lguest: allow any process to send interrupts

We currently only allow the Launcher process to send interrupts, but it
as we already send interrupts from the hrtimer, it's a simple matter of
extracting that code into a common set_interrupt routine.

As we switch to a thread per virtqueue, this avoids a bottleneck through the
main Launcher process.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

3 files changed, 18 insertions, 12 deletions

diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c
index 5a10754b479..0e9067b0d50 100644
--- a/drivers/lguest/interrupts_and_traps.c
+++ b/drivers/lguest/interrupts_and_traps.c
@@ -213,6 +213,20 @@ void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq, bool more)
         if (!more)
                 put_user(0, &cpu->lg->lguest_data->irq_pending);
 }
+
+/* And this is the routine when we want to set an interrupt for the Guest. */
+void set_interrupt(struct lg_cpu *cpu, unsigned int irq)
+{
+        /* Next time the Guest runs, the core code will see if it can deliver
+         * this interrupt. */
+        set_bit(irq, cpu->irqs_pending);
+
+        /* Make sure it sees it; it might be asleep (eg. halted), or
+         * running the Guest right now, in which case kick_process()
+         * will knock it out. */
+        if (!wake_up_process(cpu->tsk))
+                kick_process(cpu->tsk);
+}
 /*:*/
 
 /* Linux uses trap 128 for system calls.  Plan9 uses 64, and Ron Minnich sent
@@ -528,10 +542,7 @@ static enum hrtimer_restart clockdev_fn(struct hrtimer *timer)
         struct lg_cpu *cpu = container_of(timer, struct lg_cpu, hrt);
 
         /* Remember the first interrupt is the timer interrupt. */
-        set_bit(0, cpu->irqs_pending);
-        /* Guest may be stopped or running on another CPU. */
-        if (!wake_up_process(cpu->tsk))
-                kick_process(cpu->tsk);
+        set_interrupt(cpu, 0);
         return HRTIMER_NORESTART;
 }
 
diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index 6201ce59e88..040cb70780e 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -143,6 +143,7 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user);
 /* interrupts_and_traps.c: */
 unsigned int interrupt_pending(struct lg_cpu *cpu, bool *more);
 void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq, bool more);
+void set_interrupt(struct lg_cpu *cpu, unsigned int irq);
 bool deliver_trap(struct lg_cpu *cpu, unsigned int num);
 void load_guest_idt_entry(struct lg_cpu *cpu, unsigned int i,
                           u32 low, u32 hi);
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index bcdcf3453e7..1982b45bd93 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -45,9 +45,8 @@ static int user_send_irq(struct lg_cpu *cpu, const unsigned long __user *input)
                 return -EFAULT;
         if (irq >= LGUEST_IRQS)
                 return -EINVAL;
-        /* Next time the Guest runs, the core code will see if it can deliver
-         * this interrupt. */
-        set_bit(irq, cpu->irqs_pending);
+
+        set_interrupt(cpu, irq);
         return 0;
 }
 
@@ -252,11 +251,6 @@ static ssize_t write(struct file *file, const char __user *in,
                 /* Once the Guest is dead, you can only read() why it died. */
                 if (lg->dead)
                         return -ENOENT;
-
-                /* If you're not the task which owns the Guest, all you can do
-                 * is break the Launcher out of running the Guest. */
-                if (current != cpu->tsk && req != LHREQ_BREAK)
-                        return -EPERM;
         }
 
         switch (req) {