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From:   "Yang, Shunyong" <shunyong.yang@hxt-semitech.com>
To:     "joro@8bytes.org" <joro@8bytes.org>,
        "olof@lixom.net" <olof@lixom.net>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>
Subject: Re: [PATCH 1/2] iommu: Add config option to set passthrough as
 default
Thread-Topic: [PATCH 1/2] iommu: Add config option to set passthrough as
 default
Thread-Index: AQHUGVos72k0FiF+U0exr2V+rYPox6SKUI0A
Date:   Thu, 12 Jul 2018 02:04:41 +0000
Message-ID: <1531361076.3757.5.camel@hxt-semitech.com>
References: <20180711205936.18614-1-olof@lixom.net>
In-Reply-To: <20180711205936.18614-1-olof@lixom.net>
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Hi, Olof,

Tired of changing command line. I like this patch.

Thanks.
Shunyong.?

On Wed, 2018-07-11 at 13:59 -0700, Olof Johansson wrote:
> This allows the default behavior to be controlled by a kernel config
> option instead of changing the commandline for the kernel to include
> "iommu.passthrough=on" on machines where this is desired.
> 
> Signed-off-by: Olof Johansson <olof@lixom.net>
> ---
> ?drivers/iommu/Kconfig | 10 ++++++++++
> ?drivers/iommu/iommu.c |??4 ++++
> ?2 files changed, 14 insertions(+)
> 
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index 689ffe538370..a9bb1a5b5e43 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -60,6 +60,16 @@ config IOMMU_IO_PGTABLE_ARMV7S_SELFTEST
> ?
> ?endmenu
> ?
> +config IOMMU_DEFAULT_PASSTHROUGH
> +	bool "IOMMU passthrough by default"
> +	depends on IOMMU_API
> +????????help
> +	??Enable passthrough by default (removing the need to pass
> in
> +	??iommu.passthrough=on through command line). If this is
> enabled,
> +	??you can still disable with iommu.passthrough=off
> +
> +	??If unsure, say N here.
> +
> ?config IOMMU_IOVA
> ?	tristate
> ?
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 63b37563db7e..ab8fc54467e0 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -36,7 +36,11 @@
> ?
> ?static struct kset *iommu_group_kset;
> ?static DEFINE_IDA(iommu_group_ida);
> +#ifdef CONFIG_IOMMU_DEFAULT_PASSTHROUGH
> +static unsigned int iommu_def_domain_type = IOMMU_DOMAIN_IDENTITY;
> +#else
> ?static unsigned int iommu_def_domain_type = IOMMU_DOMAIN_DMA;
> +#endif
> ?
> ?struct iommu_callback_data {
> ?	const struct iommu_ops *ops;