From d35925b34996196d22a4357dc5212ab03af75151 Mon Sep 17 00:00:00 2001
From: Alexander Gordeev <agordeev@linux.ibm.com>
Date: Fri, 18 Jun 2021 08:17:16 +0200
Subject: [PATCH] s390/mcck: move storage error checks to assembler
The current storage errors tackling is wrong - the DAT is
enabled in assembler code before the actual storage checks
in C half are executed. In case the page tables themselves
are damaged such approach is not going to work.
With this update unrecoverable storage errors are not
passed to C code for handling, but rather the machine
is stopped right away. The only exception to this flow
is when a machine check occurred in KVM guest - in this
case the errors are reinjected by the handler.
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
---
arch/s390/include/asm/nmi.h | 4 ++++
arch/s390/kernel/entry.S | 43 +++++++++++++++++++++++++++----------
arch/s390/kernel/nmi.c | 15 -------------
3 files changed, 36 insertions(+), 26 deletions(-)
diff --git a/arch/s390/include/asm/nmi.h b/arch/s390/include/asm/nmi.h
index 20e51c9ff2403..5e1307486984f 100644
--- a/arch/s390/include/asm/nmi.h
+++ b/arch/s390/include/asm/nmi.h
@@ -24,8 +24,12 @@
#define MCCK_CODE_EXT_DAMAGE BIT(63 - 5)
#define MCCK_CODE_CP BIT(63 - 9)
#define MCCK_CODE_CPU_TIMER_VALID BIT(63 - 46)
+#define MCCK_CODE_STG_ERROR BIT(63 - 16)
+#define MCCK_CODE_STG_KEY_ERROR BIT(63 - 18)
+#define MCCK_CODE_STG_DEGRAD BIT(63 - 19)
#define MCCK_CODE_PSW_MWP_VALID BIT(63 - 20)
#define MCCK_CODE_PSW_IA_VALID BIT(63 - 23)
+#define MCCK_CODE_STG_FAIL_ADDR BIT(63 - 24)
#define MCCK_CODE_CR_VALID BIT(63 - 29)
#define MCCK_CODE_GS_VALID BIT(63 - 36)
#define MCCK_CODE_FC_VALID BIT(63 - 43)
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 6bc8ed8004589..8f72a8f9bc333 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -129,6 +129,24 @@ _LPP_OFFSET = __LC_LPP
"jnz .+8; .long 0xb2e8d000", 82
.endm
+ /*
+ * The CHKSTG macro jumps to the provided label in case the
+ * machine check interruption code reports one of unrecoverable
+ * storage errors:
+ * - Storage error uncorrected
+ * - Storage key error uncorrected
+ * - Storage degradation with Failing-storage-address validity
+ */
+ .macro CHKSTG errlabel
+ TSTMSK __LC_MCCK_CODE,(MCCK_CODE_STG_ERROR|MCCK_CODE_STG_KEY_ERROR)
+ jnz \errlabel
+ TSTMSK __LC_MCCK_CODE,MCCK_CODE_STG_DEGRAD
+ jz oklabel\@
+ TSTMSK __LC_MCCK_CODE,MCCK_CODE_STG_FAIL_ADDR
+ jnz \errlabel
+oklabel\@:
+ .endm
+
#if IS_ENABLED(CONFIG_KVM)
/*
* The OUTSIDE macro jumps to the provided label in case the value
@@ -550,23 +568,26 @@ ENTRY(mcck_int_handler)
3: TSTMSK __LC_MCCK_CODE,MCCK_CODE_PSW_MWP_VALID
jno .Lmcck_panic
tmhh %r8,0x0001 # interrupting from user ?
- jnz 4f
+ jnz 6f
TSTMSK __LC_MCCK_CODE,MCCK_CODE_PSW_IA_VALID
jno .Lmcck_panic
-4: ssm __LC_PGM_NEW_PSW # turn dat on, keep irqs off
- tmhh %r8,0x0001 # interrupting from user ?
#if IS_ENABLED(CONFIG_KVM)
- jnz .Lmcck_user
- OUTSIDE %r9,.Lsie_gmap,.Lsie_done,.Lmcck_stack
- OUTSIDE %r9,.Lsie_entry,.Lsie_skip,5f
+ OUTSIDE %r9,.Lsie_gmap,.Lsie_done,6f
+ OUTSIDE %r9,.Lsie_entry,.Lsie_skip,4f
oi __LC_CPU_FLAGS+7, _CIF_MCCK_GUEST
-5: BPENTER __SF_SIE_FLAGS(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
+ j 5f
+4: CHKSTG .Lmcck_panic
+5: larl %r14,.Lstosm_tmp
+ stosm 0(%r14),0x04 # turn dat on, keep irqs off
+ BPENTER __SF_SIE_FLAGS(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
SIEEXIT
j .Lmcck_stack
-#else
- jz .Lmcck_stack
#endif
-.Lmcck_user:
+6: CHKSTG .Lmcck_panic
+ larl %r14,.Lstosm_tmp
+ stosm 0(%r14),0x04 # turn dat on, keep irqs off
+ tmhh %r8,0x0001 # interrupting from user ?
+ jz .Lmcck_stack
BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP
.Lmcck_stack:
lg %r15,__LC_MCCK_STACK
@@ -692,7 +713,7 @@ ENDPROC(stack_overflow)
.align 4
.Lstop_lock: .long 0
.Lthis_cpu: .short 0
-
+.Lstosm_tmp: .byte 0
.section .rodata, "a"
#define SYSCALL(esame,emu) .quad __s390x_ ## esame
.globl sys_call_table
diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c
index a424f6e69b953..fdb5d23ac9957 100644
--- a/arch/s390/kernel/nmi.c
+++ b/arch/s390/kernel/nmi.c
@@ -399,21 +399,6 @@ int notrace s390_do_machine_check(struct pt_regs *regs)
mcck_pending = 1;
}
- /*
- * Reinject storage related machine checks into the guest if they
- * happen when the guest is running.
- */
- if (!test_cpu_flag(CIF_MCCK_GUEST)) {
- if (mci.se)
- /* Storage error uncorrected */
- s390_handle_damage();
- if (mci.ke)
- /* Storage key-error uncorrected */
- s390_handle_damage();
- if (mci.ds && mci.fa)
- /* Storage degradation */
- s390_handle_damage();
- }
if (mci.cp) {
/* Channel report word pending */
mcck->channel_report = 1;