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

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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: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2025-06-11 15:45:07 -07:00
parent cb21073767
commit 05c5e23657
3 changed files with 36 additions and 48 deletions
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71
arch/x86/kvm/svm/avic.c
View File

@ -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;
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))
@ -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;
}

10
arch/x86/kvm/svm/svm.h
View File

@ -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;

3
include/linux/kvm_irqfd.h
View File

@ -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 */