Re: [Xen-devel] [PATCH v4 23/27] ARM: vITS: handle INV command

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andre,

On 03/04/17 21:28, Andre Przywara wrote:
> The INV command instructs the ITS to update the configuration data for
> a given LPI by re-reading its entry from the property table.
> We don't need to care so much about the priority value, but enabling
> or disabling an LPI has some effect: We remove or push virtual LPIs
> to their VCPUs, also check the virtual pending bit if an LPI gets enabled.
>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
>  xen/arch/arm/vgic-v3-its.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 62 insertions(+)
>
> diff --git a/xen/arch/arm/vgic-v3-its.c b/xen/arch/arm/vgic-v3-its.c
> index 2f024b1..920c437 100644
> --- a/xen/arch/arm/vgic-v3-its.c
> +++ b/xen/arch/arm/vgic-v3-its.c
> @@ -366,6 +366,65 @@ static int its_handle_int(struct virt_its *its, uint64_t 
> *cmdptr)
>      return 0;
>  }
>
> +/*
> + * For a given virtual LPI read the enabled bit and priority from the virtual
> + * property table and update the virtual IRQ's state.
> + * This takes care of removing or pushing of virtual LPIs to their VCPUs.
> + */
> +static void update_lpi_enabled_status(struct virt_its* its,
> +                                      struct vcpu *vcpu, uint32_t vlpi)
> +{
> +    struct pending_irq *p = lpi_to_pending(its->d, vlpi);
> +    paddr_t proptable_addr;
> +    uint8_t *property;
> +
> +    if ( !p )
> +        return;
Looking at the spec, I don't think it is mandatory to do an INV/INVALL 
after MAPTI. This could be done before, so how the priority will get 
updated?
> +
> +    proptable_addr = its->d->arch.vgic.rdist_propbase & GENMASK_ULL(51, 12);
> +    property = map_one_guest_page(its->d, proptable_addr + vlpi - LPI_OFFSET);
What if the property table has not been configured correctly? I cannot 
find any code checking the re-distributor has been enabled before 
handling command and therefore no sanitizing.
> +
> +    p->lpi_priority = *property & LPI_PROP_PRIO_MASK;
> +
> +    if ( *property & LPI_PROP_ENABLED )
> +    {
> +        unsigned long flags;
> +
> +        set_bit(GIC_IRQ_GUEST_ENABLED, &p->status);
> +        spin_lock_irqsave(&vcpu->arch.vgic.lock, flags);
> +        if ( !list_empty(&p->inflight) &&
> +             !test_bit(GIC_IRQ_GUEST_VISIBLE, &p->status) )
> +            gic_raise_guest_irq(vcpu, vlpi, p->lpi_priority);
> +        spin_unlock_irqrestore(&vcpu->arch.vgic.lock, flags);
> +
> +        /* Check whether the LPI has fired while the guest had it disabled. */
> +        if ( test_and_clear_bit(GIC_IRQ_GUEST_LPI_PENDING, &p->status) )
> +            vgic_vcpu_inject_irq(vcpu, vlpi);
> +    }
> +    else
> +    {
> +        clear_bit(GIC_IRQ_GUEST_ENABLED, &p->status);
> +        gic_remove_from_queues(vcpu, vlpi);
> +    }
This could looks quite similar to vgic_{enable,disable}_irqs. This is a 
call to refactor the code there.
> +
> +    unmap_one_guest_page(property);
> +}
> +
> +static int its_handle_inv(struct virt_its *its, uint64_t *cmdptr)
> +{
> +    uint32_t devid = its_cmd_get_deviceid(cmdptr);
> +    uint32_t eventid = its_cmd_get_id(cmdptr);
> +    struct vcpu *vcpu;
> +    uint32_t vlpi;
> +
> +    if ( !read_itte(its, devid, eventid, &vcpu, &vlpi) )
> +        return -1;
> +
> +    update_lpi_enabled_status(its, vcpu, vlpi);
> +
> +    return 0;
> +}
> +
>  static int its_handle_mapc(struct virt_its *its, uint64_t *cmdptr)
>  {
>      uint32_t collid = its_cmd_get_collection(cmdptr);
> @@ -546,6 +605,9 @@ static int vgic_its_handle_cmds(struct domain *d, struct 
> virt_its *its,
>          case GITS_CMD_INT:
>              ret = its_handle_int(its, cmdptr);
>              break;
> +        case GITS_CMD_INV:
> +            ret = its_handle_inv(its, cmdptr);
> +           break;
>          case GITS_CMD_MAPC:
>              ret = its_handle_mapc(its, cmdptr);
>              break;
Cheers,

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel