On 11/23/2009 04:06 PM, Gleb Natapov wrote:
Asynchronous page fault notifies vcpu that page it is trying to access
is swapped out by a host. In response guest puts a task that caused the
fault to sleep until page is swapped in again. When missing page is
brought back into the memory guest is notified and task resumes execution.
+
+static void apf_task_wait(struct task_struct *tsk, u32 token)
+{
+ u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
+ struct kvm_task_sleep_head *b =&async_pf_sleepers[key];
+ struct kvm_task_sleep_node n, *e;
+ DEFINE_WAIT(wait);
+
+ spin_lock(&b->lock);
+ e = _find_apf_task(b, token);
+ if (e) {
+ /* dummy entry exist -> wake up was delivered ahead of PF */
+ hlist_del(&e->link);
+ kfree(e);
+ spin_unlock(&b->lock);
+ return;
+ }
+
+ n.token = token;
+ init_waitqueue_head(&n.wq);
+ hlist_add_head(&n.link,&b->list);
+ spin_unlock(&b->lock);
+
+ for (;;) {
+ prepare_to_wait(&n.wq,&wait, TASK_UNINTERRUPTIBLE);
+ if (hlist_unhashed(&n.link))
+ break;
This looks safe without b->lock, but please add a comment explaining why
it is safe.
+int kvm_handle_pf(struct pt_regs *regs, unsigned long error_code)
+{
+ u32 reason, token;
+
+ if (!per_cpu(apf_reason, smp_processor_id()).enabled)
+ return 0;
+
+ reason = per_cpu(apf_reason, smp_processor_id()).reason;
+ per_cpu(apf_reason, smp_processor_id()).reason = 0;
Use __get_cpu_var(), shorter.
@@ -270,11 +399,14 @@ static void __init kvm_smp_prepare_boot_cpu(void)
void __init kvm_guest_init(void)
{
+ int i;
\n
if (!kvm_para_available())
return;
paravirt_ops_setup();
register_reboot_notifier(&kvm_pv_reboot_nb);
+ for (i = 0; i< KVM_TASK_SLEEP_HASHSIZE; i++)
+ spin_lock_init(&async_pf_sleepers[i].lock);
#ifdef CONFIG_SMP
smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
#else
--
error compiling committee.c: too many arguments to function
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