Re: [Xen-devel] [PATCH] VT-d: improve RMRR validity checking

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

Hello Weidong,

Wouldn't it be more clear to add an option to iommu= for this case ?

if iommu=on,..,..,security

With the security option specified:
     -it would be most strict in it's checks, since enforcing security with the 
iommu requires that as you have pointed out.
     -warn,fail or panic incase it can't enable all to enforce the security.

Without the security option specified (default)
     - it tries to work as with the security option specified
     - but incase of problems makes the assumption the iommu's main task is not 
security, but making as much of vt-d working to keep the passthrough 
functionality
     - it will only warn, that you will lose the security part, that it would 
be wise to let your bios be fixed, and not making it panic
     - and keep vt-d enabled


Regards,

Sander



Friday, January 22, 2010, 9:47:11 AM, you wrote:

> diff -r 207fba95a7d5 xen/drivers/passthrough/vtd/dmar.c
> --- a/xen/drivers/passthrough/vtd/dmar.c        Fri Jan 22 13:12:45 2010 +0800
> +++ b/xen/drivers/passthrough/vtd/dmar.c        Fri Jan 22 22:32:10 2010 +0800
> @@ -396,8 +396,49 @@ acpi_parse_one_drhd(struct acpi_dmar_ent
>  
>      if ( ret )
>          xfree(dmaru);
> +    else if ( force_iommu || dmaru->include_all )
> +        acpi_register_drhd_unit(dmaru);
>      else
> -        acpi_register_drhd_unit(dmaru);
> +    {
> +        u8 b, d, f;
> +        int i, invalid_cnt = 0;
> +
> +        for ( i = 0; i < dmaru->scope.devices_cnt; i++ )
> +        {
> +            b = PCI_BUS(dmaru->scope.devices[i]);
> +            d = PCI_SLOT(dmaru->scope.devices[i]);
> +            f = PCI_FUNC(dmaru->scope.devices[i]);
> +
> +            if ( pci_device_detect(b, d, f) == 0 )
> +            {
> +                dprintk(XENLOG_WARNING VTDPREFIX,
> +                    "  Non-existent device (%x:%x.%x) is reported "
> +                    "in this DRHD's scope!\n", b, d, f);
> +                invalid_cnt++;
> +            }
> +        }
> +
> +        if ( invalid_cnt )
> +        {
> +            xfree(dmaru);
> +            if ( invalid_cnt == dmaru->scope.devices_cnt )
> +            {
> +                dprintk(XENLOG_WARNING VTDPREFIX,
> +                    "  Ignore the DRHD due to all devices under "
> +                    "its scope are not PCI discoverable!\n");
> +            }
> +            else
> +            {
> +                dprintk(XENLOG_WARNING VTDPREFIX,
> +                    "  The DRHD is invalid due to some devices under "
> +                    "its scope are not PCI discoverable!\n");
> +                ret = -EINVAL;
> +            }
> +        }
> +        else
> +            acpi_register_drhd_unit(dmaru);
> +    }
> +
>      return ret;
>  }
>  



-- 
Best regards,
 Sander                            mailto:linux@xxxxxxxxxxxxxx


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