linux-kernel - Re: [RFC PATCH 0/5] Add TDX intra host migration support

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Date:   Fri, 14 Apr 2023 12:09:15 -0700
From:   Sagi Shahar <sagis@...gle.com>
To:     Zhi Wang <zhi.wang.linux@...il.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org,
        Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Isaku Yamahata <isaku.yamahata@...el.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Kai Huang <kai.huang@...el.com>,
        Chao Peng <chao.p.peng@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [RFC PATCH 0/5] Add TDX intra host migration support

On Fri, Apr 14, 2023 at 12:04 AM Zhi Wang <zhi.wang.linux@...il.com> wrote:
>
> On Fri,  7 Apr 2023 20:19:16 +0000
> Sagi Shahar <sagis@...gle.com> wrote:
>
> Hi:
>
> Is there any userspace using these APIs? I cant find them in AMD-QEMU repo
> and upstream QEMU repo. It would nice to first take a look on how userspace
> is going to use it.
>
We are using a different userspace VMM internally so we didn't make
changes to QEMU.
I've uploaded our selftests which exercise these APIs to our public
GitHub so you can take a look there:
https://github.com/googleprodkernel/linux-cc/commit/62c8dba4c3cf06e375018077a6d9f491c933dc6d

Note that these are a slightly older version based on TDX V10 API.
They also use the
KVM_CAP_VM_COPY_ENC_CONTEXT_FROM instead of KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM

> > This patchset adds support for TDX intra host migration using the same
> > API which was added for SEV intra host migration here:
> > https://lore.kernel.org/all/20211021174303.385706-1-pgonda@google.com/
> >
> > This patchset relies on the latest TDX patches from Intel:
> > - fd-based approach for supporing KVM v10 and
> >   https://lore.kernel.org/lkml/20221202061347.1070246-1-chao.p.peng@linux.intel.com/
> > - TDX host kernel support v10
> >   https://lore.kernel.org/lkml/cover.1678111292.git.kai.huang@intel.com/
> > - KVM TDX basic feature support v13
> >   https://lore.kernel.org/cover.1678643051.git.isaku.yamahata@intel.com
> >
> > The tree can be found at https://github.com/googleprodkernel/linux-cc/tree/copyless
> > and is based on Intel's tdx tree at https://github.com/intel/tdx/tree/kvm-upstream
> >
> > In the TDX case, we need to transfer the VM state from multiple sources:
> >
> >  * HKID and encrypted VM state is transfered between the kvm_tdx
> >    objects.
> >  * Encrypted and runtime state is transfered between the vcpu_tdx
> >    objects.
> >  * The EPT table backing TD's private memory is transfered at the
> >    kvm-mmu level. This is needed since the secure EPT table managed by
> >    the TD module remains the same after the migration so moving the
> >    current private EPT table eliminates the need to rebuild the private
> >    EPT table to match the secure EPT table on the destination.
> >  * Information regarding the current shared/private memory is trasfered
> >    using the mem_attr_array stored at the kvm object.
> >  * Additional information derived from shared/private memory state is
> >    trasfered at the memslot level.
> >
> > Tested with selftests locally. I will attach the self test in the next
> > version after we send the new TDX selftest framework patches based on
> > KVM TDX basic feature support v13.
> >
> > Sagi Shahar (5):
> >   KVM: Split tdp_mmu_pages to private and shared lists
> >   KVM: SEV: Refactor common code out of sev_vm_move_enc_context_from
> >   KVM: TDX: Add base implementation for tdx_vm_move_enc_context_from
> >   KVM: TDX: Implement moving private pages between 2 TDs
> >   KVM: TDX: Add core logic for TDX intra-host migration
> >
> >  arch/x86/include/asm/kvm_host.h |   5 +-
> >  arch/x86/kvm/mmu.h              |   2 +
> >  arch/x86/kvm/mmu/mmu.c          |  60 ++++++++
> >  arch/x86/kvm/mmu/tdp_mmu.c      |  88 +++++++++++-
> >  arch/x86/kvm/mmu/tdp_mmu.h      |   3 +
> >  arch/x86/kvm/svm/sev.c          | 175 +++--------------------
> >  arch/x86/kvm/vmx/main.c         |  10 ++
> >  arch/x86/kvm/vmx/tdx.c          | 245 ++++++++++++++++++++++++++++++++
> >  arch/x86/kvm/vmx/tdx.h          |   2 +
> >  arch/x86/kvm/vmx/x86_ops.h      |   5 +
> >  arch/x86/kvm/x86.c              | 166 ++++++++++++++++++++++
> >  arch/x86/kvm/x86.h              |  16 +++
> >  12 files changed, 613 insertions(+), 164 deletions(-)
> >
>