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[PULL 11/27] arm/hvf: Add a WFI handler
From: |
Peter Maydell |
Subject: |
[PULL 11/27] arm/hvf: Add a WFI handler |
Date: |
Mon, 20 Sep 2021 15:19:31 +0100 |
From: Peter Collingbourne <pcc@google.com>
Sleep on WFI until the VTIMER is due but allow ourselves to be woken
up on IPI.
In this implementation IPI is blocked on the CPU thread at startup and
pselect() is used to atomically unblock the signal and begin sleeping.
The signal is sent unconditionally so there's no need to worry about
races between actually sleeping and the "we think we're sleeping"
state. It may lead to an extra wakeup but that's better than missing
it entirely.
Signed-off-by: Peter Collingbourne <pcc@google.com>
Signed-off-by: Alexander Graf <agraf@csgraf.de>
Acked-by: Roman Bolshakov <r.bolshakov@yadro.com>
Reviewed-by: Sergio Lopez <slp@redhat.com>
Message-id: 20210916155404.86958-6-agraf@csgraf.de
[agraf: Remove unused 'set' variable, always advance PC on WFX trap,
support vm stop / continue operations and cntv offsets]
Signed-off-by: Alexander Graf <agraf@csgraf.de>
Acked-by: Roman Bolshakov <r.bolshakov@yadro.com>
Reviewed-by: Sergio Lopez <slp@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
include/sysemu/hvf_int.h | 1 +
accel/hvf/hvf-accel-ops.c | 5 +--
target/arm/hvf/hvf.c | 79 +++++++++++++++++++++++++++++++++++++++
3 files changed, 82 insertions(+), 3 deletions(-)
diff --git a/include/sysemu/hvf_int.h b/include/sysemu/hvf_int.h
index 7c245c7b111..6545f7cd613 100644
--- a/include/sysemu/hvf_int.h
+++ b/include/sysemu/hvf_int.h
@@ -52,6 +52,7 @@ struct hvf_vcpu_state {
uint64_t fd;
void *exit;
bool vtimer_masked;
+ sigset_t unblock_ipi_mask;
};
void assert_hvf_ok(hv_return_t ret);
diff --git a/accel/hvf/hvf-accel-ops.c b/accel/hvf/hvf-accel-ops.c
index 4f75927a8ef..93976f4ecea 100644
--- a/accel/hvf/hvf-accel-ops.c
+++ b/accel/hvf/hvf-accel-ops.c
@@ -370,15 +370,14 @@ static int hvf_init_vcpu(CPUState *cpu)
cpu->hvf = g_malloc0(sizeof(*cpu->hvf));
/* init cpu signals */
- sigset_t set;
struct sigaction sigact;
memset(&sigact, 0, sizeof(sigact));
sigact.sa_handler = dummy_signal;
sigaction(SIG_IPI, &sigact, NULL);
- pthread_sigmask(SIG_BLOCK, NULL, &set);
- sigdelset(&set, SIG_IPI);
+ 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/target/arm/hvf/hvf.c b/target/arm/hvf/hvf.c
index f3b4023030a..110a9d547d8 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.
@@ -490,6 +491,7 @@ int hvf_arch_init_vcpu(CPUState *cpu)
void hvf_kick_vcpu_thread(CPUState *cpu)
{
+ cpus_kick_thread(cpu);
hv_vcpus_exit(&cpu->hvf->fd, 1);
}
@@ -608,6 +610,80 @@ static uint64_t hvf_vtimer_val_raw(void)
return mach_absolute_time() - hvf_state->vtimer_offset;
}
+static uint64_t hvf_vtimer_val(void)
+{
+ 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_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();
+}
+
+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->interrupt_request & (CPU_INTERRUPT_HARD | CPU_INTERRUPT_FIQ)) {
+ /* Interrupt pending, no need to wait */
+ return;
+ }
+
+ r = hv_vcpu_get_sys_reg(cpu->hvf->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->hvf->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);
+}
+
static void hvf_sync_vtimer(CPUState *cpu)
{
ARMCPU *arm_cpu = ARM_CPU(cpu);
@@ -728,6 +804,9 @@ int hvf_vcpu_exec(CPUState *cpu)
}
case EC_WFX_TRAP:
advance_pc = true;
+ if (!(syndrome & WFX_IS_WFE)) {
+ hvf_wfi(cpu);
+ }
break;
case EC_AA64_HVC:
cpu_synchronize_state(cpu);
--
2.20.1
- [PULL 03/27] target/arm: Don't skip M-profile reset entirely in user mode, (continued)
- [PULL 03/27] target/arm: Don't skip M-profile reset entirely in user mode, Peter Maydell, 2021/09/20
- [PULL 06/27] hw/intc: Set GIC maintenance interrupt level to only 0 or 1, Peter Maydell, 2021/09/20
- [PULL 04/27] target/arm: Always clear exclusive monitor on reset, Peter Maydell, 2021/09/20
- [PULL 07/27] arm: Move PMC register definitions to internals.h, Peter Maydell, 2021/09/20
- [PULL 12/27] hvf: arm: Implement -cpu host, Peter Maydell, 2021/09/20
- [PULL 10/27] hvf: Add Apple Silicon support, Peter Maydell, 2021/09/20
- [PULL 01/27] elf2dmp: Check curl_easy_setopt() return value, Peter Maydell, 2021/09/20
- [PULL 09/27] hvf: Introduce hvf_arch_init() callback, Peter Maydell, 2021/09/20
- [PULL 08/27] hvf: Add execute to dirty log permission bitmap, Peter Maydell, 2021/09/20
- [PULL 05/27] target/arm: Consolidate ifdef blocks in reset, Peter Maydell, 2021/09/20
- [PULL 11/27] arm/hvf: Add a WFI handler,
Peter Maydell <=
- [PULL 13/27] hvf: arm: Implement PSCI handling, Peter Maydell, 2021/09/20
- [PULL 15/27] hvf: arm: Add rudimentary PMC support, Peter Maydell, 2021/09/20
- [PULL 20/27] target/arm: Optimize MVE arithmetic ops, Peter Maydell, 2021/09/20
- [PULL 21/27] target/arm: Optimize MVE VNEG, VABS, Peter Maydell, 2021/09/20
- [PULL 24/27] target/arm: Optimize MVE VSHL, VSHR immediate forms, Peter Maydell, 2021/09/20
- [PULL 16/27] target/arm: Avoid goto_tb if we're trying to exit to the main loop, Peter Maydell, 2021/09/20
- [PULL 26/27] target/arm: Optimize MVE VSLI and VSRI, Peter Maydell, 2021/09/20
- [PULL 19/27] target/arm: Optimize MVE logic ops, Peter Maydell, 2021/09/20
- [PULL 17/27] target/arm: Enforce that FPDSCR.LTPSIZE is 4 on inbound migration, Peter Maydell, 2021/09/20
- [PULL 22/27] target/arm: Optimize MVE VDUP, Peter Maydell, 2021/09/20