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

[Auger Eric <eric.auger@redhat.com>]

Hi Andre,

On 21/03/2017 19:13, Andre Przywara wrote:
> 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@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.
sure
> 
>> +
>> +	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.
fixed now as dev->nb_eventid_bits actually matches the number of bits.
Sorry for the confusion. I must have been in orbit when I wrote that 2
<< stuff.

Thanks

Eric
> 
> 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
>>