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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: |
Tue, 23 Nov 2021 16:20:02 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 |
On 23.11.21 10:06, Paolo Bonzini wrote:
> On 11/19/21 16:39, David Hildenbrand wrote:
>>> If qmeu can put all the guest memory in a memfd and not map it, then
>>> I'd also like to see that the IOMMU can use this interface too so we
>>> can have VFIO working in this configuration.
>>
>> In QEMU we usually want to (and must) be able to access guest memory
>> from user space, with the current design we wouldn't even be able to
>> temporarily mmap it -- which makes sense for encrypted memory only. The
>> corner case really is encrypted memory. So I don't think we'll see a
>> broad use of this feature outside of encrypted VMs in QEMU. I might be
>> wrong, most probably I am:)
>
> It's not _that_ crazy an idea, but it's going to be some work to teach
> KVM that it has to kmap/kunmap around all memory accesses.
I'm also concerned about userspace access. But you sound like you have a
plan :)
--
Thanks,
David / dhildenb
- Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, (continued)
- 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
- 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, 2021/11/23
Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST, Paolo Bonzini, 2021/11/23
[RFC v2 PATCH 02/13] KVM: Add KVM_EXIT_MEMORY_ERROR exit, Chao Peng, 2021/11/19
[RFC v2 PATCH 03/13] KVM: Extend kvm_userspace_memory_region to support fd based memslot, Chao Peng, 2021/11/19
[RFC v2 PATCH 04/13] KVM: Add fd-based memslot data structure and utils, Chao Peng, 2021/11/19
[RFC v2 PATCH 05/13] KVM: Implement fd-based memory using new memfd interfaces, Chao Peng, 2021/11/19
[RFC v2 PATCH 06/13] KVM: Register/unregister memfd backed memslot, Chao Peng, 2021/11/19