linux-kernel - Re: [PATCH v14 1/6] iommu: Deprecate Intel and AMD cmdline methods to enable strict mode

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Date:   Fri, 18 Jun 2021 21:09:40 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     John Garry <john.garry@...wei.com>, joro@...tes.org,
        will@...nel.org, dwmw2@...radead.org, robin.murphy@....com,
        corbet@....net
Cc:     baolu.lu@...ux.intel.com, linux-kernel@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linuxarm@...wei.com,
        thunder.leizhen@...wei.com, chenxiang66@...ilicon.com,
        linux-doc@...r.kernel.org
Subject: Re: [PATCH v14 1/6] iommu: Deprecate Intel and AMD cmdline methods to
 enable strict mode

On 2021/6/18 19:34, John Garry wrote:
> Now that the x86 drivers support iommu.strict, deprecate the custom
> methods.
> 
> Signed-off-by: John Garry <john.garry@...wei.com>
> Acked-by: Robin Murphy <robin.murphy@....com>
> ---
>   Documentation/admin-guide/kernel-parameters.txt | 9 ++-------
>   drivers/iommu/amd/init.c                        | 4 +++-
>   drivers/iommu/intel/iommu.c                     | 1 +
>   3 files changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 30e9dd52464e..673952379900 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -290,10 +290,7 @@
>   	amd_iommu=	[HW,X86-64]
>   			Pass parameters to the AMD IOMMU driver in the system.
>   			Possible values are:
> -			fullflush - enable flushing of IO/TLB entries when
> -				    they are unmapped. Otherwise they are
> -				    flushed before they will be reused, which
> -				    is a lot of faster
> +			fullflush - Deprecated, equivalent to iommu.strict=1
>   			off	  - do not initialize any AMD IOMMU found in
>   				    the system
>   			force_isolation - Force device isolation for all
> @@ -1948,9 +1945,7 @@
>   			this case, gfx device will use physical address for
>   			DMA.
>   		strict [Default Off]
> -			With this option on every unmap_single operation will
> -			result in a hardware IOTLB flush operation as opposed
> -			to batching them for performance.
> +			Deprecated, equivalent to iommu.strict=1.
>   		sp_off [Default Off]
>   			By default, super page will be supported if Intel IOMMU
>   			has the capability. With this option, super page will
> diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
> index 46280e6e1535..3a2fb805f11e 100644
> --- a/drivers/iommu/amd/init.c
> +++ b/drivers/iommu/amd/init.c
> @@ -3098,8 +3098,10 @@ static int __init parse_amd_iommu_intr(char *str)
>   static int __init parse_amd_iommu_options(char *str)
>   {
>   	for (; *str; ++str) {
> -		if (strncmp(str, "fullflush", 9) == 0)
> +		if (strncmp(str, "fullflush", 9) == 0) {
> +			pr_warn("amd_iommu=fullflush deprecated; use iommu.strict=1 instead\n");
>   			amd_iommu_unmap_flush = true;
> +		}
>   		if (strncmp(str, "force_enable", 12) == 0)
>   			amd_iommu_force_enable = true;
>   		if (strncmp(str, "off", 3) == 0)
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index bd93c7ec879e..29497113d748 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -454,6 +454,7 @@ static int __init intel_iommu_setup(char *str)
>   			pr_warn("intel_iommu=forcedac deprecated; use iommu.forcedac instead\n");
>   			iommu_dma_forcedac = true;
>   		} else if (!strncmp(str, "strict", 6)) {
> +			pr_warn("intel_iommu=strict deprecated; use iommu.strict=1 instead\n");
>   			pr_info("Disable batched IOTLB flush\n");
>   			intel_iommu_strict = 1;
>   		} else if (!strncmp(str, "sp_off", 6)) {
> 

Reviewed-by: Lu Baolu <baolu.lu@...ux.intel.com>

Best regards,
baolu