On 8/10/21 12:48 PM, Tom Lendacky wrote:

On 8/10/21 1:45 PM, Kuppuswamy, Sathyanarayanan wrote:

quoted

On 7/27/21 3:26 PM, Tom Lendacky wrote:

quoted

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index de01903c3735..cafed6456d45 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c

@@ -19,7 +19,7 @@
   #include <linux/start_kernel.h>
   #include <linux/io.h>
   #include <linux/memblock.h>
-#include <linux/mem_encrypt.h>
+#include <linux/protected_guest.h>
   #include <linux/pgtable.h>
     #include <asm/processor.h>

@@ -285,7 +285,7 @@ unsigned long __head __startup_64(unsigned long

physaddr,
        * there is no need to zero it after changing the memory encryption
        * attribute.
        */
-    if (mem_encrypt_active()) {
+    if (prot_guest_has(PATTR_MEM_ENCRYPT)) {
           vaddr = (unsigned long)__start_bss_decrypted;
           vaddr_end = (unsigned long)__end_bss_decrypted;

Since this change is specific to AMD, can you replace PATTR_MEM_ENCRYPT with
prot_guest_has(PATTR_SME) || prot_guest_has(PATTR_SEV). It is not used in
TDX.

This is a direct replacement for now. I think the change you're requesting
should be done as part of the TDX support patches so it's clear why it is
being changed.

Ok. I will include it part of TDX changes.

But, wouldn't TDX still need to do something with this shared/unencrypted
area, though? Or since it is shared, there's actually nothing you need to
do (the bss decrpyted section exists even if CONFIG_AMD_MEM_ENCRYPT is not
configured)?

Kirill had a requirement to turn on CONFIG_AMD_MEM_ENCRYPT for adding lazy
accept support in TDX guest kernel. Kirill, can you add details here?

Thanks,
Tom

quoted

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer