Re: [Xen-devel] [PATCH v6 10/10] introduce a 'passthrough' configuration option to xl.cfg...

[Jan Beulich <jbeulich@xxxxxxxx>]

On 16.08.2019 19:20, Paul Durrant wrote:
> ...and hence the ability to disable IOMMU mappings, and control EPT
> sharing.
> 
> This patch introduces a new 'libxl_passthrough' enumeration into
> libxl_domain_create_info. The value will be set by xl either when it parses
> a new 'passthrough' option in xl.cfg, or implicitly if there is passthrough
> hardware specified for the domain.
> 
> If the value of the passthrough configuration option is 'disabled' then
> the XEN_DOMCTL_CDF_iommu flag will be clear in the xen_domctl_createdomain
> flags, thus allowing the toolstack to control whether the domain gets
> IOMMU mappings or not (where previously they were globally set).
> 
> If the value of the passthrough configuration option is 'sync_pt' then
> a new 'iommu_opts' field in xen_domctl_createdomain will be set with the
> value XEN_DOMCTL_IOMMU_no_sharept. This will override the global default
> set in iommu_hap_pt_share, thus allowing the toolstack to control whether
> EPT sharing is used for the domain.
> 
> Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
with a question/suggestion and a nit:

> --- a/xen/common/domain.c
> +++ b/xen/common/domain.c
> @@ -308,6 +308,13 @@ static int sanitise_domain_config(struct 
> xen_domctl_createdomain *config)
>          return -EINVAL;
>      }
>  
> +    if ( !(config->flags & XEN_DOMCTL_CDF_iommu) && config->iommu_opts )
> +    {
> +        dprintk(XENLOG_INFO,
> +                "IOMMU options specified but IOMMU not enabled\n");
> +        return -EINVAL;
> +    }

Seeing this I wonder whether XEN_DOMCTL_CDF_iommu wouldn't better be
bit 0 of iommu_opts.

> @@ -70,6 +70,10 @@ struct xen_domctl_createdomain {
>  
>      uint32_t flags;
>  
> +#define _XEN_DOMCTL_IOMMU_no_sharept  0
> +#define XEN_DOMCTL_IOMMU_no_sharept   (1U<<_XEN_DOMCTL_IOMMU_no_sharept)

Please can you add the missing blanks around << ?

Jan

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