x86/mm: Add Secure Encrypted Virtualization (SEV) support

x86/mm: Add Secure Encrypted Virtualization (SEV) support

Provide support for Secure Encrypted Virtualization (SEV). This initial
support defines a flag that is used by the kernel to determine if it is
running with SEV active.

Signed-off-by: Tom Lendacky <[email protected]>
Signed-off-by: Brijesh Singh <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Borislav Petkov <[email protected]>
Tested-by: Borislav Petkov <[email protected]>
Cc: [email protected]
Cc: Borislav Petkov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]