linux-kernel - [PATCH RFC] KVM: arm64: vgic: Decouple the check of the EnableLPIs bit from the ITS LPI translation

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Date:   Thu, 31 Dec 2020 14:28:13 +0800
From:   Shenming Lu <lushenming@...wei.com>
To:     Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>,
        Eric Auger <eric.auger@...hat.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <kvmarm@...ts.cs.columbia.edu>, <linux-kernel@...r.kernel.org>
CC:     <wanghaibin.wang@...wei.com>, <yuzenghui@...wei.com>
Subject: [PATCH RFC] KVM: arm64: vgic: Decouple the check of the EnableLPIs bit from the ITS LPI translation

When the EnableLPIs bit is set to 0, any ITS LPI requests in the
Redistributor would be ignored. And this check is independent from
the ITS LPI translation. So it might be better to move the check
of the EnableLPIs bit out of the LPI resolving, and also add it
to the path that uses the translation cache. Besides it seems that
by this the invalidating of the translation cache caused by the LPI
disabling is unnecessary.

Not sure if I have missed something... Thanks.

Signed-off-by: Shenming Lu <lushenming@...wei.com>
---
 arch/arm64/kvm/vgic/vgic-its.c     | 9 +++++----
 arch/arm64/kvm/vgic/vgic-mmio-v3.c | 4 +---
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
index 40cbaca81333..f53446bc154e 100644
--- a/arch/arm64/kvm/vgic/vgic-its.c
+++ b/arch/arm64/kvm/vgic/vgic-its.c
@@ -683,9 +683,6 @@ int vgic_its_resolve_lpi(struct kvm *kvm, struct vgic_its *its,
 	if (!vcpu)
 		return E_ITS_INT_UNMAPPED_INTERRUPT;
 
-	if (!vcpu->arch.vgic_cpu.lpis_enabled)
-		return -EBUSY;
-
 	vgic_its_cache_translation(kvm, its, devid, eventid, ite->irq);
 
 	*irq = ite->irq;
@@ -738,6 +735,9 @@ static int vgic_its_trigger_msi(struct kvm *kvm, struct vgic_its *its,
 	if (err)
 		return err;
 
+	if (!irq->target_vcpu->arch.vgic_cpu.lpis_enabled)
+		return -EBUSY;
+
 	if (irq->hw)
 		return irq_set_irqchip_state(irq->host_irq,
 					     IRQCHIP_STATE_PENDING, true);
@@ -757,7 +757,8 @@ int vgic_its_inject_cached_translation(struct kvm *kvm, struct kvm_msi *msi)
 
 	db = (u64)msi->address_hi << 32 | msi->address_lo;
 	irq = vgic_its_check_cache(kvm, db, msi->devid, msi->data);
-	if (!irq)
+
+	if (!irq || !irq->target_vcpu->arch.vgic_cpu.lpis_enabled)
 		return -EWOULDBLOCK;
 
 	raw_spin_lock_irqsave(&irq->irq_lock, flags);
diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
index 15a6c98ee92f..7b0749f7660d 100644
--- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
@@ -242,10 +242,8 @@ static void vgic_mmio_write_v3r_ctlr(struct kvm_vcpu *vcpu,
 
 	vgic_cpu->lpis_enabled = val & GICR_CTLR_ENABLE_LPIS;
 
-	if (was_enabled && !vgic_cpu->lpis_enabled) {
+	if (was_enabled && !vgic_cpu->lpis_enabled)
 		vgic_flush_pending_lpis(vcpu);
-		vgic_its_invalidate_cache(vcpu->kvm);
-	}
 
 	if (!was_enabled && vgic_cpu->lpis_enabled)
 		vgic_enable_lpis(vcpu);
-- 
2.19.1