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MIPS: mark KVM_GUEST (T&E KVM) as BROKEN_ON_SMP

Message ID 51DFE7D3.3090002@imgtec.com (mailing list archive)
State New, archived
Headers show

Commit Message

James Hogan July 12, 2013, 11:26 a.m. UTC
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
---
 arch/mips/Kconfig | 1 +
 1 file changed, 1 insertion(+)
diff mbox

Patch

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 7a58ab9..6a6a096 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1736,6 +1736,7 @@  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