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Date: Wed, 30 Aug 2017 15:08:01 +0100 From: Marc Zyngier <marc.zyngier@....com> To: Christoffer Dall <cdall@...aro.org> Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu, kvm@...r.kernel.org, Christoffer Dall <christoffer.dall@...aro.org>, Thomas Gleixner <tglx@...utronix.de>, Jason Cooper <jason@...edaemon.net>, Eric Auger <eric.auger@...hat.com>, Shanker Donthineni <shankerd@...eaurora.org>, Mark Rutland <mark.rutland@....com>, Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com> Subject: Re: [PATCH v3 44/59] KVM: arm/arm64: GICv4: Handle MOVI applied to a VLPI On 28/08/17 19:18, Christoffer Dall wrote: > On Mon, Jul 31, 2017 at 06:26:22PM +0100, Marc Zyngier wrote: >> When the guest issues a MOVI, we need to tell the physical ITS >> that we're now targetting a new vcpu. This is done by extracting >> the current mapping, updating the target, and reapplying the >> mapping. The core ITS code should do the right thing. >> >> Signed-off-by: Marc Zyngier <marc.zyngier@....com> >> --- >> virt/kvm/arm/vgic/vgic-its.c | 13 +++++++++++++ >> 1 file changed, 13 insertions(+) >> >> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c >> index 79bac93d3e7d..aaad577ce328 100644 >> --- a/virt/kvm/arm/vgic/vgic-its.c >> +++ b/virt/kvm/arm/vgic/vgic-its.c >> @@ -706,6 +706,19 @@ static int vgic_its_cmd_handle_movi(struct kvm *kvm, struct vgic_its *its, >> ite->irq->target_vcpu = vcpu; >> spin_unlock(&ite->irq->irq_lock); >> >> + if (ite->irq->hw) { >> + struct its_vlpi_map map; >> + int ret; >> + >> + ret = its_get_vlpi(ite->irq->host_irq, &map); >> + if (ret) >> + return ret; >> + >> + map.vpe_idx = vcpu->vcpu_id; >> + >> + return its_map_vlpi(ite->irq->host_irq, &map); > > Since you're not holding the irq_lock across these two calls, would it > be possible that the forwarding was removed through some other call path > here, and could you end up passing an invalid host_irq to its_map_vlpi? I believe we should be OK here, as we hold the ITS mutex during any command processing, and both the forward/unforward paths take that same mutex. On a slightly different note, it looks like the MOVI code could benefit from using vgic_its_resolve_lpi(), which has been introduce earlier in this series. Thanks, M. -- Jazz is not dead. It just smells funny...
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