linux-kernel - Re: [PATCH] iommu/vt-d: Add Scalable Mode fault information

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Message-ID: <20190910080823.GA3247@8bytes.org>
Date:   Tue, 10 Sep 2019 10:08:23 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Kyung Min Park <kyung.min.park@...el.com>
Cc:     dwmw2@...radead.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, sohil.mehta@...el.com,
        ashok.raj@...el.com, jacob.jun.pan@...ux.intel.com,
        baolu.lu@...el.com, andriy.shevchenko@...el.com
Subject: Re: [PATCH] iommu/vt-d: Add Scalable Mode fault information

On Fri, Sep 06, 2019 at 11:14:02AM -0700, Kyung Min Park wrote:
> Intel VT-d specification revision 3 added support for Scalable Mode
> Translation for DMA remapping. Add the Scalable Mode fault reasons to
> show detailed fault reasons when the translation fault happens.
> 
> Link: https://software.intel.com/sites/default/files/managed/c5/15/vt-directed-io-spec.pdf
> 
> Reviewed-by: Sohil Mehta <sohil.mehta@...el.com>
> Signed-off-by: Kyung Min Park <kyung.min.park@...el.com>
> ---
>  drivers/iommu/dmar.c        | 77 ++++++++++++++++++++++++++++++++++++++++++---
>  include/linux/intel-iommu.h |  2 ++
>  2 files changed, 75 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
> index 1207e05..5cb63c5 100644
> --- a/drivers/iommu/dmar.c
> +++ b/drivers/iommu/dmar.c
> @@ -1532,6 +1532,64 @@ static const char *dma_remap_fault_reasons[] =
>  	"PCE for translation request specifies blocking",
>  };
>  
> +static const char * const dma_remap_sm_fault_reasons[] = {
> +	"SM: Invalid Root Table Address",
> +	"SM: TTM 0 for request with PASID",
> +	"SM: TTM 0 for page group request",
> +	"Unknown", "Unknown", "Unknown", "Unknown", "Unknown", /* 0x33-0x37 */
> +	"SM: Error attempting to access Root Entry",
> +	"SM: Present bit in Root Entry is clear",
> +	"SM: Non-zero reserved field set in Root Entry",
> +	"Unknown", "Unknown", "Unknown", "Unknown", "Unknown", /* 0x3B-0x3F */
> +	"SM: Error attempting to access Context Entry",
> +	"SM: Present bit in Context Entry is clear",
> +	"SM: Non-zero reserved field set in the Context Entry",
> +	"SM: Invalid Context Entry",
> +	"SM: DTE field in Context Entry is clear",
> +	"SM: PASID Enable field in Context Entry is clear",
> +	"SM: PASID is larger than the max in Context Entry",
> +	"SM: PRE field in Context-Entry is clear",
> +	"SM: RID_PASID field error in Context-Entry",
> +	"Unknown", "Unknown", "Unknown", "Unknown", "Unknown", "Unknown", "Unknown", /* 0x49-0x4F */

Maybe add the number (0x49-0x4f) to the respecting "Unknown" fields? If
we can't give a reason we should give the number for easier debugging in
the future. Same for the "Unknown" fields below.

Other than that, the patch looks good.

Regards,

	Joerg