[PATCH v3 17/19] KVM: arm64: ITS: ITT flush and restore

[Andre Przywara]

Hi,

On 06/03/17 11:34, Eric Auger wrote:
> Introduce routines to flush and restore device ITT and their
> interrupt table entries (ITE).
> 
> The routines will be called on device table flush and
> restore.
> 
> Signed-off-by: Eric Auger <eric.auger at redhat.com>
> 
> ---
> v2 -> v3:
> - add return 0 in vgic_its_restore_ite (was in subsequent patch)
> 
> v2: creation
> ---
>  virt/kvm/arm/vgic/vgic-its.c | 100 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 100 insertions(+)
> 
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index 1060125..a216849 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -1748,6 +1748,106 @@ static int vgic_its_restore_pending_tables(struct vgic_its *its)
>  	return -ENXIO;
>  }
>  
> +static int vgic_its_flush_ite(struct vgic_its *its, struct its_device *dev,
> +			      struct its_ite *ite, gpa_t gpa)
> +{
> +	struct kvm *kvm = its->dev->kvm;
> +	u32 next_offset;
> +	u64 val;
> +
> +	next_offset = compute_next_eventid_offset(&dev->itt_head, ite);
> +	val = ((u64)next_offset << 48) | ((u64)ite->lpi << 16) |
> +		ite->collection->collection_id;
> +	val = cpu_to_le64(val);
> +	return kvm_write_guest(kvm, gpa, &val, VITS_ESZ);
> +}
> +
> +/**
> + * vgic_its_restore_ite - restore an interrupt translation entry
> + * @event_id: id used for indexing
> + * @ptr: kernel VA where the 8 byte ITE is located
> + * @opaque: pointer to the its_device
> + * @next: id offset to the next entry
> + */
> +static int vgic_its_restore_ite(struct vgic_its *its, u32 event_id,
> +				void *ptr, void *opaque, u32 *next)
> +{
> +	struct its_device *dev = (struct its_device *)opaque;
> +	struct its_collection *collection;
> +	struct kvm *kvm = its->dev->kvm;
> +	u64 val, *p = (u64 *)ptr;
> +	struct vgic_irq *irq;
> +	u32 coll_id, lpi_id;
> +	struct its_ite *ite;
> +	int ret;
> +
> +	val = *p;
> +	*next = 1;
> +
> +	val = le64_to_cpu(val);
> +
> +	coll_id = val & GENMASK_ULL(15, 0);
> +	lpi_id = (val & GENMASK_ULL(47, 16)) >> 16;
> +
> +	if (!lpi_id)
> +		return 0;
> +
> +	*next = (val & GENMASK_ULL(63, 48)) >> 48;

No need for the mask here, just ">> 48" would be enough.

> +
> +	collection = find_collection(its, coll_id);
> +	if (!collection)
> +		return -EINVAL;
> +
> +	ret = vgic_its_alloc_ite(dev, &ite, collection,
> +				  lpi_id, event_id);
> +	if (ret)
> +		return ret;
> +
> +	irq = vgic_add_lpi(kvm, lpi_id);
> +	if (IS_ERR(irq))
> +		return PTR_ERR(irq);
> +	ite->irq = irq;
> +
> +	/* restore the configuration of the LPI */
> +	ret = update_lpi_config(kvm, irq, NULL);
> +	if (ret)
> +		return ret;
> +
> +	update_affinity_ite(kvm, ite);
> +	return 0;
> +}
> +
> +static int vgic_its_flush_itt(struct vgic_its *its, struct its_device *device)
> +{
> +	gpa_t base = device->itt_addr;
> +	struct its_ite *ite;
> +	int ret;
> +
> +	list_for_each_entry(ite, &device->itt_head, ite_list) {
> +		gpa_t gpa = base + ite->event_id * VITS_ESZ;
> +
> +		ret = vgic_its_flush_ite(its, device, ite, gpa);
> +		if (ret)
> +			return ret;
> +	}
> +	return 0;
> +}
> +
> +static int vgic_its_restore_itt(struct vgic_its *its,
> +				struct its_device *dev)
> +{
> +	size_t max_size = (2 << dev->nb_eventid_bits) * VITS_ESZ;

I think that depends on your usage of nb_eventid_bits, but this "2 <<"
is really confusing here. So I really think you should just hold the
actual number of bits in this variable and handle the +/- 1 encoding
just once when sourcing the information.

The rest looks fine.

Cheers,
Andre.

> +	gpa_t base = dev->itt_addr;
> +	int ret;
> +
> +	ret =  lookup_table(its, base, max_size, VITS_ESZ, 0,
> +			    vgic_its_restore_ite, dev);
> +
> +	if (ret < 0)
> +		return ret;
> +	return 0;
> +}
> +
>  /**
>   * vgic_its_flush_device_tables - flush the device table and all ITT
>   * into guest RAM
>