Commit d35925b3 authored by Alexander Gordeev's avatar Alexander Gordeev Committed by Vasily Gorbik
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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: default avatarAlexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 7f6dc8d4

arch/s390/include/asm/nmi.h

+4 −0
Original line number Diff line number Diff line
@@ -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)

arch/s390/kernel/entry.S

+32 −11
Original line number Diff line number Diff line
@@ -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

arch/s390/kernel/nmi.c

+0 −15
Original line number Diff line number Diff line
@@ -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;