From: Michael Roth <michael.roth@amd.com>
To: Chao Peng <chao.p.peng@linux.intel.com>
Cc: <kvm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-mm@kvack.org>, <linux-fsdevel@vger.kernel.org>,
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Jonathan Corbet <corbet@lwn.net>,
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Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
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Subject: Re: [PATCH v7 00/14] KVM: mm: fd-based approach for supporting KVM guest private memory
Date: Fri, 9 Sep 2022 10:35:22 -0500 [thread overview]
Message-ID: <20220909153522.r2a4amvtfp7l56zo@amd.com> (raw)
In-Reply-To: <20220706082016.2603916-1-chao.p.peng@linux.intel.com>
On Wed, Jul 06, 2022 at 04:20:02PM +0800, Chao Peng wrote:
> This is the v7 of this series which tries to implement the fd-based KVM
> guest private memory. The patches are based on latest kvm/queue branch
> commit:
>
> b9b71f43683a (kvm/queue) KVM: x86/mmu: Buffer nested MMU
> split_desc_cache only by default capacity
>
> Introduction
> ------------
> In general this patch series introduce fd-based memslot which provides
> guest memory through memory file descriptor fd[offset,size] instead of
> hva/size. The fd can be created from a supported memory filesystem
> like tmpfs/hugetlbfs etc. which we refer as memory backing store. KVM
> and the the memory backing store exchange callbacks when such memslot
> gets created. At runtime KVM will call into callbacks provided by the
> backing store to get the pfn with the fd+offset. Memory backing store
> will also call into KVM callbacks when userspace punch hole on the fd
> to notify KVM to unmap secondary MMU page table entries.
>
> Comparing to existing hva-based memslot, this new type of memslot allows
> guest memory unmapped from host userspace like QEMU and even the kernel
> itself, therefore reduce attack surface and prevent bugs.
>
> Based on this fd-based memslot, we can build guest private memory that
> is going to be used in confidential computing environments such as Intel
> TDX and AMD SEV. When supported, the memory backing store can provide
> more enforcement on the fd and KVM can use a single memslot to hold both
> the private and shared part of the guest memory.
Hi everyone,
Just wanted to let you all know that I reserved a slot at the LPC
Confidential Computing Microconference to discuss some topics related
to unmapped/inaccessible private memory support:
"Unmapped Private Memory for Confidential Guests"
Tuesday, Sep 13th, 10:00am (Dublin time)
https://lpc.events/event/16/sessions/133/#20220913
The discussion agenda is still a bit in flux, but one topic I really
wanted to cover is how we intend to deal with the kernel directmap
for TDX/SNP, where there is a need to either remove or split mappings
so that KVM or other kernel threads writing to non-private pages
don't run into issues due mappings overlapping with private pages.[1]
Other possible discussion topics:
- guarding against shared->private conversions while KVM is
attempting to access a shared page (separate PFN pools for
shared/private seems to resolve this nicely, but may not be
compatible with things like pKVM where the underlying PFN
is the same for shared/private)[2]
- extending KVM_EXIT_MEMORY_FAULT to handle batched requests to
better handle things like explicit batched conversions initiated
by the guest
It's a short session so not sure how much time we'll actually have
to discuss things in detail, but maybe this can at least be a good
jumping off point for other discussions.
Thanks, and hope to see you there!
