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arm/arm64: KVM: vgic: Factor out level irq processing on guest exit 

Currently vgic_process_maintenance() processes dealing with a completed
level-triggered interrupt directly, but we are soon going to reuse this
logic for level-triggered mapped interrupts with the HW bit set, so
move this logic into a separate static function.

Probably the most scary part of this commit is convincing yourself that
the current flow is safe compared to the old one.  In the following I
try to list the changes and why they are harmless:

  Move vgic_irq_clear_queued after kvm_notify_acked_irq:
    Harmless because the only potential effect of clearing the queued
    flag wrt.  kvm_set_irq is that vgic_update_irq_pending does not set
    the pending bit on the emulated CPU interface or in the
    pending_on_cpu bitmask if the function is called with level=1.
    However, the point of kvm_notify_acked_irq is to call kvm_set_irq
    with level=0, and we set the queued flag again in
    __kvm_vgic_sync_hwstate later on if the level is stil high.

  Move vgic_set_lr before kvm_notify_acked_irq:
    Also, harmless because the LR are cpu-local operations and
    kvm_notify_acked only affects the dist

  Move vgic_dist_irq_clear_soft_pend after kvm_notify_acked_irq:
    Also harmless, because now we check the level state in the
    clear_soft_pend function and lower the pending bits if the level is
    low.

Reviewed-by: Eric Auger <eric.auger@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
This commit is contained in:
Christoffer Dall 2015-08-25 22:50:57 +02:00
parent d35268da66
commit 9103617df2
1 changed files with 56 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

94
virt/kvm/arm/vgic.c
View File

@ -107,6 +107,7 @@ static struct vgic_lr vgic_get_lr(const struct kvm_vcpu *vcpu, int lr);
static void vgic_set_lr(struct kvm_vcpu *vcpu, int lr, struct vgic_lr lr_desc);
static struct irq_phys_map *vgic_irq_map_search(struct kvm_vcpu *vcpu,
int virt_irq);
static int compute_pending_for_cpu(struct kvm_vcpu *vcpu);
static const struct vgic_ops *vgic_ops;
static const struct vgic_params *vgic;
@ -357,6 +358,11 @@ static void vgic_dist_irq_clear_soft_pend(struct kvm_vcpu *vcpu, int irq)
struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
vgic_bitmap_set_irq_val(&dist->irq_soft_pend, vcpu->vcpu_id, irq, 0);
if (!vgic_dist_irq_get_level(vcpu, irq)) {
vgic_dist_irq_clear_pending(vcpu, irq);
if (!compute_pending_for_cpu(vcpu))
clear_bit(vcpu->vcpu_id, dist->irq_pending_on_cpu);
}
}
static int vgic_dist_irq_is_pending(struct kvm_vcpu *vcpu, int irq)
@ -1338,12 +1344,56 @@ static void __kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
}
}
static int process_level_irq(struct kvm_vcpu *vcpu, int lr, struct vgic_lr vlr)
{
int level_pending = 0;
vlr.state = 0;
vlr.hwirq = 0;
vgic_set_lr(vcpu, lr, vlr);
/*
* If the IRQ was EOIed (called from vgic_process_maintenance) or it
* went from active to non-active (called from vgic_sync_hwirq) it was
* also ACKed and we we therefore assume we can clear the soft pending
* state (should it had been set) for this interrupt.
*
* Note: if the IRQ soft pending state was set after the IRQ was
* acked, it actually shouldn't be cleared, but we have no way of
* knowing that unless we start trapping ACKs when the soft-pending
* state is set.
*/
vgic_dist_irq_clear_soft_pend(vcpu, vlr.irq);
/*
* Tell the gic to start sampling the line of this interrupt again.
*/
vgic_irq_clear_queued(vcpu, vlr.irq);
/* Any additional pending interrupt? */
if (vgic_dist_irq_get_level(vcpu, vlr.irq)) {
vgic_cpu_irq_set(vcpu, vlr.irq);
level_pending = 1;
} else {
vgic_dist_irq_clear_pending(vcpu, vlr.irq);
vgic_cpu_irq_clear(vcpu, vlr.irq);
}
/*
* Despite being EOIed, the LR may not have
* been marked as empty.
*/
vgic_sync_lr_elrsr(vcpu, lr, vlr);
return level_pending;
}
static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
{
u32 status = vgic_get_interrupt_status(vcpu);
struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
bool level_pending = false;
struct kvm *kvm = vcpu->kvm;
int level_pending = 0;
kvm_debug("STATUS = %08x\n", status);
@ -1358,54 +1408,22 @@ static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
for_each_set_bit(lr, eisr_ptr, vgic->nr_lr) {
struct vgic_lr vlr = vgic_get_lr(vcpu, lr);
WARN_ON(vgic_irq_is_edge(vcpu, vlr.irq));
spin_lock(&dist->lock);
vgic_irq_clear_queued(vcpu, vlr.irq);
WARN_ON(vlr.state & LR_STATE_MASK);
vlr.state = 0;
vgic_set_lr(vcpu, lr, vlr);
/*
* If the IRQ was EOIed it was also ACKed and we we
* therefore assume we can clear the soft pending
* state (should it had been set) for this interrupt.
*
* Note: if the IRQ soft pending state was set after
* the IRQ was acked, it actually shouldn't be
* cleared, but we have no way of knowing that unless
* we start trapping ACKs when the soft-pending state
* is set.
*/
vgic_dist_irq_clear_soft_pend(vcpu, vlr.irq);
/*
* kvm_notify_acked_irq calls kvm_set_irq()
* to reset the IRQ level. Need to release the
* lock for kvm_set_irq to grab it.
* to reset the IRQ level, which grabs the dist->lock
* so we call this before taking the dist->lock.
*/
spin_unlock(&dist->lock);
kvm_notify_acked_irq(kvm, 0,
vlr.irq - VGIC_NR_PRIVATE_IRQS);
spin_lock(&dist->lock);
/* Any additional pending interrupt? */
if (vgic_dist_irq_get_level(vcpu, vlr.irq)) {
vgic_cpu_irq_set(vcpu, vlr.irq);
level_pending = true;
} else {
vgic_dist_irq_clear_pending(vcpu, vlr.irq);
vgic_cpu_irq_clear(vcpu, vlr.irq);
}
level_pending |= process_level_irq(vcpu, lr, vlr);
spin_unlock(&dist->lock);
/*
* Despite being EOIed, the LR may not have
* been marked as empty.
*/
vgic_sync_lr_elrsr(vcpu, lr, vlr);
}
}