[1/2] s390: Convert gmap code to use ptdesc

Commit Message

Matthew Wilcox (Oracle) Dec. 19, 2024, 4:22 p.m. UTC

There was originally some doubt about whether these page tables
should be represented by a vanilla struct page or whether they
should be a ptdesc.  As we continue on our quest to shrink
struct page, we seem to have crossed the line into believing that
thse page tables should be a ptdesc.  At least for now.

Signed-off-by: Matthew Wilcox (Oracle) <[e-mail]>
---
 arch/s390/mm/gmap.c | 181 ++++++++++++++++++++++----------------------
 1 file changed, 89 insertions(+), 92 deletions(-)

Comments

Matthew Wilcox (Oracle) Dec. 19, 2024, 9:23 p.m. UTC | #1

On Thu, Dec 19, 2024 at 04:22:49PM +0000, Matthew Wilcox (Oracle) wrote:
> There was originally some doubt about whether these page tables
> should be represented by a vanilla struct page or whether they
> should be a ptdesc.  As we continue on our quest to shrink
> struct page, we seem to have crossed the line into believing that
> thse page tables should be a ptdesc.  At least for now.

Looking at this patch some more, I'm not sure that pt_index is really
what we should be calling this.  Would pt_gmap_addr make sense?  If
not, what's the right name?

David Hildenbrand Dec. 20, 2024, 9:22 a.m. UTC | #2

On 19.12.24 22:23, Matthew Wilcox wrote:
> On Thu, Dec 19, 2024 at 04:22:49PM +0000, Matthew Wilcox (Oracle) wrote:
>> There was originally some doubt about whether these page tables
>> should be represented by a vanilla struct page or whether they
>> should be a ptdesc.  As we continue on our quest to shrink
>> struct page, we seem to have crossed the line into believing that
>> thse page tables should be a ptdesc.  At least for now.
> 
> Looking at this patch some more, I'm not sure that pt_index is really
> what we should be calling this.  Would pt_gmap_addr make sense?  If
> not, what's the right name?

Let me try to refresh my memory.

(1) Ordinary gmap for running virtual machines

We set it to the guest physical address that this page table is 
responsible for. So we can easily translate from a given gmap page table 
+ offset back to the guest physical address.

We set it for PGD/P4D/PUD/PMD page tables in gmap_alloc_table(), and to 
0 for the highest level (which logically corresponds to guest physical 
address 0: page->index = 0).

We really only use it for PMD page tables in __gmap_segment_gaddr(), to 
calculate the guest physical address.

(PTE page tables are shared with the process space page tables, which is 
why we don't maually allocate them or set/get page->index)


(2) Shadow gmaps for nested virtualization

We set it to the guest physical address of the page table we are 
shadowing. Meaning, this gmap page table shadows a page table in guest 
physical address space, and we have to

We set it for all page table levels when shadowing them (when marking 
the to-be-shadowed page table R/O in the gmap so we can catch 
modifications).

We use it in gmap_shadow_pgt_lookup() to translate from a nested guest 
physical address to a guest physical address, required to resolve faults 
for our nested guest.

We only used "ptdesc->pt_index" in gmap_shadow_pgt() so far, because 
there we allocate PTE page tables as a shadow page table (not for user 
space page tables, though!).



Long story short, they are "guest physical addresses", which we simply 
call "gaddr" in that code. So "pt_gaddr" or "pt_gmap_gaddr" make sense. 
(we should fixup that one pt_index user)

Patch

diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 16b8a36c56de..2ca100aae1f7 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -26,15 +26,15 @@ 
 
 #define GMAP_SHADOW_FAKE_TABLE 1ULL
 
-static struct page *gmap_alloc_crst(void)
+static struct ptdesc *gmap_alloc_crst(void)
 {
-	struct page *page;
+	struct ptdesc *ptdesc;
 
-	page = alloc_pages(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER);
-	if (!page)
+	ptdesc = pagetable_alloc(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER);
+	if (!ptdesc)
 		return NULL;
-	__arch_set_page_dat(page_to_virt(page), 1UL << CRST_ALLOC_ORDER);
-	return page;
+	__arch_set_page_dat(ptdesc_to_virt(ptdesc), 1UL << CRST_ALLOC_ORDER);
+	return ptdesc;
 }
 
