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Commit 7c470539 authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Gleb Natapov
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s390/kvm: avoid automatic sie reentry 



Do not automatically restart the sie instruction in entry64.S after an
interrupt, return to the caller with a reason code instead. That allows
to deal with RCU and other conditions in C code.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
parent 2c70fe44

arch/s390/kernel/entry64.S

+33 −43
Original line number Diff line number Diff line
@@ -47,7 +47,6 @@ _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \ 
		 _TIF_MCCK_PENDING)

_TIF_TRACE    = (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | \

		 _TIF_SYSCALL_TRACEPOINT)

_TIF_EXIT_SIE = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | _TIF_MCCK_PENDING)



#define BASED(name) name-system_call(%r13)
@@ -81,25 +80,27 @@ _TIF_EXIT_SIE = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | _TIF_MCCK_PENDING) 
#endif

	.endm



	.macro	HANDLE_SIE_INTERCEPT scratch,pgmcheck

	.macro	HANDLE_SIE_INTERCEPT scratch,reason

#if defined(CONFIG_KVM) || defined(CONFIG_KVM_MODULE)

	tmhh	%r8,0x0001		# interrupting from user ?

	jnz	.+52

	jnz	.+62

	lgr	\scratch,%r9

	slg	\scratch,BASED(.Lsie_loop)

	clg	\scratch,BASED(.Lsie_length)

	.if	\pgmcheck

	slg	\scratch,BASED(.Lsie_critical)

	clg	\scratch,BASED(.Lsie_critical_length)

	.if	\reason==1

	# Some program interrupts are suppressing (e.g. protection).

	# We must also check the instruction after SIE in that case.

	# do_protection_exception will rewind to rewind_pad

	jh	.+32

	jh	.+42

	.else

	jhe	.+32

	jhe	.+42

	.endif

	lg	%r9,BASED(.Lsie_loop)

	LPP	BASED(.Lhost_id)	# set host id

	lg	%r14,__SF_EMPTY(%r15)		# get control block pointer

	LPP	__SF_EMPTY+16(%r15)		# set host id

	ni	__SIE_PROG0C+3(%r14),0xfe	# no longer in SIE

	lctlg	%c1,%c1,__LC_USER_ASCE		# load primary asce

	larl	%r9,sie_exit			# skip forward to sie_exit

	mvi	__SF_EMPTY+31(%r15),\reason	# set exit reason

#endif

	.endm
@@ -452,7 +453,7 @@ ENTRY(io_int_handler) 
	lg	%r12,__LC_THREAD_INFO

	larl	%r13,system_call

	lmg	%r8,%r9,__LC_IO_OLD_PSW

	HANDLE_SIE_INTERCEPT %r14,0

	HANDLE_SIE_INTERCEPT %r14,2

	SWITCH_ASYNC __LC_SAVE_AREA_ASYNC,__LC_ASYNC_STACK,STACK_SHIFT

	tmhh	%r8,0x0001		# interrupting from user?

	jz	io_skip
@@ -597,7 +598,7 @@ ENTRY(ext_int_handler) 
	lg	%r12,__LC_THREAD_INFO

	larl	%r13,system_call

	lmg	%r8,%r9,__LC_EXT_OLD_PSW

	HANDLE_SIE_INTERCEPT %r14,0

	HANDLE_SIE_INTERCEPT %r14,3

	SWITCH_ASYNC __LC_SAVE_AREA_ASYNC,__LC_ASYNC_STACK,STACK_SHIFT

	tmhh	%r8,0x0001		# interrupting from user ?

	jz	ext_skip
@@ -645,7 +646,7 @@ ENTRY(mcck_int_handler) 
	lg	%r12,__LC_THREAD_INFO

	larl	%r13,system_call

	lmg	%r8,%r9,__LC_MCK_OLD_PSW

	HANDLE_SIE_INTERCEPT %r14,0

	HANDLE_SIE_INTERCEPT %r14,4

	tm	__LC_MCCK_CODE,0x80	# system damage?

