linux-kernel - [PATCH v2 2/2] acpi, x86: Remove encryption mask from ACPI page protection type

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Message-Id: <e1cb9395b2f061cd96f1e59c3cbbe5ff5d4ec26e.1501186516.git.thomas.lendacky@amd.com>
Date:   Fri, 28 Jul 2017 11:01:17 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     x86@...nel.org, linux-kernel@...r.kernel.org
Cc:     Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dave Young <dyoung@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH v2 2/2] acpi, x86: Remove encryption mask from ACPI page protection type

The function arch_apei_get_mem_attributes() is used to set the page
protection type for ACPI physical addresses. When SME is active, the
associated protection type cannot have the encryption mask set since the
ACPI tables live in un-encrypted memory. Create a new protection type,
PAGE_KERNEL_NOENC, that is a no encryption version of PAGE_KERNEL, and
return that from arch_apei_get_mem_attributes().

Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 arch/x86/include/asm/acpi.h          | 11 ++++++-----
 arch/x86/include/asm/pgtable_types.h |  1 +
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/acpi.h b/arch/x86/include/asm/acpi.h
index 562286f..543a3f0 100644
--- a/arch/x86/include/asm/acpi.h
+++ b/arch/x86/include/asm/acpi.h
@@ -160,12 +160,13 @@ static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
 	 * you call efi_mem_attributes() during boot and at runtime,
 	 * you could theoretically see different attributes.
 	 *
-	 * Since we are yet to see any x86 platforms that require
-	 * anything other than PAGE_KERNEL (some arm64 platforms
-	 * require the equivalent of PAGE_KERNEL_NOCACHE), return that
-	 * until we know differently.
+	 * We are yet to see any x86 platforms that require anything
+	 * other than PAGE_KERNEL (some arm64 platforms require the
+	 * equivalent of PAGE_KERNEL_NOCACHE). Additionally, if SME
+	 * is active, the ACPI information will not be encrypted,
+	 * so return PAGE_KERNEL_NOENC until we know differently.
 	 */
-	 return PAGE_KERNEL;
+	return PAGE_KERNEL_NOENC;
 }
 #endif
 
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index 6c55973..399261c 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -211,6 +211,7 @@ enum page_cache_mode {
 #define __PAGE_KERNEL_NOENC_WP	(__PAGE_KERNEL_WP)
 
 #define PAGE_KERNEL		__pgprot(__PAGE_KERNEL | _PAGE_ENC)
+#define PAGE_KERNEL_NOENC	__pgprot(__PAGE_KERNEL)
 #define PAGE_KERNEL_RO		__pgprot(__PAGE_KERNEL_RO | _PAGE_ENC)
 #define PAGE_KERNEL_EXEC	__pgprot(__PAGE_KERNEL_EXEC | _PAGE_ENC)
 #define PAGE_KERNEL_EXEC_NOENC	__pgprot(__PAGE_KERNEL_EXEC)
-- 
1.9.1