Re: [Xen-devel] [PATCH] xen/vtd/iommu: permit group devices to passthrough in relaxed mode

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 08.09.15 at 02:57, <tiejun.chen@xxxxxxxxx> wrote:
> Currently we don't allow passing through any group devices which are
> sharing same RMRR entry since it would break security among VMs. And
> indeed, we expect we can figure out a better way to handle this kind
> of case completely.
> 
> But before the group assignment gets implemented, we might make this
> permission dependent on our RMRR policy. So, now it would be allowed
> in the relaxed mode.
> 
> CC: Yang Zhang <yang.z.zhang@xxxxxxxxx>
> CC: Kevin Tian <kevin.tian@xxxxxxxxx>
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
> ---
>  xen/drivers/passthrough/vtd/iommu.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/drivers/passthrough/vtd/iommu.c 
> b/xen/drivers/passthrough/vtd/iommu.c
> index 836aed5..4249cfa 100644
> --- a/xen/drivers/passthrough/vtd/iommu.c
> +++ b/xen/drivers/passthrough/vtd/iommu.c
> @@ -2310,12 +2310,16 @@ static int intel_iommu_assign_device(
>               PCI_DEVFN2(bdf) == devfn &&
>               rmrr->scope.devices_cnt > 1 )
>          {
> +            u32 relaxed = flag & XEN_DOMCTL_DEV_RDM_RELAXED;

Conventionally this ought to be a bool_t.

>              printk(XENLOG_G_ERR VTDPREFIX
> -                   " cannot assign %04x:%02x:%02x.%u"
> +                   " Currently its %s to assign %04x:%02x:%02x.%u"

In addition to what Wei said - what meaning is "currently" supposed
to have here? To a reader of the resulting log it might look as if
(s)he'd need to reconfigure the hypervisor (via some command line
option perhaps), while acceptance / refusal solely depends on the
arguments the caller provides.

Apart from that in the relaxed case the message level should be
XENLOG_G_WARNING, not XENLOG_G_ERR.

Jan


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