[RFC PATCH 0/4] SEV-SNP guest policy bit support updates

Tom Lendacky posted 4 patches 1 month, 1 week ago
There is a newer version of this series
arch/x86/include/uapi/asm/kvm.h |  1 +
arch/x86/kvm/svm/sev.c          | 45 +++++++++++++++++++++------------
arch/x86/kvm/svm/svm.h          |  3 ---
drivers/crypto/ccp/sev-dev.c    | 37 +++++++++++++++++++++++++++
include/linux/psp-sev.h         | 39 ++++++++++++++++++++++++++++
5 files changed, 106 insertions(+), 19 deletions(-)
[RFC PATCH 0/4] SEV-SNP guest policy bit support updates
Posted by Tom Lendacky 1 month, 1 week ago
This series aims to allow more flexibility in specifying SEV-SNP policy
bits by improving discoverability of supported policy bits from userspace
and enabling support for newer policy bits.

- The first patch adds a new KVM_X86_GRP_SEV attribute group,
  KVM_X86_SNP_POLICY_BITS, that can be used to return the supported
  SEV-SNP policy bits. The initial support for this attribute will return
  the current KVM supported policy bitmask.

- The next 3 patches provide for adding to the known SEV-SNP policy
  bits. Since some policy bits are dependent on specific levels of SEV
  firmware support, the CCP driver is updated to provide an API to return
  the supported policy bits.

  The supported policy bits bitmask used by KVM is generated by taking the
  policy bitmask returned by the CCP driver and ANDing it with the KVM
  supported policy bits. KVM supported policy bits are policy bits that
  do not require any specific implementation support from KVM to allow.

This series has a prereq against the ciphertext hiding patches that were
recently accepted into the cryptodev tree.

The series is based off of:
  git://git.kernel.org/pub/scm/virt/kvm/kvm.git next

  with the added the ciphertext hiding patches

Tom Lendacky (4):
  KVM: SEV: Publish supported SEV-SNP policy bits
  KVM: SEV: Consolidate the SEV policy bits in a single header file
  crypto: ccp - Add an API to return the supported SEV-SNP policy bits
  KVM: SEV: Add known supported SEV-SNP policy bits

 arch/x86/include/uapi/asm/kvm.h |  1 +
 arch/x86/kvm/svm/sev.c          | 45 +++++++++++++++++++++------------
 arch/x86/kvm/svm/svm.h          |  3 ---
 drivers/crypto/ccp/sev-dev.c    | 37 +++++++++++++++++++++++++++
 include/linux/psp-sev.h         | 39 ++++++++++++++++++++++++++++
 5 files changed, 106 insertions(+), 19 deletions(-)


base-commit: 82a56258ec2d48f9bb1e9ce8f26b14c161dfe4fb
-- 
2.46.2
Re: [RFC PATCH 0/4] SEV-SNP guest policy bit support updates
Posted by Sean Christopherson 3 weeks, 2 days ago
On Fri, Aug 22, 2025, Tom Lendacky wrote:
> This series aims to allow more flexibility in specifying SEV-SNP policy
> bits by improving discoverability of supported policy bits from userspace
> and enabling support for newer policy bits.
> 
> - The first patch adds a new KVM_X86_GRP_SEV attribute group,
>   KVM_X86_SNP_POLICY_BITS, that can be used to return the supported
>   SEV-SNP policy bits. The initial support for this attribute will return
>   the current KVM supported policy bitmask.
> 
> - The next 3 patches provide for adding to the known SEV-SNP policy
>   bits. Since some policy bits are dependent on specific levels of SEV
>   firmware support, the CCP driver is updated to provide an API to return
>   the supported policy bits.
> 
>   The supported policy bits bitmask used by KVM is generated by taking the
>   policy bitmask returned by the CCP driver and ANDing it with the KVM
>   supported policy bits. KVM supported policy bits are policy bits that
>   do not require any specific implementation support from KVM to allow.
> 
> This series has a prereq against the ciphertext hiding patches that were
> recently accepted into the cryptodev tree.

I'm still waiting on a stable tag for that branch.  Can I get that, and if the
CCP changes look good, Acks on those patches?  I'd prefer to take this through
kvm-x86 since it adds new uAPI, even though that uAPI is fairly trivial.

Uber nits aside, looks good (though I admittedly haven't stared all that hard).

> The series is based off of:
>   git://git.kernel.org/pub/scm/virt/kvm/kvm.git next
> 
>   with the added the ciphertext hiding patches
> 
> Tom Lendacky (4):
>   KVM: SEV: Publish supported SEV-SNP policy bits
>   KVM: SEV: Consolidate the SEV policy bits in a single header file
>   crypto: ccp - Add an API to return the supported SEV-SNP policy bits
>   KVM: SEV: Add known supported SEV-SNP policy bits
> 
>  arch/x86/include/uapi/asm/kvm.h |  1 +
>  arch/x86/kvm/svm/sev.c          | 45 +++++++++++++++++++++------------
>  arch/x86/kvm/svm/svm.h          |  3 ---
>  drivers/crypto/ccp/sev-dev.c    | 37 +++++++++++++++++++++++++++
>  include/linux/psp-sev.h         | 39 ++++++++++++++++++++++++++++
>  5 files changed, 106 insertions(+), 19 deletions(-)
> 
> 
> base-commit: 82a56258ec2d48f9bb1e9ce8f26b14c161dfe4fb
> -- 
> 2.46.2
>