lguest: per-vcpu lguest timers

Here, I introduce per-vcpu timers. With this, we can have
local expiries, needed for accounting time in smp guests

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/lguest/hypercalls.c

@@ -80,7 +80,7 @@ static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args)
 		guest_set_pmd(lg, args->arg1, args->arg2);
 		break;
 	case LHCALL_SET_CLOCKEVENT:
-		guest_set_clockevent(lg, args->arg1);
+		guest_set_clockevent(cpu, args->arg1);
 		break;
 	case LHCALL_TS:
 		/* This sets the TS flag, as we saw used in run_guest(). */

drivers/lguest/interrupts_and_traps.c

@@ -470,39 +470,39 @@ void copy_traps(const struct lguest *lg, struct desc_struct *idt,
  * infrastructure to set a callback at that time.
  *
  * 0 means "turn off the clock". */
-void guest_set_clockevent(struct lguest *lg, unsigned long delta)
+void guest_set_clockevent(struct lg_cpu *cpu, unsigned long delta)
 {
 	ktime_t expires;
 
 	if (unlikely(delta == 0)) {
 		/* Clock event device is shutting down. */
-		hrtimer_cancel(&lg->hrt);
+		hrtimer_cancel(&cpu->hrt);
 		return;
 	}
 
 	/* We use wallclock time here, so the Guest might not be running for
 	 * all the time between now and the timer interrupt it asked for.  This
 	 * is almost always the right thing to do. */
 	expires = ktime_add_ns(ktime_get_real(), delta);
-	hrtimer_start(&lg->hrt, expires, HRTIMER_MODE_ABS);
+	hrtimer_start(&cpu->hrt, expires, HRTIMER_MODE_ABS);
 }
 
 /* This is the function called when the Guest's timer expires. */
 static enum hrtimer_restart clockdev_fn(struct hrtimer *timer)
 {
-	struct lguest *lg = container_of(timer, struct lguest, hrt);
+	struct lg_cpu *cpu = container_of(timer, struct lg_cpu, hrt);
 
 	/* Remember the first interrupt is the timer interrupt. */
-	set_bit(0, lg->irqs_pending);
+	set_bit(0, cpu->lg->irqs_pending);
 	/* If the Guest is actually stopped, we need to wake it up. */
-	if (lg->halted)
-		wake_up_process(lg->tsk);
+	if (cpu->lg->halted)
+		wake_up_process(cpu->lg->tsk);
 	return HRTIMER_NORESTART;
 }
 
 /* This sets up the timer for this Guest. */
-void init_clockdev(struct lguest *lg)
+void init_clockdev(struct lg_cpu *cpu)
 {
-	hrtimer_init(&lg->hrt, CLOCK_REALTIME, HRTIMER_MODE_ABS);
-	lg->hrt.function = clockdev_fn;
+	hrtimer_init(&cpu->hrt, CLOCK_REALTIME, HRTIMER_MODE_ABS);
+	cpu->hrt.function = clockdev_fn;
 }

drivers/lguest/lg.h

@@ -47,6 +47,9 @@ struct lg_cpu {
 	/* If a hypercall was asked for, this points to the arguments. */
 	struct hcall_args *hcall;
 	u32 next_hcall;
+
+	/* Virtual clock device */
+	struct hrtimer hrt;
 };
 
 /* The private info the thread maintains about the guest. */
@@ -95,9 +98,6 @@ struct lguest
 
 	struct lguest_arch arch;
 
-	/* Virtual clock device */
-	struct hrtimer hrt;
-
 	/* Pending virtual interrupts */
 	DECLARE_BITMAP(irqs_pending, LGUEST_IRQS);
 };
@@ -145,8 +145,8 @@ void setup_default_idt_entries(struct lguest_ro_state *state,
 			       const unsigned long *def);
 void copy_traps(const struct lguest *lg, struct desc_struct *idt,
 		const unsigned long *def);
-void guest_set_clockevent(struct lguest *lg, unsigned long delta);
-void init_clockdev(struct lguest *lg);
+void guest_set_clockevent(struct lg_cpu *cpu, unsigned long delta);
+void init_clockdev(struct lg_cpu *cpu);
 bool check_syscall_vector(struct lguest *lg);
 int init_interrupts(void);
 void free_interrupts(void);

drivers/lguest/lguest_user.c

@@ -104,6 +104,7 @@ static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
 	cpu->id = id;
 	cpu->lg = container_of((cpu - id), struct lguest, cpus[0]);
 	cpu->lg->nr_cpus++;
+	init_clockdev(cpu);
 
 	return 0;
 }
@@ -180,9 +181,6 @@ static int initialize(struct file *file, const unsigned long __user *input)
 	 * address. */
 	lguest_arch_setup_regs(lg, args[3]);
 
-	/* The timer for lguest's clock needs initialization. */
-	init_clockdev(lg);
-
 	/* We keep a pointer to the Launcher task (ie. current task) for when
 	 * other Guests want to wake this one (inter-Guest I/O). */
 	lg->tsk = current;
@@ -273,6 +271,7 @@ static ssize_t write(struct file *file, const char __user *in,
 static int close(struct inode *inode, struct file *file)
 {
 	struct lguest *lg = file->private_data;
+	unsigned int i;
 
 	/* If we never successfully initialized, there's nothing to clean up */
 	if (!lg)
@@ -281,8 +280,9 @@ static int close(struct inode *inode, struct file *file)
 	/* We need the big lock, to protect from inter-guest I/O and other
 	 * Launchers initializing guests. */
 	mutex_lock(&lguest_lock);
-	/* Cancels the hrtimer set via LHCALL_SET_CLOCKEVENT. */
-	hrtimer_cancel(&lg->hrt);
+	for (i = 0; i < lg->nr_cpus; i++)
+		/* Cancels the hrtimer set via LHCALL_SET_CLOCKEVENT. */
+		hrtimer_cancel(&lg->cpus[i].hrt);
 	/* Free up the shadow page tables for the Guest. */
 	free_guest_pagetable(lg);
 	/* Now all the memory cleanups are done, it's safe to release the