On 9/20/21 2:23 PM, Kirill A. Shutemov wrote:

On Wed, Sep 08, 2021 at 05:58:36PM -0500, Tom Lendacky wrote:

quoted

diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
index 470b20208430..eff4d19f9cb4 100644
--- a/arch/x86/mm/mem_encrypt_identity.c
+++ b/arch/x86/mm/mem_encrypt_identity.c

@@ -30,6 +30,7 @@
  #include <linux/kernel.h>
  #include <linux/mm.h>
  #include <linux/mem_encrypt.h>
+#include <linux/cc_platform.h>
  
  #include <asm/setup.h>
  #include <asm/sections.h>

@@ -287,7 +288,7 @@ void __init sme_encrypt_kernel(struct boot_params *bp)
  	unsigned long pgtable_area_len;
  	unsigned long decrypted_base;
  
-	if (!sme_active())
+	if (!cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
  		return;
  
  	/*

This change break boot for me (in KVM on Intel host). It only reproduces
with allyesconfig. More reasonable config works fine, but I didn't try to
find exact cause in config.

Looks like instrumentation during early boot. I worked with Boris offline 
to exclude arch/x86/kernel/cc_platform.c from some of the instrumentation 
and that allowed an allyesconfig to boot.

Thanks,
Tom

Convertion to cc_platform_has() in __startup_64() in 8/8 has the same
effect.

I believe it caused by sme_me_mask access from __startup_64() without
fixup_pointer() magic. I think __startup_64() requires special treatement
and we should avoid cc_platform_has() there (or have a special version of
the helper). Note that only AMD requires these cc_platform_has() to return
true.