// SPDX-License-Identifier: GPL-2.0 /* * Common Ultravisor functions and initialization * * Copyright IBM Corp. 2019, 2020 */ #define KMSG_COMPONENT "prot_virt" #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt #include #include #include #include #include #include #include #include #include #include /* the bootdata_preserved fields come from ones in arch/s390/boot/uv.c */ #ifdef CONFIG_PROTECTED_VIRTUALIZATION_GUEST int __bootdata_preserved(prot_virt_guest); #endif /* * uv_info contains both host and guest information but it's currently only * expected to be used within modules if it's the KVM module or for * any PV guest module. * * The kernel itself will write these values once in uv_query_info() * and then make some of them readable via a sysfs interface. */ struct uv_info __bootdata_preserved(uv_info); EXPORT_SYMBOL(uv_info); #if IS_ENABLED(CONFIG_KVM) int __bootdata_preserved(prot_virt_host); EXPORT_SYMBOL(prot_virt_host); static int __init uv_init(phys_addr_t stor_base, unsigned long stor_len) { struct uv_cb_init uvcb = { .header.cmd = UVC_CMD_INIT_UV, .header.len = sizeof(uvcb), .stor_origin = stor_base, .stor_len = stor_len, }; if (uv_call(0, (uint64_t)&uvcb)) { pr_err("Ultravisor init failed with rc: 0x%x rrc: 0%x\n", uvcb.header.rc, uvcb.header.rrc); return -1; } return 0; } void __init setup_uv(void) { void *uv_stor_base; if (!is_prot_virt_host()) return; uv_stor_base = memblock_alloc_try_nid( uv_info.uv_base_stor_len, SZ_1M, SZ_2G, MEMBLOCK_ALLOC_ACCESSIBLE, NUMA_NO_NODE); if (!uv_stor_base) { pr_warn("Failed to reserve %lu bytes for ultravisor base storage\n", uv_info.uv_base_stor_len); goto fail; } if (uv_init(__pa(uv_stor_base), uv_info.uv_base_stor_len)) { memblock_free(uv_stor_base, uv_info.uv_base_stor_len); goto fail; } pr_info("Reserving %luMB as ultravisor base storage\n", uv_info.uv_base_stor_len >> 20); return; fail: pr_info("Disabling support for protected virtualization"); prot_virt_host = 0; } /* * Requests the Ultravisor to pin the page in the shared state. This will * cause an intercept when the guest attempts to unshare the pinned page. */ int uv_pin_shared(unsigned long paddr) { struct uv_cb_cfs uvcb = { .header.cmd = UVC_CMD_PIN_PAGE_SHARED, .header.len = sizeof(uvcb), .paddr = paddr, }; if (uv_call(0, (u64)&uvcb)) return -EINVAL; return 0; } EXPORT_SYMBOL_GPL(uv_pin_shared); /* * Requests the Ultravisor to destroy a guest page and make it * accessible to the host. The destroy clears the page instead of * exporting. * * @paddr: Absolute host address of page to be destroyed */ static int uv_destroy_page(unsigned long paddr) { struct uv_cb_cfs uvcb = { .header.cmd = UVC_CMD_DESTR_SEC_STOR, .header.len = sizeof(uvcb), .paddr = paddr }; if (uv_call(0, (u64)&uvcb)) { /* * Older firmware uses 107/d as an indication of a non secure * page. Let us emulate the newer variant (no-op). */ if (uvcb.header.rc == 0x107 && uvcb.header.rrc == 0xd) return 0; return -EINVAL; } return 0; } /* * The caller must already hold a reference to the page */ int uv_destroy_owned_page(unsigned long paddr) { struct page *page = phys_to_page(paddr); int rc; get_page(page); rc = uv_destroy_page(paddr); if (!rc) clear_bit(PG_arch_1, &page->flags); put_page(page); return rc; } /* * Requests the Ultravisor to encrypt a guest page and make it * accessible to the host for paging (export). * * @paddr: Absolute host address of page to be exported */ int uv_convert_from_secure(unsigned long paddr) { struct uv_cb_cfs uvcb = { .header.cmd = UVC_CMD_CONV_FROM_SEC_STOR, .header.len = sizeof(uvcb), .paddr = paddr }; if (uv_call(0, (u64)&uvcb)) return -EINVAL; return 0; } /* * The caller must already hold a reference to the page */ int uv_convert_owned_from_secure(unsigned long