linux-kernel - Re: [ANNOUNCE] KVM Microconference at LPC 2023

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Message-ID: <ce7689c9-1c23-68ff-9afb-7d0aeaa9c80a@amazon.es>
Date:   Wed, 7 Jun 2023 14:20:57 +0200
From:   Babis Chalios <bchalios@...zon.es>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        KVM list <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Sean Christopherson <seanjc@...gle.com>,
        Marc Zyngier <maz@...nel.org>, Alexander Graf <graf@...zon.de>,
        "Cali, Marco" <xmarcalx@...zon.co.uk>
Subject: Re: [ANNOUNCE] KVM Microconference at LPC 2023

On 7/6/23 12:37, Paolo Bonzini wrote:
> CAUTION: This email originated from outside of the organization. Do 
> not click links or open attachments unless you can confirm the sender 
> and know the content is safe.
>
>
>
> On 6/7/23 12:13, Babis Chalios wrote:
>>
>>
>> On our side, we 've been working on providing ways to let VMs (kernel
>>  and user space) know that they have been cloned/snapshotted/restored
>> from snapshots[1].
>>
>> This is tightly coupled with PRNGs both in kernel and user space and
>>  there needs to be some collaboration with random.c to tie everything
>> together [2][3]. It sounds like it could be a good fit for this MC
>> (?).
>
> Does the VM generation ID ACPI device from Microsoft work for you?  It
> is not tied to Hyper-V.
>
> Paolo
>

It's a long story :P

TLDR:

For some use-cases it should be enough [1]. For PRNGs though it doesn't 
seem to work as is. (1) The Linux implementation of VMGENID is racy and 
(2) last year there were long discussions related to the user-space
ABI, which diverged us away from it.

BTW, just saw that you have already submitted the proposal for the MC, 
sorry for being late :)

Cheers,
Babis