lguest: add infrastructure for userspace to deliver a trap to the guest.

This is required for instruction emulation to move to userspace.

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

2 files changed, 20 insertions, 0 deletions

diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index dcf9efd94cf4..be996d173615 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -243,6 +243,23 @@ static int user_send_irq(struct lg_cpu *cpu, const unsigned long __user *input)
         return 0;
 }
 
+/*L:053
+ * Deliver a trap: this is used by the Launcher if it can't emulate
+ * an instruction.
+ */
+static int trap(struct lg_cpu *cpu, const unsigned long __user *input)
+{
+        unsigned long trapnum;
+
+        if (get_user(trapnum, input) != 0)
+                return -EFAULT;
+
+        if (!deliver_trap(cpu, trapnum))
+                return -EINVAL;
+
+        return 0;
+}
+
 /*L:040
  * Once our Guest is initialized, the Launcher makes it run by reading
  * from /dev/lguest.
@@ -487,6 +504,8 @@ static ssize_t write(struct file *file, const char __user *in,
                 return getreg_setup(cpu, input);
         case LHREQ_SETREG:
                 return setreg(cpu, input);
+        case LHREQ_TRAP:
+                return trap(cpu, input);
         default:
                 return -EINVAL;
         }
diff --git a/include/linux/lguest_launcher.h b/include/linux/lguest_launcher.h
index c4451ebece47..3c402b843e03 100644
--- a/include/linux/lguest_launcher.h
+++ b/include/linux/lguest_launcher.h
@@ -65,6 +65,7 @@ enum lguest_req
         LHREQ_EVENTFD, /* + address, fd. */
         LHREQ_GETREG, /* + offset within struct pt_regs (then read value). */
         LHREQ_SETREG, /* + offset within struct pt_regs, value. */
+        LHREQ_TRAP, /* + trap number to deliver to guest. */
 };
 
 /*