paddr) { struct page *page = phys_to_page(paddr); int rc; get_page(page); rc = uv_convert_from_secure(paddr); if (!rc) clear_bit(PG_arch_1, &page->flags); put_page(page); return rc; } /* * Calculate the expected ref_count for a folio that would otherwise have no * further pins. This was cribbed from similar functions in other places in * the kernel, but with some slight modifications. We know that a secure * folio can not be a large folio, for example. */ static int expected_folio_refs(struct folio *folio) { int res; res = folio_mapcount(folio); if (folio_test_swapcache(folio)) { res++; } else if (folio_mapping(folio)) { res++; if (folio->private) res++; } return res; } static int make_folio_secure(struct folio *folio, struct uv_cb_header *uvcb) { int expected, cc = 0; if (folio_test_writeback(folio)) return -EAGAIN; expected = expected_folio_refs(folio); if (!folio_ref_freeze(folio, expected)) return -EBUSY; set_bit(PG_arch_1, &folio->flags); /* * If the UVC does not succeed or fail immediately, we don't want to * loop for long, or we might get stall notifications. * On the other hand, this is a complex scenario and we are holding a lot of * locks, so we can't easily sleep and reschedule. We try only once, * and if the UVC returned busy or partial completion, we return * -EAGAIN and we let the callers deal with it. */ cc = __uv_call(0, (u64)uvcb); folio_ref_unfreeze(folio, expected); /* * Return -ENXIO if the folio was not mapped, -EINVAL for other errors. * If busy or partially completed, return -EAGAIN. */ if (cc == UVC_CC_OK) return 0; else if (cc == UVC_CC_BUSY || cc == UVC_CC_PARTIAL) return -EAGAIN; return uvcb->rc == 0x10a ? -ENXIO : -EINVAL; } /** * should_export_before_import - Determine whether an export is needed * before an import-like operation * @uvcb: the Ultravisor control block of the UVC to be performed * @mm: the mm of the process * * Returns whether an export is needed before every import-like operation. * This is needed for shared pages, which don't trigger a secure storage * exception when accessed from a different guest. * * Although considered as one, the Unpin Page UVC is not an actual import, * so it is not affected. * * No export is needed also when there is only one protected VM, because the * page cannot belong to the wrong VM in that case (there is no "other VM" * it can belong to). * * Return: true if an export is needed before every import, otherwise false. */ static bool should_export_before_import(struct uv_cb_header *uvcb, struct mm_struct *mm) { /* * The misc feature indicates, among other things, that importing a * shared page from a different protected VM will automatically also * transfer its ownership. */ if (uv_has_feature(BIT_UV_FEAT_MISC)) return false; if (uvcb->cmd == UVC_CMD_UNPIN_PAGE_SHARED) return false; return atomic_read(&mm->context.protected_count) > 1; } /* * Requests the Ultravisor to make a page accessible to a guest. * If it's brought in the first time, it will be cleared. If * it has been exported before, it will be decrypted and integrity * checked. */ int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb) { struct vm_area_struct *vma; bool local_drain = false; spinlock_t *ptelock; unsigned long uaddr; struct folio *folio; pte_t *ptep; int rc; again: rc = -EFAULT; mmap_read_lock(gmap->mm); uaddr = __gmap_translate(gmap, gaddr); if (IS_ERR_VALUE(uaddr)) goto out; vma = vma_lookup(gmap->mm, uaddr); if (!vma) goto out; /* * Secure pages cannot be huge and userspace should not combine both. * In case userspace does it anyway this will result in an -EFAULT for * the unpack. The guest is thus never reaching secure mode. If * userspace is playing dirty tricky with mapping huge pages later * on this will result in a segmentation fault. */ if (is_vm_hugetlb_page(vma)) goto out; rc = -ENXIO; ptep = get_locked_pte(gmap->mm, uaddr, &ptelock); if (!ptep) goto out; if (pte_present(*ptep) && !