linux-kernel - Re: [PATCH 09/10] KVM: arm/arm64: vgic: Implement forwarding setting

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Message-ID: <877f14lp76.fsf@arm.com>
Date:   Thu, 25 May 2017 20:19:09 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Eric Auger <eric.auger@...hat.com>
Cc:     <eric.auger.pro@...il.com>, <linux-kernel@...r.kernel.org>,
        <kvm@...r.kernel.org>, <kvmarm@...ts.cs.columbia.edu>,
        <alex.williamson@...hat.com>, <pbonzini@...hat.com>,
        <christoffer.dall@...aro.org>, <drjones@...hat.com>,
        <wei@...hat.com>
Subject: Re: [PATCH 09/10] KVM: arm/arm64: vgic: Implement forwarding setting

On Wed, May 24 2017 at 10:13:22 pm BST, Eric Auger <eric.auger@...hat.com> wrote:
> Implements kvm_vgic_[set|unset]_forwarding.
>
> Handle low-level VGIC programming and consistent irqchip
> programming.
>
> Signed-off-by: Eric Auger <eric.auger@...hat.com>
>
> ---
> ---
>  include/kvm/arm_vgic.h   |   5 +++
>  virt/kvm/arm/vgic/vgic.c | 105 +++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 110 insertions(+)
>
> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
> index 695ebc7..7ddac8a 100644
> --- a/include/kvm/arm_vgic.h
> +++ b/include/kvm/arm_vgic.h
> @@ -343,4 +343,9 @@ int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi);
>   */
>  int kvm_vgic_setup_default_irq_routing(struct kvm *kvm);
>  
> +int kvm_vgic_set_forwarding(struct kvm *kvm, unsigned int irq,
> +			    unsigned int virt_irq);
> +void kvm_vgic_unset_forwarding(struct kvm *kvm, unsigned int irq,
> +			       unsigned int virt_irq);

nit: the name of the variables do not match that of the function
definition, and are much clearer there.

> +
>  #endif /* __KVM_ARM_VGIC_H */
> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
> index aa0618c..c2add8d 100644
> --- a/virt/kvm/arm/vgic/vgic.c
> +++ b/virt/kvm/arm/vgic/vgic.c
> @@ -17,6 +17,8 @@
>  #include <linux/kvm.h>
>  #include <linux/kvm_host.h>
>  #include <linux/list_sort.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
>  
>  #include "vgic.h"
>  
> @@ -771,3 +773,106 @@ bool kvm_vgic_map_is_active(struct kvm_vcpu *vcpu, unsigned int virt_irq)
>  	return map_is_active;
>  }
>  
> +/**
> + * kvm_vgic_set_forwarding - Set IRQ forwarding
> + *
> + * @kvm: kvm handle
> + * @host_irq: the host linux IRQ
> + * @vintid: the virtual INTID
> + *
> + * This function must be called when the IRQ is not active:
> + * ie. not active at GIC level and not currently under injection
> + * into the guest using the unforwarded mode. The physical IRQ must
> + * be disabled and all vCPUs must have been exited and prevented
> + * from being re-entered.
> + */
> +int kvm_vgic_set_forwarding(struct kvm *kvm, unsigned int host_irq,
> +			    unsigned int vintid)
> +{
> +	struct kvm_vcpu *vcpu;
> +	struct vgic_irq *irq;
> +	struct irq_desc *desc;
> +	struct irq_data *data;
> +	unsigned int pintid;
> +	int ret = 0;
> +
> +
> +	kvm_debug("%s host linux irq=%d vintid=%d\n",
> +		  __func__, host_irq, vintid);
> +
> +	if (!vgic_valid_spi(kvm, vintid))
> +		return 0;
> +
> +	/* find the INTID corresponding to @host_irq */
> +	desc = irq_to_desc(host_irq);
> +	if (!desc) {
> +		kvm_err("%s: no interrupt descriptor\n", __func__);
> +		return -EINVAL;
> +	}
> +
> +	data = irq_desc_get_irq_data(desc);
> +	while (data->parent_data)
> +		data = data->parent_data;
> +
> +	pintid = data->hwirq;
> +
> +	irq = vgic_get_irq(kvm, NULL, vintid);
> +
> +	spin_lock(&irq->irq_lock);
> +
> +	vcpu = irq->target_vcpu;
> +
> +	if (!vcpu) {
> +		ret = -EAGAIN;
> +		goto unlock;
> +	}
> +
> +	irq_set_vcpu_affinity(host_irq, vcpu);
> +
> +	irq->hw = true;
> +	irq->hwintid = pintid;
> +	irq->host_irq = host_irq;

This feels like a duplication of kvm_vgic_map_phys_irq(), specially if
you move the pintid discovery there. Can we somehow unify them?

> +
> +unlock:
> +	spin_unlock(&irq->irq_lock);
> +	vgic_put_irq(kvm, irq);
> +	return ret;
> +}
> +
> +/**
> + * kvm_vgic_unset_forwarding - Unset IRQ forwarding
> + *
> + * @kvm: KVM handle
> + * @host_irq: the host Linux IRQ number
> + * @vintid: virtual INTID
> + *
> + * This function must be called when the host irq is disabled and
> + * all vCPUs have been exited and prevented from being re-entered.
> + */
> +void kvm_vgic_unset_forwarding(struct kvm *kvm,
> +			       unsigned int host_irq,
> +			       unsigned int vintid)
> +{
> +	struct vgic_irq *irq;
> +	bool active;
> +
> +	kvm_debug("%s host_irq=%d virt_irq=%d\n", __func__, host_irq, vintid);
> +
> +	irq_get_irqchip_state(host_irq, IRQCHIP_STATE_ACTIVE, &active);
> +
> +	irq = vgic_get_irq(kvm, NULL, vintid);
> +	spin_lock(&irq->irq_lock);
> +
> +	if (!is_unshared_mapped(irq))
> +		goto unlock;
> +
> +	if (active)
> +		irq_set_irqchip_state(host_irq, IRQCHIP_STATE_ACTIVE, false);
> +
> +	irq->hw = false;
> +	irq_set_vcpu_affinity(host_irq, NULL);
> +
> +unlock:
> +	spin_unlock(&irq->irq_lock);

Same here.

> +}
> +


Thanks,

        M.
-- 
Jazz is not dead, it just smell funny.