/*L:025 This actually initializes a CPU. For the moment, a Guest is only
* uniprocessor, so "id" is always 0. */
static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
{
/* We have a limited number the number of CPUs in the lguest struct. */
if (id >= ARRAY_SIZE(cpu->lg->cpus))
return -EINVAL;
/* Set up this CPU's id, and pointer back to the lguest struct. */
cpu->id = id;
cpu->lg = container_of((cpu - id), struct lguest, cpus[0]);
cpu->lg->nr_cpus++;
/* Each CPU has a timer it can set. */
init_clockdev(cpu);
/* We need a complete page for the Guest registers: they are accessible
* to the Guest and we can only grant it access to whole pages. */
cpu->regs_page = get_zeroed_page(GFP_KERNEL);
if (!cpu->regs_page)
return -ENOMEM;
/* We actually put the registers at the bottom of the page. */
cpu->regs = (void *)cpu->regs_page + PAGE_SIZE - sizeof(*cpu->regs);
/* Now we initialize the Guest's registers, handing it the start
* address. */
lguest_arch_setup_regs(cpu, start_ip);
/* Initialize the queue for the Waker to wait on */
init_waitqueue_head(&cpu->break_wq);
/* We keep a pointer to the Launcher task (ie. current task) for when
* other Guests want to wake this one (eg. console input). */
cpu->tsk = current;
/* We need to keep a pointer to the Launcher's memory map, because if
* the Launcher dies we need to clean it up. If we don't keep a
* reference, it is destroyed before close() is called. */
cpu->mm = get_task_mm(cpu->tsk);
/* We remember which CPU's pages this Guest used last, for optimization
* when the same Guest runs on the same CPU twice. */
cpu->last_pages = NULL;
/* No error == success. */
return 0;
}
/*H:030
* Let's jump straight to the the main loop which runs the Guest.
* Remember, this is called by the Launcher reading /dev/lguest, and we keep
* going around and around until something interesting happens.
*/
int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
{
/* We stop running once the Guest is dead. */
while (!cpu->lg->dead) {
unsigned int irq;
bool more;
/* First we run any hypercalls the Guest wants done. */
if (cpu->hcall) {
// printk("=== DUMPING REGISTERS HYPERCALL ===\n");
// dump_cpu_regs(cpu);
do_hypercalls(cpu);
}
/*
* It's possible the Guest did a NOTIFY hypercall to the
* Launcher.
*/
if (cpu->pending_notify) {
/*
* Does it just needs to write to a registered
* eventfd (ie. the appropriate virtqueue thread)?
*/
if (!send_notify_to_eventfd(cpu)) {
/* OK, we tell the main Launcher. */
if (put_user(cpu->pending_notify, user))
return -EFAULT;
return sizeof(cpu->pending_notify);
}
}
/*
* All long-lived kernel loops need to check with this horrible
* thing called the freezer. If the Host is trying to suspend,
* it stops us.
*/
try_to_freeze();
/* Check for signals */
if (signal_pending(current))
return -ERESTARTSYS;
/*
* Check if there are any interrupts which can be delivered now:
* if so, this sets up the hander to be executed when we next
* run the Guest.
*/
irq = interrupt_pending(cpu, &more);
if (irq < LGUEST_IRQS)
try_deliver_interrupt(cpu, irq, more);
/*
* Just make absolutely sure the Guest is still alive. One of
* those hypercalls could have been fatal, for example.
*/
if (cpu->lg->dead)
break;
/**
* If the guest is suspended skip.
*/
// printk("Checking for suspend\n");
if(cpu->suspended) {
// Sleep
down_interruptible(&cpu->suspend_lock);
// Unlock the lock since we no longer need it
up(&cpu->suspend_lock);
// set_current_state(TASK_INTERRUPTIBLE);
// cond_resched();
// schedule();
// printk("Suspended\n");
// continue;
// TODO: Attempt to fix clock skew and nmi here?
init_clockdev(cpu);
}
/*
* If the Guest asked to be stopped, we sleep. The Guest's
* clock timer will wake us.
*/
if (cpu->halted) {
set_current_state(TASK_INTERRUPTIBLE);
/*
* Just before we sleep, make sure no interrupt snuck in
* which we should be doing.
*/
if (interrupt_pending(cpu, &more) < LGUEST_IRQS)
set_current_state(TASK_RUNNING);
else
schedule();
continue;
}
/*
* OK, now we're ready to jump into the Guest. First we put up
* the "Do Not Disturb" sign:
*/
local_irq_disable();
/* Actually run the Guest until something happens. */
lguest_arch_run_guest(cpu);
/* Now we're ready to be interrupted or moved to other CPUs */
local_irq_enable();
/* Now we deal with whatever happened to the Guest. */
lguest_arch_handle_trap(cpu);
}
/* Special case: Guest is 'dead' but wants a reboot. */
if (cpu->lg->dead == ERR_PTR(-ERESTART))
return -ERESTART;
/* The Guest is dead => "No such file or directory" */
return -ENOENT;
}
