linux-kernel - [PATCH 2/3] KVM: arm64: vgic: Allow registration of a non-maskable maintenance interrupt

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Date:   Tue,  3 Jan 2023 09:50:21 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     <kvmarm@...ts.cs.columbia.edu>, <kvmarm@...ts.linux.dev>
Cc:     Hector Martin <marcan@...can.st>, Sven Peter <sven@...npeter.dev>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        James Morse <james.morse@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Oliver Upton <oliver.upton@...ux.dev>, asahi@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] KVM: arm64: vgic: Allow registration of a non-maskable maintenance interrupt

Our Apple M1/M2 friends do have a per-CPU maintenance interrupt,
but no mask to make use of it in the standard Linux framework.

Given that KVM directly drives the *source* of the interrupt and
leaves the GIC interrupt always enabled, there is no harm in tolerating
such a setup. It will become useful once we enable NV on M2 HW.

Signed-off-by: Marc Zyngier <maz@...nel.org>
---
 arch/arm64/kvm/vgic/vgic-init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c
index f6d4f4052555..e61d9ca01768 100644
--- a/arch/arm64/kvm/vgic/vgic-init.c
+++ b/arch/arm64/kvm/vgic/vgic-init.c
@@ -572,7 +572,7 @@ int kvm_vgic_hyp_init(void)
 	if (ret)
 		return ret;
 
-	if (!has_mask)
+	if (!has_mask && !kvm_vgic_global_state.maint_irq)
 		return 0;
 
 	ret = request_percpu_irq(kvm_vgic_global_state.maint_irq,
-- 
2.34.1