From d879ac6756b662a085a743e76023c768c3241579 Mon Sep 17 00:00:00 2001 From: Alexander Gordeev Date: Tue, 24 Feb 2026 07:41:07 +0100 Subject: [PATCH] s390/pfault: Fix virtual vs physical address confusion When Linux is running as guest, runs a user space process and the user space process accesses a page that the host has paged out, the guest gets a pfault interrupt and schedules a different process. Without this mechanism the host would have to suspend the whole virtual CPU until the page has been paged in. To setup the pfault interrupt the real address of parameter list should be passed to DIAGNOSE 0x258, but a virtual address is passed instead. That has a performance impact, since the pfault setup never succeeds, the interrupt is never delivered to a guest and the whole virtual CPU is suspended as result. Cc: stable@vger.kernel.org Fixes: c98d2ecae08f ("s390/mm: Uncouple physical vs virtual address spaces") Reported-by: Claudio Imbrenda Reviewed-by: Heiko Carstens Signed-off-by: Alexander Gordeev Signed-off-by: Vasily Gorbik --- arch/s390/mm/pfault.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/s390/mm/pfault.c b/arch/s390/mm/pfault.c index 2f829448c719..6ecd6b0a22a8 100644 --- a/arch/s390/mm/pfault.c +++ b/arch/s390/mm/pfault.c @@ -62,7 +62,7 @@ int __pfault_init(void) "0: nopr %%r7\n" EX_TABLE(0b, 0b) : [rc] "+d" (rc) - : [refbk] "a" (&pfault_init_refbk), "m" (pfault_init_refbk) + : [refbk] "a" (virt_to_phys(&pfault_init_refbk)), "m" (pfault_init_refbk) : "cc"); return rc; } @@ -84,7 +84,7 @@ void __pfault_fini(void) "0: nopr %%r7\n" EX_TABLE(0b, 0b) : - : [refbk] "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) + : [refbk] "a" (virt_to_phys(&pfault_fini_refbk)), "m" (pfault_fini_refbk) : "cc"); }