The workqueue "irqfd_cleanup_wq" queues a single work item
&irqfd->shutdown and hence doesn't require ordering. It is a host-wide
workqueue for issuing deferred shutdown requests aggregated from all
vm* instances. It is not being used on a memory reclaim path.
Hence, it has been converted to use system_wq.
The work item has been flushed in kvm_irqfd_release().
The workqueue "wqueue" queues a single work item &timer->expired
and hence doesn't require ordering. Also, it is not being used on
a memory reclaim path. Hence, it has been converted to use system_wq.
System workqueues have been able to handle high level of concurrency
for a long time now and hence it's not required to have a singlethreaded
workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue
created with create_singlethread_workqueue(), system_wq allows multiple
work items to overlap executions even on the same CPU; however, a
per-cpu workqueue doesn't have any CPU locality or global ordering
guarantee unless the target CPU is explicitly specified and thus the
increase of local concurrency shouldn't make any difference.
Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@xxxxxxxxx>
---
virt/kvm/arm/arch_timer.c | 11 ++---------
virt/kvm/eventfd.c | 22 +++-------------------
virt/kvm/kvm_main.c | 6 ------
3 files changed, 5 insertions(+), 34 deletions(-)
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index e2d5b6f..56e0c15 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -31,7 +31,6 @@
#include "trace.h"
static struct timecounter *timecounter;
-static struct workqueue_struct *wqueue;
static unsigned int host_vtimer_irq;
void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
@@ -140,7 +139,7 @@ static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)
return HRTIMER_RESTART;
}
- queue_work(wqueue, &timer->expired);
+ schedule_work(&timer->expired);
return HRTIMER_NORESTART;
}
@@ -455,12 +454,6 @@ int kvm_timer_hyp_init(void)
goto out_free;
}
- wqueue = create_singlethread_workqueue("kvm_arch_timer");
- if (!wqueue) {
- err = -ENOMEM;
- goto out_free;
- }
-
kvm_info("virtual timer IRQ%d\n", host_vtimer_irq);
on_each_cpu(kvm_timer_init_interrupt, NULL, 1);
@@ -522,7 +515,7 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu)
* VCPUs have the enabled variable set, before entering the guest, if
* the arch timers are enabled.
*/
- if (timecounter && wqueue)
+ if (timecounter)
timer->enabled = 1;
return 0;
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index e469b60..f397e9b 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -42,7 +42,6 @@
#ifdef CONFIG_HAVE_KVM_IRQFD
-static struct workqueue_struct *irqfd_cleanup_wq;
static void
irqfd_inject(struct work_struct *work)
@@ -168,7 +167,7 @@ irqfd_deactivate(struct kvm_kernel_irqfd *irqfd)
list_del_init(&irqfd->list);
- queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
+ schedule_work(&irqfd->shutdown);
}
int __attribute__((weak)) kvm_arch_set_irq_inatomic(
@@ -555,7 +554,7 @@ kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
* so that we guarantee there will not be any more interrupts on this
* gsi once this deassign function returns.
*/
- flush_workqueue(irqfd_cleanup_wq);
+ flush_work(&irqfd->shutdown);
return 0;
}
@@ -592,7 +591,7 @@ kvm_irqfd_release(struct kvm *kvm)
* Block until we know all outstanding shutdown jobs have completed
* since we do not take a kvm* reference.
*/
- flush_workqueue(irqfd_cleanup_wq);
+ flush_work(&irqfd->shutdown);
}
@@ -622,23 +621,8 @@ void kvm_irq_routing_update(struct kvm *kvm)
spin_unlock_irq(&kvm->irqfds.lock);
}
-/*
- * create a host-wide workqueue for issuing deferred shutdown requests
- * aggregated from all vm* instances. We need our own isolated single-thread
- * queue to prevent deadlock against flushing the normal work-queue.
- */
-int kvm_irqfd_init(void)
-{
- irqfd_cleanup_wq = create_singlethread_workqueue("kvm-irqfd-cleanup");
- if (!irqfd_cleanup_wq)
- return -ENOMEM;
-
- return 0;
-}
-
void kvm_irqfd_exit(void)
{
- destroy_workqueue(irqfd_cleanup_wq);
}
#endif
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 02e98f3..93506d2 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3719,12 +3719,7 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
* kvm_arch_init makes sure there's at most one caller
* for architectures that support multiple implementations,
* like intel and amd on x86.
- * kvm_arch_init must be called before kvm_irqfd_init to avoid creating
- * conflicts in case kvm is already setup for another implementation.
*/
- r = kvm_irqfd_init();
- if (r)
- goto out_irqfd;
if (!zalloc_cpumask_var(&cpus_hardware_enabled, GFP_KERNEL)) {
r = -ENOMEM;
@@ -3805,7 +3800,6 @@ out_free_0a:
free_cpumask_var(cpus_hardware_enabled);
out_free_0:
kvm_irqfd_exit();
-out_irqfd:
kvm_arch_exit();
out_fail:
return r;
--
2.1.4
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