* [PATCH] MIPS: mark KVM_GUEST (T&E KVM) as BROKEN_ON_SMP
@ 2013-07-12 11:26 James Hogan
0 siblings, 0 replies; only message in thread
From: James Hogan @ 2013-07-12 11:26 UTC (permalink / raw)
To: linux-mips, Sanjay Lal, Ralf Baechle; +Cc: David Daney, kvm
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 --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
--
1.8.1.2
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2013-07-12 11:26 [PATCH] MIPS: mark KVM_GUEST (T&E KVM) as BROKEN_ON_SMP James Hogan
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