	jo	mcck_panic		# yes -> rest of mcck code invalid

	lghi	%r14,__LC_CPU_TIMER_SAVE_AREA
@@ -939,19 +940,8 @@ ENTRY(sie64a) 
	stmg	%r6,%r14,__SF_GPRS(%r15)	# save kernel registers

	stg	%r2,__SF_EMPTY(%r15)		# save control block pointer

	stg	%r3,__SF_EMPTY+8(%r15)		# save guest register save area

	xc	__SF_EMPTY+16(8,%r15),__SF_EMPTY+16(%r15) # host id == 0

	xc	__SF_EMPTY+16(16,%r15),__SF_EMPTY+16(%r15) # host id & reason

	lmg	%r0,%r13,0(%r3)			# load guest gprs 0-13

# some program checks are suppressing. C code (e.g. do_protection_exception)

# will rewind the PSW by the ILC, which is 4 bytes in case of SIE. Other

# instructions in the sie_loop should not cause program interrupts. So

# lets use a nop (47 00 00 00) as a landing pad.

# See also HANDLE_SIE_INTERCEPT

rewind_pad:

	nop	0

sie_loop:

	lg	%r14,__LC_THREAD_INFO		# pointer thread_info struct

	tm	__TI_flags+7(%r14),_TIF_EXIT_SIE

	jnz	sie_exit

	lg	%r14,__LC_GMAP			# get gmap pointer

	ltgr	%r14,%r14

	jz	sie_gmap
@@ -966,33 +956,33 @@ sie_gmap: 
sie_done:

	LPP	__SF_EMPTY+16(%r15)		# set host id

	ni	__SIE_PROG0C+3(%r14),0xfe	# no longer in SIE

	lg	%r14,__LC_THREAD_INFO		# pointer thread_info struct

sie_exit:

	lctlg	%c1,%c1,__LC_USER_ASCE		# load primary asce

# some program checks are suppressing. C code (e.g. do_protection_exception)

# will rewind the PSW by the ILC, which is 4 bytes in case of SIE. Other

# instructions beween sie64a and sie_done should not cause program

# interrupts. So lets use a nop (47 00 00 00) as a landing pad.

# See also HANDLE_SIE_INTERCEPT

rewind_pad:

	nop	0

sie_exit:

	lg	%r14,__SF_EMPTY+8(%r15)		# load guest register save area

	stmg	%r0,%r13,0(%r14)		# save guest gprs 0-13

	lmg	%r6,%r14,__SF_GPRS(%r15)	# restore kernel registers

	lghi	%r2,0

	lg	%r2,__SF_EMPTY+24(%r15)		# return exit reason code

	br	%r14

sie_fault:

	lctlg	%c1,%c1,__LC_USER_ASCE		# load primary asce

	lg	%r14,__LC_THREAD_INFO		# pointer thread_info struct

	lg	%r14,__SF_EMPTY+8(%r15)		# load guest register save area

	stmg	%r0,%r13,0(%r14)		# save guest gprs 0-13

	lmg	%r6,%r14,__SF_GPRS(%r15)	# restore kernel registers

	lghi	%r2,-EFAULT

	br	%r14

	lghi	%r14,-EFAULT

	stg	%r14,__SF_EMPTY+24(%r15)	# set exit reason code

	j	sie_exit



	.align	8

.Lsie_loop:

	.quad	sie_loop

.Lsie_length:

	.quad	sie_done - sie_loop

.Lhost_id:

	.quad	0

.Lsie_critical:

	.quad	sie_gmap

.Lsie_critical_length:

	.quad	sie_done - sie_gmap



	EX_TABLE(rewind_pad,sie_fault)

	EX_TABLE(sie_loop,sie_fault)

	EX_TABLE(sie_exit,sie_fault)

#endif



		.section .rodata, "a"

arch/s390/kvm/kvm-s390.c

+3 −1
Original line number Diff line number Diff line
@@ -707,7 +707,9 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) 
	trace_kvm_s390_sie_enter(vcpu,

				 atomic_read(&vcpu->arch.sie_block->cpuflags));

	rc = sie64a(vcpu->arch.sie_block, vcpu->run->s.regs.gprs);

	if (rc) {

	if (rc > 0)

		rc = 0;

	if (rc < 0) {

		if (kvm_is_ucontrol(vcpu->kvm)) {

			rc = SIE_INTERCEPT_UCONTROL;

		} else {