linux-kernel - Re: [PATCH 0/2] iommu/dmar: expose fault counters via sysfs

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Date:   Wed, 16 Oct 2019 08:45:55 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Yuri Volchkov <volchkov@...zon.de>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org
Cc:     baolu.lu@...ux.intel.com, joro@...tes.org, bhelgaas@...gle.com,
        dwmw2@...radead.org, neugebar@...zon.co.uk
Subject: Re: [PATCH 0/2] iommu/dmar: expose fault counters via sysfs

Hi,

On 10/15/19 11:11 PM, Yuri Volchkov wrote:
> For health monitoring, it can be useful to know if iommu is behaving as
> expected. DMAR faults can be an indicator that a device:
>   - has been misconfigured, or
>   - has experienced a hardware hiccup and replacement should
>     be considered, or
>   - has been issuing faults due to malicious activity
> 
> Currently the only way to check if there were any DMAR faults on the
> host is to scan the dmesg output. However this approach is not very
> elegant. The information we are looking for can be wrapped out of the
> buffer, or masked (since it is a rate-limited print) by another
> device.
> 
> The series adds counters for DMAR faults and exposes them via sysfs.
> 

We now have an iommu API named iommu_register_fault_handler() to
register callbacks for dmar faults. How about monitoring the dmar
fault through this api so that your code could be generic and vendor
agnostic?

Best regards,
Baolu

> Yuri Volchkov (2):
>    iommu/dmar: collect fault statistics
>    iommu/dmar: catch early fault occurrences
> 
>   drivers/iommu/dmar.c        | 182 ++++++++++++++++++++++++++++++++----
>   drivers/iommu/intel-iommu.c |   1 +
>   drivers/pci/pci-sysfs.c     |  20 ++++
>   include/linux/intel-iommu.h |   4 +
>   include/linux/pci.h         |  11 +++
>   5 files changed, 201 insertions(+), 17 deletions(-)
>