Re: [Xen-devel] [PATCH 17/28] ARM: vITS: handle CLEAR command

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 30 Jan 2017, Andre Przywara wrote:
> This introduces the ITS command handler for the CLEAR command, which
> clears the pending state of an LPI.
> This removes a not-yet injected, but already queued IRQ from a VCPU.
> 
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>

Please see alpine.DEB.2.10.1611081608580.3491@sstabellini-ThinkPad-X260


> ---
>  xen/arch/arm/vgic-v3-its.c | 35 +++++++++++++++++++++++++++++++++--
>  1 file changed, 33 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/arch/arm/vgic-v3-its.c b/xen/arch/arm/vgic-v3-its.c
> index 982c51d..48eb924 100644
> --- a/xen/arch/arm/vgic-v3-its.c
> +++ b/xen/arch/arm/vgic-v3-its.c
> @@ -129,8 +129,8 @@ static void put_devid_evid(struct virt_its *its, struct 
> vits_itte *itte)
>   * protect the ITTs with their less-than-page-size granularity.
>   * Takes and drops the its_lock.
>   */
> -bool read_itte(struct virt_its *its, uint32_t devid, uint32_t evid,
> -               struct vcpu **vcpu, uint32_t *vlpi)
> +static bool read_itte(struct virt_its *its, uint32_t devid, uint32_t evid,
> +                      struct vcpu **vcpu, uint32_t *vlpi)
>  {
>      struct vits_itte *itte;
>      int collid;
> @@ -214,6 +214,34 @@ static uint64_t its_cmd_mask_field(uint64_t *its_cmd,
>  #define its_cmd_get_target_addr(cmd)    its_cmd_mask_field(cmd, 2, 16, 32)
>  #define its_cmd_get_validbit(cmd)       its_cmd_mask_field(cmd, 2, 63,  1)
>  
> +static int its_handle_clear(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;
> +
> +    /* Remove a pending, but not yet injected guest IRQ. */
> +    pirq = lpi_to_pending(vcpu, vlpi, false);
> +    if ( pirq )
> +    {
> +        clear_bit(GIC_IRQ_GUEST_QUEUED, &pirq->status);
> +        gic_remove_from_queues(vcpu, vlpi);
> +
> +        /* Mark this pending IRQ struct as availabe again. */
> +        if ( !test_bit(GIC_IRQ_GUEST_VISIBLE, &pirq->status) )
> +            pirq->irq = 0;
> +    }
> +
> +    clear_bit(vlpi - LPI_OFFSET, vcpu->arch.vgic.pendtable);
> +
> +    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,
> @@ -234,6 +262,9 @@ static int vgic_its_handle_cmds(struct domain *d, struct 
> virt_its *its,
>          cmdptr = its->cmdbuf + (its->creadr / sizeof(*its->cmdbuf));
>          switch (its_cmd_get_command(cmdptr))
>          {
> +        case GITS_CMD_CLEAR:
> +            its_handle_clear(its, cmdptr);
> +            break;
>          case GITS_CMD_SYNC:
>              /* We handle ITS commands synchronously, so we ignore SYNC. */
>           break;
> -- 
> 2.9.0
> 

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