linux-kernel - Re: [GIT PULL] KVM: GUEST

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Message-ID: <ZdkO0bgL40l10YnU@google.com>
Date: Fri, 23 Feb 2024 13:32:01 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [GIT PULL] KVM: GUEST_MEMFD fixes for 6.8

On Fri, Feb 23, 2024, Sean Christopherson wrote:
> Minor fixes related GUEST_MEMFD.  I _just_ posted these, and they've only
> been in -next for one night, but I am sending this now to ensure you see it
> asap, as patch 1 in particular affects KVM's ABI, i.e. really should land
> in 6.8 before GUEST_MEMFD support is officially released.
> 
> The following changes since commit c48617fbbe831d4c80fe84056033f17b70a31136:
> 
>   Merge tag 'kvmarm-fixes-6.8-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD (2024-02-21 05:18:56 -0500)
> 
> are available in the Git repository at:
> 
>   https://github.com/kvm-x86/linux.git tags/kvm-x86-guest_memfd_fixes-6.8
> 
> for you to fetch changes up to 2dfd2383034421101300a3b7325cf339a182d218:
> 
>   KVM: selftests: Add a testcase to verify GUEST_MEMFD and READONLY are exclusive (2024-02-22 17:07:06 -0800)
> 
> ----------------------------------------------------------------
> KVM GUEST_MEMFD fixes for 6.8:
> 
>  - Make KVM_MEM_GUEST_MEMFD mutually exclusive with KVM_MEM_READONLY to
>    avoid creating ABI that KVM can't sanely support.
> 
>  - Update documentation for KVM_SW_PROTECTED_VM to make it abundantly
>    clear that such VMs are purely a development and testing vehicle, and
>    come with zero guarantees.
> 
>  - Limit KVM_SW_PROTECTED_VM guests to the TDP MMU, as the long term plan
>    is to support confidential VMs with deterministic private memory (SNP
>    and TDX) only in the TDP MMU.
> 
>  - Fix a bug in a GUEST_MEMFD negative test that resulted in false passes
>    when verifying that KVM_MEM_GUEST_MEMFD memslots can't be dirty logged.
> 
> ----------------------------------------------------------------
> Sean Christopherson (5):
>       KVM: Make KVM_MEM_GUEST_MEMFD mutually exclusive with KVM_MEM_READONLY

Almost forgot, just as an FYI, this has a minor conflict with your kvm/kvm-uapi
branch.  I've been fixing it up in kvm-x86/next, and IIUC you don't feed kvm/master
into -next, so I don't think Stephen will see a conflict?

>       KVM: x86: Update KVM_SW_PROTECTED_VM docs to make it clear they're a WIP
>       KVM: x86/mmu: Restrict KVM_SW_PROTECTED_VM to the TDP MMU
>       KVM: selftests: Create GUEST_MEMFD for relevant invalid flags testcases
>       KVM: selftests: Add a testcase to verify GUEST_MEMFD and READONLY are exclusive
> 
>  Documentation/virt/kvm/api.rst                       |  5 +++++
>  arch/x86/kvm/Kconfig                                 |  7 ++++---
>  arch/x86/kvm/x86.c                                   |  2 +-
>  tools/testing/selftests/kvm/set_memory_region_test.c | 12 +++++++++++-
>  virt/kvm/kvm_main.c                                  |  8 +++++++-
>  5 files changed, 28 insertions(+), 6 deletions(-)