */

#include <linux/file.h>
#include <linux/freezer.h>
#include <linux/highmem.h>
#include <linux/kthread.h>
#include <linux/kvm_types.h>
#include <linux/miscdevice.h>
#include <linux/node.h>
#include <linux/pagemap.h>
#include <linux/ratelimit.h>
#include <linux/sched/mm.h>
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/vmalloc.h>
#include <asm/msr.h>
#include <asm/sgx.h>
#include <asm/archrandom.h>
#include "driver.h"
#include "encl.h"
#include "encls.h"

struct sgx_epc_section sgx_epc_sections[SGX_MAX_EPC_SECTIONS];
static int sgx_nr_epc_sections;
static struct task_struct *ksgxd_tsk;
static DECLARE_WAIT_QUEUE_HEAD(ksgxd_waitq);
static DEFINE_XARRAY(sgx_epc_address_space);

/*
 * These variables are part of the state of the reclaimer, and must be accessed
 * with sgx_reclaimer_lock acquired.
 */
static LIST_HEAD(sgx_active_page_list);
static DEFINE_SPINLOCK(sgx_reclaimer_lock);

static atomic_long_t sgx_nr_free_pages = ATOMIC_LONG_INIT(0);

/* Nodes with one or more EPC sections. */
static nodemask_t sgx_numa_mask;

/*
 * Array with one list_head for each possible NUMA node.  Each
 * list contains all the sgx_epc_section's which are on that
 * node.
 */
static struct sgx_numa_node *sgx_numa_nodes;

static LIST_HEAD(sgx_dirty_page_list);

/*
 * Reset post-kexec EPC pages to the uninitialized state. The pages are removed
 * from the input list, and made available for the page allocator. SECS pages
 * prepending their children in the input list are left intact.
 *
 * Return 0 when sanitization was successful or kthread was stopped, and the
 * number of unsanitized pages otherwise.
 */
static unsigned long __sgx_sanitize_pages(struct list_head *dirty_page_list)
{
	unsigned long left_dirty = 0;
	struct sgx_epc_page *page;
	LIST_HEAD(dirty);
	int ret;

	/* dirty_page_list is thread-local, no need for a lock: */
	while (!list_empty(dirty_page_list)) {
		if (kthread_should_stop())
			return 0;

		page = list_first_entry(dirty_page_list, struct sgx_epc_page, list);

		/*
		 * Checking page->poison without holding the node->lock
		 * is racy, but losing the race (i.e. poison is set just
		 * after the check) just means __eremove() will be uselessly
		 * called for a page that sgx_free_epc_page() will put onto
		 * the node->sgx_poison_page_list later.
		 */
		if (page->poison) {
			struct sgx_epc_section *section = &sgx_epc_sections[page->section];
			struct sgx_numa_node *node = section->node;

			spin_lock(&node->lock);
			list_move(&page->list, &node->sgx_poison_page_list);
			spin_unlock(&node->lock);

			continue;
		}

		ret = __eremove(sgx_get_epc_virt_addr(page));
		if (!ret) {
			/*
			 * page is now sanitized.  Make it available via the SGX
			 * page allocator:
			 */
			list_del(&page->list);
			sgx_free_epc_page(page);
		} else {
			/* The page is not yet clean - move to the dirty list. */
			list_move_tail(&page->list, &dirty);
			left_dirty++;
		}

		cond_resched();
	}

	list_splice(&dirty, dirty_page_list);
	return left_dirty;
}

static bool sgx_reclaimer_age(struct sgx_epc_page *epc_page)
{
	struct sgx_encl_page *page = epc_page->owner;
	struct sgx_encl *encl = page->encl;
	struct sgx_encl_mm *encl_mm;
	bool ret = true;
	int idx;

	idx = srcu_read_lock(&encl->srcu);

	list_for_each_entry_rcu(encl_mm, &encl->mm_list, list) {
		if (!mmget_not_zero(encl_mm->mm))
			continue;

		mmap_read_lock(encl_mm->mm);
		ret = !sgx_encl_test_and_clear_young(encl_mm->mm, page);
		mmap_read_unlock(encl_mm->mm);

		mmput_async(encl_mm->mm);

		if (!ret)
			break;
	}

	srcu_read_unlock(&encl->srcu, idx);

	if (!ret)
		return false;

	return true;
}

static void sgx_reclaimer_block(struct sgx_epc_page *epc_page)
{
	struct sgx_encl_page *page = epc_page->owner;
	unsigned long addr = page->desc & PAGE_MASK;
	struct sgx_encl *encl = page->encl;
	int