(pte_val(*ptep) & _PAGE_INVALID) && pte_write(*ptep)) { folio = page_folio(pte_page(*ptep)); rc = -EINVAL; if (folio_test_large(folio)) goto unlock; rc = -EAGAIN; if (folio_trylock(folio)) { if (should_export_before_import(uvcb, gmap->mm)) uv_convert_from_secure(PFN_PHYS(folio_pfn(folio))); rc = make_folio_secure(folio, uvcb); folio_unlock(folio); } /* * Once we drop the PTL, the folio may get unmapped and * freed immediately. We need a temporary reference. */ if (rc == -EAGAIN) folio_get(folio); } unlock: pte_unmap_unlock(ptep, ptelock); out: mmap_read_unlock(gmap->mm); if (rc == -EAGAIN) { /* * If we are here because the UVC returned busy or partial * completion, this is just a useless check, but it is safe. */ folio_wait_writeback(folio); folio_put(folio); } else if (rc == -EBUSY) { /* * If we have tried a local drain and the folio refcount * still does not match our expected safe value, try with a * system wide drain. This is needed if the pagevecs holding * the page are on a different CPU. */ if (local_drain) { lru_add_drain_all(); /* We give up here, and let the caller try again */ return -EAGAIN; } /* * We are here if the folio refcount does not match the * expected safe value. The main culprits are usually * pagevecs. With lru_add_drain() we drain the pagevecs * on the local CPU so that hopefully the refcount will * reach the expected safe value. */ lru_add_drain(); local_drain = true; /* And now we try again immediately after draining */ goto again; } else if (rc == -ENXIO) { if (gmap_fault(gmap, gaddr, FAULT_FLAG_WRITE)) return -EFAULT; return -EAGAIN; } return rc; } EXPORT_SYMBOL_GPL(gmap_make_secure); int gmap_convert_to_secure(struct gmap *gmap, unsigned long gaddr) { struct uv_cb_cts uvcb = { .header.cmd = UVC_CMD_CONV_TO_SEC_STOR, .header.len = sizeof(uvcb), .guest_handle = gmap->guest_handle, .gaddr = gaddr, }; return gmap_make_secure(gmap, gaddr, &uvcb); } EXPORT_SYMBOL_GPL(gmap_convert_to_secure); /** * gmap_destroy_page - Destroy a guest page. * @gmap: the gmap of the guest * @gaddr: the guest address to destroy * * An attempt will be made to destroy the given guest page. If the attempt * fails, an attempt is made to export the page. If both attempts fail, an * appropriate error is returned. */ int gmap_destroy_page(struct gmap *gmap, unsigned long gaddr) { struct vm_area_struct *vma; unsigned long uaddr; struct page *page; int rc; rc = -EFAULT; mmap_read_lock(gmap->mm); uaddr = __gmap_translate(gmap, gaddr); if (IS_ERR_VALUE(uaddr)) goto out; vma = vma_lookup(gmap->mm, uaddr); if (!vma) goto out; /* * Huge pages should not be able to become secure */ if (is_vm_hugetlb_page(vma)) goto out; rc = 0; /* we take an extra reference here */ page = follow_page(vma, uaddr, FOLL_WRITE | FOLL_GET); if (IS_ERR_OR_NULL(page)) goto out; rc = uv_destroy_owned_page(page_to_phys(page)); /* * Fault handlers can race; it is possible that two CPUs will fault * on the same secure page. One CPU can destroy the page, reboot, * re-enter secure mode and import it, while the second CPU was * stuck at the beginning of the handler. At some point the second * CPU will be able to progress, and it will not be able to destroy * the page. In that case we do not want to terminate the process, * we instead try to export the page. */ if (rc) rc = uv_convert_owned_from_secure(page_to_phys(page)); put_page(page); out: mmap_read_unlock(gmap->mm); return rc; } EXPORT_SYMBOL_GPL(gmap_destroy_page); /* * To be called with the page locked or with an extra reference! This will * prevent gmap_make_secure from touching the page