linux-kernel - Re: [RFC PATCH 26/39] KVM: guest_memfd: Track faultability within a struct kvm_gmem

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <a63f0f7a-e367-4f0e-8d8e-ca7b632712df@redhat.com>
Date: Thu, 17 Oct 2024 19:11:46 +0200
From: David Hildenbrand <david@...hat.com>
To: Jason Gunthorpe <jgg@...dia.com>, Peter Xu <peterx@...hat.com>
Cc: Ackerley Tng <ackerleytng@...gle.com>, tabba@...gle.com,
 quic_eberman@...cinc.com, roypat@...zon.co.uk, rientjes@...gle.com,
 fvdl@...gle.com, jthoughton@...gle.com, seanjc@...gle.com,
 pbonzini@...hat.com, zhiquan1.li@...el.com, fan.du@...el.com,
 jun.miao@...el.com, isaku.yamahata@...el.com, muchun.song@...ux.dev,
 erdemaktas@...gle.com, vannapurve@...gle.com, qperret@...gle.com,
 jhubbard@...dia.com, willy@...radead.org, shuah@...nel.org,
 brauner@...nel.org, bfoster@...hat.com, kent.overstreet@...ux.dev,
 pvorel@...e.cz, rppt@...nel.org, richard.weiyang@...il.com,
 anup@...infault.org, haibo1.xu@...el.com, ajones@...tanamicro.com,
 vkuznets@...hat.com, maciej.wieczor-retman@...el.com, pgonda@...gle.com,
 oliver.upton@...ux.dev, linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 kvm@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [RFC PATCH 26/39] KVM: guest_memfd: Track faultability within a
 struct kvm_gmem_private

On 17.10.24 18:47, Jason Gunthorpe wrote:
> On Thu, Oct 17, 2024 at 10:58:29AM -0400, Peter Xu wrote:
> 
>> My question was more torwards whether gmemfd could still expose the
>> possibility to be used in VA forms to other modules that may not support
>> fd+offsets yet.
> 
> I keep hearing they don't want to support page pinning on a guestmemfd
> mapping, so VA based paths could not work.

For shared pages it absolutely must work. That's what I keep hearing :)

> 
>> I think as long as we can provide gmemfd VMAs like what this series
>> provides, it sounds possible to reuse the old VA interfaces before the CoCo
>> interfaces are ready, so that people can already start leveraging gmemfd
>> backing pages.
> 
> And you definitely can't get the private pages out of the VA interface
> because all the VMA PTEs of private pages are non-present by definition.

Agreed.

-- 
Cheers,

David / dhildenb