linux-kernel - [patch] percpu: Separate decrypted varaibles anytime encryption can be enabled

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Message-ID: <alpine.DEB.2.21.1912131330150.51759@chino.kir.corp.google.com>
Date:   Fri, 13 Dec 2019 13:31:46 -0800 (PST)
From:   David Rientjes <rientjes@...gle.com>
To:     Dennis Zhou <dennis@...nel.org>, Tejun Heo <tj@...nel.org>,
        Christoph Lameter <cl@...ux.com>
cc:     Erdem Aktas <erdemaktas@...gle.com>, Borislav Petkov <bp@...e.de>,
        Brijesh Singh <brijesh.singh@....com>,
        linux-kernel@...r.kernel.org
Subject: [patch] percpu: Separate decrypted varaibles anytime encryption can
 be enabled

From: Erdem Aktas <erdemaktas@...gle.com>

CONFIG_VIRTUALIZATION may not be enabled for memory encrypted guests.  If
disabled, decrypted per-CPU variables may end up sharing the same page
with variables that should be left encrypted.

Always separate per-CPU variables that should be decrypted into their own
page anytime memory encryption can be enabled in the guest rather than
rely on any other config option that may not be enabled.

Fixes: ac26963a1175 ("percpu: Introduce DEFINE_PER_CPU_DECRYPTED")
Cc: stable@...r.kernel.org # 4.15+
Signed-off-by: Erdem Aktas <erdemaktas@...gle.com>
Signed-off-by: David Rientjes <rientjes@...gle.com>
---
 include/linux/percpu-defs.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
--- a/include/linux/percpu-defs.h
+++ b/include/linux/percpu-defs.h
@@ -175,8 +175,7 @@
  * Declaration/definition used for per-CPU variables that should be accessed
  * as decrypted when memory encryption is enabled in the guest.
  */
-#if defined(CONFIG_VIRTUALIZATION) && defined(CONFIG_AMD_MEM_ENCRYPT)
-
+#ifdef CONFIG_AMD_MEM_ENCRYPT
 #define DECLARE_PER_CPU_DECRYPTED(type, name)				\
 	DECLARE_PER_CPU_SECTION(type, name, "..decrypted")