On Tue, Oct 08, 2013 at 06:17:08PM +0100, Marc Zyngier wrote:
> It appears we have an arbitrary limitation where we refuse to
> create more than 4 virtual A15 in a single VM.
>
> This limitation doesn't make much sense (the number 4 probably
> comes from the maximum number of CPUs in a A15 cluster, but
> KVM doesn't have any notion of cluster), and directly
> contradicts CONFIG_MAX_VCPUS.
So this comes from the early days where I looked at the A15 TRM and the
MPIDR bit field for the CPU ID is limited to 2 bits. Exactly because
I wasn't sure what remifications (if any) it would have to start
populating this register with cluster id = (vcpu_id / 4) and cpu id =
(vcpu_id % 4) I put this nice arbitrary restriction in there.
I think we need to fix how we show this register to the guest
otherwise... No?
-Christoffer
>
> Just remove this code altogether.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> ---
> arch/arm/kvm/reset.c | 4 ----
> 1 file changed, 4 deletions(-)
>
> diff --git a/arch/arm/kvm/reset.c b/arch/arm/kvm/reset.c
> index c02ba4a..8e259d2 100644
> --- a/arch/arm/kvm/reset.c
> +++ b/arch/arm/kvm/reset.c
> @@ -33,8 +33,6 @@
> * Cortex-A15 Reset Values
> */
>
> -static const int a15_max_cpu_idx = 3;
> -
> static struct kvm_regs a15_regs_reset = {
> .usr_regs.ARM_cpsr = SVC_MODE | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT,
> };
> @@ -63,8 +61,6 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
>
> switch (vcpu->arch.target) {
> case KVM_ARM_TARGET_CORTEX_A15:
> - if (vcpu->vcpu_id > a15_max_cpu_idx)
> - return -EINVAL;
> reset_regs = &a15_regs_reset;
> vcpu->arch.midr = read_cpuid_id();
> cpu_vtimer_irq = &a15_vtimer_irq;
> --
> 1.8.2.3
>
>
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