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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: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
This commit is contained in:
Martin Schwidefsky 2013-05-17 14:41:37 +02:00 committed by Gleb Natapov
parent 2c70fe4416
commit 7c470539c9
2 changed files with 36 additions and 44 deletions
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76
arch/s390/kernel/entry64.S
View File

@ -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
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"

4
arch/s390/kvm/kvm-s390.c
View File

@ -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 {