Subject: Re: [RFC 03/11] powerpc: kvm: add interface to control kvm function on a core

From: Srikar Dronamraju <[email-masked]>
Date: Wed, 12 Nov 2014 18:31:35 +0530

* [email-masked] <[email-masked]> [2014-10-16 15:29:52]:

> When kvm is enabled on a core, we migrate all external irq to primary
> thread. Since currently, the kvmirq logic is handled by the primary
> hwthread.
> 
> Todo: this patch lacks re-enable of irqbalance when kvm is disable on
> the core
> 
> Signed-off-by: Liu Ping Fan <[email-masked]>
> ---
>  arch/powerpc/kernel/sysfs.c            | 39 ++++++++++++++++++++++++++++++++++
>  arch/powerpc/sysdev/xics/xics-common.c | 12 +++++++++++
>  2 files changed, 51 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
> index 67fd2fd..a2595dd 100644
> --- a/arch/powerpc/kernel/sysfs.c
> +++ b/arch/powerpc/kernel/sysfs.c
> @@ -552,6 +552,45 @@ static void sysfs_create_dscr_default(void)
>  	if (cpu_has_feature(CPU_FTR_DSCR))
>  		err = device_create_file(cpu_subsys.dev_root, &dev_attr_dscr_default);
>  }
> +
> +#ifdef CONFIG_KVMPPC_ENABLE_SECONDARY
> +#define NR_CORES	(CONFIG_NR_CPUS/threads_per_core)
> +static DECLARE_BITMAP(kvm_on_core, NR_CORES) __read_mostly
> +
> +static ssize_t show_kvm_enable(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +}
> +
> +static ssize_t __used store_kvm_enable(struct device *dev,
> +		struct device_attribute *attr, const char *buf,
> +		size_t count)
> +{
> +	struct cpumask stop_cpus;
> +	unsigned long core, thr;
> +
> +	sscanf(buf, "%lx", &core);
> +	if (core > NR_CORES)
> +		return -1;
> +	if (!test_bit(core, &kvm_on_core))
> +		for (thr = 1; thr< threads_per_core; thr++)
> +			if (cpu_online(thr * threads_per_core + thr))
> +				cpumask_set_cpu(thr * threads_per_core + thr, &stop_cpus);

Shouldnt this be 
			if (cpu_online(core * threads_per_core + thr))
				cpumask_set_cpu(core * threads_per_core + thr, &stop_cpus);
?

-- 
Thanks and Regards
Srikar Dronamraju