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)
29 int __bootdata_preserved(prot_virt_host);
30 EXPORT_SYMBOL(prot_virt_host);
31 EXPORT_SYMBOL(uv_info);
33 static int __init uv_init(unsigned long stor_base, unsigned long stor_len)
35 struct uv_cb_init uvcb = {
36 .header.cmd = UVC_CMD_INIT_UV,
37 .header.len = sizeof(uvcb),
38 .stor_origin = stor_base,
42 if (uv_call(0, (uint64_t)&uvcb)) {
43 pr_err("Ultravisor init failed with rc: 0x%x rrc: 0%x\n",
44 uvcb.header.rc, uvcb.header.rrc);
50 void __init setup_uv(void)
52 unsigned long uv_stor_base;
55 * keep these conditions in line with has_uv_sec_stor_limit()
57 if (!is_prot_virt_host())
60 if (is_prot_virt_guest()) {
62 pr_warn("Protected virtualization not available in protected guests.");
66 if (!test_facility(158)) {
68 pr_warn("Protected virtualization not supported by the hardware.");
72 uv_stor_base = (unsigned long)memblock_alloc_try_nid(
73 uv_info.uv_base_stor_len, SZ_1M, SZ_2G,
74 MEMBLOCK_ALLOC_ACCESSIBLE, NUMA_NO_NODE);
76 pr_warn("Failed to reserve %lu bytes for ultravisor base storage\n",
77 uv_info.uv_base_stor_len);
81 if (uv_init(uv_stor_base, uv_info.uv_base_stor_len)) {
82 memblock_free(uv_stor_base, uv_info.uv_base_stor_len);
86 pr_info("Reserving %luMB as ultravisor base storage\n",
87 uv_info.uv_base_stor_len >> 20);
90 pr_info("Disabling support for protected virtualization");
95 * Requests the Ultravisor to pin the page in the shared state. This will
96 * cause an intercept when the guest attempts to unshare the pinned page.
98 static int uv_pin_shared(unsigned long paddr)
100 struct uv_cb_cfs uvcb = {
101 .header.cmd = UVC_CMD_PIN_PAGE_SHARED,
102 .header.len = sizeof(uvcb),
106 if (uv_call(0, (u64)&uvcb))
112 * Requests the Ultravisor to destroy a guest page and make it
113 * accessible to the host. The destroy clears the page instead of
116 * @paddr: Absolute host address of page to be destroyed
118 int uv_destroy_page(unsigned long paddr)
120 struct uv_cb_cfs uvcb = {
121 .header.cmd = UVC_CMD_DESTR_SEC_STOR,
122 .header.len = sizeof(uvcb),
126 if (uv_call(0, (u64)&uvcb)) {
128 * Older firmware uses 107/d as an indication of a non secure
129 * page. Let us emulate the newer variant (no-op).
131 if (uvcb.header.rc == 0x107 && uvcb.header.rrc == 0xd)
139 * Requests the Ultravisor to encrypt a guest page and make it
140 * accessible to the host for paging (export).
142 * @paddr: Absolute host address of page to be exported
144 int uv_convert_from_secure(unsigned long paddr)
146 struct uv_cb_cfs uvcb = {
147 .header.cmd = UVC_CMD_CONV_FROM_SEC_STOR,
148 .header.len = sizeof(uvcb),
152 if (uv_call(0, (u64)&uvcb))
158 * Calculate the expected ref_count for a page that would otherwise have no
159 * further pins. This was cribbed from similar functions in other places in
160 * the kernel, but with some slight modifications. We know that a secure
161 * page can not be a huge page for example.
163 static int expected_page_refs(struct page *page)
167 res = page_mapcount(page);
168 if (PageSwapCache(page)) {
170 } else if (page_mapping(page)) {
172 if (page_has_private(page))
178 static int make_secure_pte(pte_t *ptep, unsigned long addr,
179 struct page *exp_page, struct uv_cb_header *uvcb)
181 pte_t entry = READ_ONCE(*ptep);
183 int expected, rc = 0;
185 if (!pte_present(entry))
187 if (pte_val(entry) & _PAGE_INVALID)
190 page = pte_page(entry);
191 if (page != exp_page)
193 if (PageWriteback(page))
195 expected = expected_page_refs(page);
196 if (!page_ref_freeze(page, expected))
198 set_bit(PG_arch_1, &page->flags);
199 rc = uv_call(0, (u64)uvcb);
200 page_ref_unfreeze(page, expected);
201 /* Return -ENXIO if the page was not mapped, -EINVAL otherwise */
203 rc = uvcb->rc == 0x10a ? -ENXIO : -EINVAL;
208 * Requests the Ultravisor to make a page accessible to a guest.
