From: Paolo Bonzini Date: Tue, 16 Jul 2024 15:44:23 +0000 (-0400) Subject: Merge branch 'kvm-6.11-sev-attestation' into HEAD X-Git-Tag: block-6.11-20240726~19^2~4 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=bc9cd5a219aa6c00515aa8f0904c8d49706f0760;p=linux-block.git Merge branch 'kvm-6.11-sev-attestation' into HEAD The GHCB 2.0 specification defines 2 GHCB request types to allow SNP guests to send encrypted messages/requests to firmware: SNP Guest Requests and SNP Extended Guest Requests. These encrypted messages are used for things like servicing attestation requests issued by the guest. Implementing support for these is required to be fully GHCB-compliant. For the most part, KVM only needs to handle forwarding these requests to firmware (to be issued via the SNP_GUEST_REQUEST firmware command defined in the SEV-SNP Firmware ABI), and then forwarding the encrypted response to the guest. However, in the case of SNP Extended Guest Requests, the host is also able to provide the certificate data corresponding to the endorsement key used by firmware to sign attestation report requests. This certificate data is provided by userspace because: 1) It allows for different keys/key types to be used for each particular guest with requiring any sort of KVM API to configure the certificate table in advance on a per-guest basis. 2) It provides additional flexibility with how attestation requests might be handled during live migration where the certificate data for source/dest might be different. 3) It allows all synchronization between certificates and firmware/signing key updates to be handled purely by userspace rather than requiring some in-kernel mechanism to facilitate it. [1] To support fetching certificate data from userspace, a new KVM exit type will be needed to handle fetching the certificate from userspace. An attempt to define a new KVM_EXIT_COCO/KVM_EXIT_COCO_REQ_CERTS exit type to handle this was introduced in v1 of this patchset, but is still being discussed by community, so for now this patchset only implements a stub version of SNP Extended Guest Requests that does not provide certificate data, but is still enough to provide compliance with the GHCB 2.0 spec. --- bc9cd5a219aa6c00515aa8f0904c8d49706f0760