Re: [PATCH v4 20/22] KVM: arm64: ITS: ITT flush and restore

Auger Eric
2017-04-11T10:16:50Z

Hi Marc,
On 10/04/2017 14:39, Marc Zyngier wrote:
> On 27/03/17 10:31, 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. They will become static in subsequent patches.
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>>
>> ---
>>
>> v3 -> v4:
>> - lookup_table and compute_next_eventid_offset become static in this
>> patch
>> - remove static along with vgic_its_flush/restore_itt to avoid
>> compilation warnings
>> - next field only computed with a shift (mask removed)
>> - handle the case where the last element has not been found
>>
>> v2 -> v3:
>> - add return 0 in vgic_its_restore_ite (was in subsequent patch)
>>
>> v2: creation
>> ---
>> virt/kvm/arm/vgic/vgic-its.c | 107 +++++++++++++++++++++++++++++++++++++++++--
>> 1 file changed, 104 insertions(+), 3 deletions(-)
>>
>> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
>> index b907e3c..02c0694 100644
>> --- a/virt/kvm/arm/vgic/vgic-its.c
>> +++ b/virt/kvm/arm/vgic/vgic-its.c
>> @@ -1707,7 +1707,7 @@ u32 compute_next_devid_offset(struct list_head *h, struct its_device *dev)
>> return min_t(u32, next_offset, VITS_DTE_MAX_DEVID_OFFSET);
>> }
>>
>> -u32 compute_next_eventid_offset(struct list_head *h, struct its_ite *ite)
>> +static u32 compute_next_eventid_offset(struct list_head *h, struct its_ite *ite)
>> {
>> struct list_head *e = &ite->ite_list;
>> struct its_ite *next;
>> @@ -1749,8 +1749,8 @@ typedef int (*entry_fn_t)(struct vgic_its *its, u32 id, void *addr,
>> *
>> * Return: < 0 on error, 1 if last element identified, 0 otherwise
>> */
>> -int lookup_table(struct vgic_its *its, gpa_t base, int size, int esz,
>> - int start_id, entry_fn_t fn, void *opaque)
>> +static int lookup_table(struct vgic_its *its, gpa_t base, int size, int esz,
>> + int start_id, entry_fn_t fn, void *opaque)
>> {
>> gpa_t gpa = base, top = base + size - 1;
>> unsigned long len = size;
>> @@ -1815,6 +1815,107 @@ static int vgic_its_restore_pending_tables(struct kvm *kvm)
>> 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;
>
> Same remark as before concerning the #define-ing of the encoding and the
> name of the function.
>
>> + 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 >> 48;
>> +
>> + 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;
>> +}
>> +
>> +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;
>> +}
>> +
>> +int vgic_its_restore_itt(struct vgic_its *its, struct its_device *dev)
>> +{
>> + size_t max_size = BIT_ULL(dev->nb_eventid_bits) * VITS_ESZ;
>> + 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;
>> +
>> + /* if the last element has not been found we are in trouble */
>> + return ret ? 0 : -EINVAL;
>
> This makes me wonder. Can't lookup_table perform that check on its own
> and always return an error when something went wrong?
No I don't think this is possible due to the fact we have 2 levels of
tables for the device tables. If a second level table lookup does not
find the last entry, this is not an issue.

Thanks

Eric
>
>> +}
>> +
>> /**
>> * vgic_its_flush_device_tables - flush the device table and all ITT
>> * into guest RAM
>>
>
> Thanks,
>
> M.
>