 /**
@@ -46,7 +46,7 @@  static struct page *gmap_alloc_crst(void)
 static struct gmap *gmap_alloc(unsigned long limit)
 {
 	struct gmap *gmap;
-	struct page *page;
+	struct ptdesc *ptdesc;
 	unsigned long *table;
 	unsigned long etype, atype;
 
@@ -79,12 +79,12 @@  static struct gmap *gmap_alloc(unsigned long limit)
 	spin_lock_init(&gmap->guest_table_lock);
 	spin_lock_init(&gmap->shadow_lock);
 	refcount_set(&gmap->ref_count, 1);
-	page = gmap_alloc_crst();
-	if (!page)
+	ptdesc = gmap_alloc_crst();
+	if (!ptdesc)
 		goto out_free;
-	page->index = 0;
-	list_add(&page->lru, &gmap->crst_list);
-	table = page_to_virt(page);
+	ptdesc->pt_index = 0;
+	list_add(&ptdesc->pt_list, &gmap->crst_list);
+	table = ptdesc_to_virt(ptdesc);
 	crst_table_init(table, etype);
 	gmap->table = table;
 	gmap->asce = atype | _ASCE_TABLE_LENGTH |
@@ -193,23 +193,21 @@  static void gmap_rmap_radix_tree_free(struct radix_tree_root *root)
  */
 static void gmap_free(struct gmap *gmap)
 {
-	struct page *page, *next;
+	struct ptdesc *ptdesc, *next;
 
 	/* Flush tlb of all gmaps (if not already done for shadows) */
 	if (!(gmap_is_shadow(gmap) && gmap->removed))
 		gmap_flush_tlb(gmap);
 	/* Free all segment & region tables. */
-	list_for_each_entry_safe(page, next, &gmap->crst_list, lru)
-		__free_pages(page, CRST_ALLOC_ORDER);
+	list_for_each_entry_safe(ptdesc, next, &gmap->crst_list, pt_list)
+		pagetable_free(ptdesc);
 	gmap_radix_tree_free(&gmap->guest_to_host);
 	gmap_radix_tree_free(&gmap->host_to_guest);
 
 	/* Free additional data for a shadow gmap */
 	if (gmap_is_shadow(gmap)) {
-		struct ptdesc *ptdesc, *n;
-
 		/* Free all page tables. */
-		list_for_each_entry_safe(ptdesc, n, &gmap->pt_list, pt_list)
+		list_for_each_entry_safe(ptdesc, next, &gmap->pt_list, pt_list)
 			page_table_free_pgste(ptdesc);
 		gmap_rmap_radix_tree_free(&gmap->host_to_rmap);
 		/* Release reference to the parent */
@@ -287,26 +285,26 @@  EXPORT_SYMBOL_GPL(gmap_remove);
 static int gmap_alloc_table(struct gmap *gmap, unsigned long *table,
 			    unsigned long init, unsigned long gaddr)
 {
-	struct page *page;
+	struct ptdesc *ptdesc;
 	unsigned long *new;
 
 	/* since we dont free the gmap table until gmap_free we can unlock */
-	page = gmap_alloc_crst();
-	if (!page)
+	ptdesc = gmap_alloc_crst();
+	if (!ptdesc)
 		return -ENOMEM;
-	new = page_to_virt(page);
+	new = ptdesc_to_virt(ptdesc);
 	crst_table_init(new, init);
 	spin_lock(&gmap->guest_table_lock);
 	if (*table & _REGION_ENTRY_INVALID) {
-		list_add(&page->lru, &gmap->crst_list);
+		list_add(&ptdesc->pt_list, &gmap->crst_list);
 		*table = __pa(new) | _REGION_ENTRY_LENGTH |
 			(*table & _REGION_ENTRY_TYPE_MASK);
-		page->index = gaddr;
-		page = NULL;
+		ptdesc->pt_index = gaddr;
+		ptdesc = NULL;
 	}
 	spin_unlock(&gmap->guest_table_lock);
-	if (page)
-		__free_pages(page, CRST_ALLOC_ORDER);
+	if (ptdesc)
+		pagetable_free(ptdesc);
 	return 0;
 }
 
