Allow guest to specify syscall vector to use.

(Based on Ron Minnich's LGUEST_PLAN9_SYSCALL patch).

This patch allows Guests to specify what system call vector they want,
and we try to reserve it.  We only allow one non-Linux system call
vector, to try to avoid DoS on the Host.

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

1 files changed, 20 insertions, 10 deletions

diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index 02556bae9e9f..41b26e592d38 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -281,37 +281,47 @@ static int __init init(void)
         /* First we put the Switcher up in very high virtual memory. */
         err = map_switcher();
         if (err)
-                return err;
+                goto out;
 
         /* Now we set up the pagetable implementation for the Guests. */
         err = init_pagetables(switcher_page, SHARED_SWITCHER_PAGES);
-        if (err) {
-                unmap_switcher();
-                return err;
-        }
+        if (err)
+                goto unmap;
 
         /* The I/O subsystem needs some things initialized. */
         lguest_io_init();
 
+        /* We might need to reserve an interrupt vector. */
+        err = init_interrupts();
+        if (err)
+                goto free_pgtables;
+
         /* /dev/lguest needs to be registered. */
         err = lguest_device_init();
-        if (err) {
-                free_pagetables();
-                unmap_switcher();
-                return err;
-        }
+        if (err)
+                goto free_interrupts;
 
         /* Finally we do some architecture-specific setup. */
         lguest_arch_host_init();
 
         /* All good! */
         return 0;
+
+free_interrupts:
+        free_interrupts();
+free_pgtables:
+        free_pagetables();
+unmap:
+        unmap_switcher();
+out:
+        return err;
 }
 
 /* Cleaning up is just the same code, backwards.  With a little French. */
 static void __exit fini(void)
 {
         lguest_device_remove();
+        free_interrupts();
         free_pagetables();
         unmap_switcher();