From 1158fca401e09665c440a9fe4fd4f131ee85c13b Mon Sep 17 00:00:00 2001 From: Jonathan Austin Date: Thu, 26 Sep 2013 16:49:27 +0100 Subject: KVM: ARM: Fix calculation of virtual CPU ID KVM does not have a notion of multiple clusters for CPUs, just a linear array of CPUs. When using a system with cores in more than one cluster, the current method for calculating the virtual MPIDR will leak the (physical) cluster information into the virtual MPIDR. One effect of this is that Linux under KVM fails to boot multiple CPUs that aren't in the 0th cluster. This patch does away with exposing the real MPIDR fields in favour of simply using the virtual CPU number (but preserving the U bit, as before). Signed-off-by: Jonathan Austin Acked-by: Marc Zyngier Signed-off-by: Christoffer Dall --- arch/arm/kvm/coproc_a15.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) (limited to 'arch/arm/kvm') diff --git a/arch/arm/kvm/coproc_a15.c b/arch/arm/kvm/coproc_a15.c index cf93472b9dd6..bbd4b888dbf3 100644 --- a/arch/arm/kvm/coproc_a15.c +++ b/arch/arm/kvm/coproc_a15.c @@ -27,14 +27,11 @@ static void reset_mpidr(struct kvm_vcpu *vcpu, const struct coproc_reg *r) { /* - * Compute guest MPIDR: - * (Even if we present only one VCPU to the guest on an SMP - * host we don't set the U bit in the MPIDR, or vice versa, as - * revealing the underlying hardware properties is likely to - * be the best choice). + * Compute guest MPIDR. No need to mess around with different clusters + * but we read the 'U' bit from the underlying hardware directly. */ - vcpu->arch.cp15[c0_MPIDR] = (read_cpuid_mpidr() & ~MPIDR_LEVEL_MASK) - | (vcpu->vcpu_id & MPIDR_LEVEL_MASK); + vcpu->arch.cp15[c0_MPIDR] = (read_cpuid_mpidr() & MPIDR_SMP_BITMASK) + | vcpu->vcpu_id; } #include "coproc.h" -- cgit v1.2.3