Re: [Xen-devel] [PATCH 2/3] amd-iommu: disable iommu_hap_pt_share with AMD IOMMUs

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Mon, Apr 07, 2014 at 06:02:03PM +0200, Roger Pau Monne wrote:
> According to the comment in p2m.h, AMD IOMMUs don't work correctly
> with page types different than p2m_ram_rw when the p2m is shared
> between HAP and IOMMU, so disable this sharing when using AMD IOMMUs

s/between/amongst/

And you are missing an '.' at the off the sentence.

> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
> Cc: Xiantao Zhang <xiantao.zhang@xxxxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> ---
> I have not tested this patch on AMD hardware, so I would like some
> confirmation that this actually works.
> ---
>  xen/drivers/passthrough/amd/iommu_init.c |    7 +++++++
>  1 files changed, 7 insertions(+), 0 deletions(-)
> 
> diff --git a/xen/drivers/passthrough/amd/iommu_init.c 
> b/xen/drivers/passthrough/amd/iommu_init.c
> index 4686813..7f75b3e 100644
> --- a/xen/drivers/passthrough/amd/iommu_init.c
> +++ b/xen/drivers/passthrough/amd/iommu_init.c
> @@ -1255,6 +1255,13 @@ int __init amd_iommu_init(void)
>      if ( iterate_ivrs_mappings(amd_iommu_setup_device_table) != 0 )
>          goto error_out;
>  
> +    /*
> +     * Disable sharing HAP page tables with AMD IOMMU,
> +     * since it only supports p2m_ram_rw, and this would
> +     * prevent doing IO to/from mapped grant frames.
> +     */
> +    iommu_hap_pt_share = 0;
> +
>      /* per iommu initialization  */
>      for_each_amd_iommu ( iommu )
>          if ( amd_iommu_init_one(iommu) != 0 )
> -- 
> 1.7.7.5 (Apple Git-26)
> 
> 
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