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s390x/kvm: proper use of the cpu states OPERATING and STOPPED
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This patch makes sure that halting a cpu and stopping a cpu are two different
things. Stopping a cpu will also set the cpu halted - this is needed for common
infrastructure to work (note that the stop and stopped flag cannot be used for
our purpose because they are already used by other mechanisms).

A cpu can be halted ("waiting") when it is operating. If interrupts are
disabled, this is called a "disabled wait", as it can't be woken up anymore. A
stopped cpu is treated like a "disabled wait" cpu, but in order to prepare for a
proper cpu state synchronization with the kvm part, we need to track the real
logical state of a cpu.

Signed-off-by: David Hildenbrand <[email protected]>
Signed-off-by: Jens Freimann <[email protected]>
Reviewed-by: Cornelia Huck <[email protected]>
Reviewed-by: Christian Borntraeger <[email protected]>
CC: Andreas Faerber <[email protected]>
Tested-by: Christian Borntraeger <[email protected]>
Signed-off-by: Cornelia Huck <[email protected]>
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@cohuck
David Hildenbrand authored and cohuck committed Oct 10, 2014
1 parent 75973bf commit eb24f7c
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Showing 6 changed files with 79 additions and 50 deletions.
2 changes: 1 addition & 1 deletion hw/s390x/ipl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -176,7 +176,7 @@ static void s390_ipl_reset(DeviceState *dev)
}
}

s390_add_running_cpu(cpu);
s390_cpu_set_state(CPU_STATE_OPERATING, cpu);
}

static void s390_ipl_class_init(ObjectClass *klass, void *data)
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78 changes: 50 additions & 28 deletions target-s390x/cpu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,9 @@
#include "cpu.h"
#include "qemu-common.h"
#include "qemu/timer.h"
#include "qemu/error-report.h"
#include "hw/hw.h"
#include "trace.h"
#ifndef CONFIG_USER_ONLY
#include "sysemu/arch_init.h"
#endif
Expand Down Expand Up @@ -81,7 +83,7 @@ static void s390_cpu_load_normal(CPUState *s)
S390CPU *cpu = S390_CPU(s);
cpu->env.psw.addr = ldl_phys(s->as, 4) & PSW_MASK_ESA_ADDR;
cpu->env.psw.mask = PSW_MASK_32 | PSW_MASK_64;
s390_add_running_cpu(cpu);
s390_cpu_set_state(CPU_STATE_OPERATING, cpu);
}
#endif

Expand All @@ -93,11 +95,8 @@ static void s390_cpu_reset(CPUState *s)
CPUS390XState *env = &cpu->env;

env->pfault_token = -1UL;
s390_del_running_cpu(cpu);
scc->parent_reset(s);
#if !defined(CONFIG_USER_ONLY)
s->halted = 1;
#endif
s390_cpu_set_state(CPU_STATE_STOPPED, cpu);
tlb_flush(s, 1);
}

Expand Down Expand Up @@ -135,9 +134,8 @@ static void s390_cpu_full_reset(CPUState *s)
S390CPUClass *scc = S390_CPU_GET_CLASS(cpu);
CPUS390XState *env = &cpu->env;

s390_del_running_cpu(cpu);

scc->parent_reset(s);
s390_cpu_set_state(CPU_STATE_STOPPED, cpu);

memset(env, 0, offsetof(CPUS390XState, cpu_num));

Expand All @@ -147,12 +145,7 @@ static void s390_cpu_full_reset(CPUState *s)

env->pfault_token = -1UL;

/* set halted to 1 to make sure we can add the cpu in
* s390_ipl_cpu code, where CPUState::halted is set back to 0
* after incrementing the cpu counter */
#if !defined(CONFIG_USER_ONLY)
s->halted = 1;

if (kvm_enabled()) {
kvm_s390_reset_vcpu(cpu);
}
Expand Down Expand Up @@ -206,10 +199,7 @@ static void s390_cpu_initfn(Object *obj)
env->tod_basetime = 0;
env->tod_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, s390x_tod_timer, cpu);
env->cpu_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, s390x_cpu_timer, cpu);
/* set CPUState::halted state to 1 to avoid decrementing the running
* cpu counter in s390_cpu_reset to a negative number at
* initial ipl */
cs->halted = 1;
s390_cpu_set_state(CPU_STATE_STOPPED, cpu);
#endif
env->cpu_num = cpu_num++;
env->ext_index = -1;
Expand All @@ -230,6 +220,12 @@ static void s390_cpu_finalize(Object *obj)
}