209 * If it's brought in the first time, it will be cleared. If
210 * it has been exported before, it will be decrypted and integrity
213 int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb)
215 struct vm_area_struct *vma;
216 bool local_drain = false;
225 mmap_read_lock(gmap->mm);
227 uaddr = __gmap_translate(gmap, gaddr);
228 if (IS_ERR_VALUE(uaddr))
230 vma = find_vma(gmap->mm, uaddr);
234 * Secure pages cannot be huge and userspace should not combine both.
235 * In case userspace does it anyway this will result in an -EFAULT for
236 * the unpack. The guest is thus never reaching secure mode. If
237 * userspace is playing dirty tricky with mapping huge pages later
238 * on this will result in a segmentation fault.
240 if (is_vm_hugetlb_page(vma))
244 page = follow_page(vma, uaddr, FOLL_WRITE);
245 if (IS_ERR_OR_NULL(page))
249 ptep = get_locked_pte(gmap->mm, uaddr, &ptelock);
250 rc = make_secure_pte(ptep, uaddr, page, uvcb);
251 pte_unmap_unlock(ptep, ptelock);
254 mmap_read_unlock(gmap->mm);
257 wait_on_page_writeback(page);
258 } else if (rc == -EBUSY) {
260 * If we have tried a local drain and the page refcount
261 * still does not match our expected safe value, try with a
262 * system wide drain. This is needed if the pagevecs holding
263 * the page are on a different CPU.
267 /* We give up here, and let the caller try again */
271 * We are here if the page refcount does not match the
272 * expected safe value. The main culprits are usually
273 * pagevecs. With lru_add_drain() we drain the pagevecs
274 * on the local CPU so that hopefully the refcount will
275 * reach the expected safe value.
279 /* And now we try again immediately after draining */
281 } else if (rc == -ENXIO) {
282 if (gmap_fault(gmap, gaddr, FAULT_FLAG_WRITE))
288 EXPORT_SYMBOL_GPL(gmap_make_secure);
290 int gmap_convert_to_secure(struct gmap *gmap, unsigned long gaddr)
292 struct uv_cb_cts uvcb = {
293 .header.cmd = UVC_CMD_CONV_TO_SEC_STOR,
294 .header.len = sizeof(uvcb),
295 .guest_handle = gmap->guest_handle,
299 return gmap_make_secure(gmap, gaddr, &uvcb);
301 EXPORT_SYMBOL_GPL(gmap_convert_to_secure);
304 * To be called with the page locked or with an extra reference! This will
305 * prevent gmap_make_secure from touching the page concurrently. Having 2
306 * parallel make_page_accessible is fine, as the UV calls will become a
307 * no-op if the page is already exported.
309 int arch_make_page_accessible(struct page *page)
313 /* Hugepage cannot be protected, so nothing to do */
318 * PG_arch_1 is used in 3 places:
319 * 1. for kernel page tables during early boot
320 * 2. for storage keys of huge pages and KVM
321 * 3. As an indication that this page might be secure. This can
322 * overindicate, e.g. we set the bit before calling
324 * As secure pages are never huge, all 3 variants can co-exists.
