Re: [PATCH v6 07/12] Add async PF initialization to PV guest.

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 On 10/04/2010 05:56 PM, Gleb Natapov wrote:
Enable async PF in a guest if async PF capability is discovered.


+void __cpuinit kvm_guest_cpu_init(void)
+{
+	if (!kvm_para_available())
+		return;
+
+	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF)&&  kvmapf) {
+		u64 pa = __pa(&__get_cpu_var(apf_reason));
+
+		if (native_write_msr_safe(MSR_KVM_ASYNC_PF_EN,
+					  pa | KVM_ASYNC_PF_ENABLED, pa>>  32))

native_ versions of processor accessors shouldn't be used generally.

Also, the MSR isn't documented to fail on valid input, so you can use a normal wrmsrl() here.

+			return;
+		__get_cpu_var(apf_reason).enabled = 1;
+		printk(KERN_INFO"KVM setup async PF for cpu %d\n",
+		       smp_processor_id());
+	}
+}
+

+static int kvm_pv_reboot_notify(struct notifier_block *nb,
+				unsigned long code, void *unused)
+{
+	if (code == SYS_RESTART)
+		on_each_cpu(kvm_pv_disable_apf, NULL, 1);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block kvm_pv_reboot_nb = {
+	.notifier_call = kvm_pv_reboot_notify,
+};

Does this handle kexec?

+
+static void kvm_guest_cpu_notify(void *dummy)
+{
+	if (!dummy)
+		kvm_guest_cpu_init();
+	else
+		kvm_pv_disable_apf(NULL);
+}

Why are you making decisions based on a dummy input?

The whole thing looks strange.  Use two functions?


--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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