x86/asm: Tidy up TSS limit code

In an earlier version of the patch ("x86/kvm/vmx: Defer TR reload
after VM exit") that introduced TSS limit validity tracking, I
confused which helper was which.  On reflection, the names I chose
sucked.  Rename the helpers to make it more obvious what's going on
and add some comments.

While I'm at it, clear __tss_limit_invalid when force-reloading as
well as when contitionally reloading, since any TR reload fixes the
limit.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
index b01bc8517450..875d3d25dd6a 100644
--- a/arch/x86/kernel/ioport.c
+++ b/arch/x86/kernel/ioport.c
@@ -47,8 +47,14 @@ asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
 		t->io_bitmap_ptr = bitmap;
 		set_thread_flag(TIF_IO_BITMAP);
 
+		/*
+		 * Now that we have an IO bitmap, we need our TSS limit to be
+		 * correct.  It's fine if we are preempted after doing this:
+		 * with TIF_IO_BITMAP set, context switches will keep our TSS
+		 * limit correct.
+		 */
 		preempt_disable();
-		refresh_TR();
+		refresh_tss_limit();
 		preempt_enable();
 	}