linux-kernel - Re: [PATCH v1] KVM: X86: Introduce vfio_intr

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Date:   Mon, 7 Feb 2022 18:59:47 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Yuan ZhaoXiong <yuanzhaoxiong@...du.com>
Cc:     pbonzini@...hat.com, vkuznets@...hat.com, wanpengli@...cent.com,
        jmattson@...gle.com, joro@...tes.org, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        hpa@...or.com, lirongqing@...du.com, kvm@...r.kernel.org,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] KVM: X86: Introduce vfio_intr_stat per-vm debugfs file

On Wed, Jan 19, 2022, Yuan ZhaoXiong wrote:
> +#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS

This is pointless, KVM x86 unconditionally selects HAVE_KVM_IRQ_BYPASS.

> +#include <linux/kvm_irqfd.h>
> +#include <asm/irq_remapping.h>
> +#endif
> +
>  static int vcpu_get_timer_advance_ns(void *data, u64 *val)
>  {
>  	struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data;
> @@ -181,9 +186,94 @@ static int kvm_mmu_rmaps_stat_release(struct inode *inode, struct file *file)
>  	.release	= kvm_mmu_rmaps_stat_release,
>  };
>  
> +#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
> +static int kvm_vfio_intr_stat_show(struct seq_file *m, void *v)
> +{
> +	struct kvm_kernel_irq_routing_entry *e;
> +	struct kvm_irq_routing_table *irq_rt;
> +	unsigned int host_irq, guest_irq;
> +	struct kvm_kernel_irqfd *irqfd;
> +	struct kvm *kvm = m->private;
> +	struct kvm_lapic_irq irq;
> +	struct kvm_vcpu *vcpu;
> +	int idx;
> +
> +	if (!kvm_arch_has_assigned_device(kvm) ||
> +			!irq_remapping_cap(IRQ_POSTING_CAP)) {

Bad indentation and unnecessary curly braces.

	if (!kvm_arch_has_assigned_device(kvm) ||
	    !irq_remapping_cap(IRQ_POSTING_CAP))
		return 0;


> +		return 0;
> +	}
> +
> +	seq_printf(m, "%12s %12s %12s %12s\n",
> +			"guest_irq", "host_irq", "vector", "vcpu");

Bad indentation.  Ditto for many cases below.


	seq_printf(m, "%12s %12s %12s %12s\n",
		   "guest_irq", "host_irq", "vector", "vcpu");
	   
> +
> +	spin_lock_irq(&kvm->irqfds.lock);
> +	idx = srcu_read_lock(&kvm->irq_srcu);
> +	irq_rt = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu);
> +
> +	list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
> +		if (!irqfd->producer)
> +			continue;
> +
> +		host_irq = irqfd->producer->irq;
> +		guest_irq = irqfd->gsi;
> +
> +		if (guest_irq >= irq_rt->nr_rt_entries ||
> +				hlist_empty(&irq_rt->map[guest_irq])) {

Indentation.

> +			pr_warn_once("no route for guest_irq %u/%u (broken user space?)\n",
> +					guest_irq, irq_rt->nr_rt_entries);

Indentation, though I personally don't see much point of duplicating the message
from vmx_pi_update_irte(), just continue on.

> +			continue;
> +		}
> +
> +		hlist_for_each_entry(e, &irq_rt->map[guest_irq], link) {
> +			if (e->type != KVM_IRQ_ROUTING_MSI)
> +				continue;
> +
> +			kvm_set_msi_irq(kvm, e, &irq);
> +			if (kvm_intr_is_single_vcpu(kvm, &irq, &vcpu)) {

Unnecessary curly braces (though this one is debatable).

> +				seq_printf(m, "%12u %12u %12u %12u\n",
> +						guest_irq, host_irq, irq.vector, vcpu->vcpu_id);

Indentation.

> +			}
> +		}
> +	}
> +	srcu_read_unlock(&kvm->irq_srcu, idx);
> +	spin_unlock_irq(&kvm->irqfds.lock);
> +	return 0;
> +}
> +