Hi Marc,
On 7/23/19 5:45 PM, Marc Zyngier wrote:
> Hi Eric,
>
> On 23/07/2019 16:10, Auger Eric wrote:
>> Hi Marc,
>>
>> On 6/11/19 7:03 PM, Marc Zyngier wrote:
>>> When performing an MSI injection, let's first check if the translation
>>> is already in the cache. If so, let's inject it quickly without
>>> going through the whole translation process.
>>>
>>> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
>>> ---
>>> virt/kvm/arm/vgic/vgic-its.c | 36 ++++++++++++++++++++++++++++++++++++
>>> virt/kvm/arm/vgic/vgic.h | 1 +
>>> 2 files changed, 37 insertions(+)
>>>
>>> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
>>> index 62932458476a..83d80ec33473 100644
>>> --- a/virt/kvm/arm/vgic/vgic-its.c
>>> +++ b/virt/kvm/arm/vgic/vgic-its.c
>>> @@ -577,6 +577,20 @@ static struct vgic_irq *__vgic_its_check_cache(struct vgic_dist *dist,
>>> return irq;
>>> }
>>>
>>> +static struct vgic_irq *vgic_its_check_cache(struct kvm *kvm, phys_addr_t db,
>>> + u32 devid, u32 eventid)
>>> +{
>>> + struct vgic_dist *dist = &kvm->arch.vgic;
>>> + struct vgic_irq *irq;
>>> + unsigned long flags;
>>> +
>>> + raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
>>> + irq = __vgic_its_check_cache(dist, db, devid, eventid);
>>> + raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
>>> +
>>> + return irq;
>>> +}
>>> +
>>> static void vgic_its_cache_translation(struct kvm *kvm, struct vgic_its *its,
>>> u32 devid, u32 eventid,
>>> struct vgic_irq *irq)
>>> @@ -736,6 +750,25 @@ static int vgic_its_trigger_msi(struct kvm *kvm, struct vgic_its *its,
>>> return 0;
>>> }
>>>
>>> +int vgic_its_inject_cached_translation(struct kvm *kvm, struct kvm_msi *msi)
>>> +{
>>> + struct vgic_irq *irq;
>>> + unsigned long flags;
>>> + phys_addr_t db;
>>> +
>>> + db = (u64)msi->address_hi << 32 | msi->address_lo;
>>> + irq = vgic_its_check_cache(kvm, db, msi->devid, msi->data);
>>
>> I think we miss a check of its->enabled. This is currently done in
>> vgic_its_resolve_lpi() but now likely to be bypassed.
>
> But why would a translation be cached if the ITS is disabled? It should
> never haver been there the first place (vgic_its_resolve_lpi does check
> for the ITS being enabled, as you pointed out).
>
> Which makes me think that we miss an invalidate on an ITS being disabled:
>
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index 2633b0e88981..5f2ad74ad834 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -1719,6 +1719,8 @@ static void vgic_mmio_write_its_ctlr(struct kvm *kvm, struct vgic_its *its,
> goto out;
>
> its->enabled = !!(val & GITS_CTLR_ENABLE);
> + if (!its->enabled)
> + vgic_its_invalidate_cache(kvm);
>
> /*
> * Try to process any pending commands. This function bails out early
>
>
> What do you think?
Yes I agree this is the right way to fix it.
Thanks
Eric
>
> M.
>
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