s390/uv: Convert uv_destroy_owned_page() to uv_destroy_(folio|pte)()

Let's have the following variants for destroying pages:

(1) uv_destroy(): Like uv_pin_shared() and uv_convert_from_secure(),
"low level" helper that operates on paddr and doesn't mess with folios.

(2) uv_destroy_folio(): Consumes a folio to which we hold a reference.

(3) uv_destroy_pte(): Consumes a PTE that holds a reference through the
mapping.

Unfortunately we need uv_destroy_pte(), because pfn_folio() and
friends are not available in pgtable.h.

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20240508182955.358628-8-david@redhat.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

1 files changed, 17 insertions, 7 deletions

diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index 3d3250b406a6..61c1ce51c883 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -110,7 +110,7 @@ EXPORT_SYMBOL_GPL(uv_pin_shared);
  *
  * @paddr: Absolute host address of page to be destroyed
  */
-static int uv_destroy_page(unsigned long paddr)
+static int uv_destroy(unsigned long paddr)
 {
 	struct uv_cb_cfs uvcb = {
 		.header.cmd = UVC_CMD_DESTR_SEC_STOR,
@@ -131,11 +131,10 @@ static int uv_destroy_page(unsigned long paddr)
 }
 
 /*
- * The caller must already hold a reference to the page
+ * The caller must already hold a reference to the folio
  */
-int uv_destroy_owned_page(unsigned long paddr)
+int uv_destroy_folio(struct folio *folio)
 {
-	struct folio *folio = phys_to_folio(paddr);
 	int rc;
 
 	/* See gmap_make_secure(): large folios cannot be secure */
@@ -143,7 +142,7 @@ int uv_destroy_owned_page(unsigned long paddr)
 		return 0;
 
 	folio_get(folio);
-	rc = uv_destroy_page(paddr);
+	rc = uv_destroy(folio_to_phys(folio));
 	if (!rc)
 		clear_bit(PG_arch_1, &folio->flags);
 	folio_put(folio);
@@ -151,6 +150,15 @@ int uv_destroy_owned_page(unsigned long paddr)
 }
 
 /*
+ * The present PTE still indirectly holds a folio reference through the mapping.
+ */
+int uv_destroy_pte(pte_t pte)
+{
+	VM_WARN_ON(!pte_present(pte));
+	return uv_destroy_folio(pfn_folio(pte_pfn(pte)));
+}
+
+/*
  * Requests the Ultravisor to encrypt a guest page and make it
  * accessible to the host for paging (export).
  *
@@ -437,6 +445,7 @@ int gmap_destroy_page(struct gmap *gmap, unsigned long gaddr)
 {
 	struct vm_area_struct *vma;
 	unsigned long uaddr;
+	struct folio *folio;
 	struct page *page;
 	int rc;
 
@@ -460,7 +469,8 @@ int gmap_destroy_page(struct gmap *gmap, unsigned long gaddr)
 	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));
+	folio = page_folio(page);
+	rc = uv_destroy_folio(folio);
 	/*
 	 * Fault handlers can race; it is possible that two CPUs will fault
 	 * on the same secure page. One CPU can destroy the page, reboot,
@@ -472,7 +482,7 @@ int gmap_destroy_page(struct gmap *gmap, unsigned long gaddr)
 	 */
 	if (rc)
 		rc = uv_convert_owned_from_secure(page_to_phys(page));
-	put_page(page);
+	folio_put(folio);
 out:
 	mmap_read_unlock(gmap->mm);
 	return rc;