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SubjectRe: [PATCH v1] iommu/ipmmu-vmsa: Don't register as BUS IOMMU if machine doesn't have IPMMU-VMSA
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Hi Dmitry,

(CC'ing Geert and Magnus)

Thank you for the patch.

On Friday, 27 July 2018 00:19:16 EEST Dmitry Osipenko wrote:
> This fixes kernel crashing on NVIDIA Tegra if kernel is compiled in
> a multiplatform configuration and IPMMU-VMSA driver is enabled.
>
> Cc: <stable@vger.kernel.org> # v3.20+
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
> drivers/iommu/ipmmu-vmsa.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
> index 9e8495762bc8..78c50db9cd71 100644
> --- a/drivers/iommu/ipmmu-vmsa.c
> +++ b/drivers/iommu/ipmmu-vmsa.c
> @@ -1109,12 +1109,19 @@ static struct platform_driver ipmmu_driver = {
>
> static int __init ipmmu_init(void)
> {
> + struct device_node *np;
> static bool setup_done;
> int ret;
>
> if (setup_done)
> return 0;
>
> + np = of_find_matching_node(NULL, ipmmu_of_ids);
> + if (!np)
> + return 0;
> +
> + of_node_put(np);
> +

While functionally correct, this will add some unnecessary overhead when
iommu_init() is called from IOMMU_OF_DECLARE(). I'm OK with this fix as a
temporary measure to solve your problem, but we need to address the underlying
issue properly.

Geert, Magnus, the ipmmu-vmsa driver is a bit of a mess. We should brush it up
and start using IOMMU_OF_DECLARE() on all platforms (and eventually get rid of
bus_set_iommu() completely...). Do you have plans to address this ? If not,
could you please add it to your to-do list ?

> ret = platform_driver_register(&ipmmu_driver);
> if (ret < 0)
> return ret;

--
Regards,

Laurent Pinchart



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