Commit 05c5e236 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: SVM: Track per-vCPU IRTEs using kvm_kernel_irqfd structure 

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.

Cc: Sairaj Kodilkar <sarunkod@amd.com>
Link: https://lore.kernel.org/r/20250611224604.313496-6-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent cb210737

arch/x86/kvm/svm/avic.c

+27 −44
Original line number Diff line number Diff line
@@ -76,14 +76,6 @@ static bool next_vm_id_wrapped = 0; 
static DEFINE_SPINLOCK(svm_vm_data_hash_lock);

bool x2avic_enabled;



/*

 * This is a wrapper of struct amd_iommu_ir_data.

 */

struct amd_svm_iommu_ir {

	struct list_head node;	/* Used by SVM for per-vcpu ir_list */

	void *data;		/* Storing pointer to struct amd_ir_data */

};



static void avic_activate_vmcb(struct vcpu_svm *svm)

{

	struct vmcb *vmcb = svm->vmcb01.ptr;
@@ -747,8 +739,8 @@ static int avic_set_pi_irte_mode(struct kvm_vcpu *vcpu, bool activate) 
{

	int ret = 0;

	unsigned long flags;

	struct amd_svm_iommu_ir *ir;

	struct vcpu_svm *svm = to_svm(vcpu);

	struct kvm_kernel_irqfd *irqfd;



	if (!kvm_arch_has_assigned_device(vcpu->kvm))

		return 0;
@@ -762,11 +754,11 @@ static int avic_set_pi_irte_mode(struct kvm_vcpu *vcpu, bool activate) 
	if (list_empty(&svm->ir_list))

		goto out;



	list_for_each_entry(ir, &svm->ir_list, node) {

	list_for_each_entry(irqfd, &svm->ir_list, vcpu_list) {

		if (activate)

			ret = amd_iommu_activate_guest_mode(ir->data);

			ret = amd_iommu_activate_guest_mode(irqfd->irq_bypass_data);

		else

			ret = amd_iommu_deactivate_guest_mode(ir->data);

			ret = amd_iommu_deactivate_guest_mode(irqfd->irq_bypass_data);

		if (ret)

			break;

	}
@@ -775,27 +767,30 @@ 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;

		if (WARN_ON_ONCE(cur != irqfd))

			continue;

		list_del(&cur->node);

		kfree(cur);

		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))
@@ -812,25 +807,14 @@ 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);
@@ -845,10 +829,9 @@ 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;

}



/*
@@ -952,7 +935,7 @@ 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) {
@@ -993,7 +976,7 @@ 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);

		}

	}

out:
@@ -1005,8 +988,8 @@ static inline int 
avic_update_iommu_vcpu_affinity(struct kvm_vcpu *vcpu, int cpu, bool r)

{

	int ret = 0;

	struct amd_svm_iommu_ir *ir;

	struct vcpu_svm *svm = to_svm(vcpu);

	struct kvm_kernel_irqfd *irqfd;



	lockdep_assert_held(&svm->ir_list_lock);
@@ -1020,8 +1003,8 @@ avic_update_iommu_vcpu_affinity(struct kvm_vcpu *vcpu, int cpu, bool r) 
	if (list_empty(&svm->ir_list))

		return 0;



	list_for_each_entry(ir, &svm->ir_list, node) {

		ret = amd_iommu_update_ga(cpu, r, ir->data);

	list_for_each_entry(irqfd, &svm->ir_list, vcpu_list) {

		ret = amd_iommu_update_ga(cpu, r, irqfd->irq_bypass_data);

		if (ret)

			return ret;

	}

arch/x86/kvm/svm/svm.h

+6 −4
Original line number Diff line number Diff line
@@ -310,10 +310,12 @@ struct vcpu_svm { 
	u64 *avic_physical_id_cache;



	/*

	 * Per-vcpu list of struct amd_svm_iommu_ir:

	 * This is used mainly to store interrupt remapping information used

	 * when update the vcpu affinity. This avoids the need to scan for

	 * IRTE and try to match ga_tag in the IOMMU driver.

	 * Per-vCPU list of irqfds that are eligible to post IRQs directly to

	 * the vCPU (a.k.a. device posted IRQs, a.k.a. IRQ bypass).  The list

	 * is used to reconfigure IRTEs when the vCPU is loaded/put (to set the

	 * target pCPU), when AVIC is toggled on/off (to (de)activate bypass),

	 * and if the irqfd becomes ineligible for posting (to put the IRTE

	 * back into remapped mode).

	 */

	struct list_head ir_list;

	spinlock_t ir_list_lock;

include/linux/kvm_irqfd.h

+3 −0
Original line number Diff line number Diff line
@@ -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 */