[tip:x86/asm] x86/realmode: Don't decrypt trampoline area under SEV

tip-bot for Tom Lendacky
2017-11-07T14:47:29Z

Commit-ID: fcdcd6cdd98ff4d0cf876f863024a2fb0b491d41
Gitweb: https://git.kernel.org/tip/fcdcd6cdd98ff4d0cf876f863024a2fb0b491d41
Author: Tom Lendacky <thomas.lendacky@amd.com>
AuthorDate: Fri, 20 Oct 2017 09:30:46 -0500
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 7 Nov 2017 15:35:55 +0100

x86/realmode: Don't decrypt trampoline area under SEV

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

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Tested-by: Borislav Petkov <bp@suse.de>
Cc: Laura Abbott <labbott@redhat.com>
Cc: kvm@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: https://lkml.kernel.org/r/20171020143059.3291-5-brijesh.singh@amd.com

---
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 ed84d39..d101058 100644
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c
@@ -64,9 +64,10 @@ 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);