regression suspend/resume on Lenovo T420

[Konstantin Belousov]

On Sun, May 14, 2017 at 08:02:52PM +0000, Poul-Henning Kamp wrote:
> --------
> In message <20170514193006.GA1298 at brick>, Edward Tomasz =?utf-8?Q?Napiera=C5=82
> a?= writes:
> 
> >I've tried to verify that, and sadly it wasn't it for me.  The commit
> >that does break resume for me is r316767.  The current -CURRENT with
> >this one commit reverted ("svn merge -c -r316767 .") suspends and resumes
> >correctly, at least in VT; I decided to take X out of the picture for
> >now.
> 
> I can confirm that this also makes resume work on my T430s running:
> 
> 	FreeBSD 12.0-CURRENT #0 r318250M amd64

Try this.  If it works, I will write a proper patch.

diff --git a/sys/amd64/amd64/cpu_switch.S b/sys/amd64/amd64/cpu_switch.S
index 33437ad16e6..9c0cd05ebea 100644
--- a/sys/amd64/amd64/cpu_switch.S
+++ b/sys/amd64/amd64/cpu_switch.S
@@ -369,6 +369,11 @@ END(savectx)
  * Resuming processor state from pcb.
  */     
 ENTRY(resumectx)
+	movl	$MSR_EFER,%ecx
+	rdmsr
+	orl	$EFER_NXE,%eax
+	wrmsr
+
 	/* Switch to KPML4phys. */
 	movq	KPML4phys,%rax
 	movq	%rax,%cr3