326 if (!test_bit(PG_arch_1, &page->flags))
329 rc = uv_pin_shared(page_to_phys(page));
331 clear_bit(PG_arch_1, &page->flags);
335 rc = uv_convert_from_secure(page_to_phys(page));
337 clear_bit(PG_arch_1, &page->flags);
343 EXPORT_SYMBOL_GPL(arch_make_page_accessible);
347 #if defined(CONFIG_PROTECTED_VIRTUALIZATION_GUEST) || IS_ENABLED(CONFIG_KVM)
348 static ssize_t uv_query_facilities(struct kobject *kobj,
349 struct kobj_attribute *attr, char *page)
351 return scnprintf(page, PAGE_SIZE, "%lx\n%lx\n%lx\n%lx\n",
352 uv_info.inst_calls_list[0],
353 uv_info.inst_calls_list[1],
354 uv_info.inst_calls_list[2],
355 uv_info.inst_calls_list[3]);
358 static struct kobj_attribute uv_query_facilities_attr =
359 __ATTR(facilities, 0444, uv_query_facilities, NULL);
361 static ssize_t uv_query_feature_indications(struct kobject *kobj,
362 struct kobj_attribute *attr, char *buf)
364 return sysfs_emit(buf, "%lx\n", uv_info.uv_feature_indications);
367 static struct kobj_attribute uv_query_feature_indications_attr =
368 __ATTR(feature_indications, 0444, uv_query_feature_indications, NULL);
370 static ssize_t uv_query_max_guest_cpus(struct kobject *kobj,
371 struct kobj_attribute *attr, char *page)
373 return scnprintf(page, PAGE_SIZE, "%d\n",
374 uv_info.max_guest_cpu_id + 1);
377 static struct kobj_attribute uv_query_max_guest_cpus_attr =
378 __ATTR(max_cpus, 0444, uv_query_max_guest_cpus, NULL);
380 static ssize_t uv_query_max_guest_vms(struct kobject *kobj,
381 struct kobj_attribute *attr, char *page)
383 return scnprintf(page, PAGE_SIZE, "%d\n",
384 uv_info.max_num_sec_conf);
387 static struct kobj_attribute uv_query_max_guest_vms_attr =
388 __ATTR(max_guests, 0444, uv_query_max_guest_vms, NULL);
390 static ssize_t uv_query_max_guest_addr(struct kobject *kobj,
391 struct kobj_attribute *attr, char *page)
393 return scnprintf(page, PAGE_SIZE, "%lx\n",
394 uv_info.max_sec_stor_addr);
397 static struct kobj_attribute uv_query_max_guest_addr_attr =
398 __ATTR(max_address, 0444, uv_query_max_guest_addr, NULL);
400 static struct attribute *uv_query_attrs[] = {
401 &uv_query_facilities_attr.attr,
402 &uv_query_feature_indications_attr.attr,
403 &uv_query_max_guest_cpus_attr.attr,
404 &uv_query_max_guest_vms_attr.attr,
405 &uv_query_max_guest_addr_attr.attr,
409 static struct attribute_group uv_query_attr_group = {
410 .attrs = uv_query_attrs,
413 static ssize_t uv_is_prot_virt_guest(struct kobject *kobj,
414 struct kobj_attribute *attr, char *page)
418 #ifdef CONFIG_PROTECTED_VIRTUALIZATION_GUEST
419 val = prot_virt_guest;
421 return scnprintf(page, PAGE_SIZE, "%d\n", val);
424 static ssize_t uv_is_prot_virt_host(struct kobject *kobj,
425 struct kobj_attribute *attr, char *page)
429 #if IS_ENABLED(CONFIG_KVM)
430 val = prot_virt_host;
433 return scnprintf(page, PAGE_SIZE, "%d\n", val);
436 static struct kobj_attribute uv_prot_virt_guest =
437 __ATTR(prot_virt_guest, 0444, uv_is_prot_virt_guest, NULL);
439 static struct kobj_attribute uv_prot_virt_host =
440 __ATTR(prot_virt_host, 0444, uv_is_prot_virt_host, NULL);
442 static const struct attribute *uv_prot_virt_attrs[] = {
443 &uv_prot_virt_guest.attr,
444 &uv_prot_virt_host.attr,
448 static struct kset *uv_query_kset;
449 static struct kobject *uv_kobj;
451 static int __init uv_info_init(void)
455 if (!test_facility(158))
458 uv_kobj = kobject_create_and_add("uv", firmware_kobj);
462 rc = sysfs_create_files(uv_kobj, uv_prot_virt_attrs);
466 uv_query_kset = kset_create_and_add("query", NULL, uv_kobj);
467 if (!uv_query_kset) {
472 rc = sysfs_create_group(&uv_query_kset->kobj, &uv_query_attr_group);
476 kset_unregister(uv_query_kset);
478 sysfs_remove_files(uv_kobj, uv_prot_virt_attrs);
480 kobject_del(uv_kobj);
481 kobject_put(uv_kobj);
484 device_initcall(uv_info_init);