Re: [PATCH] KVM: PPC: Book3S HV: XIVE: Clear escalation interrupt pointers on device close

["Cédric Le Goater" <clg@kaod.org>]

On 4/26/19 8:54 AM, Paul Mackerras wrote:
> This adds code to ensure that after a XIVE or XICS-on-XIVE KVM device
> is closed, KVM will not try to enable or disable any of the escalation
> interrupts for the VCPUs.  

Yes. This is a required cleanup.

Reviewed-by: Cédric Le Goater <clg@kaod.org>

Thanks,

C.


> We don't have to worry about races between
> clearing the pointers and use of the pointers by the XIVE context
> push/pull code, because the callers hold the vcpu->mutex, which is
> also taken by the KVM_RUN code.  Therefore the vcpu cannot be entering
> or exiting the guest concurrently.
> 
> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
> ---
>  arch/powerpc/kvm/book3s_xive.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
> index 4280cd8..4953957 100644
> --- a/arch/powerpc/kvm/book3s_xive.c
> +++ b/arch/powerpc/kvm/book3s_xive.c
> @@ -1096,6 +1096,21 @@ void kvmppc_xive_disable_vcpu_interrupts(struct kvm_vcpu *vcpu)
>  			arch_spin_unlock(&sb->lock);
>  		}
>  	}
> +
> +	/* Disable vcpu's escalation interrupt */
> +	if (vcpu->arch.xive_esc_on) {
> +		__raw_readq((void __iomem *)(vcpu->arch.xive_esc_vaddr +
> +					     XIVE_ESB_SET_PQ_01));
> +		vcpu->arch.xive_esc_on = false;
> +	}
> +
> +	/*
> +	 * Clear pointers to escalation interrupt ESB.
> +	 * This is safe because the vcpu->mutex is held, preventing
> +	 * any other CPU from concurrently executing a KVM_RUN ioctl.
> +	 */
> +	vcpu->arch.xive_esc_vaddr = 0;
> +	vcpu->arch.xive_esc_raddr = 0;
>  }
>  
>  void kvmppc_xive_cleanup_vcpu(struct kvm_vcpu *vcpu)
>