[Linuxarm] Re: [PATCH v3 1/3] iommu/iopf: add a timeout parameter for IOPF

On 2023/1/6 1:15, Shameerali Kolothum Thodi wrote:

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-----Original Message----- From: liulongfang Sent: 05 January 2023 07:48 To: Shameerali Kolothum Thodi shameerali.kolothum.thodi@huawei.com; Jonathan Cameron jonathan.cameron@huawei.com; Zengtao (B) prime.zeng@hisilicon.com Cc: linuxarm@openeuler.org; yekai (A) yekai13@huawei.com; fanghao (A) fanghao11@huawei.com; Wangzhou (B) wangzhou1@hisilicon.com; shenyang (M) shenyang39@huawei.com; liulongfang liulongfang@huawei.com; qianweili qianweili@huawei.com; liudongdong (C) liudongdong3@huawei.com Subject: [PATCH v3 1/3] iommu/iopf: add a timeout parameter for IOPF

In the current IOMMU subsystem, IO page fault processing has delays or unresponsive problems. By adding a tunable setup parameter, users can decide whether to use a timeout timer to prevent unresponsive problems.

This implementation refers to Intel's previous patch, URL: https://lore.kernel.org/lkml/1565900005-62508-2-git-

send-email-jacob.jun.pan@linux.intel.com/

Looks like the link has a line break.

Yes, But that will cause checkpatch to report a warning. I need to find out if there is a way to have both.

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Signed-off-by: Longfang Liu liulongfang@huawei.com

Since this is almost similar to Jacob's patch, you should make him as the author and add your sign off tag after his.

Yes, this author needs to be added.

Thanks, Shameer

Thanks, Longfang.

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.../admin-guide/kernel-parameters.txt | 8 +++++ drivers/iommu/io-pgfault.c | 32 +++++++++++++++++++ 2 files changed, 40 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 6b838869554b..425d446d92c6 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2176,6 +2176,14 @@ 1 - Bypass the IOMMU for DMA. unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.

• iommu.iopf_timeout=

• 	Timeout in milliseconds to wait for page response
  

• 	of a IO page fault request.
  

• 	Format: <integer>
  

• 	Default: 600
  

• 	0 - no timeout tracking
  

• 	100 to 10000 - allowed range
  

• io7= [HW] IO7 for Marvel-based Alpha systems See comment before marvel_specify_io7 in arch/alpha/kernel/core_marvel.c.

diff --git a/drivers/iommu/io-pgfault.c b/drivers/iommu/io-pgfault.c index e5b8b9110c13..cd7ebbfe4a67 100644 --- a/drivers/iommu/io-pgfault.c +++ b/drivers/iommu/io-pgfault.c @@ -45,6 +45,17 @@ struct iopf_fault { struct list_head list; };

+/**

• • Timeout to wait for page response of a pending page request. This is
• • intended as a basic safety net in case a pending page request is not
• • responded for an exceptionally long time. Device may also implement
• • its own protection mechanism against this exception.
• • default to 600 milliseconds.
• */

+#define IOPF_RESPONSE_DEF_TIMEOUT 600 +#define IOPF_RESPONSE_MAX_TIMEOUT 10000 +static unsigned long iopf_timeout_ms = IOPF_RESPONSE_DEF_TIMEOUT;

struct iopf_group { struct iopf_fault last_fault; struct list_head faults; @@ -52,6 +63,27 @@ struct iopf_group { struct device *dev; };

+static int __init iommu_set_iopf_timeout(char *str) +{

• unsigned long timeout;
• int ret;
• if (!str)

• return -EINVAL;
  

• ret = kstrtoul(str, 10, &timeout);
• if (ret)

• return ret;
  

• if (timeout > IOPF_RESPONSE_MAX_TIMEOUT)

• return -EINVAL;
  

• iopf_timeout_ms = timeout;
• return 0;

+} +early_param("iommu.iopf_timeout", iommu_set_iopf_timeout);

static int iopf_complete_group(struct device *dev, struct iopf_fault *iopf, enum iommu_page_response_code status) { -- 2.24.0

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