@@ -318,13 +316,13 @@  static int gmap_alloc_table(struct gmap *gmap, unsigned long *table,
  */
 static unsigned long __gmap_segment_gaddr(unsigned long *entry)
 {
-	struct page *page;
+	struct ptdesc *ptdesc;
 	unsigned long offset;
 
 	offset = (unsigned long) entry / sizeof(unsigned long);
 	offset = (offset & (PTRS_PER_PMD - 1)) * PMD_SIZE;
-	page = pmd_pgtable_page((pmd_t *) entry);
-	return page->index + offset;
+	ptdesc = pmd_ptdesc((pmd_t *) entry);
+	return ptdesc->pt_index + offset;
 }
 
 /**
@@ -1458,7 +1456,7 @@  static void gmap_unshadow_sgt(struct gmap *sg, unsigned long raddr)
 {
 	unsigned long r3o, *r3e;
 	phys_addr_t sgt;
-	struct page *page;
+	struct ptdesc *ptdesc;
 
 	BUG_ON(!gmap_is_shadow(sg));
 	r3e = gmap_table_walk(sg, raddr, 2); /* get region-3 pointer */
@@ -1471,9 +1469,9 @@  static void gmap_unshadow_sgt(struct gmap *sg, unsigned long raddr)
 	*r3e = _REGION3_ENTRY_EMPTY;
 	__gmap_unshadow_sgt(sg, raddr, __va(sgt));
 	/* Free segment table */
-	page = phys_to_page(sgt);
-	list_del(&page->lru);
-	__free_pages(page, CRST_ALLOC_ORDER);
+	ptdesc = page_ptdesc(phys_to_page(sgt));
+	list_del(&ptdesc->pt_list);
+	pagetable_free(ptdesc);
 }
 
 /**
@@ -1487,7 +1485,7 @@  static void gmap_unshadow_sgt(struct gmap *sg, unsigned long raddr)
 static void __gmap_unshadow_r3t(struct gmap *sg, unsigned long raddr,
 				unsigned long *r3t)
 {
-	struct page *page;
+	struct ptdesc *ptdesc;
 	phys_addr_t sgt;
 	int i;
 
@@ -1499,9 +1497,9 @@  static void __gmap_unshadow_r3t(struct gmap *sg, unsigned long raddr,
 		r3t[i] = _REGION3_ENTRY_EMPTY;
 		__gmap_unshadow_sgt(sg, raddr, __va(sgt));
 		/* Free segment table */
-		page = phys_to_page(sgt);
-		list_del(&page->lru);
-		__free_pages(page, CRST_ALLOC_ORDER);
+		ptdesc = page_ptdesc(phys_to_page(sgt));
+		list_del(&ptdesc->pt_list);
+		pagetable_free(ptdesc);
 	}
 }
 
@@ -1516,7 +1514,7 @@  static void gmap_unshadow_r3t(struct gmap *sg, unsigned long raddr)
 {
 	unsigned long r2o, *r2e;
 	phys_addr_t r3t;
-	struct page *page;
+	struct ptdesc *ptdesc;
 
 	BUG_ON(!gmap_is_shadow(sg));
 	r2e = gmap_table_walk(sg, raddr, 3); /* get region-2 pointer */
@@ -1529,9 +1527,9 @@  static void gmap_unshadow_r3t(struct gmap *sg, unsigned long raddr)
 	*r2e = _REGION2_ENTRY_EMPTY;
 	__gmap_unshadow_r3t(sg, raddr, __va(r3t));
 	/* Free region 3 table */
-	page = phys_to_page(r3t);
-	list_del(&page->lru);
-	__free_pages(page, CRST_ALLOC_ORDER);
+	ptdesc = page_ptdesc(phys_to_page(r3t));
+	list_del(&ptdesc->pt_list);
+	pagetable_free(ptdesc);
 }
 
 /**
@@ -1546,7 +1544,7 @@  static void __gmap_unshadow_r2t(struct gmap *sg, unsigned long raddr,
 				unsigned long *r2t)
 {
 	phys_addr_t r3t;
-	struct page *page;
+	struct ptdesc *ptdesc;
 	int i;
 
 	BUG_ON(!gmap_is_shadow(sg));
@@ -1557,9 +1555,9 @@  static void __gmap_unshadow_r2t(struct gmap *sg, unsigned long raddr,
 		r2t[i] = _REGION2_ENTRY_EMPTY;
 		__gmap_unshadow_r3t(sg, raddr, __va(r3t));
 		/* Free region 3 table */
-		page = phys_to_page(r3t);
-		list_del(&page->lru);
-		__free_pages(page, CRST_ALLOC_ORDER);
+		ptdesc = page_ptdesc(phys_to_page(r3t));
+		list_del(&ptdesc->pt_list);
+		pagetable_free(ptdesc);
 	}
 }
 
