[PATCHv2 05/59] mm/page_alloc: Handle allocation for encrypted memory

Kirill A. Shutemov
2019-07-31T15:10:16Z

For encrypted memory, we need to allocate pages for a specific
encryption KeyID.

There are two cases when we need to allocate a page for encryption:

- Allocation for an encrypted VMA;

- Allocation for migration of encrypted page;

The first case can be covered within alloc_page_vma(). We know KeyID
from the VMA.

The second case requires few new page allocation routines that would
allocate the page for a specific KeyID.

An encrypted page has to be cleared after KeyID set. This is handled
in prep_encrypted_page() that will be provided by arch-specific code.

Any custom allocator that deals with encrypted pages has to call
prep_encrypted_page() too. See compaction_alloc() for instance.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
include/linux/gfp.h | 50 +++++++++++++++++++++++++---
include/linux/migrate.h | 14 ++++++--
mm/compaction.c | 3 ++
mm/mempolicy.c | 27 +++++++++++----
mm/migrate.c | 4 +--
mm/page_alloc.c | 74 +++++++++++++++++++++++++++++++++++++++++
6 files changed, 155 insertions(+), 17 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 3d4cb9fea417..014aef082821 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -463,16 +463,48 @@ static inline void arch_free_page(struct page *page, int order) { }
static inline void arch_alloc_page(struct page *page, int order) { }
#endif

+#ifndef prep_encrypted_page
+/*
+ * An architecture may override the helper to prepare the page
+ * to be used for with specific KeyID. To be called on encrypted
+ * page allocation.
+ */
+static inline void prep_encrypted_page(struct page *page, int order,
+ int keyid, bool zero)
+{
+}
+#endif
+
+/*
+ * Encrypted page has to be cleared once keyid is set, not on allocation.
+ */
+static inline bool deferred_page_zero(int keyid, gfp_t *gfp_mask)
+{
+ if (keyid && (*gfp_mask & __GFP_ZERO)) {
+ *gfp_mask &= ~__GFP_ZERO;
+ return true;
+ }
+
+ return false;
+}
+
struct page *
__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
nodemask_t *nodemask);

+struct page *
+__alloc_pages_nodemask_keyid(gfp_t gfp_mask, unsigned int order,
+ int preferred_nid, nodemask_t *nodemask, int keyid);
+
static inline struct page *
__alloc_pages(gfp_t gfp_mask, unsigned int order, int preferred_nid)
{
return __alloc_pages_nodemask(gfp_mask, order, preferred_nid, NULL);
}

+struct page *__alloc_pages_node_keyid(int nid, int keyid,
+ gfp_t gfp_mask, unsigned int order);
+
/*
* Allocate pages, preferring the node given as nid. The node must be valid and
* online. For more general interface, see alloc_pages_node().
@@ -500,6 +532,19 @@ static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask,
return __alloc_pages_node(nid, gfp_mask, order);
}

+static inline struct page *alloc_pages_node_keyid(int nid, int keyid,
+ gfp_t gfp_mask, unsigned int order)
+{
+ if (nid == NUMA_NO_NODE)
+ nid = numa_mem_id();
+
+ return __alloc_pages_node_keyid(nid, keyid, gfp_mask, order);
+}
+
+extern struct page *alloc_pages_vma(gfp_t gfp_mask, int order,
+ struct vm_area_struct *vma, unsigned long addr,
+ int node, bool hugepage);
+
#ifdef CONFIG_NUMA
extern struct page *alloc_pages_current(gfp_t gfp_mask, unsigned order);

@@ -508,14 +553,9 @@ alloc_pages(gfp_t gfp_mask, unsigned int order)
{
return alloc_pages_current(gfp_mask, order);
}
-extern struct page *alloc_pages_vma(gfp_t gfp_mask, int order,
- struct vm_area_struct *vma, unsigned long addr,
- int node, bool hugepage);
#else
#define alloc_pages(gfp_mask, order) \
alloc_pages_node(numa_node_id(), gfp_mask, order)
-#define alloc_pages_vma(gfp_mask, order, vma, addr, node, false)\
- alloc_pages(gfp_mask, order)
#endif
#define alloc_page(gfp_mask) alloc_pages(gfp_mask, 0)
#define alloc_page_vma(gfp_mask, vma, addr) \
diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 7f04754c7f2b..a68516271c40 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -38,9 +38,16 @@ static inline struct page *new_page_nodemask(struct page *page,
unsigned int order = 0;
struct page *new_page = NULL;