[1] https://lore.kernel.org/all/YWb8WG6Ravbs1nbx@google.com/
[2] https://lore.kernel.org/lkml/CA+EHjTy6NF=BkCqK0vhXLdtKZMahp55JUMSfxN96-NT3YiMXYQ@mail.gmail.com/
prev parent reply other threads:[~2022-09-09 15:38 UTC|newest]
Thread overview: 172+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-06 8:20 [PATCH v7 00/14] KVM: mm: fd-based approach for supporting KVM guest private memory Chao Peng
2022-07-06 8:20 ` [PATCH v7 01/14] mm: Add F_SEAL_AUTO_ALLOCATE seal to memfd Chao Peng
2022-07-21 9:44 ` David Hildenbrand
2022-07-21 9:50 ` David Hildenbrand
2022-07-21 15:05 ` Sean Christopherson
2022-07-25 13:46 ` Chao Peng
2022-07-21 10:27 ` Gupta, Pankaj
2022-07-25 13:54 ` Chao Peng
2022-07-25 14:49 ` Gupta, Pankaj
2022-07-25 13:42 ` Chao Peng
2022-08-05 17:55 ` Paolo Bonzini
2022-08-05 18:06 ` David Hildenbrand
2022-08-10 9:40 ` Chao Peng
2022-08-10 9:38 ` Chao Peng
2022-08-17 23:41 ` Kirill A. Shutemov
2022-08-18 9:09 ` Paolo Bonzini
2022-08-23 7:36 ` David Hildenbrand
2022-08-24 10:20 ` Chao Peng
2022-08-26 15:19 ` Fuad Tabba
2022-08-29 15:18 ` Chao Peng
2022-07-06 8:20 ` [PATCH v7 02/14] selftests/memfd: Add tests for F_SEAL_AUTO_ALLOCATE Chao Peng
2022-08-05 13:11 ` David Hildenbrand
2022-07-06 8:20 ` [PATCH v7 03/14] mm: Introduce memfile_notifier Chao Peng
2022-08-05 13:22 ` David Hildenbrand
2022-08-10 9:22 ` Chao Peng
2022-08-10 10:05 ` David Hildenbrand
2022-08-10 14:38 ` Sean Christopherson
2022-08-11 12:27 ` Quentin Perret
2022-08-11 13:39 ` Chao Peng
2022-07-06 8:20 ` [PATCH v7 04/14] mm/shmem: Support memfile_notifier Chao Peng
2022-07-12 18:02 ` Gupta, Pankaj
2022-07-13 7:44 ` Chao Peng
2022-07-13 10:01 ` Gupta, Pankaj
2022-07-13 23:49 ` Chao Peng
2022-07-14 4:15 ` Gupta, Pankaj
2022-08-05 13:26 ` David Hildenbrand
2022-08-10 9:25 ` Chao Peng
2022-07-06 8:20 ` [PATCH v7 05/14] mm/memfd: Introduce MFD_INACCESSIBLE flag Chao Peng
2022-08-05 13:28 ` David Hildenbrand
2022-08-10 9:37 ` Chao Peng
2022-08-10 9:55 ` David Hildenbrand
2022-08-11 13:17 ` Chao Peng
2022-09-07 16:18 ` Kirill A. Shutemov
2022-07-06 8:20 ` [PATCH v7 06/14] KVM: Rename KVM_PRIVATE_MEM_SLOTS to KVM_INTERNAL_MEM_SLOTS Chao Peng
2022-07-06 8:20 ` [PATCH v7 07/14] KVM: Use gfn instead of hva for mmu_notifier_retry Chao Peng
2022-07-15 11:36 ` Gupta, Pankaj
2022-07-18 13:29 ` Chao Peng
2022-07-18 15:26 ` Sean Christopherson
2022-07-19 14:02 ` Chao Peng
2022-08-04 7:10 ` Isaku Yamahata
2022-08-10 8:19 ` Chao Peng
2022-07-06 8:20 ` [PATCH v7 08/14] KVM: Rename mmu_notifier_* Chao Peng
2022-07-29 19:02 ` Sean Christopherson
2022-08-03 10:13 ` Chao Peng
2022-08-05 19:54 ` Paolo Bonzini
2022-08-10 8:09 ` Chao Peng
2023-05-23 7:19 ` Kautuk Consul
2023-05-23 14:19 ` Sean Christopherson
2023-05-24 6:12 ` Kautuk Consul
2023-05-24 20:16 ` Sean Christopherson
2023-05-24 20:33 ` Peter Zijlstra
2023-05-24 21:39 ` Sean Christopherson
2023-05-25 8:54 ` Peter Zijlstra
2023-05-25 3:52 ` Kautuk Consul
2023-05-24 20:28 ` Peter Zijlstra
2022-07-06 8:20 ` [PATCH v7 09/14] KVM: Extend the memslot to support fd-based private memory Chao Peng
2022-07-29 19:51 ` Sean Christopherson
2022-08-03 10:08 ` Chao Peng
2022-08-03 14:42 ` Sean Christopherson
2022-07-06 8:20 ` [PATCH v7 10/14] KVM: Add KVM_EXIT_MEMORY_FAULT exit Chao Peng
2022-07-06 8:20 ` [PATCH v7 11/14] KVM: Register/unregister the guest private memory regions Chao Peng
2022-07-19 8:00 ` Gupta, Pankaj
2022-07-19 14:08 ` Chao Peng
2022-07-19 14:23 ` Gupta, Pankaj
2022-07-20 15:07 ` Chao Peng
2022-07-20 15:31 ` Gupta, Pankaj
2022-07-20 16:21 ` Sean Christopherson
2022-07-20 17:41 ` Gupta, Pankaj
2022-07-21 7:34 ` Wei Wang
