1 // SPDX-License-Identifier: GPL-2.0
3 * Common Ultravisor functions and initialization
5 * Copyright IBM Corp. 2019, 2020
7 #define KMSG_COMPONENT "prot_virt"
8 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
10 #include <linux/kernel.h>
11 #include <linux/types.h>
12 #include <linux/sizes.h>
13 #include <linux/bitmap.h>
14 #include <linux/memblock.h>
15 #include <linux/pagemap.h>
16 #include <linux/swap.h>
17 #include <asm/facility.h>
18 #include <asm/sections.h>
21 /* the bootdata_preserved fields come from ones in arch/s390/boot/uv.c */
22 #ifdef CONFIG_PROTECTED_VIRTUALIZATION_GUEST
23 int __bootdata_preserved(prot_virt_guest);
26 struct uv_info __bootdata_preserved(uv_info);
28 #if IS_ENABLED(CONFIG_KVM)
30 EXPORT_SYMBOL(prot_virt_host);
31 EXPORT_SYMBOL(uv_info);
33 static int __init prot_virt_setup(char *val)
38 rc = kstrtobool(val, &enabled);
42 if (is_prot_virt_guest() && prot_virt_host) {
44 pr_warn("Protected virtualization not available in protected guests.");
47 if (prot_virt_host && !test_facility(158)) {
49 pr_warn("Protected virtualization not supported by the hardware.");
54 early_param("prot_virt", prot_virt_setup);
56 static int __init uv_init(unsigned long stor_base, unsigned long stor_len)
58 struct uv_cb_init uvcb = {
59 .header.cmd = UVC_CMD_INIT_UV,
60 .header.len = sizeof(uvcb),
61 .stor_origin = stor_base,
65 if (uv_call(0, (uint64_t)&uvcb)) {
66 pr_err("Ultravisor init failed with rc: 0x%x rrc: 0%x\n",
67 uvcb.header.rc, uvcb.header.rrc);
73 void __init setup_uv(void)
75 unsigned long uv_stor_base;
77 uv_stor_base = (unsigned long)memblock_alloc_try_nid(
78 uv_info.uv_base_stor_len, SZ_1M, SZ_2G,
79 MEMBLOCK_ALLOC_ACCESSIBLE, NUMA_NO_NODE);
81 pr_warn("Failed to reserve %lu bytes for ultravisor base storage\n",
82 uv_info.uv_base_stor_len);
86 if (uv_init(uv_stor_base, uv_info.uv_base_stor_len)) {
87 memblock_free(uv_stor_base, uv_info.uv_base_stor_len);
91 pr_info("Reserving %luMB as ultravisor base storage\n",
92 uv_info.uv_base_stor_len >> 20);
95 pr_info("Disabling support for protected virtualization");
99 void adjust_to_uv_max(unsigned long *vmax)
101 *vmax = min_t(unsigned long, *vmax, uv_info.max_sec_stor_addr);
105 * Requests the Ultravisor to pin the page in the shared state. This will
106 * cause an intercept when the guest attempts to unshare the pinned page.
108 static int uv_pin_shared(unsigned long paddr)
110 struct uv_cb_cfs uvcb = {
111 .header.cmd = UVC_CMD_PIN_PAGE_SHARED,
112 .header.len = sizeof(uvcb),
116 if (uv_call(0, (u64)&uvcb))
122 * Requests the Ultravisor to encrypt a guest page and make it
123 * accessible to the host for paging (export).
125 * @paddr: Absolute host address of page to be exported
127 int uv_convert_from_secure(unsigned long paddr)
129 struct uv_cb_cfs uvcb = {
130 .header.cmd = UVC_CMD_CONV_FROM_SEC_STOR,
131 .header.len = sizeof(uvcb),
135 if (uv_call(0, (u64)&uvcb))
141 * Calculate the expected ref_count for a page that would otherwise have no
142 * further pins. This was cribbed from similar functions in other places in
143 * the kernel, but with some slight modifications. We know that a secure
144 * page can not be a huge page for example.
146 static int expected_page_refs(struct page *page)
150 res = page_mapcount(page);
151 if (PageSwapCache(page)) {
153 } else if (page_mapping(page)) {
155 if (page_has_private(page))
161 static int make_secure_pte(pte_t *ptep, unsigned long addr,
162 struct page *exp_page, struct uv_cb_header *uvcb)
164 pte_t entry = READ_ONCE(*ptep);
166 int expected, rc = 0;
168 if (!pte_present(entry))
170 if (pte_val(entry) & _PAGE_INVALID)
173 page = pte_page(entry);
174 if (page != exp_page)
176 if (PageWriteback(page))
178 expected = expected_page_refs(page);
179 if (!page_ref_freeze(page, expected))
181 set_bit(PG_arch_1, &page->flags);
182 rc = uv_call(0, (u64)uvcb);
183 page_ref_unfreeze(page, expected);
184 /* Return -ENXIO if the page was not mapped, -EINVAL otherwise */
186 rc = uvcb->rc == 0x10a ? -ENXIO : -EINVAL;
191 * Requests the Ultravisor to make a page accessible to a guest.
192 * If it's brought in the first time, it will be cleared. If
193 * it has been exported before, it will be decrypted and integrity
196 int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb)
198 struct vm_area_struct *vma;
199 bool local_drain = false;
208 mmap_read_lock(gmap->mm);
210 uaddr = __gmap_translate(gmap, gaddr);
211 if (IS_ERR_VALUE(uaddr))
213 vma = find_vma(gmap->mm, uaddr);
217 * Secure pages cannot be huge and userspace should not combine both.
218 * In case userspace does it anyway this will result in an -EFAULT for
219 * the unpack. The guest is thus never reaching secure mode. If
220 * userspace is playing dirty tricky with mapping huge pages later
221 * on this will result in a segmentation fault.
