From: Marc Zyngier <maz@kernel.org>
To: Shenming Lu <lushenming@huawei.com>
Cc: Eric Auger <eric.auger@redhat.com>, Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org,
Alex Williamson <alex.williamson@redhat.com>,
Cornelia Huck <cohuck@redhat.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
wanghaibin.wang@huawei.com, yuzenghui@huawei.com
Subject: Re: [PATCH v4 5/6] KVM: arm64: GICv4.1: Restore VLPI pending state to physical side
Date: Mon, 15 Mar 2021 09:20:58 +0000 [thread overview]
Message-ID: <b03ec1e5447024f9f990377e2c28e84f@kernel.org> (raw)
In-Reply-To: <81fbadda-0489-ffc3-cb38-08e89871ec95@huawei.com>
On 2021-03-15 09:11, Shenming Lu wrote:
> On 2021/3/15 16:30, Marc Zyngier wrote:
>> On 2021-03-13 08:38, Shenming Lu wrote:
>>> From: Zenghui Yu <yuzenghui@huawei.com>
>>>
>>> When setting the forwarding path of a VLPI (switch to the HW mode),
>>> we can also transfer the pending state from irq->pending_latch to
>>> VPT (especially in migration, the pending states of VLPIs are
>>> restored
>>> into kvm’s vgic first). And we currently send "INT+VSYNC" to trigger
>>> a VLPI to pending.
>>>
>>> Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
>>> Signed-off-by: Shenming Lu <lushenming@huawei.com>
>>> ---
>>> arch/arm64/kvm/vgic/vgic-v4.c | 18 ++++++++++++++++++
>>> 1 file changed, 18 insertions(+)
>>>
>>> diff --git a/arch/arm64/kvm/vgic/vgic-v4.c
>>> b/arch/arm64/kvm/vgic/vgic-v4.c
>>> index ac029ba3d337..3b82ab80c2f3 100644
>>> --- a/arch/arm64/kvm/vgic/vgic-v4.c
>>> +++ b/arch/arm64/kvm/vgic/vgic-v4.c
>>> @@ -449,6 +449,24 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm,
>>> int virq,
>>> irq->host_irq = virq;
>>> atomic_inc(&map.vpe->vlpi_count);
>>>
>>> + /* Transfer pending state */
>>> + if (irq->pending_latch) {
>>> + unsigned long flags;
>>> +
>>> + ret = irq_set_irqchip_state(irq->host_irq,
>>> + IRQCHIP_STATE_PENDING,
>>> + irq->pending_latch);
>>> + WARN_RATELIMIT(ret, "IRQ %d", irq->host_irq);
>>> +
>>> + /*
>>> + * Clear pending_latch and communicate this state
>>> + * change via vgic_queue_irq_unlock.
>>> + */
>>> + raw_spin_lock_irqsave(&irq->irq_lock, flags);
>>> + irq->pending_latch = false;
>>> + vgic_queue_irq_unlock(kvm, irq, flags);
>>> + }
>>> +
>>> out:
>>> mutex_unlock(&its->its_lock);
>>> return ret;
>>
>> The read side of the pending state isn't locked, but the write side
>> is.
>> I'd rather you lock the whole sequence for peace of mind.
>
> Did you mean to lock before emitting the mapping request, Or just
> before reading
> the pending state?
Just before reading the pending state, so that we can't get a concurrent
modification of that state while we make the interrupt pending in the
VPT
and clearing it in the emulation.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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next prev parent reply other threads:[~2021-03-15 9:22 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-13 8:38 [PATCH v4 0/6] KVM: arm64: Add VLPI migration support on GICv4.1 Shenming Lu
2021-03-13 8:38 ` [PATCH v4 1/6] irqchip/gic-v3-its: Add a cache invalidation right after vPE unmapping Shenming Lu
2021-03-13 8:38 ` [PATCH v4 2/6] irqchip/gic-v3-its: Drop the setting of PTZ altogether Shenming Lu
2021-03-13 8:38 ` [PATCH v4 3/6] KVM: arm64: GICv4.1: Add function to get VLPI state Shenming Lu
2021-03-13 8:38 ` [PATCH v4 4/6] KVM: arm64: GICv4.1: Try to save VLPI state in save_pending_tables Shenming Lu
2021-03-13 8:38 ` [PATCH v4 5/6] KVM: arm64: GICv4.1: Restore VLPI pending state to physical side Shenming Lu
2021-03-15 8:30 ` Marc Zyngier
2021-03-15 9:11 ` Shenming Lu
2021-03-15 9:20 ` Marc Zyngier [this message]
2021-03-15 9:25 ` Shenming Lu
2021-03-15 9:30 ` Marc Zyngier
2021-03-13 8:39 ` [PATCH v4 6/6] KVM: arm64: GICv4.1: Give a chance to save VLPI state Shenming Lu
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