Re: [Xen-devel] [PATCH] x86/iommu: improve logging message

[Jan Beulich <jbeulich@xxxxxxxx>]

On 27.09.2019 12:48, Roger Pau Monne wrote:
> Switch to using pd and also print the pfn that failed.
> 
> No functional change intended.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Nevertheless, ...

> --- a/xen/drivers/passthrough/x86/iommu.c
> +++ b/xen/drivers/passthrough/x86/iommu.c
> @@ -200,8 +200,8 @@ void __hwdom_init arch_iommu_hwdom_init(struct domain *d)
>                             IOMMUF_readable | IOMMUF_writable, &flush_flags);
>  
>          if ( rc )
> -            printk(XENLOG_WARNING " d%d: IOMMU mapping failed: %d\n",
> -                   d->domain_id, rc);
> +            printk(XENLOG_WARNING "%pd: identity %smapping of %lx failed: 
> %d\n",
> +                   d, !paging_mode_translate(d) ? "IOMMU " : "", pfn, rc);

... have you observed this getting logged? If so, how many of them
did you see? IOW I wonder whether logging every occurrence of this
may be overly verbose.

As an aside I also think that we need to urgently make this use
larger page sizes where suitable.

Jan

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