On Wed, 21 Jun 2017, Tom Lendacky wrote:
On 6/21/2017 2:16 AM, Thomas Gleixner wrote:
Why is this an unconditional function? Isn't the mask simply 0 when the MEM
ENCRYPT support is disabled?
I made it unconditional because of the call from head_64.S. I can't make
use of the C level static inline function and since the mask is not a
variable if CONFIG_AMD_MEM_ENCRYPT is not configured (#defined to 0) I
can't reference the variable directly.
I could create a #define in head_64.S that changes this to load rax with
the variable if CONFIG_AMD_MEM_ENCRYPT is configured or a zero if it's
not or add a #ifdef at that point in the code directly. Thoughts on
That does not make any sense. Neither the call to sme_encrypt_kernel() nor
the following call to sme_get_me_mask().
__startup_64() is already C code, so why can't you simply call that from
__startup_64() in C and return the mask from there?
I was trying to keep it explicit as to what was happening, but I can
move those calls into __startup_64().
That's much preferred. And the return value wants to be documented in both
C and ASM code.
I'll still need the call to sme_get_me_mask() in the secondary_startup_64
path, though (depending on your thoughts to the above response).
movq $(init_top_pgt - __START_KERNEL_map), %rax
So if you make that:
* Sanitize CPU configuration and retrieve the modifier
* for the initial pgdir entry which will be programmed
* into CR3. Depends on enabled SME encryption, normally 0.
addq $(init_top_pgt - __START_KERNEL_map), %rax
You can hide that stuff in C-code nicely without adding any cruft to the