223 if (is_vm_hugetlb_page(vma))
227 page = follow_page(vma, uaddr, FOLL_WRITE);
228 if (IS_ERR_OR_NULL(page))
232 ptep = get_locked_pte(gmap->mm, uaddr, &ptelock);
233 rc = make_secure_pte(ptep, uaddr, page, uvcb);
234 pte_unmap_unlock(ptep, ptelock);
237 mmap_read_unlock(gmap->mm);
240 wait_on_page_writeback(page);
241 } else if (rc == -EBUSY) {
243 * If we have tried a local drain and the page refcount
244 * still does not match our expected safe value, try with a
245 * system wide drain. This is needed if the pagevecs holding
246 * the page are on a different CPU.
250 /* We give up here, and let the caller try again */
254 * We are here if the page refcount does not match the
255 * expected safe value. The main culprits are usually
256 * pagevecs. With lru_add_drain() we drain the pagevecs
257 * on the local CPU so that hopefully the refcount will
258 * reach the expected safe value.
262 /* And now we try again immediately after draining */
264 } else if (rc == -ENXIO) {
265 if (gmap_fault(gmap, gaddr, FAULT_FLAG_WRITE))
271 EXPORT_SYMBOL_GPL(gmap_make_secure);
273 int gmap_convert_to_secure(struct gmap *gmap, unsigned long gaddr)
275 struct uv_cb_cts uvcb = {
276 .header.cmd = UVC_CMD_CONV_TO_SEC_STOR,
277 .header.len = sizeof(uvcb),
278 .guest_handle = gmap->guest_handle,
282 return gmap_make_secure(gmap, gaddr, &uvcb);
284 EXPORT_SYMBOL_GPL(gmap_convert_to_secure);
287 * To be called with the page locked or with an extra reference! This will
288 * prevent gmap_make_secure from touching the page concurrently. Having 2
289 * parallel make_page_accessible is fine, as the UV calls will become a
290 * no-op if the page is already exported.
292 int arch_make_page_accessible(struct page *page)
296 /* Hugepage cannot be protected, so nothing to do */
301 * PG_arch_1 is used in 3 places:
302 * 1. for kernel page tables during early boot
303 * 2. for storage keys of huge pages and KVM
304 * 3. As an indication that this page might be secure. This can
305 * overindicate, e.g. we set the bit before calling
307 * As secure pages are never huge, all 3 variants can co-exists.
309 if (!test_bit(PG_arch_1, &page->flags))
312 rc = uv_pin_shared(page_to_phys(page));
314 clear_bit(PG_arch_1, &page->flags);
318 rc = uv_convert_from_secure(page_to_phys(page));
320 clear_bit(PG_arch_1, &page->flags);
326 EXPORT_SYMBOL_GPL(arch_make_page_accessible);
330 #if defined(CONFIG_PROTECTED_VIRTUALIZATION_GUEST) || IS_ENABLED(CONFIG_KVM)
331 static ssize_t uv_query_facilities(struct kobject *kobj,
332 struct kobj_attribute *attr, char *page)
334 return snprintf(page, PAGE_SIZE, "%lx\n%lx\n%lx\n%lx\n",
335 uv_info.inst_calls_list[0],
336 uv_info.inst_calls_list[1],
337 uv_info.inst_calls_list[2],
338 uv_info.inst_calls_list[3]);
341 static struct kobj_attribute uv_query_facilities_attr =
342 __ATTR(facilities, 0444, uv_query_facilities, NULL);
344 static ssize_t uv_query_max_guest_cpus(struct kobject *kobj,
345 struct kobj_attribute *attr, char *page)
347 return snprintf(page, PAGE_SIZE, "%d\n",
348 uv_info.max_guest_cpus);
351 static struct kobj_attribute uv_query_max_guest_cpus_attr =
352 __ATTR(max_cpus, 0444, uv_query_max_guest_cpus, NULL);
354 static ssize_t uv_query_max_guest_vms(struct kobject *kobj,
355 struct kobj_attribute *attr, char *page)
357 return snprintf(page, PAGE_SIZE, "%d\n",
358 uv_info.max_num_sec_conf);
361 static struct kobj_attribute uv_query_max_guest_vms_attr =
362 __ATTR(max_guests, 0444, uv_query_max_guest_vms, NULL);
364 static ssize_t uv_query_max_guest_addr(struct kobject *kobj,
365 struct kobj_attribute *attr, char *page)
367 return snprintf(page, PAGE_SIZE, "%lx\n",
368 uv_info.max_sec_stor_addr);
371 static struct kobj_attribute uv_query_max_guest_addr_attr =
372 __ATTR(max_address, 0444, uv_query_max_guest_addr, NULL);
374 static struct attribute *uv_query_attrs[] = {
375 &uv_query_facilities_attr.attr,
376 &uv_query_max_guest_cpus_attr.attr,
377 &uv_query_max_guest_vms_attr.attr,
378 &uv_query_max_guest_addr_attr.attr,
382 static struct attribute_group uv_query_attr_group = {
383 .attrs = uv_query_attrs,
386 static struct kset *uv_query_kset;
387 static struct kobject *uv_kobj;
389 static int __init uv_info_init(void)
393 if (!test_facility(158))
396 uv_kobj = kobject_create_and_add("uv", firmware_kobj);
400 uv_query_kset = kset_create_and_add("query", NULL, uv_kobj);
404 rc = sysfs_create_group(&uv_query_kset->kobj, &uv_query_attr_group);
408 kset_unregister(uv_query_kset);
410 kobject_del(uv_kobj);
411 kobject_put(uv_kobj);
414 device_initcall(uv_info_init);