2022-07-21 9:29 ` Chao Peng
2022-07-21 17:58 ` Sean Christopherson
2022-07-25 13:04 ` Chao Peng
2022-07-29 19:54 ` Sean Christopherson
2022-08-02 0:49 ` Sean Christopherson
2022-08-02 16:38 ` Sean Christopherson
2022-08-03 9:48 ` Chao Peng
2022-08-03 15:51 ` Sean Christopherson
2022-08-04 7:58 ` Chao Peng
2022-07-20 16:44 ` Sean Christopherson
2022-07-21 9:37 ` Chao Peng
2022-08-19 19:37 ` Vishal Annapurve
2022-08-24 10:37 ` Chao Peng
2022-08-26 15:19 ` Fuad Tabba
2022-08-29 15:21 ` Chao Peng
2022-07-06 8:20 ` [PATCH v7 12/14] KVM: Handle page fault for private memory Chao Peng
2022-07-29 20:58 ` Sean Christopherson
2022-08-03 9:52 ` Chao Peng
2022-07-06 8:20 ` [PATCH v7 13/14] KVM: Enable and expose KVM_MEM_PRIVATE Chao Peng
2022-07-19 9:55 ` Gupta, Pankaj
2022-07-19 14:12 ` Chao Peng
2022-07-06 8:20 ` [PATCH v7 14/14] memfd_create.2: Describe MFD_INACCESSIBLE flag Chao Peng
2022-08-01 14:40 ` Dave Hansen
2022-08-03 9:53 ` Chao Peng
2022-07-13 3:58 ` [PATCH v7 00/14] KVM: mm: fd-based approach for supporting KVM guest private memory Gupta, Pankaj
2022-07-13 7:57 ` Chao Peng
2022-07-13 10:35 ` Gupta, Pankaj
2022-07-13 23:59 ` Chao Peng
2022-07-14 4:39 ` Gupta, Pankaj
2022-07-14 5:06 ` Gupta, Pankaj
2022-07-14 4:29 ` Andy Lutomirski
2022-07-14 5:13 ` Gupta, Pankaj
2022-08-11 10:02 ` Nikunj A. Dadhania
2022-08-11 11:30 ` Gupta, Pankaj
2022-08-11 13:32 ` Chao Peng
2022-08-11 17:28 ` Nikunj A. Dadhania
2022-08-12 3:22 ` Nikunj A. Dadhania
2022-08-11 17:18 ` Nikunj A. Dadhania
2022-08-11 23:02 ` Gupta, Pankaj
2022-08-12 6:02 ` Gupta, Pankaj
2022-08-12 7:18 ` Gupta, Pankaj
2022-08-12 8:48 ` Nikunj A. Dadhania
2022-08-12 9:33 ` Gupta, Pankaj
2022-08-15 13:04 ` Chao Peng
2022-08-16 4:28 ` Nikunj A. Dadhania
2022-08-16 11:33 ` Gupta, Pankaj
2022-08-16 12:24 ` Kirill A . Shutemov
2022-08-16 13:03 ` Gupta, Pankaj
2022-08-16 15:38 ` Sean Christopherson
2022-08-17 15:27 ` Michael Roth
2022-08-23 1:25 ` Isaku Yamahata
2022-08-23 17:41 ` Gupta, Pankaj
2022-08-18 5:40 ` Hugh Dickins
2022-08-18 13:24 ` Kirill A . Shutemov
2022-08-19 0:20 ` Sean Christopherson
2022-08-19 3:38 ` Hugh Dickins
2022-08-19 22:53 ` Sean Christopherson
2022-08-23 7:55 ` David Hildenbrand
2022-08-23 16:05 ` Sean Christopherson
2022-08-24 9:41 ` Chao Peng
2022-09-09 4:55 ` Andy Lutomirski
2022-08-19 3:00 ` Hugh Dickins
2022-08-20 0:27 ` Kirill A. Shutemov
2022-08-21 5:15 ` Hugh Dickins
2022-08-31 14:24 ` Kirill A . Shutemov
2022-09-02 10:27 ` Chao Peng
2022-09-02 12:30 ` Kirill A . Shutemov
2022-09-08 1:10 ` Kirill A. Shutemov
2022-09-13 9:44 ` Sean Christopherson
2022-09-13 13:28 ` Kirill A. Shutemov
2022-09-13 14:53 ` Sean Christopherson
2022-09-13 16:00 ` Kirill A. Shutemov
2022-09-13 16:12 ` Sean Christopherson
2022-09-09 4:48 ` Andy Lutomirski
2022-09-09 14:32 ` Kirill A . Shutemov
2022-09-09 19:11 ` Andy Lutomirski
2022-09-09 23:02 ` Kirill A . Shutemov
2022-08-21 10:27 ` Matthew Wilcox
2022-08-24 10:27 ` Chao Peng
2022-09-09 4:44 ` Andy Lutomirski
[not found] ` <diqzlej60z57.fsf@ackerleytng-cloudtop.c.googlers.com>
[not found] ` <20221202061347.1070246-2-chao.p.peng@linux.intel.com>
2023-04-13 15:25 ` Christian Brauner
2023-04-13 22:28 ` Sean Christopherson
2023-04-14 22:38 ` Ackerley Tng
2023-04-14 23:26 ` Sean Christopherson
2023-04-15 0:06 ` Sean Christopherson
2023-04-19 8:29 ` Christian Brauner
2023-04-20 0:49 ` Sean Christopherson
2023-04-20 8:35 ` Christian Brauner
2022-08-26 15:19 ` Fuad Tabba
2022-08-29 15:17 ` Chao Peng
2022-08-31 9:12 ` Fuad Tabba
2022-09-02 10:19 ` Chao Peng
2022-09-09 15:35 ` Michael Roth [this message]
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