From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
---
arch/s390/kernel/entry64.S | 76 ++++++++++++++++++++--------------------------
arch/s390/kvm/kvm-s390.c | 4 ++-
2 files changed, 36 insertions(+), 44 deletions(-)
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index c7daeef..51d99ac 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -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"
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 08227c1..93444c4 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -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 {
--
1.8.1.4
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