| Message ID | 20180629170520.13671-1-david@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v1] s390x/tcg: fix locking problem with tcg_s390_tod_updated | expand |
On 06/29/2018 10:05 AM, David Hildenbrand wrote: > tcg_s390_tod_updated() is always called with the iothread being locked > (e.g. from S390TODClass->set() e.g. via HELPER(sck) or on incomming > migration). The helper we call takes the lock itself - bad. > > Let's change that by factoring out updating the ckc timer. This now looks > much nicer than having to call a helper from another function. > > While touch it we also make sure that env->ckc is updated even if the new > value is -1ULL, for now it would not have been modified in that case. > > Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> > Signed-off-by: David Hildenbrand <david@redhat.com> > --- > > This survives my tests and the iotests Christian mentioned. > > target/s390x/misc_helper.c | 26 ++++++++++++++++---------- > 1 file changed, 16 insertions(+), 10 deletions(-) Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
On Fri, 29 Jun 2018 19:05:20 +0200 David Hildenbrand <david@redhat.com> wrote: > tcg_s390_tod_updated() is always called with the iothread being locked > (e.g. from S390TODClass->set() e.g. via HELPER(sck) or on incomming s/incomming/incoming/ > migration). The helper we call takes the lock itself - bad. > > Let's change that by factoring out updating the ckc timer. This now looks > much nicer than having to call a helper from another function. > > While touch it we also make sure that env->ckc is updated even if the new s/touch/touching/ > value is -1ULL, for now it would not have been modified in that case. > > Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> > Signed-off-by: David Hildenbrand <david@redhat.com> > --- > > This survives my tests and the iotests Christian mentioned. OK, this will the last patch (I guess) before I send my final 3.0 pull request. > > target/s390x/misc_helper.c | 26 ++++++++++++++++---------- > 1 file changed, 16 insertions(+), 10 deletions(-) Thanks, applied.
diff --git a/target/s390x/misc_helper.c b/target/s390x/misc_helper.c index 7656a9b90a..3f91579570 100644 --- a/target/s390x/misc_helper.c +++ b/target/s390x/misc_helper.c @@ -149,26 +149,23 @@ uint64_t HELPER(stck)(CPUS390XState *env) return tod.low; } -/* Set Clock Comparator */ -void HELPER(sckc)(CPUS390XState *env, uint64_t time) +static void update_ckc_timer(CPUS390XState *env) { S390TODState *td = s390_get_todstate(); + uint64_t time; /* stop the timer and remove pending CKC IRQs */ timer_del(env->tod_timer); - qemu_mutex_lock_iothread(); + g_assert(qemu_mutex_iothread_locked()); env->pending_int &= ~INTERRUPT_EXT_CLOCK_COMPARATOR; - qemu_mutex_unlock_iothread(); /* the tod has to exceed the ckc, this can never happen if ckc is all 1's */ - if (time == -1ULL) { + if (env->ckc == -1ULL) { return; } - env->ckc = time; - /* difference between origins */ - time -= td->base.low; + time = env->ckc - td->base.low; /* nanoseconds */ time = tod2time(time); @@ -176,12 +173,21 @@ void HELPER(sckc)(CPUS390XState *env, uint64_t time) timer_mod(env->tod_timer, time); } +/* Set Clock Comparator */ +void HELPER(sckc)(CPUS390XState *env, uint64_t ckc) +{ + env->ckc = ckc; + + qemu_mutex_lock_iothread(); + update_ckc_timer(env); + qemu_mutex_unlock_iothread(); +} + void tcg_s390_tod_updated(CPUState *cs, run_on_cpu_data opaque) { S390CPU *cpu = S390_CPU(cs); - CPUS390XState *env = &cpu->env; - helper_sckc(env, env->ckc); + update_ckc_timer(&cpu->env); } /* Set Clock */
tcg_s390_tod_updated() is always called with the iothread being locked (e.g. from S390TODClass->set() e.g. via HELPER(sck) or on incomming migration). The helper we call takes the lock itself - bad. Let's change that by factoring out updating the ckc timer. This now looks much nicer than having to call a helper from another function. While touch it we also make sure that env->ckc is updated even if the new value is -1ULL, for now it would not have been modified in that case. Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: David Hildenbrand <david@redhat.com> --- This survives my tests and the iotests Christian mentioned. target/s390x/misc_helper.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-)