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KVM: arm64: Compute vgic state irrespective of the number of interrupts

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As we are going to rely on the [G]ICH_HCR{,_EL2} register to be
programmed with MI information at all times, slightly de-optimise
the flush/sync code to always be called. This is rather lightweight
when no interrupts are in flight.

Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Link: https://msgid.link/20251120172540.2267180-20-maz@kernel.org
Signed-off-by: Oliver Upton <oupton@kernel.org>
This commit is contained in:
Marc Zyngier 2025-11-20 17:25:09 +00:00 committed by Oliver Upton
parent 0660bc4a2b
commit dd598fc113
1 changed files with 2 additions and 33 deletions
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35
arch/arm64/kvm/vgic/vgic.c
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@ -985,8 +985,6 @@ static inline void vgic_save_state(struct kvm_vcpu *vcpu)
/* Sync back the hardware VGIC state into our emulation after a guest's run. */
void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
{
int used_lrs;
/* If nesting, emulate the HW effect from L0 to L1 */
if (vgic_state_is_nested(vcpu)) {
vgic_v3_sync_nested(vcpu);
@ -996,20 +994,10 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
if (vcpu_has_nv(vcpu))
vgic_v3_nested_update_mi(vcpu);
/* An empty ap_list_head implies used_lrs == 0 */
if (list_empty(&vcpu->arch.vgic_cpu.ap_list_head))
return;
if (can_access_vgic_from_kernel())
vgic_save_state(vcpu);
if (!static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif))
used_lrs = vcpu->arch.vgic_cpu.vgic_v2.used_lrs;
else
used_lrs = vcpu->arch.vgic_cpu.vgic_v3.used_lrs;
if (used_lrs)
vgic_fold_lr_state(vcpu);
vgic_fold_lr_state(vcpu);
vgic_prune_ap_list(vcpu);
}
@ -1053,29 +1041,10 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
if (vcpu_has_nv(vcpu))
vgic_v3_nested_update_mi(vcpu);
/*
* If there are no virtual interrupts active or pending for this
* VCPU, then there is no work to do and we can bail out without
* taking any lock. There is a potential race with someone injecting
* interrupts to the VCPU, but it is a benign race as the VCPU will
* either observe the new interrupt before or after doing this check,
* and introducing additional synchronization mechanism doesn't change
* this.
*
* Note that we still need to go through the whole thing if anything
* can be directly injected (GICv4).
*/
if (list_empty(&vcpu->arch.vgic_cpu.ap_list_head) &&
!vgic_supports_direct_irqs(vcpu->kvm))
return;
DEBUG_SPINLOCK_BUG_ON(!irqs_disabled());
if (!list_empty(&vcpu->arch.vgic_cpu.ap_list_head)) {
raw_spin_lock(&vcpu->arch.vgic_cpu.ap_list_lock);
scoped_guard(raw_spinlock, &vcpu->arch.vgic_cpu.ap_list_lock)
vgic_flush_lr_state(vcpu);
raw_spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
}
if (can_access_vgic_from_kernel())
vgic_restore_state(vcpu);