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Groups > linux.kernel > #1721870 > unrolled thread
| Started by | Christoffer Dall <cdall@linaro.org> |
|---|---|
| First post | 2017-08-28 20:20 +0200 |
| Last post | 2017-08-30 22:10 +0200 |
| Articles | 3 — 2 participants |
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Re: [PATCH v3 44/59] KVM: arm/arm64: GICv4: Handle MOVI applied to a VLPI Christoffer Dall <cdall@linaro.org> - 2017-08-28 20:20 +0200
Re: [PATCH v3 44/59] KVM: arm/arm64: GICv4: Handle MOVI applied to a VLPI Marc Zyngier <marc.zyngier@arm.com> - 2017-08-30 16:10 +0200
Re: [PATCH v3 44/59] KVM: arm/arm64: GICv4: Handle MOVI applied to a VLPI Christoffer Dall <cdall@linaro.org> - 2017-08-30 22:10 +0200
| From | Christoffer Dall <cdall@linaro.org> |
|---|---|
| Date | 2017-08-28 20:20 +0200 |
| Subject | Re: [PATCH v3 44/59] KVM: arm/arm64: GICv4: Handle MOVI applied to a VLPI |
| Message-ID | <ujwNI-sx-13@gated-at.bofh.it> |
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@arm.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?
Thanks,
-Christoffer
> + }
> +
> return 0;
> }
>
> --
> 2.11.0
>
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| From | Marc Zyngier <marc.zyngier@arm.com> |
|---|---|
| Date | 2017-08-30 16:10 +0200 |
| Message-ID | <ukbQS-R3-19@gated-at.bofh.it> |
| In reply to | #1721870 |
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@arm.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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| From | Christoffer Dall <cdall@linaro.org> |
|---|---|
| Date | 2017-08-30 22:10 +0200 |
| Message-ID | <ukhtg-4rH-9@gated-at.bofh.it> |
| In reply to | #1723363 |
On Wed, Aug 30, 2017 at 03:08:01PM +0100, Marc Zyngier wrote:
> 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@arm.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.
ok, yes, as long as the only other modifirs are the forward/unforward
paths and they hold the mutex, we should be fine.
>
> 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.
Only problem is you'd need to get a handle to the ite as well to change
the collection pointer. I suppose you could add another pointer
pointer.
-Christoffer
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