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

Marc Zyngier
2017-04-10T12:39:21Z

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?

> +}
> +
> /**
> * vgic_its_flush_device_tables - flush the device table and all ITT
> * into guest RAM
>

Thanks,

M.
--
Jazz is not dead. It just smells funny...