starred/qemu
1
0
Fork 0
mirror of https://github.com/qemu/qemu.git synced 2026-07-09 01:56:21 +00:00
Code Issues 380 Packages Projects Releases Wiki Activity

accel/hvf: Implement WFI without using pselect()

Browse Source 
Return to the main loop where we'll be waken again.
This avoid a tricky race with signals introduced in
commit 219c101fa7 ("Add HVF WFI handler").

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
Message-ID: <20260112103034.65310-14-philmd@linaro.org>
This commit is contained in:
Philippe Mathieu-Daudé
2025-10-03 16:15:27 +02:00
parent a14afa985e
commit b5f8f77271
3 changed files with 5 additions and 72 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
accel/hvf/hvf-accel-ops.c
View File

@@ -135,8 +135,6 @@ static int hvf_init_vcpu(CPUState *cpu)
sigaction(SIG_IPI, &sigact, NULL);
#ifdef __aarch64__
pthread_sigmask(SIG_BLOCK, NULL, &cpu->accel->unblock_ipi_mask);
sigdelset(&cpu->accel->unblock_ipi_mask, SIG_IPI);
cpu->accel->guest_debug_enabled = false;
r = hv_vcpu_create(&cpu->accel->fd,

1
include/system/hvf_int.h
View File

@@ -47,7 +47,6 @@ struct AccelCPUState {
#ifdef __aarch64__
hv_vcpu_exit_t *exit;
bool vtimer_masked;
sigset_t unblock_ipi_mask;
bool guest_debug_enabled;
#endif
};

74
target/arm/hvf/hvf.c
View File

@@ -301,7 +301,7 @@ void hvf_arm_init_debug(void)
#define TMR_CTL_IMASK (1 << 1)
#define TMR_CTL_ISTATUS (1 << 2)
static void hvf_wfi(CPUState *cpu);
static int hvf_wfi(CPUState *cpu);
static uint32_t chosen_ipa_bit_size;
@@ -1703,81 +1703,17 @@ static uint64_t hvf_vtimer_val_raw(void)
return mach_absolute_time() - hvf_state->vtimer_offset;
}
static uint64_t hvf_vtimer_val(void)
static int hvf_wfi(CPUState *cpu)
{
if (!runstate_is_running()) {
/* VM is paused, the vtimer value is in vtimer.vtimer_val */
return vtimer.vtimer_val;
}
return hvf_vtimer_val_raw();
}
static void hvf_wait_for_ipi(CPUState *cpu, struct timespec *ts)
{
/*
* Use pselect to sleep so that other threads can IPI us while we're
* sleeping.
*/
qatomic_set_mb(&cpu->thread_kicked, false);
bql_unlock();
pselect(0, 0, 0, 0, ts, &cpu->accel->unblock_ipi_mask);
bql_lock();
}
static void hvf_wfi(CPUState *cpu)
{
ARMCPU *arm_cpu = ARM_CPU(cpu);
struct timespec ts;
hv_return_t r;
uint64_t ctl;
uint64_t cval;
int64_t ticks_to_sleep;
uint64_t seconds;
uint64_t nanos;
uint32_t cntfrq;
if (cpu_has_work(cpu)) {
/*
* Don't bother to go into our "low power state" if
* we would just wake up immediately.
*/
return;
return 0;
}
r = hv_vcpu_get_sys_reg(cpu->accel->fd, HV_SYS_REG_CNTV_CTL_EL0, &ctl);
assert_hvf_ok(r);
if (!(ctl & 1) || (ctl & 2)) {
/* Timer disabled or masked, just wait for an IPI. */
hvf_wait_for_ipi(cpu, NULL);
return;
}
r = hv_vcpu_get_sys_reg(cpu->accel->fd, HV_SYS_REG_CNTV_CVAL_EL0, &cval);
assert_hvf_ok(r);
ticks_to_sleep = cval - hvf_vtimer_val();
if (ticks_to_sleep < 0) {
return;
}
cntfrq = gt_cntfrq_period_ns(arm_cpu);
seconds = muldiv64(ticks_to_sleep, cntfrq, NANOSECONDS_PER_SECOND);
ticks_to_sleep -= muldiv64(seconds, NANOSECONDS_PER_SECOND, cntfrq);
nanos = ticks_to_sleep * cntfrq;
/*
* Don't sleep for less than the time a context switch would take,
* so that we can satisfy fast timer requests on the same CPU.
* Measurements on M1 show the sweet spot to be ~2ms.
*/
if (!seconds && nanos < (2 * SCALE_MS)) {
return;
}
ts = (struct timespec) { seconds, nanos };
hvf_wait_for_ipi(cpu, &ts);
return EXCP_HLT;
}
/* Must be called by the owning thread */
@@ -1967,7 +1903,7 @@ static int hvf_handle_exception(CPUState *cpu, hv_vcpu_exit_exception_t *excp)
case EC_WFX_TRAP:
advance_pc = true;
if (!(syndrome & WFX_IS_WFE)) {
hvf_wfi(cpu);
ret = hvf_wfi(cpu);
}
break;
case EC_AA64_HVC: