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SubjectRe: [PATCH v4 15/20] KVM: arm64: GICv4.1: Add direct injection capability to SGI registers
On 2020-02-18 08:46, Zenghui Yu wrote:
> Hi Marc,
>
> On 2020/2/14 22:57, Marc Zyngier wrote:
>> Most of the GICv3 emulation code that deals with SGIs now has to be
>> aware of the v4.1 capabilities in order to benefit from it.
>>
>> Add such support, keyed on the interrupt having the hw flag set and
>> being a SGI.
>>
>> Signed-off-by: Marc Zyngier <maz@kernel.org>
>> ---
>> virt/kvm/arm/vgic/vgic-mmio-v3.c | 15 +++++-
>> virt/kvm/arm/vgic/vgic-mmio.c | 88
>> ++++++++++++++++++++++++++++++--
>> 2 files changed, 96 insertions(+), 7 deletions(-)
>>
>> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c
>> b/virt/kvm/arm/vgic/vgic-mmio-v3.c
>> index ebc218840fc2..de89da76a379 100644
>> --- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
>> +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
>> @@ -6,6 +6,7 @@
>> #include <linux/irqchip/arm-gic-v3.h>
>> #include <linux/kvm.h>
>> #include <linux/kvm_host.h>
>> +#include <linux/interrupt.h>
>> #include <kvm/iodev.h>
>> #include <kvm/arm_vgic.h>
>> @@ -942,8 +943,18 @@ void vgic_v3_dispatch_sgi(struct kvm_vcpu
>> *vcpu, u64 reg, bool allow_group1)
>> * generate interrupts of either group.
>> */
>> if (!irq->group || allow_group1) {
>> - irq->pending_latch = true;
>> - vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
>> + if (!irq->hw) {
>> + irq->pending_latch = true;
>> + vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
>> + } else {
>> + /* HW SGI? Ask the GIC to inject it */
>> + int err;
>> + err = irq_set_irqchip_state(irq->host_irq,
>> + IRQCHIP_STATE_PENDING,
>> + true);
>> + WARN_RATELIMIT(err, "IRQ %d", irq->host_irq);
>> + raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
>> + }
>> } else {
>> raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
>> }
>> diff --git a/virt/kvm/arm/vgic/vgic-mmio.c
>> b/virt/kvm/arm/vgic/vgic-mmio.c
>> index d656ebd5f9d4..0a1fb61e5b89 100644
>> --- a/virt/kvm/arm/vgic/vgic-mmio.c
>> +++ b/virt/kvm/arm/vgic/vgic-mmio.c
>> @@ -5,6 +5,8 @@
>> #include <linux/bitops.h>
>> #include <linux/bsearch.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/irq.h>
>> #include <linux/kvm.h>
>> #include <linux/kvm_host.h>
>> #include <kvm/iodev.h>
>> @@ -59,6 +61,11 @@ unsigned long vgic_mmio_read_group(struct kvm_vcpu
>> *vcpu,
>> return value;
>> }
>> +static void vgic_update_vsgi(struct vgic_irq *irq)
>> +{
>> + WARN_ON(its_prop_update_vsgi(irq->host_irq, irq->priority,
>> irq->group));
>> +}
>> +
>> void vgic_mmio_write_group(struct kvm_vcpu *vcpu, gpa_t addr,
>> unsigned int len, unsigned long val)
>> {
>> @@ -71,7 +78,12 @@ void vgic_mmio_write_group(struct kvm_vcpu *vcpu,
>> gpa_t addr,
>> raw_spin_lock_irqsave(&irq->irq_lock, flags);
>> irq->group = !!(val & BIT(i));
>> - vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
>> + if (irq->hw && vgic_irq_is_sgi(irq->intid)) {
>> + vgic_update_vsgi(irq);
>> + raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
>> + } else {
>> + vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
>> + }
>> vgic_put_irq(vcpu->kvm, irq);
>> }
>> @@ -113,7 +125,21 @@ void vgic_mmio_write_senable(struct kvm_vcpu
>> *vcpu,
>> struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
>> raw_spin_lock_irqsave(&irq->irq_lock, flags);
>> - if (vgic_irq_is_mapped_level(irq)) {
>> + if (irq->hw && vgic_irq_is_sgi(irq->intid)) {
>> + if (!irq->enabled) {
>> + struct irq_data *data;
>> +
>> + irq->enabled = true;
>> + data = &irq_to_desc(irq->host_irq)->irq_data;
>> + while (irqd_irq_disabled(data))
>> + enable_irq(irq->host_irq);
>> + }
>> +
>> + raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
>> + vgic_put_irq(vcpu->kvm, irq);
>> +
>> + continue;
>> + } else if (vgic_irq_is_mapped_level(irq)) {
>> bool was_high = irq->line_level;
>> /*
>> @@ -148,6 +174,8 @@ void vgic_mmio_write_cenable(struct kvm_vcpu
>> *vcpu,
>> struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
>> raw_spin_lock_irqsave(&irq->irq_lock, flags);
>> + if (irq->hw && vgic_irq_is_sgi(irq->intid) && irq->enabled)
>> + disable_irq_nosync(irq->host_irq);
>> irq->enabled = false;
>> @@ -167,10 +195,22 @@ unsigned long vgic_mmio_read_pending(struct
>> kvm_vcpu *vcpu,
>> for (i = 0; i < len * 8; i++) {
>> struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
>> unsigned long flags;
>> + bool val;
>> raw_spin_lock_irqsave(&irq->irq_lock, flags);
>> - if (irq_is_pending(irq))
>> - value |= (1U << i);
>> + if (irq->hw && vgic_irq_is_sgi(irq->intid)) {
>> + int err;
>> +
>> + val = false;
>> + err = irq_get_irqchip_state(irq->host_irq,
>> + IRQCHIP_STATE_PENDING,
>> + &val);
>> + WARN_RATELIMIT(err, "IRQ %d", irq->host_irq);
>> + } else {
>> + val = irq_is_pending(irq);
>> + }
>> +
>> + value |= ((u32)val << i);
>> raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
>> vgic_put_irq(vcpu->kvm, irq);
>> @@ -227,6 +267,21 @@ void vgic_mmio_write_spending(struct kvm_vcpu
>> *vcpu,
>> }
>> raw_spin_lock_irqsave(&irq->irq_lock, flags);
>> +
>> + if (irq->hw && vgic_irq_is_sgi(irq->intid)) {
>> + /* HW SGI? Ask the GIC to inject it */
>> + int err;
>> + err = irq_set_irqchip_state(irq->host_irq,
>> + IRQCHIP_STATE_PENDING,
>> + true);
>> + WARN_RATELIMIT(err, "IRQ %d", irq->host_irq);
>> +
>> + raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
>> + vgic_put_irq(vcpu->kvm, irq);
>> +
>> + continue;
>> + }
>> +
>> if (irq->hw)
>> vgic_hw_irq_spending(vcpu, irq, is_uaccess);
>> else
>
> Should we consider taking the GICv4.1 support into uaccess_{read/write}
> callbacks for GICR_ISPENDR0 so that userspace can properly save/restore
> the pending state of GICv4.1 vSGIs?
>
> I *think* we can do it because on restoration, GICD_CTLR(.nASSGIreq) is
> restored before GICR_ISPENDR0. So we know whether we're restoring
> pending for vSGIs, and we can restore it to the HW level if v4.1 is
> supported by GIC. Otherwise restore it by the normal way.
>
> And saving is easy with the get_irqchip_state callback, right?

Yes, this should be pretty easy to do, but I haven't completely worked
out
the ordering dependencies (you're way ahead of me here!).

There is still a chance that userspace will play with us trying to set
and
reset nASSGIreq, so we need to define what is acceptable...

>
>> @@ -281,6 +336,20 @@ void vgic_mmio_write_cpending(struct kvm_vcpu
>> *vcpu,
>> raw_spin_lock_irqsave(&irq->irq_lock, flags);
>> + if (irq->hw && vgic_irq_is_sgi(irq->intid)) {
>> + /* HW SGI? Ask the GIC to inject it */
>
> "Ask the GIC to clear its pending state" :-)

One day, I'll ban copy/paste from my editor... ;-)

M.
--
Jazz is not dead. It just smells funny...

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