1 files changed, 415 insertions, 0 deletions
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
new file mode 100644
index 000000000000..4c0677fc8904
--- /dev/null
+++ b/arch/s390/kernel/uv.c
@@ -0,0 +1,415 @@
+// 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;
+	down_read(&gmap->mm->mmap_sem);
+
+	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:
+	up_read(&gmap->mm->mmap_sem);
+
+	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 snprintf(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 snprintf(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 snprintf(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 snprintf(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