Re: [RFC PATCH 0/6] Add AMD Secure Nested Paging (SEV-SNP) support

Dov Murik
2021-07-13T08:05:59Z

Brijesh,

On 10/07/2021 0:55, Brijesh Singh wrote:
> SEV-SNP builds upon existing SEV and SEV-ES functionality while adding
> new hardware-based memory protections. SEV-SNP adds strong memory integrity
> protection to help prevent malicious hypervisor-based attacks like data
> replay, memory re-mapping and more in order to create an isolated memory
> encryption environment.
>
> The patches to support the SEV-SNP in Linux kernel and OVMF are available:
> https://lore.kernel.org/kvm/20210707181506.30489-1-brijesh.singh@amd.com/
> https://lore.kernel.org/kvm/20210707183616.5620-1-brijesh.singh@amd.com/
> https://edk2.groups.io/g/devel/message/77335?p=,,,20,0,0,0::Created,,posterid%3A5969970,20,2,20,83891508
>
> The Qemu patches uses the command id added by the SEV-SNP hypervisor
> patches to bootstrap the SEV-SNP VMs.
>
> TODO:
> * Add support to filter CPUID values through the PSP.
>
> Additional resources
> ---------------------
> SEV-SNP whitepaper
> https://www.amd.com/system/files/TechDocs/SEV-SNP-strengthening-vm-isolation-with-integrity-protection-and-more.pdf
>
> APM 2: https://www.amd.com/system/files/TechDocs/24593.pdf (section 15.36)
>
> GHCB spec:
> https://developer.amd.com/wp-content/resources/56421.pdf
>
> SEV-SNP firmware specification:
> https://www.amd.com/system/files/TechDocs/56860.pdf
>
> Brijesh Singh (6):
> linux-header: add the SNP specific command
> i386/sev: extend sev-guest property to include SEV-SNP
> i386/sev: initialize SNP context
> i386/sev: add the SNP launch start context
> i386/sev: add support to encrypt BIOS when SEV-SNP is enabled
> i386/sev: populate secrets and cpuid page and finalize the SNP launch
>
> docs/amd-memory-encryption.txt | 81 +++++-
> linux-headers/linux/kvm.h | 47 ++++
> qapi/qom.json | 6 +
> target/i386/sev.c | 498 ++++++++++++++++++++++++++++++++-
> target/i386/sev_i386.h | 1 +
> target/i386/trace-events | 4 +
> 6 files changed, 628 insertions(+), 9 deletions(-)
>

It might be useful to allow the user to view SNP-related status/settings
in HMP's `info sev` and QMP's qom-list/qom-get under
/machine/confidential-guest-support .

(Not sure whether HMP is deprecated and new stuff should not be added
there.)

Particularly confusing is the `policy` attribute which is only relevant
for SEV / SEV-ES, while there's a new `snp.policy` attribute for SNP...
Maybe the irrelevant attributes should not be added to the tree when not
in SNP.

-Dov