From: Marc Zyngier <marc.zyngier@arm.com>
Date: Wed, 17 Apr 2013 19:09:09 +0000 (-0700)
Subject: ARM: KVM: fix unbalanced get_cpu() in access_dcsw
X-Git-Tag: v3.12-rc1~1045
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=15bbc1b28ff65767922f78c266821cc138b90a47;p=kernel%2Fkernel-generic.git

ARM: KVM: fix unbalanced get_cpu() in access_dcsw

In the very unlikely event where a guest would be foolish enough to
*read* from a write-only cache maintainance register, we end up
with preemption disabled, due to a misplaced get_cpu().

Just move the "is_write" test outside of the critical section.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@cs.columbia.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/arch/arm/kvm/coproc.c b/arch/arm/kvm/coproc.c
index 4ea9a98..7bed755 100644
--- a/arch/arm/kvm/coproc.c
+++ b/arch/arm/kvm/coproc.c
@@ -79,11 +79,11 @@ static bool access_dcsw(struct kvm_vcpu *vcpu,
 	u32 val;
 	int cpu;
 
-	cpu = get_cpu();
-
 	if (!p->is_write)
 		return read_from_write_only(vcpu, p);
 
+	cpu = get_cpu();
+
 	cpumask_setall(&vcpu->arch.require_dcache_flush);
 	cpumask_clear_cpu(cpu, &vcpu->arch.require_dcache_flush);