KVM: s390/mm: Properly reset no-dat

Claudio Imbrenda · Claudio Imbrenda · commit 27072b8e18a7 · 2023-11-14T18:56:46.000+01:00
When the CMMA state needs to be reset, the no-dat bit also needs to be
reset. Failure to do so could cause issues in the guest, since the
guest expects the bit to be cleared after a reset.

Cc: &lt;stable@vger.kernel.org&gt;
Reviewed-by: Nico Boehr &lt;nrb@linux.ibm.com&gt;
Message-ID: &lt;20231109123624.37314-1-imbrenda@linux.ibm.com&gt;
Signed-off-by: Claudio Imbrenda &lt;imbrenda@linux.ibm.com&gt;
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
@@ -756,7 +756,7 @@ void ptep_zap_unused(struct mm_struct *mm, unsigned long addr,
 		pte_clear(mm, addr, ptep);
 	}
 	if (reset)
-		pgste_val(pgste) &= ~_PGSTE_GPS_USAGE_MASK;
+		pgste_val(pgste) &= ~(_PGSTE_GPS_USAGE_MASK | _PGSTE_GPS_NODAT);
 	pgste_set_unlock(ptep, pgste);
 	preempt_enable();
 }

Original file line number	Diff line number	Diff line change
`@@ -756,7 +756,7 @@ void ptep_zap_unused(struct mm_struct *mm, unsigned long addr,`
`756`	`756`	`pte_clear(mm, addr, ptep);`
`757`	`757`	`}`
`758`	`758`	`if (reset)`
`759`		`- pgste_val(pgste) &= ~_PGSTE_GPS_USAGE_MASK;`
	`759`	`+ pgste_val(pgste) &= ~(_PGSTE_GPS_USAGE_MASK \| _PGSTE_GPS_NODAT);`
`760`	`760`	`pgste_set_unlock(ptep, pgste);`
`761`	`761`	`preempt_enable();`
`762`	`762`	`}`