On 06/15/2009 02:30 PM, Alexander Graf wrote:
X86 CPUs need to have some magic happening to enable the virtualization
extensions on them. This magic can result in unpleasant results for
users, like blocking other VMMs from working (vmx) or using invalid TLB
entries (svm).
Currently KVM activates virtualization when the respective kernel module
is loaded. This blocks us from autoloading KVM modules without breaking
other VMMs.
To circumvent this problem at least a bit, this patch introduces on
demand activation of virtualization. This means, that instead
virtualization is enabled on creation of the first virtual machine
and disabled on destruction of the last one.
So using this, KVM can be easily autoloaded, while keeping other
hypervisors usable.
+static int hardware_enable_all(void)
+{
+ int r = 0;
+
+ spin_lock(&kvm_lock);
+
+ kvm_usage_count++;
+ if (kvm_usage_count == 1) {
+ atomic_set(&hardware_enable_failed, 1);
+ on_each_cpu(hardware_enable, NULL, 1);
+
+ if (!atomic_dec_and_test(&hardware_enable_failed))
+ r = -EBUSY;
+ }
That's a little obfuscated. I suggest atomic_set(..., p) and
atomic_read(...).
+
static int kvm_cpu_hotplug(struct notifier_block *notifier, unsigned long val,
void *v)
{
int cpu = (long)v;
+ if (!kvm_usage_count)
+ return NOTIFY_OK;
+
val&= ~CPU_TASKS_FROZEN;
switch (val) {
case CPU_DYING:
@@ -2513,13 +2571,15 @@ static void kvm_exit_debug(void)
static int kvm_suspend(struct sys_device *dev, pm_message_t state)
{
- hardware_disable(NULL);
+ if (kvm_usage_count)
+ hardware_disable(NULL);
return 0;
}
static int kvm_resume(struct sys_device *dev)
{
- hardware_enable(NULL);
+ if (kvm_usage_count)
+ hardware_enable(NULL);
return 0;
}
Please tell me you tested suspend/resume with/without VMs and cpu
hotunplug/hotplug.
--
error compiling committee.c: too many arguments to function
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