Sleep on WFx until the VTIMER is due but allow ourselves to be woken
up on IPI.
Signed-off-by: Peter Collingbourne <pcc@google.com>
---
v2:
- simplify locking further
- wait indefinitely on disabled or masked timers
accel/hvf/hvf-cpus.c | 5 +-
include/sysemu/hvf_int.h | 3 +-
target/arm/hvf/hvf.c | 116 ++++++++++++++-------------------------
3 files changed, 43 insertions(+), 81 deletions(-)
diff --git a/accel/hvf/hvf-cpus.c b/accel/hvf/hvf-cpus.c
index 4360f64671..b2c8fb57f6 100644
--- a/accel/hvf/hvf-cpus.c
+++ b/accel/hvf/hvf-cpus.c
@@ -344,9 +344,8 @@ static int hvf_init_vcpu(CPUState *cpu)
sigact.sa_handler = dummy_signal;
sigaction(SIG_IPI, &sigact, NULL);
- pthread_sigmask(SIG_BLOCK, NULL, &set);
- sigdelset(&set, SIG_IPI);
- pthread_sigmask(SIG_SETMASK, &set, NULL);
+ pthread_sigmask(SIG_BLOCK, NULL, &cpu->hvf->unblock_ipi_mask);
+ sigdelset(&cpu->hvf->unblock_ipi_mask, SIG_IPI);
#ifdef __aarch64__
r = hv_vcpu_create(&cpu->hvf->fd, (hv_vcpu_exit_t **)&cpu->hvf->exit,
NULL);
diff --git a/include/sysemu/hvf_int.h b/include/sysemu/hvf_int.h
index c56baa3ae8..13adf6ea77 100644
--- a/include/sysemu/hvf_int.h
+++ b/include/sysemu/hvf_int.h
@@ -62,8 +62,7 @@ extern HVFState *hvf_state;
struct hvf_vcpu_state {
uint64_t fd;
void *exit;
- struct timespec ts;
- bool sleeping;
+ sigset_t unblock_ipi_mask;
};
void assert_hvf_ok(hv_return_t ret);
diff --git a/target/arm/hvf/hvf.c b/target/arm/hvf/hvf.c
index 8fe10966d2..3321d48aa2 100644
--- a/target/arm/hvf/hvf.c
+++ b/target/arm/hvf/hvf.c
@@ -2,6 +2,7 @@
* QEMU Hypervisor.framework support for Apple Silicon
* Copyright 2020 Alexander Graf <agraf@csgraf.de>
+ * Copyright 2020 Google LLC
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
@@ -18,6 +19,7 @@
#include "sysemu/hw_accel.h"
#include <Hypervisor/Hypervisor.h>
+#include <mach/mach_time.h>
#include "exec/address-spaces.h"
#include "hw/irq.h"
@@ -320,18 +322,8 @@ int hvf_arch_init_vcpu(CPUState *cpu)
void hvf_kick_vcpu_thread(CPUState *cpu)
{
- if (cpu->hvf->sleeping) {
- /*
- * When sleeping, make sure we always send signals. Also, clear the
- * timespec, so that an IPI that arrives between setting hvf->sleeping
- * and the nanosleep syscall still aborts the sleep.
- */
- cpu->thread_kicked = false;
- cpu->hvf->ts = (struct timespec){ };
- cpus_kick_thread(cpu);
- } else {
- hv_vcpus_exit(&cpu->hvf->fd, 1);
- }
+ cpus_kick_thread(cpu);
+ hv_vcpus_exit(&cpu->hvf->fd, 1);
}
static int hvf_inject_interrupts(CPUState *cpu)
@@ -349,6 +341,18 @@ static int hvf_inject_interrupts(CPUState *cpu)
return 0;
}
+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_mb_set(&cpu->thread_kicked, false);
+ qemu_mutex_unlock_iothread();
+ pselect(0, 0, 0, 0, ts, &cpu->hvf->unblock_ipi_mask);
+ qemu_mutex_lock_iothread();
+}
+
int hvf_vcpu_exec(CPUState *cpu)
{
ARMCPU *arm_cpu = ARM_CPU(cpu);
@@ -357,15 +361,11 @@ int hvf_vcpu_exec(CPUState *cpu)
hv_return_t r;
int ret = 0;
- qemu_mutex_unlock_iothread();
-
do {
bool advance_pc = false;
- qemu_mutex_lock_iothread();
current_cpu = cpu;
qemu_wait_io_event_common(cpu);
- qemu_mutex_unlock_iothread();
flush_cpu_state(cpu);
@@ -374,10 +374,10 @@ int hvf_vcpu_exec(CPUState *cpu)