@@ -1573,7 +1571,7 @@  static void __gmap_unshadow_r2t(struct gmap *sg, unsigned long raddr,
 static void gmap_unshadow_r2t(struct gmap *sg, unsigned long raddr)
 {
 	unsigned long r1o, *r1e;
-	struct page *page;
+	struct ptdesc *ptdesc;
 	phys_addr_t r2t;
 
 	BUG_ON(!gmap_is_shadow(sg));
@@ -1587,9 +1585,9 @@  static void gmap_unshadow_r2t(struct gmap *sg, unsigned long raddr)
 	*r1e = _REGION1_ENTRY_EMPTY;
 	__gmap_unshadow_r2t(sg, raddr, __va(r2t));
 	/* Free region 2 table */
-	page = phys_to_page(r2t);
-	list_del(&page->lru);
-	__free_pages(page, CRST_ALLOC_ORDER);
+	ptdesc = page_ptdesc(phys_to_page(r2t));
+	list_del(&ptdesc->pt_list);
+	pagetable_free(ptdesc);
 }
 
 /**
@@ -1604,7 +1602,7 @@  static void __gmap_unshadow_r1t(struct gmap *sg, unsigned long raddr,
 				unsigned long *r1t)
 {
 	unsigned long asce;
-	struct page *page;
+	struct ptdesc *ptdesc;
 	phys_addr_t r2t;
 	int i;
 
@@ -1619,9 +1617,9 @@  static void __gmap_unshadow_r1t(struct gmap *sg, unsigned long raddr,
 		gmap_idte_one(asce, raddr);
 		r1t[i] = _REGION1_ENTRY_EMPTY;
 		/* Free region 2 table */
-		page = phys_to_page(r2t);
-		list_del(&page->lru);
-		__free_pages(page, CRST_ALLOC_ORDER);
+		ptdesc = page_ptdesc(phys_to_page(r2t));
+		list_del(&ptdesc->pt_list);
+		pagetable_free(ptdesc);
 	}
 }
 
@@ -1819,18 +1817,18 @@  int gmap_shadow_r2t(struct gmap *sg, unsigned long saddr, unsigned long r2t,
 	unsigned long raddr, origin, offset, len;
 	unsigned long *table;
 	phys_addr_t s_r2t;
-	struct page *page;
+	struct ptdesc *ptdesc;
 	int rc;
 
 	BUG_ON(!gmap_is_shadow(sg));
 	/* Allocate a shadow region second table */
-	page = gmap_alloc_crst();
-	if (!page)
+	ptdesc = gmap_alloc_crst();
+	if (!ptdesc)
 		return -ENOMEM;
-	page->index = r2t & _REGION_ENTRY_ORIGIN;
+	ptdesc->pt_index = r2t & _REGION_ENTRY_ORIGIN;
 	if (fake)
-		page->index |= GMAP_SHADOW_FAKE_TABLE;
-	s_r2t = page_to_phys(page);
+		ptdesc->pt_index |= GMAP_SHADOW_FAKE_TABLE;
+	s_r2t = page_to_phys(ptdesc_page(ptdesc));
 	/* Install shadow region second table */
 	spin_lock(&sg->guest_table_lock);
 	table = gmap_table_walk(sg, saddr, 4); /* get region-1 pointer */
@@ -1851,7 +1849,7 @@  int gmap_shadow_r2t(struct gmap *sg, unsigned long saddr, unsigned long r2t,
 		 _REGION_ENTRY_TYPE_R1 | _REGION_ENTRY_INVALID;
 	if (sg->edat_level >= 1)
 		*table |= (r2t & _REGION_ENTRY_PROTECT);
-	list_add(&page->lru, &sg->crst_list);
+	list_add(&ptdesc->pt_list, &sg->crst_list);
 	if (fake) {
 		/* nothing to protect for fake tables */
 		*table &= ~_REGION_ENTRY_INVALID;
@@ -1879,7 +1877,7 @@  int gmap_shadow_r2t(struct gmap *sg, unsigned long saddr, unsigned long r2t,
 	return rc;
 out_free:
 	spin_unlock(&sg->guest_table_lock);
-	__free_pages(page, CRST_ALLOC_ORDER);
+	pagetable_free(ptdesc);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(gmap_shadow_r2t);
@@ -1903,18 +1901,18 @@  int gmap_shadow_r3t(struct gmap *sg, unsigned long saddr, unsigned long r3t,
 	unsigned long raddr, origin, offset, len;
 	unsigned long *table;
 	phys_addr_t s_r3t;
-	struct page *page;
+	struct ptdesc *ptdesc;
 	int rc;
 
 	BUG_ON(!gmap_is_shadow(sg));
 	/* Allocate a shadow region second table */
-	page = gmap_alloc_crst();
-	if (!page)
+	ptdesc = gmap_alloc_crst();
+	if (!ptdesc)
 		return -ENOMEM;
-	page->index = r3t & _REGION_ENTRY_ORIGIN;
+	ptdesc->pt_index = r3t & _REGION_ENTRY_ORIGIN;
 	if (fake)
-		page->index |= GMAP_SHADOW_FAKE_TABLE;
-	s_r3t = page_to_phys(page);
+		ptdesc->pt_index |= GMAP_SHADOW_FAKE_TABLE;
+	s_r3t = page_to_phys(ptdesc_page(ptdesc));
 	/* Install shadow region second table */
 	spin_lock(&sg->guest_table_lock);
 	table = gmap_table_walk(sg, saddr, 3); /* get region-2 pointer */
@@ -1935,7 +1933,7 @@  int gmap_shadow_r3t(struct gmap *sg, unsigned long saddr, unsigned long r3t,
 		 _REGION_ENTRY_TYPE_R2 | _REGION_ENTRY_INVALID;
 	if (sg->edat_level >= 1)
 		*table |= (r3t & _REGION_ENTRY_PROTECT);
-	list_add(&page->lru, &sg->crst_list);
+	list_add(&ptdesc->pt_list, &sg->crst_list);
 	if (fake) {
 		/* nothing to protect for fake tables */
 		*table &= ~_REGION_ENTRY_INVALID;
@@ -1963,7 +1961,7 @@  int gmap_shadow_r3t(struct gmap *sg, unsigned long saddr, unsigned long r3t,
 	return rc;
 out_free:
 	spin_unlock(&sg->guest_table_lock);
-	__free_pages(page, CRST_ALLOC_ORDER);
+	pagetable_free(ptdesc);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(gmap_shadow_r3t);
@@ -1987,18 +1985,18 @@  int gmap_shadow_sgt(struct gmap *sg, unsigned long saddr, unsigned long sgt,
 	unsigned long raddr, origin, offset, len;
 	unsigned long *table;
 	phys_addr_t s_sgt;
-	struct page *page;
+	struct ptdesc *ptdesc;
 	int rc;
 
 	BUG_ON(!gmap_is_shadow(sg) || (sgt & _REGION3_ENTRY_LARGE));
 	/* Allocate a shadow segment table */
-	page = gmap_alloc_crst();
-	if (!page)
+	ptdesc = gmap_alloc_crst();
+	if (!ptdesc)
 		return -ENOMEM;
-	page->index = sgt & _REGION_ENTRY_ORIGIN;
+	ptdesc->pt_index = sgt & _REGION_ENTRY_ORIGIN;
 	if (fake)
-		page->index |= GMAP_SHADOW_FAKE_TABLE;
-	s_sgt = page_to_phys(page);
+		ptdesc->pt_index |= GMAP_SHADOW_FAKE_TABLE;
+	s_sgt = page_to_phys(ptdesc_page(ptdesc));
 	/* Install shadow region second table */
 	spin_lock(&sg->guest_table_lock);
 	table = gmap_table_walk(sg, saddr, 2); /* get region-3 pointer */
@@ -2019,7 +2017,7 @@  int gmap_shadow_sgt(struct gmap *sg, unsigned long saddr, unsigned long sgt,
 		 _REGION_ENTRY_TYPE_R3 | _REGION_ENTRY_INVALID;
 	if (sg->edat_level >= 1)
 		*table |= sgt & _REGION_ENTRY_PROTECT;
-	list_add(&page->lru, &sg->crst_list);
+	list_add(&ptdesc->pt_list, &sg->crst_list);
 	if (fake) {
 		/* nothing to protect for fake tables */
 		*table &= ~_REGION_ENTRY_INVALID;
@@ -2047,7 +2045,7 @@  int gmap_shadow_sgt(struct gmap *sg, unsigned long saddr, unsigned long sgt,
 	return rc;
 out_free:
 	spin_unlock(&sg->guest_table_lock);
-	__free_pages(page, CRST_ALLOC_ORDER);
+	pagetable_free(ptdesc);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(gmap_shadow_sgt);
@@ -2070,7 +2068,7 @@  int gmap_shadow_pgt_lookup(struct gmap *sg, unsigned long saddr,
 			   int *fake)
 {
 	unsigned long *table;
-	struct page *page;
+	struct ptdesc *ptdesc;
 	int rc;
 
