On Mon, Oct 02, 2017 at 06:32:18AM -0500, Brijesh Singh wrote:
> Because sev_enabled will always be 'false' when we are booting on bare
> metal. Whereas when we are running under hypervisor then this variable
> will be true for the SEV guest, please see [1].
Ok, then. This needs absolutely to be documented. Please add a comment
over sev_enabled's definition.
> Both sev_active() and sme_active() make use of this variable
> hence we will not be able to set the sev_enabled variable on bare
> metal. Basically none of the SEV cases will be executed on bare
> metal -- only thing which we need to take care of is clearing the
> X86_FEATURE_SEV flag so that hypervisor will never launch SEV guest
> when mem_encrypt=sme option is provided.
In that case, you want to disable SEV at the guest loading point,
i.e., sev_guest_init() AFAICT is the earliest time we start prepping
a SEV guest. You can add a __setup() early param which parses
"mem_encrypt=sme", to arch/x86/kernel/cpu/amd.c and which sets a
sev_host_enabled bool or so. sev_guest_init() can then check that
variable before going any further. No need for any of that early parsing
changes.
I'll send a patch with the rest of my cleanups ontop of yours later.
Thx.
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--