concurrently. Having 2 * parallel make_page_accessible is fine, as the UV calls will become a * no-op if the page is already exported. */ int arch_make_page_accessible(struct page *page) { int rc = 0; /* Hugepage cannot be protected, so nothing to do */ if (PageHuge(page)) return 0; /* * PG_arch_1 is used in 3 places: * 1. for kernel page tables during early boot * 2. for storage keys of huge pages and KVM * 3. As an indication that this page might be secure. This can * overindicate, e.g. we set the bit before calling * convert_to_secure. * As secure pages are never huge, all 3 variants can co-exists. */ if (!test_bit(PG_arch_1, &page->flags)) return 0; rc = uv_pin_shared(page_to_phys(page)); if (!rc) { clear_bit(PG_arch_1, &page->flags); return 0; } rc = uv_convert_from_secure(page_to_phys(page)); if (!rc) { clear_bit(PG_arch_1, &page->flags); return 0; } return rc; } EXPORT_SYMBOL_GPL(arch_make_page_accessible); #endif #if defined(CONFIG_PROTECTED_VIRTUALIZATION_GUEST) || IS_ENABLED(CONFIG_KVM) static ssize_t uv_query_facilities(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%lx\n%lx\n%lx\n%lx\n", uv_info.inst_calls_list[0], uv_info.inst_calls_list[1], uv_info.inst_calls_list[2], uv_info.inst_calls_list[3]); } static struct kobj_attribute uv_query_facilities_attr = __ATTR(facilities, 0444, uv_query_facilities, NULL); static ssize_t uv_query_supp_se_hdr_ver(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%lx\n", uv_info.supp_se_hdr_ver); } static struct kobj_attribute uv_query_supp_se_hdr_ver_attr = __ATTR(supp_se_hdr_ver, 0444, uv_query_supp_se_hdr_ver, NULL); static ssize_t uv_query_supp_se_hdr_pcf(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%lx\n", uv_info.supp_se_hdr_pcf); } static struct kobj_attribute uv_query_supp_se_hdr_pcf_attr = __ATTR(supp_se_hdr_pcf, 0444, uv_query_supp_se_hdr_pcf, NULL); static ssize_t uv_query_dump_cpu_len(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%lx\n", uv_info.guest_cpu_stor_len); } static struct kobj_attribute uv_query_dump_cpu_len_attr = __ATTR(uv_query_dump_cpu_len, 0444, uv_query_dump_cpu_len, NULL); static ssize_t uv_query_dump_storage_state_len(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%lx\n", uv_info.conf_dump_storage_state_len); } static struct kobj_attribute uv_query_dump_storage_state_len_attr = __ATTR(dump_storage_state_len, 0444, uv_query_dump_storage_state_len, NULL); static ssize_t uv_query_dump_finalize_len(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%lx\n", uv_info.conf_dump_finalize_len); } static struct kobj_attribute uv_query_dump_finalize_len_attr = __ATTR(dump_finalize_len, 0444, uv_query_dump_finalize_len, NULL); static ssize_t uv_query_feature_indications(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%lx\n", uv_info.uv_feature_indications); } static struct kobj_attribute uv_query_feature_indications_attr = __ATTR(feature_indications, 0444, uv_query_feature_indications, NULL); static ssize_t uv_query_max_guest_cpus(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%d\n", uv_info.max_guest_cpu_id + 1); } static struct kobj_attribute uv_query_max_guest_cpus_attr = __ATTR(max_cpus, 0444, uv_query_max_guest_cpus, NULL); static ssize_t uv_query_max_guest_vms(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%d\n", uv_info.max_num_sec_conf); } static struct kobj_attribute uv_query_max_guest_vms_attr = __ATTR(max_guests, 0444, uv_query_max_guest_vms, NULL); static ssize_t uv_query_max_guest_addr(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%lx\n", uv_info.max_sec_stor_addr); } static struct kobj_attribute uv_query_max_guest_addr_attr = __ATTR(max_address, 0444, uv_query_max_guest_addr, NULL); static ssize_t