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|
// 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
struct uv_info __bootdata_preserved(uv_info);
#if IS_ENABLED(CONFIG_KVM)
int __bootdata_preserved(prot_virt_host);
EXPORT_SYMBOL(prot_virt_host);
EXPORT_SYMBOL(uv_info);
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.
*/
static 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;
}
/*
* 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_secure_pte(pte_t *ptep, unsigned long addr,
struct page *exp_page, struct uv_cb_header *uvcb)
{
pte_t entry = READ_ONCE(*ptep);
struct page *page;
int expected, cc = 0;
if (!pte_present(entry))
return -ENXIO;
if (pte_val(entry) & _PAGE_INVALID)
return -ENXIO;
page = pte_page(entry);
if (page != exp_page)
return -ENXIO;
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)
{
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;
page = follow_page(vma, uaddr, FOLL_WRITE);
if (IS_ERR_OR_NULL(page))
goto out;
lock_page(page);
ptep = get_locked_pte(gmap->mm, uaddr, &ptelock);
if (should_export_before_import(uvcb, gmap->mm))
uv_convert_from_secure(page_to_phys(page));
rc = make_secure_pte(ptep, uaddr, page, uvcb);
pte_unmap_unlock(ptep, ptelock);
unlock_page(page);
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 *page)
{
return scnprintf(page, PAGE_SIZE, "%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 *page)
{
return scnprintf(page, PAGE_SIZE, "%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 *page)
{
return scnprintf(page, PAGE_SIZE, "%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 *page)
{
return scnprintf(page, PAGE_SIZE, "%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 *page)
{
return scnprintf(page, PAGE_SIZE, "%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 *page)
{
return scnprintf(page, PAGE_SIZE, "%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 *page)
{
return scnprintf(page, PAGE_SIZE, "%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 *page)
{
return scnprintf(page, PAGE_SIZE, "%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 *page)
{
return scnprintf(page, PAGE_SIZE, "%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 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,
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 *page)
{
int val = 0;
#ifdef CONFIG_PROTECTED_VIRTUALIZATION_GUEST
val = prot_virt_guest;
#endif
return scnprintf(page, PAGE_SIZE, "%d\n", val);
}
static ssize_t uv_is_prot_virt_host(struct kobject *kobj,
struct kobj_attribute *attr, char *page)
{
int val = 0;
#if IS_ENABLED(CONFIG_KVM)
val = prot_virt_host;
#endif
return scnprintf(page, PAGE_SIZE, "%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
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