Re: [PATCH v5 02/23] irqchip/gic-v4.1: Skip absent CPUs while iterating over redistributors

Auger Eric
2020-03-16T17:31:09Z

Hi Marc

On 3/4/20 9:33 PM, Marc Zyngier wrote:
> In a system that is only sparsly populated with CPUs, we can end-up with
sparsely
> redistributors structures that are not initialized. Let's make sure we
redistributor structures
> don't try and access those when iterating over them (in this case when
> checking we have a L2 VPE table).
>
> Fixes: 4e6437f12d6e ("irqchip/gic-v4.1: Ensure L2 vPE table is allocated at RD level")
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
> ---
> drivers/irqchip/irq-gic-v3-its.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index 83b1186ffcad..da883a691028 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -2452,6 +2452,10 @@ static bool allocate_vpe_l2_table(int cpu, u32 id)
> if (!gic_rdists->has_rvpeid)
> return true;
>
> + /* Skip non-present CPUs */
> + if (!base)
> + return true;
> +
> val = gicr_read_vpropbaser(base + SZ_128K + GICR_VPROPBASER);
>
> esz = FIELD_GET(GICR_VPROPBASER_4_1_ENTRY_SIZE, val) + 1;
>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric