Re: [Xen-devel] [PATCH 12/28] ARM: GICv3: enable ITS and LPIs on the host

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andre,

On 30/01/17 18:31, Andre Przywara wrote:
> Now that the host part of the ITS code is in place, we can enable the
> ITS and also LPIs on each redistributor to get the show rolling.
> At this point there would be no LPIs mapped, as guests don't know about
> the ITS yet.
>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
>  xen/arch/arm/gic-v3-its.c | 34 ++++++++++++++++++++++++++++++++--
>  xen/arch/arm/gic-v3.c     | 19 +++++++++++++++++++
>  2 files changed, 51 insertions(+), 2 deletions(-)
>
> diff --git a/xen/arch/arm/gic-v3-its.c b/xen/arch/arm/gic-v3-its.c
> index f073ab5..2a7093f 100644
> --- a/xen/arch/arm/gic-v3-its.c
> +++ b/xen/arch/arm/gic-v3-its.c
> @@ -62,6 +62,28 @@ static int its_send_command(struct host_its *hw_its, const 
> void *its_cmd)
>      return 0;
>  }
>
> +/* Wait for an ITS to finish processing all commands. */
> +static int gicv3_its_wait_commands(struct host_its *hw_its)
> +{
> +    s_time_t deadline = NOW() + MILLISECS(1000);
> +    uint64_t readp, writep;
> +
> +    do {
> +        spin_lock(&hw_its->cmd_lock);
> +        readp = readq_relaxed(hw_its->its_base + GITS_CREADR) & BUFPTR_MASK;
> +        writep = readq_relaxed(hw_its->its_base + GITS_CWRITER) & BUFPTR_MASK;
> +        spin_unlock(&hw_its->cmd_lock);
> +
> +        if ( readp == writep )
> +            return 0;
> +
> +        cpu_relax();
> +        udelay(1);
> +    } while ( NOW() <= deadline );
> +
> +    return -ETIMEDOUT;
> +}
> +
>  static uint64_t encode_rdbase(struct host_its *hw_its, int cpu, uint64_t reg)
>  {
>      reg &= ~GENMASK(51, 16);
> @@ -161,6 +183,10 @@ int gicv3_its_setup_collection(int cpu)
>          ret = its_send_cmd_sync(its, cpu);
>          if ( ret )
>              return ret;
> +
> +        ret = gicv3_its_wait_commands(its);
> +        if ( ret )
> +            return ret;
Why are all the gicv3_its_wait_commands are added now and not when the 
command was added?
Maybe I am missing something but base on the commit message, this patch 
should really just turning on the enable bit.
Cheers,

--
Julien Grall

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