linux-kernel - [PATCH v3 08/10] s390/uv: convert uv_convert_owned_from_secure() to uv_convert_from_secure

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Message-ID: <20240508182955.358628-9-david@redhat.com>
Date: Wed,  8 May 2024 20:29:53 +0200
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: kvm@...r.kernel.org,
	linux-s390@...r.kernel.org,
	David Hildenbrand <david@...hat.com>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	Christian Borntraeger <borntraeger@...ux.ibm.com>,
	Sven Schnelle <svens@...ux.ibm.com>,
	Janosch Frank <frankja@...ux.ibm.com>,
	Claudio Imbrenda <imbrenda@...ux.ibm.com>,
	Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
	Matthew Wilcox <willy@...radead.org>,
	Thomas Huth <thuth@...hat.com>
Subject: [PATCH v3 08/10] s390/uv: convert uv_convert_owned_from_secure() to uv_convert_from_secure_(folio|pte)()

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@...ux.ibm.com>
Signed-off-by: David Hildenbrand <david@...hat.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