linux-kernel - [PATCH 3.12 06/63] ARM: KVM: fix L2CTLR to be per-cluster

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Date:	Thu, 30 Apr 2015 14:11:35 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Marc Zyngier <marc.zyngier@....com>,
	Christoffer Dall <christoffer.dall@...aro.org>,
	Shannon Zhao <shannon.zhao@...aro.org>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 06/63] ARM: KVM: fix L2CTLR to be per-cluster

From: Marc Zyngier <marc.zyngier@....com>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 9cbb6d969cb6561de45d917b8bb9281cb374bb35 upstream.

The L2CTLR register contains the number of CPUs in this cluster.

Make sure the register content is actually relevant to the vcpu
that is being configured by computing the number of cores that are
part of its cluster.

Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Christoffer Dall <christoffer.dall@...aro.org>
Signed-off-by: Shannon Zhao <shannon.zhao@...aro.org>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 arch/arm/kvm/coproc_a15.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/kvm/coproc_a15.c b/arch/arm/kvm/coproc_a15.c
index 8611c5c45d93..935fa0fddb29 100644
--- a/arch/arm/kvm/coproc_a15.c
+++ b/arch/arm/kvm/coproc_a15.c
@@ -79,6 +79,10 @@ static void reset_l2ctlr(struct kvm_vcpu *vcpu, const struct coproc_reg *r)
 	asm volatile("mrc p15, 1, %0, c9, c0, 2\n" : "=r" (l2ctlr));
 	l2ctlr &= ~(3 << 24);
 	ncores = atomic_read(&vcpu->kvm->online_vcpus) - 1;
+	/* How many cores in the current cluster and the next ones */
+	ncores -= (vcpu->vcpu_id & ~3);
+	/* Cap it to the maximum number of cores in a single cluster */
+	ncores = min(ncores, 3U);
 	l2ctlr |= (ncores & 3) << 24;
 
 	vcpu->arch.cp15[c9_L2CTLR] = l2ctlr;
-- 
2.3.5

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