- if (PageHuge(page))
+ if (PageHuge(page)) {
+ /*
+ * HugeTLB doesn't support encryption. We shouldn't see
+ * such pages.
+ */
+ if (WARN_ON_ONCE(page_keyid(page)))
+ return NULL;
return alloc_huge_page_nodemask(page_hstate(compound_head(page)),
preferred_nid, nodemask);
+ }

if (PageTransHuge(page)) {
gfp_mask |= GFP_TRANSHUGE;
@@ -50,8 +57,9 @@ static inline struct page *new_page_nodemask(struct page *page,
if (PageHighMem(page) || (zone_idx(page_zone(page)) == ZONE_MOVABLE))
gfp_mask |= __GFP_HIGHMEM;

- new_page = __alloc_pages_nodemask(gfp_mask, order,
- preferred_nid, nodemask);
+ /* Allocate a page with the same KeyID as the source page */
+ new_page = __alloc_pages_nodemask_keyid(gfp_mask, order,
+ preferred_nid, nodemask, page_keyid(page));

if (new_page && PageTransHuge(new_page))
prep_transhuge_page(new_page);
diff --git a/mm/compaction.c b/mm/compaction.c
index 9e1b9acb116b..874af83214b7 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1559,6 +1559,9 @@ static struct page *compaction_alloc(struct page *migratepage,
list_del(&freepage->lru);
cc->nr_freepages--;

+ /* Prepare the page using the same KeyID as the source page */
+ if (freepage)
+ prep_encrypted_page(freepage, 0, page_keyid(migratepage), false);
return freepage;
}

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 14ee933b1ff7..f79b4fa08c30 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -961,22 +961,29 @@ static void migrate_page_add(struct page *page, struct list_head *pagelist,
/* page allocation callback for NUMA node migration */
struct page *alloc_new_node_page(struct page *page, unsigned long node)
{
- if (PageHuge(page))
+ if (PageHuge(page)) {
+ /*
+ * HugeTLB doesn't support encryption. We shouldn't see
+ * such pages.
+ */
+ if (WARN_ON_ONCE(page_keyid(page)))
+ return NULL;
return alloc_huge_page_node(page_hstate(compound_head(page)),
node);
- else if (PageTransHuge(page)) {
+ } else if (PageTransHuge(page)) {
struct page *thp;

- thp = alloc_pages_node(node,
+ thp = alloc_pages_node_keyid(node, page_keyid(page),
(GFP_TRANSHUGE | __GFP_THISNODE),
HPAGE_PMD_ORDER);
if (!thp)
return NULL;
prep_transhuge_page(thp);
return thp;
- } else
- return __alloc_pages_node(node, GFP_HIGHUSER_MOVABLE |
- __GFP_THISNODE, 0);
+ } else {
+ return __alloc_pages_node_keyid(node, page_keyid(page),
+ GFP_HIGHUSER_MOVABLE | __GFP_THISNODE, 0);
+ }
}

/*
@@ -2053,9 +2060,13 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
{
struct mempolicy *pol;
struct page *page;
- int preferred_nid;
+ bool deferred_zero;
+ int keyid, preferred_nid;
nodemask_t *nmask;

+ keyid = vma_keyid(vma);
+ deferred_zero = deferred_page_zero(keyid, &gfp);
+
pol = get_vma_policy(vma, addr);

if (pol->mode == MPOL_INTERLEAVE) {
@@ -2097,6 +2108,8 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
page = __alloc_pages_nodemask(gfp, order, preferred_nid, nmask);
mpol_cond_put(pol);
out:
+ if (page)
+ prep_encrypted_page(page, order, keyid, deferred_zero);
return page;
}
EXPORT_SYMBOL(alloc_pages_vma);
diff --git a/mm/migrate.c b/mm/migrate.c
index 8992741f10aa..c1b88eae71d8 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1873,7 +1873,7 @@ static struct page *alloc_misplaced_dst_page(struct page *page,
int nid = (int) data;
struct page *newpage;

