[PATCH v3 07/10] s390/uv: convert uv_destroy_owned_page() to uv_destroy_(folio|pte)()

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

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>
---
arch/s390/include/asm/pgtable.h | 2 +-
arch/s390/include/asm/uv.h | 10 ++++++++--
arch/s390/kernel/uv.c | 24 +++++++++++++++++-------
arch/s390/mm/gmap.c | 6 ++++--
4 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 6f11d063d545..f65db37917f2 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1215,7 +1215,7 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm,
* The notifier should have destroyed all protected vCPUs at this
* point, so the destroy should be successful.
*/
- if (full && !uv_destroy_owned_page(pte_val(res) & PAGE_MASK))
+ if (full && !uv_destroy_pte(res))
return res;
/*
* If something went wrong and the page could not be destroyed, or
diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index d2205ff97007..a1bef30066ef 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -483,7 +483,8 @@ static inline int is_prot_virt_host(void)
int uv_pin_shared(unsigned long paddr);
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_owned_page(unsigned long paddr);
+int uv_destroy_folio(struct folio *folio);
+int uv_destroy_pte(pte_t pte);
int uv_convert_owned_from_secure(unsigned long paddr);
int gmap_convert_to_secure(struct gmap *gmap, unsigned long gaddr);

@@ -497,7 +498,12 @@ static inline int uv_pin_shared(unsigned long paddr)
return 0;
}

-static inline int uv_destroy_owned_page(unsigned long paddr)
+static inline int uv_destroy_folio(struct folio *folio)
+{
+ return 0;
+}
+
+static inline int uv_destroy_pte(pte_t pte)
{
return 0;
}
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 */
@@ -143,13 +142,22 @@ 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);
return rc;
}

+/*
+ * 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;
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index f2988bbcebbe..797068dccb73 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -2841,13 +2841,15 @@ static const struct mm_walk_ops gather_pages_ops = {
*/
void s390_uv_destroy_pfns(unsigned long count, unsigned long *pfns)
{
+ struct folio *folio;
unsigned long i;

for (i = 0; i < count; i++) {
+ folio = pfn_folio(pfns[i]);
/* we always have an extra reference */
- uv_destroy_owned_page(pfn_to_phys(pfns[i]));
+ uv_destroy_folio(folio);
/* get rid of the extra reference */
- put_page(pfn_to_page(pfns[i]));
+ folio_put(folio);
cond_resched();
}
}
--
2.45.0