Re: [PULL 00/19] KVM: Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support

[Michael Roth]

On Fri, May 10, 2024 at 04:10:05PM -0500, Michael Roth wrote:
> Hi Paolo,
> 
> This pull request contains v15 of the KVM SNP support patchset[1] along
> with fixes and feedback from you and Sean regarding PSC request processing,
> fast_page_fault() handling for SNP/TDX, and avoiding uncessary
> PSMASH/zapping for KVM_EXIT_MEMORY_FAULT events. It's also been rebased
> on top of kvm/queue (commit 1451476151e0), and re-tested with/without
> 2MB gmem pages enabled.

As discussed during the PUCK call, here is a branch with fixup patches
that incorporate the additional review/testing that came in after these
patches were merged into kvm/next:

  https://github.com/mdroth/linux/commits/kvm-next-snp-fixes4/

They are intended to be squashed in but can also be applied on top if
that's preferable (but in that case the first 2 patches need to be
squashed together to maintain build bisectability):

 [SQUASH] KVM: SVM: Remove the need to trigger an UNBLOCK event on AP creation
   - drops handling for KVM_MP_STATE_UNINITIALIZED since no special
     handling for it will be needed until SVSM support is added in OVMF
     and the host kernel has the necessary support for running
     SVSM-enabled guests
   - to be squashed into:
     KVM: SEV: Support SEV-SNP AP Creation NAE event

 [SQUASH] KVM: SEV: Don't WARN() if RMP lookup fails when invalidating gmem pages
   - address the WARN() that Sean noticed when running guest_memfd_test
     kselftest on an AMD system without SNP enabled
   - to be squashed into:
     KVM: SEV: Implement gmem hook for invalidating private pages

 [SQUASH] KVM: SEV: Use new kvm_rmp_make_shared() naming
   - fixup to handle helper function being renamed in prior patch
   - to be squashed into:
     KVM: SEV: Add KVM_SEV_SNP_LAUNCH_FINISH command
     
 [SQUASH] KVM: SEV: Automatically switch reclaimed pages to shared
   - implement suggestion from Sean to always switch reclaimed pages to shared
     since that's what the callers all end up doing anyway
   - to be squashed into:
     KVM: SEV: Add KVM_SEV_SNP_LAUNCH_UPDATE command

As discussed at PUCK I will resubmit the guest requests patches
separately will all the pending changes incorporated.

Thanks!

-Mike

> 
> Thanks!
> 
> -Mike
> 
> [1] https://lore.kernel.org/kvm/20240501085210.2213060-1-michael.roth@xxxxxxx/
> 
> The following changes since commit 1451476151e08e1e83ff07ce69dd0d1d025e976e:
> 
>   Merge commit 'kvm-coco-hooks' into HEAD (2024-05-10 13:20:42 -0400)
> 
> are available in the Git repository at:
> 
>   https://github.com/mdroth/linux.git tags/tags/kvm-queue-snp
> 
> for you to fetch changes up to 4b3f0135f759bb1a54bb28d644c38a7780150eda:
> 
>   crypto: ccp: Add the SNP_VLEK_LOAD command (2024-05-10 14:44:31 -0500)
> 
> ----------------------------------------------------------------
> Base x86 KVM support for running SEV-SNP guests:
> 
>  - add some basic infrastructure and introduces a new KVM_X86_SNP_VM
>    vm_type to handle differences versus the existing KVM_X86_SEV_VM and
>    KVM_X86_SEV_ES_VM types.
> 
>  - implement the KVM API to handle the creation of a cryptographic
>    launch context, encrypt/measure the initial image into guest memory,
>    and finalize it before launching it.
> 
>  - implement handling for various guest-generated events such as page
>    state changes, onlining of additional vCPUs, etc.
> 
>  - implement the gmem/mmu hooks needed to prepare gmem-allocated pages
>    before mapping them into guest private memory ranges as well as
>    cleaning them up prior to returning them to the host for use as
>    normal memory. Because those cleanup hooks supplant certain
>    activities like issuing WBINVDs during KVM MMU invalidations, avoid
>    duplicating that work to avoid unecessary overhead.
> 
>  - add support for the servicing of guest requests to handle things like
>    attestation, as well as some related host-management interfaces to
>    handle updating firmware's signing key for attestation requests
> 
> ----------------------------------------------------------------
> Ashish Kalra (1):
>       KVM: SEV: Avoid WBINVD for HVA-based MMU notifications for SNP
> 
> Brijesh Singh (8):
>       KVM: SEV: Add initial SEV-SNP support
>       KVM: SEV: Add KVM_SEV_SNP_LAUNCH_START command
>       KVM: SEV: Add KVM_SEV_SNP_LAUNCH_UPDATE command
>       KVM: SEV: Add KVM_SEV_SNP_LAUNCH_FINISH command
>       KVM: SEV: Add support to handle GHCB GPA register VMGEXIT
>       KVM: SEV: Add support to handle RMP nested page faults
>       KVM: SVM: Add module parameter to enable SEV-SNP
>       KVM: SEV: Provide support for SNP_GUEST_REQUEST NAE event
> 
> Michael Roth (9):
>       KVM: MMU: Disable fast path if KVM_EXIT_MEMORY_FAULT is needed
>       KVM: SEV: Select KVM_GENERIC_PRIVATE_MEM when CONFIG_KVM_AMD_SEV=y
>       KVM: SEV: Add support to handle MSR based Page State Change VMGEXIT
>       KVM: SEV: Add support to handle Page State Change VMGEXIT
>       KVM: SEV: Implement gmem hook for initializing private pages
>       KVM: SEV: Implement gmem hook for invalidating private pages
>       KVM: x86: Implement hook for determining max NPT mapping level
>       KVM: SEV: Provide support for SNP_EXTENDED_GUEST_REQUEST NAE event
>       crypto: ccp: Add the SNP_VLEK_LOAD command
> 
> Tom Lendacky (1):
>       KVM: SEV: Support SEV-SNP AP Creation NAE event
> 
>  Documentation/virt/coco/sev-guest.rst              |   19 +
>  Documentation/virt/kvm/api.rst                     |   87 ++
>  .../virt/kvm/x86/amd-memory-encryption.rst         |  110 +-
>  arch/x86/include/asm/kvm_host.h                    |    2 +
>  arch/x86/include/asm/sev-common.h                  |   25 +
>  arch/x86/include/asm/sev.h                         |    3 +
>  arch/x86/include/asm/svm.h                         |    9 +-
>  arch/x86/include/uapi/asm/kvm.h                    |   48 +
>  arch/x86/kvm/Kconfig                               |    3 +
>  arch/x86/kvm/mmu.h                                 |    2 -
>  arch/x86/kvm/mmu/mmu.c                             |   25 +-
>  arch/x86/kvm/svm/sev.c                             | 1546 +++++++++++++++++++-
>  arch/x86/kvm/svm/svm.c                             |   37 +-
>  arch/x86/kvm/svm/svm.h                             |   52 +
>  arch/x86/kvm/trace.h                               |   31 +
>  arch/x86/kvm/x86.c                                 |   17 +
>  drivers/crypto/ccp/sev-dev.c                       |   36 +
>  include/linux/psp-sev.h                            |    4 +-
>  include/uapi/linux/kvm.h                           |   23 +
>  include/uapi/linux/psp-sev.h                       |   27 +
>  include/uapi/linux/sev-guest.h                     |    9 +
>  virt/kvm/guest_memfd.c                             |    4 +-
>  22 files changed, 2086 insertions(+), 33 deletions(-)
> 
>