Re: [PATCH 1/5] powerpc/64s: Kernel Hypervisor Restricted Access Prevention

On Wed, 2018-10-17 at 22:30 +1100, Michael Ellerman wrote:

Russell Currey [off-list ref] writes:

quoted

diff --git a/arch/powerpc/kernel/entry_64.S

b/arch/powerpc/kernel/entry_64.S
index 7b1693adff2a..090f72cbb02d 100644

--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S

@@ -286,6 +286,9 @@ BEGIN_FTR_SECTION
 	HMT_MEDIUM_LOW
 END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 
+	/* headed back to userspace, so unlock the AMR */
+	UNLOCK_AMR(r2)
+

This one needs an ifdef, or preferable an empty version in a header
for
non-book3s 64, otherwise we get:

  arch/powerpc/kernel/entry_64.S: Assembler messages:
  arch/powerpc/kernel/entry_64.S:290: Error: unrecognized opcode:
`unlock_amr(%r2)'
  scripts/Makefile.build:405: recipe for target
'arch/powerpc/kernel/entry_64.o' failed

That's a corenet64-ish defconfig.

Yep, sorry.  I knew it wouldn't build on non-64s but I just wanted to
get the main part out there so people could start looking at it.  Will
fix.

- Russell

cheers