 	BUG_ON(!gmap_is_shadow(sg));
@@ -2078,10 +2076,10 @@  int gmap_shadow_pgt_lookup(struct gmap *sg, unsigned long saddr,
 	table = gmap_table_walk(sg, saddr, 1); /* get segment pointer */
 	if (table && !(*table & _SEGMENT_ENTRY_INVALID)) {
 		/* Shadow page tables are full pages (pte+pgste) */
-		page = pfn_to_page(*table >> PAGE_SHIFT);
-		*pgt = page->index & ~GMAP_SHADOW_FAKE_TABLE;
+		ptdesc = page_ptdesc(pfn_to_page(*table >> PAGE_SHIFT));
+		*pgt = ptdesc->pt_index & ~GMAP_SHADOW_FAKE_TABLE;
 		*dat_protection = !!(*table & _SEGMENT_ENTRY_PROTECT);
-		*fake = !!(page->index & GMAP_SHADOW_FAKE_TABLE);
+		*fake = !!(ptdesc->pt_index & GMAP_SHADOW_FAKE_TABLE);
 		rc = 0;
 	} else  {
 		rc = -EAGAIN;
@@ -2961,11 +2959,10 @@  EXPORT_SYMBOL_GPL(__s390_uv_destroy_range);
  */
 void s390_unlist_old_asce(struct gmap *gmap)
 {
-	struct page *old;
+	struct ptdesc *old;
 
-	old = virt_to_page(gmap->table);
+	old = virt_to_ptdesc(gmap->table);
 	spin_lock(&gmap->guest_table_lock);
-	list_del(&old->lru);
 	/*
 	 * Sometimes the topmost page might need to be "removed" multiple
 	 * times, for example if the VM is rebooted into secure mode several
@@ -2980,7 +2977,7 @@  void s390_unlist_old_asce(struct gmap *gmap)
 	 * pointers, so list_del can work (and do nothing) without
 	 * dereferencing stale or invalid pointers.
 	 */
-	INIT_LIST_HEAD(&old->lru);
+	list_del_init(&old->pt_list);
 	spin_unlock(&gmap->guest_table_lock);
 }
 EXPORT_SYMBOL_GPL(s390_unlist_old_asce);
@@ -3001,7 +2998,7 @@  EXPORT_SYMBOL_GPL(s390_unlist_old_asce);
 int s390_replace_asce(struct gmap *gmap)
 {
 	unsigned long asce;
-	struct page *page;
+	struct ptdesc *ptdesc;
 	void *table;
 
 	s390_unlist_old_asce(gmap);
@@ -3010,11 +3007,11 @@  int s390_replace_asce(struct gmap *gmap)
 	if ((gmap->asce & _ASCE_TYPE_MASK) == _ASCE_TYPE_SEGMENT)
 		return -EINVAL;
 
-	page = gmap_alloc_crst();
-	if (!page)
+	ptdesc = gmap_alloc_crst();
+	if (!ptdesc)
 		return -ENOMEM;
-	page->index = 0;
-	table = page_to_virt(page);
+	ptdesc->pt_index = 0;
+	table = ptdesc_to_virt(ptdesc);
 	memcpy(table, gmap->table, 1UL << (CRST_ALLOC_ORDER + PAGE_SHIFT));
 
 	/*
@@ -3023,7 +3020,7 @@  int s390_replace_asce(struct gmap *gmap)
 	 * it will be freed when the VM is torn down.
 	 */
 	spin_lock(&gmap->guest_table_lock);
-	list_add(&page->lru, &gmap->crst_list);
+	list_add(&ptdesc->pt_list, &gmap->crst_list);
 	spin_unlock(&gmap->guest_table_lock);
 
 	/* Set new table origin while preserving existing ASCE control bits */