#if !defined(CONFIG_USER_ONLY)
static bool disabled_wait(CPUState *cpu)
{
return cpu->halted && !(S390_CPU(cpu)->env.psw.mask &
(PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK));
}

static unsigned s390_count_running_cpus(void)
{
CPUState *cpu;
Expand All @@ -239,34 +235,60 @@ static unsigned s390_count_running_cpus(void)
uint8_t state = S390_CPU(cpu)->env.cpu_state;
if (state == CPU_STATE_OPERATING ||
state == CPU_STATE_LOAD) {
nr_running++;
if (!disabled_wait(cpu)) {
nr_running++;
}
}
}

return nr_running;
}

void s390_add_running_cpu(S390CPU *cpu)
unsigned int s390_cpu_halt(S390CPU *cpu)
{
CPUState *cs = CPU(cpu);
trace_cpu_halt(cs->cpu_index);

if (cs->halted) {
cpu->env.cpu_state = CPU_STATE_OPERATING;
cs->halted = 0;
cs->exception_index = -1;
if (!cs->halted) {
cs->halted = 1;
cs->exception_index = EXCP_HLT;
}

return s390_count_running_cpus();
}

unsigned s390_del_running_cpu(S390CPU *cpu)
void s390_cpu_unhalt(S390CPU *cpu)
{
CPUState *cs = CPU(cpu);
trace_cpu_unhalt(cs->cpu_index);

if (cs->halted == 0) {
assert(s390_count_running_cpus() >= 1);
cpu->env.cpu_state = CPU_STATE_STOPPED;
cs->halted = 1;
cs->exception_index = EXCP_HLT;
if (cs->halted) {
cs->halted = 0;
cs->exception_index = -1;
}
}

unsigned int s390_cpu_set_state(uint8_t cpu_state, S390CPU *cpu)
{
trace_cpu_set_state(CPU(cpu)->cpu_index, cpu_state);

switch (cpu_state) {
case CPU_STATE_STOPPED:
case CPU_STATE_CHECK_STOP:
/* halt the cpu for common infrastructure */
s390_cpu_halt(cpu);
break;
case CPU_STATE_OPERATING:
case CPU_STATE_LOAD:
/* unhalt the cpu for common infrastructure */
s390_cpu_unhalt(cpu);
break;
default:
error_report("Requested CPU state is not a valid S390 CPU state: %u",
cpu_state);
exit(1);
}
cpu->env.cpu_state = cpu_state;

return s390_count_running_cpus();
}
Expand Down
14 changes: 10 additions & 4 deletions target-s390x/cpu.h
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Original file line number Diff line number Diff line change
Expand Up @@ -407,8 +407,9 @@ static inline void kvm_s390_service_interrupt(uint32_t parm)
}
#endif
S390CPU *s390_cpu_addr2state(uint16_t cpu_addr);
void s390_add_running_cpu(S390CPU *cpu);
unsigned s390_del_running_cpu(S390CPU *cpu);
unsigned int s390_cpu_halt(S390CPU *cpu);
void s390_cpu_unhalt(S390CPU *cpu);
unsigned int s390_cpu_set_state(uint8_t cpu_state, S390CPU *cpu);

/* service interrupts are floating therefore we must not pass an cpustate */
void s390_sclp_extint(uint32_t parm);
Expand All @@ -417,11 +418,16 @@ void s390_sclp_extint(uint32_t parm);
extern const hwaddr virtio_size;

#else
static inline void s390_add_running_cpu(S390CPU *cpu)
static inline unsigned int s390_cpu_halt(S390CPU *cpu)
{
return 0;
}

static inline void s390_cpu_unhalt(S390CPU *cpu)
{
}

static inline unsigned s390_del_running_cpu(S390CPU *cpu)
static inline unsigned int s390_cpu_set_state(uint8_t cpu_state, S390CPU *cpu)
{
return 0;
}
Expand Down
19 changes: 7 additions & 12 deletions target-s390x/helper.c
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Original file line number Diff line number Diff line change
Expand Up @@ -504,23 +504,18 @@ hwaddr s390_cpu_get_phys_addr_debug(CPUState *cs, vaddr vaddr)

