MIPS: KVM: Mark KVM_GUEST (T&E KVM) as BROKEN_ON_SMP
authorJames Hogan <james.hogan@imgtec.com>
Fri, 12 Jul 2013 10:26:11 +0000 (10:26 +0000)
committerRalf Baechle <ralf@linux-mips.org>
Fri, 19 Jul 2013 08:41:17 +0000 (10:41 +0200)
Make KVM_GUEST depend on BROKEN_ON_SMP so that it cannot be enabled with
SMP.

SMP kernels use ll/sc instructions for an atomic section in the tlb fill
handler, with a tlbp instruction contained in the middle. This cannot be
emulated with trap & emulate KVM because the tlbp instruction traps and
the eret to return to the guest code clears the LLbit which makes the sc
instruction always fail.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Sanjay Lal <sanjayl@kymasys.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/5588/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
arch/mips/Kconfig

index 4758a8f..c3abed3 100644 (file)
@@ -1702,6 +1702,7 @@ endchoice
 
 config KVM_GUEST
        bool "KVM Guest Kernel"
+       depends on BROKEN_ON_SMP
        help
          Select this option if building a guest kernel for KVM (Trap & Emulate) mode