lkml.org 
[lkml]   [2020]   [Sep]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC Patch 0/2] KVM: SVM: Cgroup support for SVM SEV ASIDs
From
Date
On 28.09.20 11:12, Janosch Frank wrote:
> On 9/23/20 2:47 PM, Paolo Bonzini wrote:
>> On 22/09/20 03:48, Sean Christopherson wrote:
>>> This should be genericized to not be SEV specific. TDX has a similar
>>> scarcity issue in the form of key IDs, which IIUC are analogous to SEV ASIDs
>>> (gave myself a quick crash course on SEV ASIDs). Functionally, I doubt it
>>> would change anything, I think it'd just be a bunch of renaming. The hardest
>>> part would probably be figuring out a name :-).
>>>
>>> Another idea would be to go even more generic and implement a KVM cgroup
>>> that accounts the number of VMs of a particular type, e.g. legacy, SEV,
>>> SEV-ES?, and TDX. That has potential future problems though as it falls
>>> apart if hardware every supports 1:MANY VMs:KEYS, or if there is a need to
>>> account keys outside of KVM, e.g. if MKTME for non-KVM cases ever sees the
>>> light of day.
>>
>> Or also MANY:1 (we are thinking of having multiple VMs share the same
>> SEV ASID).
>>
>> It might even be the same on s390 and PPC, in which case we probably
>> want to implement this in virt/kvm. Paul, Janosch, do you think this
>> would make sense for you? The original commit message is below.
>>
>> Paolo
>>
>>> On Mon, Sep 21, 2020 at 05:40:22PM -0700, Vipin Sharma wrote:
>>>> Hello,
>>>>
>>>> This patch series adds a new SEV controller for tracking and limiting
>>>> the usage of SEV ASIDs on the AMD SVM platform.
>>>>
>>>> SEV ASIDs are used in creating encrypted VM and lightweight sandboxes
>>>> but this resource is in very limited quantity on a host.
>>>>
>>>> This limited quantity creates issues like SEV ASID starvation and
>>>> unoptimized scheduling in the cloud infrastructure.
>>>>
>>>> SEV controller provides SEV ASID tracking and resource control
>>>> mechanisms.
>>
>
> On s390 we currently support a few million protected guests per LPAR so
> guest IDs are not exactly scarce. However having accounting for them
> might add some value nevertheless, especially when having large amount
> of protected containers.
>
> @Christian: Any thoughts on this?

Yes, maybe it is a good idea to limit containers to only have a sane number
of secure guests, so that a malicious pod cannot consume all IDs by calling
CREATE_VM and KVM_PV_ENABLE million times or so.


\
 
 \ /
  Last update: 2020-09-28 11:22    [W:0.049 / U:3.208 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site