This is a note to let you know that I've just added the patch titled
KVM: s390: pv: properly handle page flags for protected guests
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-s390-pv-properly-handle-page-flags-for-protected.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 0a51b33f2a72d978eb128188c1515162fc0b48b5
Author: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Date: Mon Sep 20 15:24:54 2021 +0200
KVM: s390: pv: properly handle page flags for protected guests
[ Upstream commit 380d97bd02fca7b9b41aec2d1c767874d602bc78 ]
Introduce variants of the convert and destroy page functions that also
clear the PG_arch_1 bit used to mark them as secure pages.
The PG_arch_1 flag is always allowed to overindicate; using the new
functions introduced here allows to reduce the extent of overindication
and thus improve performance.
These new functions can only be called on pages for which a reference
is already being held.
Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
Reviewed-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210920132502.36111-7-imbrenda@xxxxxxxxxxxxx
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Stable-dep-of: 3f29f6537f54 ("s390/uv: Don't call folio_wait_writeback() without a folio reference")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index b61426c9ef178..e434169502456 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1074,8 +1074,9 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
pte_t res;
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_from_secure(pte_val(res) & PAGE_MASK);
+ uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK);
return res;
}
@@ -1091,8 +1092,9 @@ static inline pte_t ptep_clear_flush(struct vm_area_struct *vma,
pte_t res;
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_from_secure(pte_val(res) & PAGE_MASK);
+ uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK);
return res;
}
@@ -1116,8 +1118,9 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm,
} else {
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_from_secure(pte_val(res) & PAGE_MASK);
+ uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK);
return res;
}
diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index fe92a4caf5ec8..bb94d2bec67bd 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -351,8 +351,9 @@ static inline int is_prot_virt_host(void)
}
int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb);
-int uv_destroy_page(unsigned long paddr);
+int uv_destroy_owned_page(unsigned long paddr);
int uv_convert_from_secure(unsigned long paddr);
+int uv_convert_owned_from_secure(unsigned long paddr);
int gmap_convert_to_secure(struct gmap *gmap, unsigned long gaddr);
void setup_uv(void);
@@ -360,7 +361,7 @@ void setup_uv(void);
#define is_prot_virt_host() 0
static inline void setup_uv(void) {}
-static inline int uv_destroy_page(unsigned long paddr)
+static inline int uv_destroy_owned_page(unsigned long paddr)
{
return 0;
}
@@ -369,6 +370,11 @@ static inline int uv_convert_from_secure(unsigned long paddr)
{
return 0;
}
+
+static inline int uv_convert_owned_from_secure(unsigned long paddr)
+{
+ return 0;
+}
#endif
#endif /* _ASM_S390_UV_H */
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index 09b80d371409b..8b0e62507d62e 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -100,7 +100,7 @@ static int uv_pin_shared(unsigned long paddr)
*
* @paddr: Absolute host address of page to be destroyed
*/
-int uv_destroy_page(unsigned long paddr)
+static int uv_destroy_page(unsigned long paddr)
{
struct uv_cb_cfs uvcb = {
.header.cmd = UVC_CMD_DESTR_SEC_STOR,
@@ -120,6 +120,22 @@ int uv_destroy_page(unsigned long paddr)
return 0;
}
+/*
+ * The caller must already hold a reference to the page
+ */
+int uv_destroy_owned_page(unsigned long paddr)
+{
+ struct page *page = phys_to_page(paddr);
+ int rc;
+
+ get_page(page);
+ rc = uv_destroy_page(paddr);
+ if (!rc)
+ clear_bit(PG_arch_1, &page->flags);
+ put_page(page);
+ return rc;
+}
+
/*
* Requests the Ultravisor to encrypt a guest page and make it
* accessible to the host for paging (export).
@@ -139,6 +155,22 @@ int uv_convert_from_secure(unsigned long paddr)
return 0;
}
+/*
+ * The caller must already hold a reference to the page
+ */
+int uv_convert_owned_from_secure(unsigned long paddr)
+{
+ struct page *page = phys_to_page(paddr);
+ int rc;
+
+ get_page(page);
+ rc = uv_convert_from_secure(paddr);
+ if (!rc)
+ clear_bit(PG_arch_1, &page->flags);
+ put_page(page);
+ return rc;
+}
+
/*
* Calculate the expected ref_count for a page that would otherwise have no
* further pins. This was cribbed from similar functions in other places in
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 32d9db5e6f53c..7a4320a9f6557 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -2698,8 +2698,10 @@ static int __s390_reset_acc(pte_t *ptep, unsigned long addr,
{
pte_t pte = READ_ONCE(*ptep);
+ /* There is a reference through the mapping */
if (pte_present(pte))
- WARN_ON_ONCE(uv_destroy_page(pte_val(pte) & PAGE_MASK));
+ WARN_ON_ONCE(uv_destroy_owned_page(pte_val(pte) & PAGE_MASK));
+
return 0;
}