void load_psw(CPUS390XState *env, uint64_t mask, uint64_t addr)
{
env->psw.addr = addr;
env->psw.mask = mask;
env->cc_op = (mask >> 44) & 3;

if (mask & PSW_MASK_WAIT) {
S390CPU *cpu = s390_env_get_cpu(env);
CPUState *cs = CPU(cpu);
if (!(mask & (PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK))) {
if (s390_del_running_cpu(cpu) == 0) {
if (s390_cpu_halt(cpu) == 0) {
#ifndef CONFIG_USER_ONLY
qemu_system_shutdown_request();
qemu_system_shutdown_request();
#endif
}
}
cs->halted = 1;
cs->exception_index = EXCP_HLT;
}

env->psw.addr = addr;
env->psw.mask = mask;
env->cc_op = (mask >> 44) & 3;
}

static uint64_t get_psw_mask(CPUS390XState *env)
Expand Down Expand Up @@ -818,7 +813,7 @@ void s390_cpu_do_interrupt(CPUState *cs)
qemu_log_mask(CPU_LOG_INT, "%s: %d at pc=%" PRIx64 "\n",
__func__, cs->exception_index, env->psw.addr);

s390_add_running_cpu(cpu);
s390_cpu_set_state(CPU_STATE_OPERATING, cpu);
/* handle machine checks */
if ((env->psw.mask & PSW_MASK_MCHECK) &&
(cs->exception_index == -1)) {
Expand Down
11 changes: 6 additions & 5 deletions target-s390x/kvm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -921,7 +921,7 @@ static void sigp_cpu_start(void *arg)
CPUState *cs = arg;
S390CPU *cpu = S390_CPU(cs);

s390_add_running_cpu(cpu);
s390_cpu_set_state(CPU_STATE_OPERATING, cpu);
DPRINTF("DONE: KVM cpu start: %p\n", &cpu->env);
}

Expand All @@ -934,7 +934,7 @@ static void sigp_cpu_restart(void *arg)
};

kvm_s390_vcpu_interrupt(cpu, &irq);
s390_add_running_cpu(cpu);
s390_cpu_set_state(CPU_STATE_OPERATING, cpu);
}

int kvm_s390_cpu_restart(S390CPU *cpu)
Expand Down Expand Up @@ -1074,7 +1074,7 @@ static void unmanageable_intercept(S390CPU *cpu, const char *str, int pswoffset)
error_report("Unmanageable %s! CPU%i new PSW: 0x%016lx:%016lx",
str, cs->cpu_index, ldq_phys(cs->as, cpu->env.psa + pswoffset),
ldq_phys(cs->as, cpu->env.psa + pswoffset + 8));
s390_del_running_cpu(cpu);
s390_cpu_halt(cpu);
guest_panicked();
}

Expand Down Expand Up @@ -1103,7 +1103,8 @@ static int handle_intercept(S390CPU *cpu)
break;
case ICPT_WAITPSW:
/* disabled wait, since enabled wait is handled in kernel */
if (s390_del_running_cpu(cpu) == 0) {
cpu_synchronize_state(cs);
if (s390_cpu_halt(cpu) == 0) {
if (is_special_wait_psw(cs)) {
qemu_system_shutdown_request();
} else {
Expand All @@ -1113,7 +1114,7 @@ static int handle_intercept(S390CPU *cpu)
r = EXCP_HALTED;
break;
case ICPT_CPU_STOP:
if (s390_del_running_cpu(cpu) == 0) {
if (s390_cpu_set_state(CPU_STATE_STOPPED, cpu) == 0) {
qemu_system_shutdown_request();
}
r = EXCP_HALTED;
Expand Down
5 changes: 5 additions & 0 deletions trace-events
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Original file line number Diff line number Diff line change
Expand Up @@ -1372,3 +1372,8 @@ kvm_clear_cmma(int rc) "CMMA: clearing with result code %d"

# hw/dma/i8257.c
i8257_unregistered_dma(int nchan, int dma_pos, int dma_len) "unregistered DMA channel used nchan=%d dma_pos=%d dma_len=%d"

# target-s390x/cpu.c
cpu_set_state(int cpu_index, uint8_t state) "setting cpu %d state to %" PRIu8
cpu_halt(int cpu_index) "halting cpu %d"
cpu_unhalt(int cpu_index) "unhalting cpu %d"

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