Re: [PATCH 2/8] KVM: arm/arm64: vgic: Add __vgic_put_lpi_locked primitive

From: Auger Eric <eric.auger@redhat.com>
To: Marc Zyngier <marc.zyngier@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Cc: "Raslan, KarimAllah" <karahmed@amazon.de>
Subject: Re: [PATCH 2/8] KVM: arm/arm64: vgic: Add __vgic_put_lpi_locked primitive
Date: Fri, 7 Jun 2019 14:11:49 +0200	[thread overview]
Message-ID: <8048ab7f-a429-df29-43da-05ef97c9dc7a@redhat.com> (raw)
In-Reply-To: <20190606165455.162478-3-marc.zyngier@arm.com>

Hi Marc,
On 6/6/19 6:54 PM, Marc Zyngier wrote:
> Our LPI translation cache needs to be able to drop the refcount
> on an LPI whilst already holding the lpi_list_lock.
> 
> Let's add a new primitive for this.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks

Eric
> ---
>  virt/kvm/arm/vgic/vgic.c | 26 +++++++++++++++++---------
>  virt/kvm/arm/vgic/vgic.h |  1 +
>  2 files changed, 18 insertions(+), 9 deletions(-)
> 
> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
> index 191deccf60bf..376a297e2169 100644
> --- a/virt/kvm/arm/vgic/vgic.c
> +++ b/virt/kvm/arm/vgic/vgic.c
> @@ -130,6 +130,22 @@ static void vgic_irq_release(struct kref *ref)
>  {
>  }
>  
> +/*
> + * Drop the refcount on the LPI. Must be called with lpi_list_lock held.
> + */
> +void __vgic_put_lpi_locked(struct kvm *kvm, struct vgic_irq *irq)
> +{
> +	struct vgic_dist *dist = &kvm->arch.vgic;
> +
> +	if (!kref_put(&irq->refcount, vgic_irq_release))
> +		return;
> +
> +	list_del(&irq->lpi_list);
> +	dist->lpi_list_count--;
> +
> +	kfree(irq);
> +}
> +
>  void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
>  {
>  	struct vgic_dist *dist = &kvm->arch.vgic;
> @@ -139,16 +155,8 @@ void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
>  		return;
>  
>  	raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
> -	if (!kref_put(&irq->refcount, vgic_irq_release)) {
> -		raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
> -		return;
> -	};
> -
> -	list_del(&irq->lpi_list);
> -	dist->lpi_list_count--;
> +	__vgic_put_lpi_locked(kvm, irq);
>  	raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
> -
> -	kfree(irq);
>  }
>  
>  void vgic_flush_pending_lpis(struct kvm_vcpu *vcpu)
> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
> index a58e1b263dca..80cd40575bc9 100644
> --- a/virt/kvm/arm/vgic/vgic.h
> +++ b/virt/kvm/arm/vgic/vgic.h
> @@ -172,6 +172,7 @@ vgic_get_mmio_region(struct kvm_vcpu *vcpu, struct vgic_io_device *iodev,
>  		     gpa_t addr, int len);
>  struct vgic_irq *vgic_get_irq(struct kvm *kvm, struct kvm_vcpu *vcpu,
>  			      u32 intid);
> +void __vgic_put_lpi_locked(struct kvm *kvm, struct vgic_irq *irq);
>  void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq);
>  bool vgic_get_phys_line_level(struct vgic_irq *irq);
>  void vgic_irq_set_phys_pending(struct vgic_irq *irq, bool pending);
> 
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