From: Claudio Imbrenda Date: Tue, 4 Nov 2025 15:40:48 +0000 (+0100) Subject: KVM: s390: Fix gmap_helper_zap_one_page() again X-Git-Tag: v6.19-rc1~32^2~2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2f393c228cc519ddf19b8c6c05bf15723241aa96;p=thirdparty%2Fkernel%2Flinux.git KVM: s390: Fix gmap_helper_zap_one_page() again A few checks were missing in gmap_helper_zap_one_page(), which can lead to memory corruption in the guest under specific circumstances. Add the missing checks. Fixes: 5deafa27d9ae ("KVM: s390: Fix to clear PTE when discarding a swapped page") Cc: stable@vger.kernel.org Reported-by: Marc Hartmayer Tested-by: Marc Hartmayer Acked-by: Christian Borntraeger Signed-off-by: Claudio Imbrenda Signed-off-by: Heiko Carstens --- diff --git a/arch/s390/mm/gmap_helpers.c b/arch/s390/mm/gmap_helpers.c index 549f14ad08afe..d41b19925a5ad 100644 --- a/arch/s390/mm/gmap_helpers.c +++ b/arch/s390/mm/gmap_helpers.c @@ -47,6 +47,7 @@ static void ptep_zap_softleaf_entry(struct mm_struct *mm, softleaf_t entry) void gmap_helper_zap_one_page(struct mm_struct *mm, unsigned long vmaddr) { struct vm_area_struct *vma; + unsigned long pgstev; spinlock_t *ptl; pgste_t pgste; pte_t *ptep; @@ -65,9 +66,13 @@ void gmap_helper_zap_one_page(struct mm_struct *mm, unsigned long vmaddr) if (pte_swap(*ptep)) { preempt_disable(); pgste = pgste_get_lock(ptep); + pgstev = pgste_val(pgste); - ptep_zap_softleaf_entry(mm, softleaf_from_pte(*ptep)); - pte_clear(mm, vmaddr, ptep); + if ((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED || + (pgstev & _PGSTE_GPS_ZERO)) { + ptep_zap_softleaf_entry(mm, softleaf_from_pte(*ptep)); + pte_clear(mm, vmaddr, ptep); + } pgste_set_unlock(ptep, pgste); preempt_enable();