linux/arch/s390/kernel/uv.c
Chen Zhou 99448016ac s390/protvirt: use scnprintf() instead of snprintf()
snprintf() returns the number of bytes that would be written,
which may be greater than the the actual length to be written.

uv_query_facilities() should return the number of bytes printed
into the buffer. This is the return value of scnprintf().
The other functions are the same.

Link: https://lkml.kernel.org/r/20200509085608.41061-4-chenzhou10@huawei.com
Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2020-06-16 13:44:05 +02:00

416 lines
10 KiB
C

// 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 prot_virt_host;
EXPORT_SYMBOL(prot_virt_host);
EXPORT_SYMBOL(uv_info);
static int __init prot_virt_setup(char *val)
{
bool enabled;
int rc;
rc = kstrtobool(val, &enabled);
if (!rc && enabled)
prot_virt_host = 1;
if (is_prot_virt_guest() && prot_virt_host) {
prot_virt_host = 0;
pr_warn("Protected virtualization not available in protected guests.");
}
if (prot_virt_host && !test_facility(158)) {
prot_virt_host = 0;
pr_warn("Protected virtualization not supported by the hardware.");
}
return rc;
}
early_param("prot_virt", prot_virt_setup);
static int __init uv_init(unsigned long 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)
{
unsigned long uv_stor_base;
uv_stor_base = (unsigned long)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(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;
}
void adjust_to_uv_max(unsigned long *vmax)
{
*vmax = min_t(unsigned long, *vmax, uv_info.max_sec_stor_addr);
}
/*
* 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 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;
}
/*
* 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, rc = 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);
rc = uv_call(0, (u64)uvcb);
page_ref_unfreeze(page, expected);
/* Return -ENXIO if the page was not mapped, -EINVAL otherwise */
if (rc)
rc = uvcb->rc == 0x10a ? -ENXIO : -EINVAL;
return rc;
}
/*
* 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 = find_vma(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);
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) {
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);
/*
* 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_max_guest_cpus(struct kobject *kobj,
struct kobj_attribute *attr, char *page)
{
return scnprintf(page, PAGE_SIZE, "%d\n",
uv_info.max_guest_cpus);
}
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 struct attribute *uv_query_attrs[] = {
&uv_query_facilities_attr.attr,
&uv_query_max_guest_cpus_attr.attr,
&uv_query_max_guest_vms_attr.attr,
&uv_query_max_guest_addr_attr.attr,
NULL,
};
static struct attribute_group uv_query_attr_group = {
.attrs = uv_query_attrs,
};
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;
uv_query_kset = kset_create_and_add("query", NULL, uv_kobj);
if (!uv_query_kset)
goto out_kobj;
rc = sysfs_create_group(&uv_query_kset->kobj, &uv_query_attr_group);
if (!rc)
return 0;
kset_unregister(uv_query_kset);
out_kobj:
kobject_del(uv_kobj);
kobject_put(uv_kobj);
return rc;
}
device_initcall(uv_info_init);
#endif