Re: [Qemu-devel] [PATCH v6 07/11] xics, xics_kvm: Handle CPU unplug correctly

[David Gibson <david@gibson.dropbear.id.au>]

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On Fri, Jan 08, 2016 at 12:25:15PM +0530, Bharata B Rao wrote:
> XICS is setup for each CPU during initialization. Provide a routine
> to undo the same when CPU is unplugged. While here, move ss->cs management
> into xics from xics_kvm since there is nothing KVM specific in it.
> Also ensure xics reset doesn't set irq for CPUs that are already unplugged.
> 
> This allows reboot of a VM that has undergone CPU hotplug and unplug
> to work correctly.
> 
> Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

Small suggestion below, but it's not of great importance.

> ---
>  hw/intc/xics.c        | 13 +++++++++++++
>  hw/intc/xics_kvm.c    |  8 ++++----
>  include/hw/ppc/xics.h |  1 +
>  3 files changed, 18 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/intc/xics.c b/hw/intc/xics.c
> index 9ff5796..37abaf4 100644
> --- a/hw/intc/xics.c
> +++ b/hw/intc/xics.c
> @@ -44,6 +44,17 @@ static int get_cpu_index_by_dt_id(int cpu_dt_id)
>      return -1;
>  }
>  
> +void xics_cpu_destroy(XICSState *icp, PowerPCCPU *cpu)
> +{
> +    CPUState *cs = CPU(cpu);
> +    ICPState *ss = &icp->ss[cs->cpu_index];
> +
> +    assert(cs->cpu_index < icp->nr_servers);

Maybe assert that ss->cs matches cs.

> +
> +    ss->output = NULL;
> +    ss->cs = NULL;
> +}
> +
>  void xics_cpu_setup(XICSState *icp, PowerPCCPU *cpu)
>  {
>      CPUState *cs = CPU(cpu);
> @@ -53,6 +64,8 @@ void xics_cpu_setup(XICSState *icp, PowerPCCPU *cpu)
>  
>      assert(cs->cpu_index < icp->nr_servers);
>  
> +    ss->cs = cs;
> +
>      if (info->cpu_setup) {
>          info->cpu_setup(icp, cpu);
>      }
> diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
> index d58729c..049d4e2 100644
> --- a/hw/intc/xics_kvm.c
> +++ b/hw/intc/xics_kvm.c
> @@ -109,8 +109,10 @@ static void icp_kvm_reset(DeviceState *dev)
>      icp->pending_priority = 0xff;
>      icp->mfrr = 0xff;
>  
> -    /* Make all outputs are deasserted */
> -    qemu_set_irq(icp->output, 0);
> +    /* Make all outputs as deasserted only if the CPU thread is in use */
> +    if (icp->output) {
> +        qemu_set_irq(icp->output, 0);
> +    }
>  
>      icp_set_kvm_state(icp, 1);
>  }
> @@ -343,8 +345,6 @@ static void xics_kvm_cpu_setup(XICSState *icp, PowerPCCPU *cpu)
>      if (icpkvm->kernel_xics_fd != -1) {
>          int ret;
>  
> -        ss->cs = cs;
> -
>          ret = kvm_vcpu_enable_cap(cs, KVM_CAP_IRQ_XICS, 0,
>                                    icpkvm->kernel_xics_fd, kvm_arch_vcpu_id(cs));
>          if (ret < 0) {
> diff --git a/include/hw/ppc/xics.h b/include/hw/ppc/xics.h
> index 355a966..640162f 100644
> --- a/include/hw/ppc/xics.h
> +++ b/include/hw/ppc/xics.h
> @@ -166,5 +166,6 @@ int xics_alloc_block(XICSState *icp, int src, int num, bool lsi, bool align);
>  void xics_free(XICSState *icp, int irq, int num);
>  
>  void xics_cpu_setup(XICSState *icp, PowerPCCPU *cpu);
> +void xics_cpu_destroy(XICSState *icp, PowerPCCPU *cpu);
>  
>  #endif /* __XICS_H__ */

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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