[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PATCH for-4.15 3/4] [RFC] xen/iommu: x86: Clear the root page-table before freeing the page-tables



On 23.12.2020 15:56, Julien Grall wrote:
> On 23/12/2020 14:12, Jan Beulich wrote:
>> On 22.12.2020 16:43, Julien Grall wrote:
>>> This is an RFC because it would break AMD IOMMU driver. One option would
>>> be to move the call to the teardown callback earlier on. Any opinions?
>>
>> We already have
>>
>> static void amd_iommu_domain_destroy(struct domain *d)
>> {
>>      dom_iommu(d)->arch.amd.root_table = NULL;
>> }
>>
>> and this function is AMD's teardown handler. Hence I suppose
>> doing the same for VT-d would be quite reasonable. And really
>> VT-d's iommu_domain_teardown() also already has
>>
>>      hd->arch.vtd.pgd_maddr = 0;
> 
> Let me have a look if that works.
> 
>>
>> I guess what's missing is prevention of the root table
>> getting re-setup. 
> 
> This is taken care in the follow-up patch by forbidding page-table 
> allocation. I can mention it in the commit message.

My expectation is that with that subsequent change the change here
(or any variant of it) would become unnecessary.

Jan



 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.