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: [RFC PATCH v2 3/4] KVM: arm64: GICv4.1: Restore VLPI's pending state to physical side
Date: Tue, 05 Jan 2021 09:25:11 +0000 [thread overview]
Message-ID: <76a7b9cca485dc8157d3be53189eac69@kernel.org> (raw)
In-Reply-To: <20210104081613.100-4-lushenming@huawei.com>
On 2021-01-04 08:16, Shenming Lu wrote:
> From: Zenghui Yu <yuzenghui@huawei.com>
>
> When setting the forwarding path of a VLPI (switch to the HW mode),
> we could 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 | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/arch/arm64/kvm/vgic/vgic-v4.c
> b/arch/arm64/kvm/vgic/vgic-v4.c
> index f211a7c32704..7945d6d09cdd 100644
> --- a/arch/arm64/kvm/vgic/vgic-v4.c
> +++ b/arch/arm64/kvm/vgic/vgic-v4.c
> @@ -454,6 +454,18 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm,
> int virq,
> irq->host_irq = virq;
> atomic_inc(&map.vpe->vlpi_count);
>
> + /* Transfer pending state */
> + ret = irq_set_irqchip_state(irq->host_irq,
> + IRQCHIP_STATE_PENDING,
> + irq->pending_latch);
> + WARN_RATELIMIT(ret, "IRQ %d", irq->host_irq);
Why do this if pending_latch is 0, which is likely to be
the overwhelming case?
> +
> + /*
> + * Let it be pruned from ap_list later and don't bother
> + * the List Register.
> + */
> + irq->pending_latch = false;
What guarantees the pruning? Pruning only happens on vcpu exit,
which means we may have the same interrupt via both the LR and
the stream interface, which I don't believe is legal (it is
like having two LRs holding the same interrupt).
> +
> out:
> mutex_unlock(&its->its_lock);
> return ret;
Thanks,
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2021-01-05 9:26 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-04 8:16 [RFC PATCH v2 0/4] KVM: arm64: Add VLPI migration support on GICv4.1 Shenming Lu
2021-01-04 8:16 ` [RFC PATCH v2 1/4] KVM: arm64: GICv4.1: Add function to get VLPI state Shenming Lu
2021-01-04 8:16 ` [RFC PATCH v2 2/4] KVM: arm64: GICv4.1: Try to save hw pending state in save_pending_tables Shenming Lu
2021-01-05 9:13 ` Marc Zyngier
2021-01-05 11:40 ` Marc Zyngier
2021-01-06 5:48 ` Shenming Lu
2021-01-05 13:02 ` Shenming Lu
2021-01-05 13:47 ` Marc Zyngier
2021-01-06 7:14 ` Shenming Lu
2021-01-04 8:16 ` [RFC PATCH v2 3/4] KVM: arm64: GICv4.1: Restore VLPI's pending state to physical side Shenming Lu
2021-01-05 9:25 ` Marc Zyngier [this message]
2021-01-06 2:12 ` Shenming Lu
2021-01-04 8:16 ` [RFC PATCH v2 4/4] KVM: arm64: GICv4.1: Give a chance to save VLPI's pending state Shenming Lu
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