uv_query_supp_att_req_hdr_ver(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%lx\n", uv_info.supp_att_req_hdr_ver); } static struct kobj_attribute uv_query_supp_att_req_hdr_ver_attr = __ATTR(supp_att_req_hdr_ver, 0444, uv_query_supp_att_req_hdr_ver, NULL); static ssize_t uv_query_supp_att_pflags(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%lx\n", uv_info.supp_att_pflags); } static struct kobj_attribute uv_query_supp_att_pflags_attr = __ATTR(supp_att_pflags, 0444, uv_query_supp_att_pflags, NULL); static ssize_t uv_query_supp_add_secret_req_ver(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%lx\n", uv_info.supp_add_secret_req_ver); } static struct kobj_attribute uv_query_supp_add_secret_req_ver_attr = __ATTR(supp_add_secret_req_ver, 0444, uv_query_supp_add_secret_req_ver, NULL); static ssize_t uv_query_supp_add_secret_pcf(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%lx\n", uv_info.supp_add_secret_pcf); } static struct kobj_attribute uv_query_supp_add_secret_pcf_attr = __ATTR(supp_add_secret_pcf, 0444, uv_query_supp_add_secret_pcf, NULL); static ssize_t uv_query_supp_secret_types(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%lx\n", uv_info.supp_secret_types); } static struct kobj_attribute uv_query_supp_secret_types_attr = __ATTR(supp_secret_types, 0444, uv_query_supp_secret_types, NULL); static ssize_t uv_query_max_secrets(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%d\n", uv_info.max_secrets); } static struct kobj_attribute uv_query_max_secrets_attr = __ATTR(max_secrets, 0444, uv_query_max_secrets, NULL); static struct attribute *uv_query_attrs[] = { &uv_query_facilities_attr.attr, &uv_query_feature_indications_attr.attr, &uv_query_max_guest_cpus_attr.attr, &uv_query_max_guest_vms_attr.attr, &uv_query_max_guest_addr_attr.attr, &uv_query_supp_se_hdr_ver_attr.attr, &uv_query_supp_se_hdr_pcf_attr.attr, &uv_query_dump_storage_state_len_attr.attr, &uv_query_dump_finalize_len_attr.attr, &uv_query_dump_cpu_len_attr.attr, &uv_query_supp_att_req_hdr_ver_attr.attr, &uv_query_supp_att_pflags_attr.attr, &uv_query_supp_add_secret_req_ver_attr.attr, &uv_query_supp_add_secret_pcf_attr.attr, &uv_query_supp_secret_types_attr.attr, &uv_query_max_secrets_attr.attr, NULL, }; static struct attribute_group uv_query_attr_group = { .attrs = uv_query_attrs, }; static ssize_t uv_is_prot_virt_guest(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { int val = 0; #ifdef CONFIG_PROTECTED_VIRTUALIZATION_GUEST val = prot_virt_guest; #endif return sysfs_emit(buf, "%d\n", val); } static ssize_t uv_is_prot_virt_host(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { int val = 0; #if IS_ENABLED(CONFIG_KVM) val = prot_virt_host; #endif return sysfs_emit(buf, "%d\n", val); } static struct kobj_attribute uv_prot_virt_guest = __ATTR(prot_virt_guest, 0444, uv_is_prot_virt_guest, NULL); static struct kobj_attribute uv_prot_virt_host = __ATTR(prot_virt_host, 0444, uv_is_prot_virt_host, NULL); static const struct attribute *uv_prot_virt_attrs[] = { &uv_prot_virt_guest.attr, &uv_prot_virt_host.attr, NULL, }; static struct kset *uv_query_kset; static struct kobject *uv_kobj; static int __init uv_info_init(void) { int rc = -ENOMEM; if (!test_facility(158)) return 0; uv_kobj = kobject_create_and_add("uv", firmware_kobj); if (!uv_kobj) return -ENOMEM; rc = sysfs_create_files(uv_kobj, uv_prot_virt_attrs); if (rc) goto out_kobj; uv_query_kset = kset_create_and_add("query", NULL, uv_kobj); if (!uv_query_kset) { rc = -ENOMEM; goto out_ind_files; } rc = sysfs_create_group(&uv_query_kset->kobj, &uv_query_attr_group); if (!rc) return 0; kset_unregister(uv_query_kset); out_ind_files: sysfs_remove_files(uv_kobj, uv_prot_virt_attrs); out_kobj: kobject_del(uv_kobj); kobject_put(uv_kobj); return rc; } device_initcall(uv_info_init); #endif