Re: [Xen-devel] [PATCH v4 22/27] ARM: vITS: handle DISCARD command

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andre,

On 03/04/17 21:28, Andre Przywara wrote:
> The DISCARD command drops the connection between a DeviceID/EventID
> and an LPI/collection pair.
> We mark the respective structure entries as not allocated and make
> sure that any queued IRQs are removed.
>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
>  xen/arch/arm/vgic-v3-its.c | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
>
> diff --git a/xen/arch/arm/vgic-v3-its.c b/xen/arch/arm/vgic-v3-its.c
> index a2758cd..2f024b1 100644
> --- a/xen/arch/arm/vgic-v3-its.c
> +++ b/xen/arch/arm/vgic-v3-its.c
> @@ -473,6 +473,33 @@ static int its_handle_movi(struct virt_its *its, uint64_t 
> *cmdptr)
>      return 0;
>  }
>
> +static int its_handle_discard(struct virt_its *its, uint64_t *cmdptr)
> +{
> +    uint32_t devid = its_cmd_get_deviceid(cmdptr);
> +    uint32_t eventid = its_cmd_get_id(cmdptr);
> +    struct pending_irq *pirq;
> +    struct vcpu *vcpu;
> +    uint32_t vlpi;
> +
> +    if ( !read_itte(its, devid, eventid, &vcpu, &vlpi) )
> +        return -1;
> +
> +    pirq = lpi_to_pending(its->d, vlpi);
Same question as usual about the pending_irq locking.

> +    if ( pirq )
> +    {
> +        clear_bit(GIC_IRQ_GUEST_QUEUED, &pirq->status);
> +        gic_remove_from_queues(vcpu, vlpi);
> +    }
> +
> +    if ( !write_itte(its, devid, eventid, UNMAPPED_COLLECTION, INVALID_LPI, 
> NULL) )
> +        return -1;
> +
> +    gicv3_assign_guest_event(its->d, its->doorbell_address,
> +                             devid, eventid, NULL, 0);
Why the return value is not checked?

> +
> +    return 0;
> +}
> +
>  #define ITS_CMD_BUFFER_SIZE(baser)      ((((baser) & 0xff) + 1) << 12)
>
>  static int vgic_its_handle_cmds(struct domain *d, struct virt_its *its,
> @@ -513,6 +540,9 @@ static int vgic_its_handle_cmds(struct domain *d, struct 
> virt_its *its,
>          case GITS_CMD_CLEAR:
>              ret = its_handle_clear(its, cmdptr);
>              break;
> +        case GITS_CMD_DISCARD:
> +            ret = its_handle_discard(its, cmdptr);
> +            break;
>          case GITS_CMD_INT:
>              ret = its_handle_int(its, cmdptr);
>              break;
Cheers,

--
Julien Grall

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