x86/mm: Free sme_early_buffer after init

The contents of sme_early_buffer should be cleared after
__sme_early_enc_dec() because it is used to move encrypted and decrypted
data, but since __sme_early_enc_dec() is __init this buffer simply can be
freed after init.

This saves a page that is otherwise unreferenced after init.

Reported-by: Cfir Cohen <[e-mail]>
Signed-off-by: David Rientjes <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Link: https://lkml.kernel.org/r/[e-mail]

arch/x86/mm/mem_encrypt.c

···
 bool sev_enabled __section(.data);
 
 /* Buffer used for early in-place encryption by BSP, no locking needed */
-static char sme_early_buffer[PAGE_SIZE] __aligned(PAGE_SIZE);
+static char sme_early_buffer[PAGE_SIZE] __initdata __aligned(PAGE_SIZE);
 
 /*
  * This routine does not change the underlying encryption setting of the