[Part1 PATCH v4 04/17] x86/realmode: Don't decrypt trampoline area under SEV

From: Brijesh Singh
Date: Sat Sep 16 2017 - 08:38:57 EST

From: Tom Lendacky <thomas.lendacky@xxxxxxx>

When SEV is active the trampoline area will need to be in encrypted
memory so only mark the area decrypted if SME is active.

Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Laura Abbott <labbott@xxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: x86@xxxxxxxxxx
Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
arch/x86/realmode/init.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index 1f71980fc5e0..d03125c2b73b 100644
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c
@@ -63,9 +63,10 @@ static void __init setup_real_mode(void)
* If SME is active, the trampoline area will need to be in
* decrypted memory in order to bring up other processors
- * successfully.
+ * successfully. This is not needed for SEV.
- set_memory_decrypted((unsigned long)base, size >> PAGE_SHIFT);
+ if (sme_active())
+ set_memory_decrypted((unsigned long)base, size >> PAGE_SHIFT);

memcpy(base, real_mode_blob, size);