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s390/mm: Warn if uv_convert_from_secure_pte() fails

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If uv_convert_from_secure_pte() fails, the page becomes unusable by the
host. The failure can only occour in case of hardware malfunction or a
serious KVM bug.

When the unusable page is reused, the system can have issues and
hang.

Print a warning to aid debugging such unlikely scenarios.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
This commit is contained in:
Claudio Imbrenda 2026-02-04 16:02:37 +01:00
parent 3ddee7e651
commit 850103b0ce
1 changed files with 5 additions and 4 deletions
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9
arch/s390/include/asm/pgtable.h
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@ -1239,7 +1239,7 @@ 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_from_secure_pte(res);
WARN_ON_ONCE(uv_convert_from_secure_pte(res));
return res;
}
@ -1257,7 +1257,7 @@ 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_from_secure_pte(res);
WARN_ON_ONCE(uv_convert_from_secure_pte(res));
return res;
}
@ -1294,9 +1294,10 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm,
/*
* If something went wrong and the page could not be destroyed, or
* if this is not a mm teardown, the slower export is used as
* fallback instead.
* fallback instead. If even that fails, print a warning and leak
* the page, to avoid crashing the whole system.
*/
uv_convert_from_secure_pte(res);
WARN_ON_ONCE(uv_convert_from_secure_pte(res));
return res;
}