}
if (cpu->halted) {
- qemu_mutex_lock_iothread();
return EXCP_HLT;
}
+ qemu_mutex_unlock_iothread();
assert_hvf_ok(hv_vcpu_run(cpu->hvf->fd));
/* handle VMEXIT */
@@ -385,15 +385,14 @@ int hvf_vcpu_exec(CPUState *cpu)
uint64_t syndrome = hvf_exit->exception.syndrome;
uint32_t ec = syn_get_ec(syndrome);
+ qemu_mutex_lock_iothread();
switch (exit_reason) {
case HV_EXIT_REASON_EXCEPTION:
/* This is the main one, handle below. */
break;
case HV_EXIT_REASON_VTIMER_ACTIVATED:
- qemu_mutex_lock_iothread();
current_cpu = cpu;
qemu_set_irq(arm_cpu->gt_timer_outputs[GTIMER_VIRT], 1);
- qemu_mutex_unlock_iothread();
continue;
case HV_EXIT_REASON_CANCELED:
/* we got kicked, no exit to process */
@@ -413,7 +412,6 @@ int hvf_vcpu_exec(CPUState *cpu)
uint32_t srt = (syndrome >> 16) & 0x1f;
uint64_t val = 0;
- qemu_mutex_lock_iothread();
current_cpu = cpu;
DPRINTF("data abort: [pc=0x%llx va=0x%016llx pa=0x%016llx isv=%x "
@@ -446,8 +444,6 @@ int hvf_vcpu_exec(CPUState *cpu)
hvf_set_reg(cpu, srt, val);
}
- qemu_mutex_unlock_iothread();
-
advance_pc = true;
break;
}
@@ -493,68 +489,40 @@ int hvf_vcpu_exec(CPUState *cpu)
case EC_WFX_TRAP:
if (!(syndrome & WFX_IS_WFE) && !(cpu->interrupt_request &
(CPU_INTERRUPT_HARD | CPU_INTERRUPT_FIQ))) {
- uint64_t cval, ctl, val, diff, now;
+ advance_pc = true;
- /* Set up a local timer for vtimer if necessary ... */
- r = hv_vcpu_get_sys_reg(cpu->hvf->fd, HV_SYS_REG_CNTV_CTL_EL0,
&ctl);
- assert_hvf_ok(r);
- r = hv_vcpu_get_sys_reg(cpu->hvf->fd, HV_SYS_REG_CNTV_CVAL_EL0,
&cval);
+ uint64_t ctl;
+ r = hv_vcpu_get_sys_reg(cpu->hvf->fd, HV_SYS_REG_CNTV_CTL_EL0,
+ &ctl);
assert_hvf_ok(r);
- asm volatile("mrs %0, cntvct_el0" : "=r"(val));
- diff = cval - val;
-
- now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) /
- gt_cntfrq_period_ns(arm_cpu);
-
- /* Timer disabled or masked, just wait for long */
if (!(ctl & 1) || (ctl & 2)) {
- diff = (120 * NANOSECONDS_PER_SECOND) /
- gt_cntfrq_period_ns(arm_cpu);
+ /* Timer disabled or masked, just wait for an IPI. */
+ hvf_wait_for_ipi(cpu, NULL);
+ break;
}
- if (diff < INT64_MAX) {
- uint64_t ns = diff * gt_cntfrq_period_ns(arm_cpu);
- struct timespec *ts = &cpu->hvf->ts;
-
- *ts = (struct timespec){
- .tv_sec = ns / NANOSECONDS_PER_SECOND,
- .tv_nsec = ns % NANOSECONDS_PER_SECOND,
- };
-
- /*
- * Waking up easily takes 1ms, don't go to sleep for
smaller
- * time periods than 2ms.
- */
- if (!ts->tv_sec && (ts->tv_nsec < (SCALE_MS * 2))) {
- advance_pc = true;
- break;
- }
-
- /* Set cpu->hvf->sleeping so that we get a SIG_IPI signal.
*/
- cpu->hvf->sleeping = true;
- smp_mb();
-
- /* Bail out if we received an IRQ meanwhile */
- if (cpu->thread_kicked || (cpu->interrupt_request &
- (CPU_INTERRUPT_HARD | CPU_INTERRUPT_FIQ))) {
- cpu->hvf->sleeping = false;
- break;
- }
-
- /* nanosleep returns on signal, so we wake up on kick. */
- nanosleep(ts, NULL);
-
- /* Out of sleep - either naturally or because of a kick */
- cpu->hvf->sleeping = false;
+ uint64_t cval;
+ r = hv_vcpu_get_sys_reg(cpu->hvf->fd, HV_SYS_REG_CNTV_CVAL_EL0,
+ &cval);
+ assert_hvf_ok(r);
+
+ int64_t ticks_to_sleep = cval - mach_absolute_time();