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Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST
From: |
David Hildenbrand |
Subject: |
Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST |
Date: |
Mon, 22 Nov 2021 15:57:17 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 |
On 22.11.21 15:01, Jason Gunthorpe wrote:
> On Mon, Nov 22, 2021 at 02:35:49PM +0100, David Hildenbrand wrote:
>> On 22.11.21 14:31, Jason Gunthorpe wrote:
>>> On Mon, Nov 22, 2021 at 10:26:12AM +0100, David Hildenbrand wrote:
>>>
>>>> I do wonder if we want to support sharing such memfds between processes
>>>> in all cases ... we most certainly don't want to be able to share
>>>> encrypted memory between VMs (I heard that the kernel has to forbid
>>>> that). It would make sense in the use case you describe, though.
>>>
>>> If there is a F_SEAL_XX that blocks every kind of new access, who
>>> cares if userspace passes the FD around or not?
>> I was imagining that you actually would want to do some kind of "change
>> ownership". But yeah, the intended semantics and all use cases we have
>> in mind are not fully clear to me yet. If it's really "no new access"
>> (side note: is "access" the right word?) then sure, we can pass the fd
>> around.
>
> What is "ownership" in a world with kvm and iommu are reading pages
> out of the same fd?
In the world of encrypted memory / TDX, KVM somewhat "owns" that memory
IMHO (for example, only it can migrate or swap out these pages; it's
might be debatable if the TDX module or KVM actually "own" these pages ).
--
Thanks,
David / dhildenb
- [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, (continued)
- [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, Chao Peng, 2021/11/19
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, David Hildenbrand, 2021/11/19
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, Jason Gunthorpe, 2021/11/19
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, David Hildenbrand, 2021/11/19
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, Jason Gunthorpe, 2021/11/19
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, David Hildenbrand, 2021/11/22
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, Jason Gunthorpe, 2021/11/22
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, David Hildenbrand, 2021/11/22
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, Jason Gunthorpe, 2021/11/22
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST,
David Hildenbrand <=
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, Jason Gunthorpe, 2021/11/22
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, David Hildenbrand, 2021/11/22
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, Sean Christopherson, 2021/11/19
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, Jason Gunthorpe, 2021/11/19
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, Sean Christopherson, 2021/11/19
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, Jason Gunthorpe, 2021/11/19
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, Sean Christopherson, 2021/11/19
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, Jason Gunthorpe, 2021/11/20
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, Paolo Bonzini, 2021/11/23
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, Chao Peng, 2021/11/23