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Message-ID: <f95252ce-f834-103b-f96d-7e35fa59d5ec@arm.com>
Date: Thu, 17 Jun 2021 20:01:58 +0100
From: Robin Murphy <robin.murphy@....com>
To: John Garry <john.garry@...wei.com>, joro@...tes.org,
will@...nel.org, dwmw2@...radead.org, baolu.lu@...ux.intel.com,
corbet@....net
Cc: 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 v13 1/6] iommu: Deprecate Intel and AMD cmdline methods to
enable strict mode
On 2021-06-16 12:03, John Garry wrote:
> Now that the x86 drivers support iommu.strict, deprecate the custom
> methods.
>
> Signed-off-by: John Garry <john.garry@...wei.com>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 5 +++--
> drivers/iommu/amd/init.c | 4 +++-
> drivers/iommu/intel/iommu.c | 1 +
> 3 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 30e9dd52464e..fcbb36d6eea7 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -290,7 +290,8 @@
> 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
> + fullflush [Deprecated, use iommu.strict instead]
> + - 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
> @@ -1947,7 +1948,7 @@
> bypassed by not enabling DMAR with this option. In
> this case, gfx device will use physical address for
> DMA.
> - strict [Default Off]
> + strict [Default Off] [Deprecated, use iommu.strict instead]
> With this option on every unmap_single operation will
> result in a hardware IOTLB flush operation as opposed
> to batching them for performance.
FWIW I'd be inclined to replace both whole descriptions with just
something like "Deprecated, equivalent to iommu.strict=1".
> diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
> index 46280e6e1535..9f3096d650aa 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 instead\n");
Nit: maybe we should spell out "...use <option>=1 instead" in all of
these messages just in case anyone takes them literally? (I'm not sure
the options parse correctly with no argument)
Either way,
Acked-by: Robin Murphy <robin.murphy@....com>
Thanks,
Robin.
> 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..821d8227a4e6 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 instead\n");
> pr_info("Disable batched IOTLB flush\n");
> intel_iommu_strict = 1;
> } else if (!strncmp(str, "sp_off", 6)) {
>
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