The patch below does not apply to the 5.11-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 26521412ae22d06caab98721757b2721c6d7c46c Mon Sep 17 00:00:00 2001
From: Sven Schnelle svens@linux.ibm.com Date: Wed, 3 Feb 2021 09:16:45 +0100 Subject: [PATCH] s390: fix kernel asce loading when sie is interrupted
If a machine check is coming in during sie, the PU saves the control registers to the machine check save area. Afterwards mcck_int_handler is called, which loads __LC_KERNEL_ASCE into %cr1. Later the code restores %cr1 from the machine check area, but that is wrong when SIE was interrupted because the machine check area still contains the gmap asce. Instead it should return with either __KERNEL_ASCE in %cr1 when interrupted in SIE or the previous %cr1 content saved in the machine check save area.
Fixes: 87d598634521 ("s390/mm: remove set_fs / rework address space handling") Signed-off-by: Sven Schnelle svens@linux.ibm.com Cc: stable@kernel.org # v5.8+ Reviewed-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index f7953bb17558..377294969954 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -558,6 +558,7 @@ ENTRY(mcck_int_handler) lg %r15,__LC_MCCK_STACK .Lmcck_skip: la %r11,STACK_FRAME_OVERHEAD(%r15) + stctg %c1,%c1,__PT_CR1(%r11) lctlg %c1,%c1,__LC_KERNEL_ASCE xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15) lghi %r14,__LC_GPREGS_SAVE_AREA+64 @@ -573,8 +574,6 @@ ENTRY(mcck_int_handler) xgr %r10,%r10 mvc __PT_R8(64,%r11),0(%r14) stmg %r8,%r9,__PT_PSW(%r11) - la %r14,4095 - mvc __PT_CR1(8,%r11),__LC_CREGS_SAVE_AREA-4095+8(%r14) xc __PT_FLAGS(8,%r11),__PT_FLAGS(%r11) xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15) lgr %r2,%r11 # pass pointer to pt_regs