1 files changed, 21 insertions, 4 deletions
diff --git a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/ioport.c b/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/ioport.c
index 798c5c5c1f..c43daee3fd 100644
--- a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/ioport.c
+++ b/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/ioport.c
@@ -7,13 +7,30 @@
 
 asmlinkage int sys_ioperm(unsigned long from, unsigned long num, int turn_on)
 {
-    /* No IO permission! */
-		return -EPERM;
+    /* No IO permission! Selective IO perms aren't virtualised yet. */
+    return -EPERM;
 }
 
 
 asmlinkage int sys_iopl(unsigned long unused)
 {
-    /* The hypervisor won't allow it! */
-			return -EPERM;
+    struct pt_regs *regs = (struct pt_regs *)&unused;
+    unsigned int level = regs->ebx;
+    unsigned int old = (regs->eflags >> 12) & 3;
+
+    if ( !(start_info.flags & SIF_PRIVILEGED) )
+        return -EPERM;
+
+    if ( level > 3 )
+        return -EINVAL;
+    if ( (level > old) && !capable(CAP_SYS_RAWIO) )
+        return -EPERM;
+    
+    /* Change the one on our stack for sanity's sake. */
+    regs->eflags = (regs->eflags & 0xffffcfff) | (level << 12);
+
+    /* Force the change at ring 0. */
+    HYPERVISOR_iopl(level);
+
+    return 0;
 }