Upgrade to 4.4.50-rt62

[kvmfornfv.git] / kernel / arch / x86 / kernel / ioport.c

diff --git a/kernel/arch/x86/kernel/ioport.c b/kernel/arch/x86/kernel/ioport.c
index 37dae79..589b319 100644 (file)
--- a/kernel/arch/x86/kernel/ioport.c
+++ b/kernel/arch/x86/kernel/ioport.c
@@ -96,9 +96,14 @@ asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
 SYSCALL_DEFINE1(iopl, unsigned int, level)
 {
        struct pt_regs *regs = current_pt_regs();
-       unsigned int old = (regs->flags >> 12) & 3;
        struct thread_struct *t = &current->thread;
 
+       /*
+        * Careful: the IOPL bits in regs->flags are undefined under Xen PV
+        * and changing them has no effect.
+        */
+       unsigned int old = t->iopl >> X86_EFLAGS_IOPL_BIT;
+
        if (level > 3)
                return -EINVAL;
        /* Trying to gain more privileges? */
@@ -106,8 +111,9 @@ SYSCALL_DEFINE1(iopl, unsigned int, level)
                if (!capable(CAP_SYS_RAWIO))
                        return -EPERM;
        }
-       regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12);
-       t->iopl = level << 12;
+       regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) |
+               (level << X86_EFLAGS_IOPL_BIT);
+       t->iopl = level << X86_EFLAGS_IOPL_BIT;
        set_iopl_mask(t->iopl);
 
        return 0;