[PATCH v3 08/10] s390/uv: convert uv_convert_owned_from_secure() to uv_convert_from_secure_(folio|pte)()

David Hildenbrand
2024-05-08T18:30:35Z

Let's do the same as we did for uv_destroy_(folio|pte)() and
have the following variants:

(1) uv_convert_from_secure(): "low level" helper that operates on paddr
and does not mess with folios.

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

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

Unfortunately we need uv_convert_from_secure_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>
---
arch/s390/include/asm/pgtable.h | 6 +++---
arch/s390/include/asm/uv.h | 4 ++--
arch/s390/kernel/uv.c | 18 +++++++++++++-----
3 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index f65db37917f2..928282bacfc7 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1165,7 +1165,7 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
res = ptep_xchg_lazy(mm, addr, ptep, __pte(_PAGE_INVALID));
/* At this point the reference through the mapping is still present */
if (mm_is_protected(mm) && pte_present(res))
- uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK);
+ uv_convert_from_secure_pte(res);
return res;
}

@@ -1183,7 +1183,7 @@ static inline pte_t ptep_clear_flush(struct vm_area_struct *vma,
res = ptep_xchg_direct(vma->vm_mm, addr, ptep, __pte(_PAGE_INVALID));
/* At this point the reference through the mapping is still present */
if (mm_is_protected(vma->vm_mm) && pte_present(res))
- uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK);
+ uv_convert_from_secure_pte(res);
return res;
}

@@ -1222,7 +1222,7 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm,
* if this is not a mm teardown, the slower export is used as
* fallback instead.
*/
- uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK);
+ uv_convert_from_secure_pte(res);
return res;
}

diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index a1bef30066ef..0679445cac0b 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -485,7 +485,7 @@ int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb);
int gmap_destroy_page(struct gmap *gmap, unsigned long gaddr);
int uv_destroy_folio(struct folio *folio);
int uv_destroy_pte(pte_t pte);
-int uv_convert_owned_from_secure(unsigned long paddr);
+int uv_convert_from_secure_pte(pte_t pte);
int gmap_convert_to_secure(struct gmap *gmap, unsigned long gaddr);

void setup_uv(void);
@@ -508,7 +508,7 @@ static inline int uv_destroy_pte(pte_t pte)
return 0;
}

-static inline int uv_convert_owned_from_secure(unsigned long paddr)
+static inline int uv_convert_from_secure_pte(pte_t pte)
{
return 0;
}
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index 61c1ce51c883..b456066d72da 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -178,11 +178,10 @@ static int uv_convert_from_secure(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_convert_owned_from_secure(unsigned long paddr)
+static int uv_convert_from_secure_folio(struct folio *folio)
{
- struct folio *folio = phys_to_folio(paddr);
int rc;

/* See gmap_make_secure(): large folios cannot be secure */
@@ -190,13 +189,22 @@ int uv_convert_owned_from_secure(unsigned long paddr)
return 0;

folio_get(folio);
- rc = uv_convert_from_secure(paddr);
+ rc = uv_convert_from_secure(folio_to_phys(folio));
if (!rc)
clear_bit(PG_arch_1, &folio->flags);
folio_put(folio);
return rc;
}

+/*
+ * The present PTE still indirectly holds a folio reference through the mapping.
+ */
+int uv_convert_from_secure_pte(pte_t pte)
+{
+ VM_WARN_ON(!pte_present(pte));
+ return uv_convert_from_secure_folio(pfn_folio(pte_pfn(pte)));
+}
+
/*
* Calculate the expected ref_count for a folio that would otherwise have no
* further pins. This was cribbed from similar functions in other places in
@@ -481,7 +489,7 @@ int gmap_destroy_page(struct gmap *gmap, unsigned long gaddr)
* we instead try to export the page.
*/
if (rc)
- rc = uv_convert_owned_from_secure(page_to_phys(page));
+ rc = uv_convert_from_secure_folio(folio);
folio_put(folio);
out:
mmap_read_unlock(gmap->mm);
--
2.45.0