Message-ID: <51AD7AC0.6020303@amd.com>
Date: Tue, 4 Jun 2013 00:27:28 -0500
From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
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To: <suravee.suthikulpanit@amd.com>
CC: <iommu@lists.linux-foundation.org>, <joro@8bytes.org>,
        <ddutile@redhat.com>, <alex.williamson@redhat.com>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/3] iommu/amd: IOMMU Error Reporting/Handling/Filtering
References: <1369250155-12226-1-git-send-email-suravee.suthikulpanit@amd.com>
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On 5/22/2013 2:15 PM, suravee.suthikulpanit@amd.com wrote:
> From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
>
> This patch set implements framework for handling errors reported via IOMMU
> event log. It also implements mechanism to filter/suppress error messages when
> IOMMU hardware generates large amount event logs, which is often caused by
> devices performing invalid operations or from misconfiguring IOMMU hardware
> (e.g. IO_PAGE_FAULT and INVALID_DEVICE_QEQUEST").
>
> DEVICE vs IOMMU ERRORS:
> =======================
> Event types in AMD IOMMU event log can be categorized as:
>      - IOMMU error : An error which is specific to IOMMU hardware
>      - Device error: An error which is specific to a device
>      - Non-error   : Miscelleneous events which are not classified as errors.
> This patch set implements frameworks for handling "IOMMU error" and "device error".
> For IOMMU error, the driver will log the event in dmesg and panic since the IOMMU
> hardware is no longer functioning. For device error, the driver will decode and
> log the error in dmesg based on the error logging level specified at boot time.
>
> ERROR LOGGING LEVEL:
> ====================
> The filtering framework introduce 3 levels of event logging,
> "AMD_IOMMU_LOG_[DEFAULT|VERBOSE|DEBUG]".  Users can specify the level
> via a new boot option "amd_iommu_log=[default|verbose|debug]".
>      - default: Each error message is truncated. Filtering is enabled.
>      - verbose: Output detail error message. Filtering is enabled.
>      - debug  : Output detail error message. Filtering is disabled.
>
> ERROR THRESHOLD LEVEL:
> ======================
> Error threshold is used by the log filtering logic to determine when to suppress
> the errors from a particular device. The threshold is defined as "the number of errors
> (X) over a specified period (Y sec)". When the threshold is reached, IOMMU driver will
> suppress subsequent error messages from the device for a predefined period (Z sec).
> X, Y, and Z is currently hard-coded to 10 errors, 5 sec, and 30 sec.
>
> DATA STRUCTURE:
> ===============
> A new structure "struct dte_err_info" is added. It contains error information
> specific to each device table entry (DTE). The structure is allocated dynamically
> per DTE when IOMMU driver handle device error for the first time.
>
> ERROR STATES and LOG FILTERING:
> ============================================
> The filtering framework define 3 device error states "NONE", "PROBATION" and "SUPPRESS".
>   1. From IOMMU driver intialization, all devices are in DEV_ERR_NONE state.
>   2. During interupt handling, IOMMU driver processes each entry in the event log.
>   3. If an entry is device error, the driver tags DTE with DEV_ERR_PROBATION and
>      report error via via dmesg.
>   4. For non-debug mode, if the device threshold is reached, the device is moved into
>      DEV_ERR_SUPPRESS state in which all error messages are suppressed.
>   5. After the suppress period has passed, the driver put the device in probation state,
>      and errors are reported once again. If the device continues to generate errors,
>      it will be re-suppress once the next threshold is reached.
>
> EXAMPLE OUTPUT:
> ===============
> AMD-Vi: Event=IO_PAGE_FAULT dev=3:0.0 dom=0x1b addr=0x97040 flg=N Ex Sup M P W Pm Ill Ta
> AMD-Vi: Event=IO_PAGE_FAULT dev=3:0.0 dom=0x1b addr=0x97070 flg=N Ex Sup M P W Pm Ill Ta
> AMD-Vi: Event=IO_PAGE_FAULT dev=3:0.0 dom=0x1b addr=0x97060 flg=N Ex Sup M P W Pm Ill Ta
> AMD-Vi: Event=IO_PAGE_FAULT dev=3:0.0 dom=0x1b addr=0x4970 flg=N Ex Sup M P W Pm Ill Ta
> AMD-Vi: Event=IO_PAGE_FAULT dev=3:0.0 dom=0x1b addr=0x98840 flg=N Ex Sup M P W Pm Ill Ta
> AMD-Vi: Event=IO_PAGE_FAULT dev=3:0.0 dom=0x1b addr=0x98870 flg=N Ex Sup M P W Pm Ill Ta
> AMD-Vi: Event=IO_PAGE_FAULT dev=3:0.0 dom=0x1b addr=0x98860 flg=N Ex Sup M P W Pm Ill Ta
> AMD-Vi: Event=IO_PAGE_FAULT dev=3:0.0 dom=0x1b addr=0x4980 flg=N Ex Sup M P W Pm Ill Ta
> AMD-Vi: Event=IO_PAGE_FAULT dev=3:0.0 dom=0x1b addr=0x99040 flg=N Ex Sup M P W Pm Ill Ta
> AMD-Vi: Event=IO_PAGE_FAULT dev=3:0.0 dom=0x1b addr=0x99060 flg=N Ex Sup M P W Pm Ill Ta
> AMD-Vi: Warning: IOMMU error threshold (10) reached for device=3:0.0. Suppress for 30 secs.!!!
>
> Suravee Suthikulpanit (3):
>    iommu/amd: Adding amd_iommu_log cmdline option
>    iommu/amd: Add error handling/reporting/filtering logic
>    iommu/amd: Remove old event printing logic
>
>   Documentation/kernel-parameters.txt |   10 +
>   drivers/iommu/Makefile              |    2 +-
>   drivers/iommu/amd_iommu.c           |   85 +-------
>   drivers/iommu/amd_iommu_fault.c     |  368 +++++++++++++++++++++++++++++++++++
>   drivers/iommu/amd_iommu_init.c      |   19 ++
>   drivers/iommu/amd_iommu_proto.h     |    6 +
>   drivers/iommu/amd_iommu_types.h     |   16 ++
>   7 files changed, 426 insertions(+), 80 deletions(-)
>   create mode 100644 drivers/iommu/amd_iommu_fault.c
>


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