[RFC PATCH 0/3] Retrieve SNP attestation from SVSM

[Dov Murik <dovmurik@linux.ibm.com>]

This is an initial attempt to allow userspace to fetch attestation
report from SVSM on SNP.  It was tested with AMD's linux-svsm to which
we added support for the attestation protocol.  The kernel patches in
this series only expose the SVSM_ATTEST_SERVICES function, for now.

The request for the attestation report is exposed to userspace as a new
ioctl call (SNP_SVSM_ATTEST_SERVICES) on /dev/sev-guest.  It returns the
VMPL0 attestation report, the services manifest, and the host
certificate chain, according to the SVSM spec.

Note that the existing SNP_GET_REPORT and SNP_GET_EXT_REPORT calls still
work under SVSM, as long as a VMPL1 report is requested.

This series should be applied on top of AMD's SVSM guest tree:
https://github.com/AMDESE/linux/tree/svsm-preview-guest

The SVSM code which supports the attestation protocol is in:
https://github.com/svsm-vtpm/linux-svsm/tree/attestation-protocol-v2
(as of writing, it hasn't yet been merged to AMD's linux-svsm.)

Dov Murik (3):
  x86/sev: Add __svsm_msr_protocol_2() which returns register values
  x86/sev: Add snp_svsm_attest_services()
  virt: sevguest: Add support to get attestation report from SVSM

 arch/x86/include/asm/sev.h            | 26 ++++++++
 arch/x86/kernel/sev-shared.c          | 49 ++++++++++++++
 arch/x86/kernel/sev.c                 | 46 +++++++++++++
 drivers/virt/coco/sevguest/sevguest.c | 95 +++++++++++++++++++++++++++
 include/uapi/linux/sev-guest.h        | 34 ++++++++++
 5 files changed, 250 insertions(+)

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2.35.3