- newpage = __alloc_pages_node(nid,
+ newpage = __alloc_pages_node_keyid(nid, page_keyid(page),
(GFP_HIGHUSER_MOVABLE |
__GFP_THISNODE | __GFP_NOMEMALLOC |
__GFP_NORETRY | __GFP_NOWARN) &
@@ -1999,7 +1999,7 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
int page_lru = page_is_file_cache(page);
unsigned long start = address & HPAGE_PMD_MASK;

- new_page = alloc_pages_node(node,
+ new_page = alloc_pages_node_keyid(node, page_keyid(page),
(GFP_TRANSHUGE_LIGHT | __GFP_THISNODE),
HPAGE_PMD_ORDER);
if (!new_page)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 272c6de1bf4e..963f959350e4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4046,6 +4046,53 @@ should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_fla
}
#endif /* CONFIG_COMPACTION */

+#ifndef CONFIG_NUMA
+struct page *alloc_pages_vma(gfp_t gfp_mask, int order,
+ struct vm_area_struct *vma, unsigned long addr,
+ int node, bool hugepage)
+{
+ struct page *page;
+ bool deferred_zero;
+ int keyid = vma_keyid(vma);
+
+ deferred_zero = deferred_page_zero(keyid, &gfp_mask);
+ page = alloc_pages(gfp_mask, order);
+ if (page)
+ prep_encrypted_page(page, order, keyid, deferred_zero);
+
+ return page;
+}
+#endif
+
+/**
+ * __alloc_pages_node_keyid - allocate a page for a specific KeyID with
+ * preferred allocation node.
+ * @nid: the preferred node ID where memory should be allocated
+ * @keyid: KeyID to use
+ * @gfp_mask: GFP flags for the allocation
+ * @order: the page order
+ *
+ * Like __alloc_pages_node(), but prepares the page for a specific KeyID.
+ *
+ * Return: pointer to the allocated page or %NULL in case of error.
+ */
+struct page * __alloc_pages_node_keyid(int nid, int keyid,
+ gfp_t gfp_mask, unsigned int order)
+{
+ struct page *page;
+ bool deferred_zero;
+
+ VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
+ VM_WARN_ON(!node_online(nid));
+
+ deferred_zero = deferred_page_zero(keyid, &gfp_mask);
+ page = __alloc_pages(gfp_mask, order, nid);
+ if (page)
+ prep_encrypted_page(page, order, keyid, deferred_zero);
+
+ return page;
+}
+
#ifdef CONFIG_LOCKDEP
static struct lockdep_map __fs_reclaim_map =
STATIC_LOCKDEP_MAP_INIT("fs_reclaim", &__fs_reclaim_map);
@@ -4757,6 +4804,33 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
}
EXPORT_SYMBOL(__alloc_pages_nodemask);

+/**
+ * __alloc_pages_nodemask_keyid - allocate a page for a specific KeyID.
+ * @gfp_mask: GFP flags for the allocation
+ * @order: the page order
+ * @preferred_nid: the preferred node ID where memory should be allocated
+ * @nodemask: allowed nodemask
+ * @keyid: KeyID to use
+ *
+ * Like __alloc_pages_nodemask(), but prepares the page for a specific KeyID.
+ *
+ * Return: pointer to the allocated page or %NULL in case of error.
+ */
+struct page *
+__alloc_pages_nodemask_keyid(gfp_t gfp_mask, unsigned int order,
+ int preferred_nid, nodemask_t *nodemask, int keyid)
+{
+ struct page *page;
+ bool deferred_zero;
+
+ deferred_zero = deferred_page_zero(keyid, &gfp_mask);
+ page = __alloc_pages_nodemask(gfp_mask, order, preferred_nid, nodemask);
+ if (page)
+ prep_encrypted_page(page, order, keyid, deferred_zero);
+ return page;
+}
+EXPORT_SYMBOL(__alloc_pages_nodemask_keyid);
+
/*
* Common helper functions. Never use with __GFP_HIGHMEM because the returned
* address cannot represent highmem pages. Use alloc_pages and then kmap if
--
2.21.0