linux-kernel - [PATCH v10 05/38] x86/CPU/AMD: Handle SME reduction in physical address size

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Date:   Mon, 17 Jul 2017 16:10:02 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     x86@...nel.org, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-efi@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-mm@...ck.org, kvm@...r.kernel.org,
        kasan-dev@...glegroups.com
Cc:     Radim Krčmář <rkrcmar@...hat.com>,
        Arnd Bergmann <arnd@...db.de>,
        Jonathan Corbet <corbet@....net>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Alexander Potapenko <glider@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Rik van Riel <riel@...hat.com>,
        Larry Woodman <lwoodman@...hat.com>,
        Dave Young <dyoung@...hat.com>,
        Toshimitsu Kani <toshi.kani@....com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH v10 05/38] x86/CPU/AMD: Handle SME reduction in physical address size

When System Memory Encryption (SME) is enabled, the physical address
space is reduced. Adjust the x86_phys_bits value to reflect this
reduction.

Reviewed-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 arch/x86/kernel/cpu/amd.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 7f658d0..e41670e 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -614,21 +614,23 @@ static void early_init_amd(struct cpuinfo_x86 *c)
 		set_cpu_bug(c, X86_BUG_AMD_E400);
 
 	/*
-	 * BIOS support is required for SME. If BIOS has not enabled SME
-	 * then don't advertise the feature (set in scattered.c). Also,
-	 * since the SME support requires long mode, don't advertise the
-	 * feature under CONFIG_X86_32.
+	 * BIOS support is required for SME. If BIOS has enabled SME then
+	 * adjust x86_phys_bits by the SME physical address space reduction
+	 * value. If BIOS has not enabled SME then don't advertise the
+	 * feature (set in scattered.c). Also, since the SME support requires
+	 * long mode, don't advertise the feature under CONFIG_X86_32.
 	 */
 	if (cpu_has(c, X86_FEATURE_SME)) {
-		if (IS_ENABLED(CONFIG_X86_32)) {
-			clear_cpu_cap(c, X86_FEATURE_SME);
-		} else {
-			u64 msr;
+		u64 msr;
 
-			/* Check if SME is enabled */
-			rdmsrl(MSR_K8_SYSCFG, msr);
-			if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT))
+		/* Check if SME is enabled */
+		rdmsrl(MSR_K8_SYSCFG, msr);
+		if (msr & MSR_K8_SYSCFG_MEM_ENCRYPT) {
+			c->x86_phys_bits -= (cpuid_ebx(0x8000001f) >> 6) & 0x3f;
+			if (IS_ENABLED(CONFIG_X86_32))
 				clear_cpu_cap(c, X86_FEATURE_SME);
+		} else {
+			clear_cpu_cap(c, X86_FEATURE_SME);
 		}
 	}
 }
-- 
1.9.1