Documentation/ABI/testing/configfs-tsm
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Merge tag 'tsm-for-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/linux
Pull unified attestation reporting from Dan Williams:
"In an ideal world there would be a cross-vendor standard attestation
report format for confidential guests along with a common device
definition to act as the transport.
In the real world the situation ended up with multiple platform
vendors inventing their own attestation report formats with the
SEV-SNP implementation being a first mover to define a custom
sev-guest character device and corresponding ioctl(). Later, this
configfs-tsm proposal intercepted an attempt to add a tdx-guest
character device and a corresponding new ioctl(). It also anticipated
ARM and RISC-V showing up with more chardevs and more ioctls().
The proposal takes for granted that Linux tolerates the vendor report
format differentiation until a standard arrives. From talking with
folks involved, it sounds like that standardization work is unlikely
to resolve anytime soon. It also takes the position that kernfs ABIs
are easier to maintain than ioctl(). The result is a shared configfs
mechanism to return per-vendor report-blobs with the option to later
support a standard when that arrives.
Part of the goal here also is to get the community into the
"uncomfortable, but beneficial to the long term maintainability of the
kernel" state of talking to each other about their differentiation and
opportunities to collaborate. Think of this like the device-driver
equivalent of the common memory-management infrastructure for
confidential-computing being built up in KVM.
As for establishing an "upstream path for cross-vendor
confidential-computing device driver infrastructure" this is something
I want to discuss at Plumbers. At present, the multiple vendor
proposals for assigning devices to confidential computing VMs likely
needs a new dedicated repository and maintainer team, but that is a
discussion for v6.8.
For now, Greg and Thomas have acked this approach and this is passing
is AMD, Intel, and Google tests.
Summary:
- Introduce configfs-tsm as a shared ABI for confidential computing
attestation reports
- Convert sev-guest to additionally support configfs-tsm alongside
its vendor specific ioctl()
- Added signed attestation report retrieval to the tdx-guest driver
forgoing a new vendor specific ioctl()
- Misc cleanups and a new __free() annotation for kvfree()"
* tag 'tsm-for-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/linux:
virt: tdx-guest: Add Quote generation support using TSM_REPORTS
virt: sevguest: Add TSM_REPORTS support for SNP_GET_EXT_REPORT
mm/slab: Add __free() support for kvfree
virt: sevguest: Prep for kernel internal get_ext_report()
configfs-tsm: Introduce a shared ABI for attestation reports
virt: coco: Add a coco/Makefile and coco/Kconfig
virt: sevguest: Fix passing a stack buffer as a scatterlist target