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SubjectRe: [PATCH 1/2] KVM: not register a IRQ bypass producer if unsupported or disabled
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On 2020/10/19 下午5:06, Zhenzhong Duan wrote:
> If Post interrupt is disabled due to hardware limit or forcely disabled
> by "intremap=nopost" parameter, return -EINVAL so that the legacy mode IRQ
> isn't registered as IRQ bypass producer.


Is there any side effect if it was still registered?


>
> With this change, below message is printed:
> "vfio-pci 0000:db:00.0: irq bypass producer (token 0000000060c8cda5) registration fails: -22"


I may miss something, but the patch only touches vhost-vDPA instead of VFIO?

Thanks


>
> ..which also hints us if a vfio or vdpa device works in PI mode or legacy
> remapping mode.
>
> Add a print to vdpa code just like what vfio_msi_set_vector_signal() does.
>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@gmail.com>
> ---
> arch/x86/kvm/svm/avic.c | 3 +--
> arch/x86/kvm/vmx/vmx.c | 5 ++---
> drivers/vhost/vdpa.c | 5 +++++
> 3 files changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> index ac830cd..316142a 100644
> --- a/arch/x86/kvm/svm/avic.c
> +++ b/arch/x86/kvm/svm/avic.c
> @@ -814,7 +814,7 @@ int svm_update_pi_irte(struct kvm *kvm, unsigned int host_irq,
>
> if (!kvm_arch_has_assigned_device(kvm) ||
> !irq_remapping_cap(IRQ_POSTING_CAP))
> - return 0;
> + return ret;
>
> pr_debug("SVM: %s: host_irq=%#x, guest_irq=%#x, set=%#x\n",
> __func__, host_irq, guest_irq, set);
> @@ -899,7 +899,6 @@ int svm_update_pi_irte(struct kvm *kvm, unsigned int host_irq,
> }
> }
>
> - ret = 0;
> out:
> srcu_read_unlock(&kvm->irq_srcu, idx);
> return ret;
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index f0a9954..1fed6d6 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -7716,12 +7716,12 @@ static int vmx_update_pi_irte(struct kvm *kvm, unsigned int host_irq,
> struct kvm_lapic_irq irq;
> struct kvm_vcpu *vcpu;
> struct vcpu_data vcpu_info;
> - int idx, ret = 0;
> + int idx, ret = -EINVAL;
>
> if (!kvm_arch_has_assigned_device(kvm) ||
> !irq_remapping_cap(IRQ_POSTING_CAP) ||
> !kvm_vcpu_apicv_active(kvm->vcpus[0]))
> - return 0;
> + return ret;
>
> idx = srcu_read_lock(&kvm->irq_srcu);
> irq_rt = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu);
> @@ -7787,7 +7787,6 @@ static int vmx_update_pi_irte(struct kvm *kvm, unsigned int host_irq,
> }
> }
>
> - ret = 0;
> out:
> srcu_read_unlock(&kvm->irq_srcu, idx);
> return ret;
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 62a9bb0..b20060a 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -107,6 +107,11 @@ static void vhost_vdpa_setup_vq_irq(struct vhost_vdpa *v, u16 qid)
> vq->call_ctx.producer.token = vq->call_ctx.ctx;
> vq->call_ctx.producer.irq = irq;
> ret = irq_bypass_register_producer(&vq->call_ctx.producer);
> + if (unlikely(ret))
> + dev_info(&vdpa->dev,
> + "irq bypass producer (token %p) registration fails: %d\n",
> + vq->call_ctx.producer.token, ret);
> +
> spin_unlock(&vq->call_ctx.ctx_lock);
> }
>

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