diff options
Diffstat (limited to '')
| -rw-r--r-- | arch/s390/kernel/uv.c | 717 |
1 files changed, 717 insertions, 0 deletions
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c new file mode 100644 index 000000000..fc07bc39e --- /dev/null +++ b/arch/s390/kernel/uv.c @@ -0,0 +1,717 @@ +// 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 <linux/kernel.h> +#include <linux/types.h> +#include <linux/sizes.h> +#include <linux/bitmap.h> +#include <linux/memblock.h> +#include <linux/pagemap.h> +#include <linux/swap.h> +#include <asm/facility.h> +#include <asm/sections.h> +#include <asm/uv.h> + +/* 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 page 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 + * page can not be a huge page for example. + */ +static int expected_page_refs(struct page *page) +{ + int res; + + res = page_mapcount(page); + if (PageSwapCache(page)) { + res++; + } else if (page_mapping(page)) { + res++; + if (page_has_private(page)) + res++; + } + return res; +} + +static int make_page_secure(struct page *page, struct uv_cb_header *uvcb) +{ + int expected, cc = 0; + + if (PageWriteback(page)) + return -EAGAIN; + expected = expected_page_refs(page); + if (!page_ref_freeze(page, expected)) + return -EBUSY; + set_bit(PG_arch_1, &page->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); + page_ref_unfreeze(page, expected); + /* + * Return -ENXIO if the page 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 page *page; + 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)) { + page = pte_page(*ptep); + rc = -EAGAIN; + if (trylock_page(page)) { + if (should_export_before_import(uvcb, gmap->mm)) + uv_convert_from_secure(page_to_phys(page)); + rc = make_page_secure(page, uvcb); + unlock_page(page); + } + } + 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. + */ + wait_on_page_writeback(page); + } else if (rc == -EBUSY) { + /* + * If we have tried a local drain and the page 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 page 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 |