x86/sev: Provide support for SNP guest request NAEs

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2081424


Upstream Status: linux.git

commit d5af44dd
Author: Brijesh Singh <brijesh.singh@amd.com>
Date:   Mon Mar 7 15:33:51 2022 -0600

    x86/sev: Provide support for SNP guest request NAEs

    Version 2 of GHCB specification provides SNP_GUEST_REQUEST and
    SNP_EXT_GUEST_REQUEST NAE that can be used by the SNP guest to
    communicate with the PSP.

    While at it, add a snp_issue_guest_request() helper that will be used by
    driver or other subsystem to issue the request to PSP.

    See SEV-SNP firmware and GHCB spec for more details.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
    Link: https://lore.kernel.org/r/20220307213356.2797205-42-brijesh.singh@amd.com



Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: John Allen <johnalle@redhat.com>