From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Chen, Tiejun" <tiejun.chen@intel.com>
Subject: Re: [v3][PATCH 16/16] xen/vtd: prevent from assign the
 device with shared rmrr
Date: Thu, 18 Jun 2015 17:23:09 +0800
Message-ID: <55828DFD.4070500@intel.com>
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To: Jan Beulich <JBeulich@suse.com>
Cc: yang.z.zhang@intel.com, andrew.cooper3@citrix.com, kevin.tian@intel.com, tim@xen.org, xen-devel@lists.xen.org
List-Id: xen-devel@lists.xenproject.org

On 2015/6/17 18:28, Jan Beulich wrote:
>>>> On 11.06.15 at 03:15, <tiejun.chen@intel.com> wrote:
>> --- a/xen/drivers/passthrough/vtd/iommu.c
>> +++ b/xen/drivers/passthrough/vtd/iommu.c
>> @@ -2277,13 +2277,37 @@ static int intel_iommu_assign_device(
>>       if ( list_empty(&acpi_drhd_units) )
>>           return -ENODEV;
>>
>> +    seg = pdev->seg;
>> +    bus = pdev->bus;
>> +    /*
>> +     * In rare cases one given rmrr is shared by multiple devices but
>> +     * obviously this would put the security of a system at risk. So
>> +     * we should prevent from this sort of device assignment.
>> +     *
>> +     * TODO: actually we can group these devices which shared rmrr, and
>> +     * then allow all devices within a group to be assigned to same domain.
>> +     */
>> +    for_each_rmrr_device( rmrr, bdf, i )
>> +    {
>> +        if ( rmrr->segment == seg &&
>> +             PCI_BUS(bdf) == bus &&
>> +             PCI_DEVFN2(bdf) == devfn )
>> +        {
>> +            if ( rmrr->scope.devices_cnt > 1 )
>> +            {
>> +                ret = -EPERM;
>> +                printk(XENLOG_G_ERR VTDPREFIX
>> +                       " cannot assign this device with shared RMRR for Dom%d (%d)\n",
>> +                       d->domain_id, ret);
>> +                return ret;
>
> return -EPERM. No need to assign the value to ret, and no need to
> add the constant error code to the log entry. What's missing otoh
> is what "this device" is - you should print SBDF instead.
>

Right.

                 printk(XENLOG_G_ERR VTDPREFIX
                        " cannot assign %04x:%02x:%02x.%u"
                        " with shared RMRR for Dom%d.\n",
                        seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
                        d->domain_id);
                 return -EPERM;


Thanks
Tiejun