On 4/5/2025 1:08 AM, Sean Christopherson wrote:
> Track the IRTEs that are posting to an SVM vCPU via the associated irqfd
> structure and GSI routing instead of dynamically allocating a separate
> data structure. In addition to eliminating an atomic allocation, this
> will allow hoisting much of the IRTE update logic to common x86.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/kvm/svm/avic.c | 49 ++++++++++++++++-----------------------
> include/linux/kvm_irqfd.h | 3 +++
> 2 files changed, 23 insertions(+), 29 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> index 04dfd898ea8d..967618ba743a 100644
> --- a/arch/x86/kvm/svm/avic.c
> +++ b/arch/x86/kvm/svm/avic.c
> @@ -774,27 +774,30 @@ static int avic_set_pi_irte_mode(struct kvm_vcpu *vcpu, bool activate)
> return ret;
> }
>
> -static void svm_ir_list_del(struct vcpu_svm *svm, struct amd_iommu_pi_data *pi)
> +static void svm_ir_list_del(struct vcpu_svm *svm,
> + struct kvm_kernel_irqfd *irqfd,
> + struct amd_iommu_pi_data *pi)
> {
> unsigned long flags;
> - struct amd_svm_iommu_ir *cur;
> + struct kvm_kernel_irqfd *cur;
>
> spin_lock_irqsave(&svm->ir_list_lock, flags);
> - list_for_each_entry(cur, &svm->ir_list, node) {
> - if (cur->data != pi->ir_data)
> + list_for_each_entry(cur, &svm->ir_list, vcpu_list) {
> + if (cur->irq_bypass_data != pi->ir_data)
> continue;
> - list_del(&cur->node);
> - kfree(cur);
> + if (WARN_ON_ONCE(cur != irqfd))
> + continue;
> + list_del(&irqfd->vcpu_list);
> break;
> }
> spin_unlock_irqrestore(&svm->ir_list_lock, flags);
> }
>
> -static int svm_ir_list_add(struct vcpu_svm *svm, struct amd_iommu_pi_data *pi)
> +static int svm_ir_list_add(struct vcpu_svm *svm,
> + struct kvm_kernel_irqfd *irqfd,
> + struct amd_iommu_pi_data *pi)
> {
> - int ret = 0;
> unsigned long flags;
> - struct amd_svm_iommu_ir *ir;
> u64 entry;
>
> if (WARN_ON_ONCE(!pi->ir_data))
> @@ -811,25 +814,14 @@ static int svm_ir_list_add(struct vcpu_svm *svm, struct amd_iommu_pi_data *pi)
> struct kvm_vcpu *prev_vcpu = kvm_get_vcpu_by_id(kvm, vcpu_id);
> struct vcpu_svm *prev_svm;
>
> - if (!prev_vcpu) {
> - ret = -EINVAL;
> - goto out;
> - }
> + if (!prev_vcpu)
> + return -EINVAL;
>
> prev_svm = to_svm(prev_vcpu);
> - svm_ir_list_del(prev_svm, pi);
> + svm_ir_list_del(prev_svm, irqfd, pi);
> }
>
> - /**
> - * Allocating new amd_iommu_pi_data, which will get
> - * add to the per-vcpu ir_list.
> - */
> - ir = kzalloc(sizeof(struct amd_svm_iommu_ir), GFP_ATOMIC | __GFP_ACCOUNT);
> - if (!ir) {
> - ret = -ENOMEM;
> - goto out;
> - }
> - ir->data = pi->ir_data;
> + irqfd->irq_bypass_data = pi->ir_data;
>
> spin_lock_irqsave(&svm->ir_list_lock, flags);
>
> @@ -844,10 +836,9 @@ static int svm_ir_list_add(struct vcpu_svm *svm, struct amd_iommu_pi_data *pi)
> amd_iommu_update_ga(entry & AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK,
> true, pi->ir_data);
>
> - list_add(&ir->node, &svm->ir_list);
> + list_add(&irqfd->vcpu_list, &svm->ir_list);
> spin_unlock_irqrestore(&svm->ir_list_lock, flags);
> -out:
> - return ret;
> + return 0;
> }
>
> /*
> @@ -951,7 +942,7 @@ int avic_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm,
> * scheduling information in IOMMU irte.
> */
> if (!ret && pi.is_guest_mode)
> - svm_ir_list_add(svm, &pi);
> + svm_ir_list_add(svm, irqfd, &pi);
> }
>
> if (!ret && svm) {
> @@ -991,7 +982,7 @@ int avic_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm,
>
> vcpu = kvm_get_vcpu_by_id(kvm, id);
> if (vcpu)
> - svm_ir_list_del(to_svm(vcpu), &pi);
> + svm_ir_list_del(to_svm(vcpu), irqfd, &pi);
> }
> } else {
> ret = 0;
> diff --git a/include/linux/kvm_irqfd.h b/include/linux/kvm_irqfd.h
> index 8ad43692e3bb..6510a48e62aa 100644
> --- a/include/linux/kvm_irqfd.h
> +++ b/include/linux/kvm_irqfd.h
> @@ -59,6 +59,9 @@ struct kvm_kernel_irqfd {
> struct work_struct shutdown;
> struct irq_bypass_consumer consumer;
> struct irq_bypass_producer *producer;
> +
> + struct list_head vcpu_list;
> + void *irq_bypass_data;
> };
>
> #endif /* __LINUX_KVM_IRQFD_H */
Hi Sean,
You missed to update the functions avic_set_pi_irte_mode and
avic_update_iommu_vcpu_affinity, which iterate over the ir_list.
Regards
Sairaj Kodilkar