linux-kernel - [PATCH v5 05/32] x86/CPU/AMD: Handle SME reduction in physical address size

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Date:   Tue, 18 Apr 2017 16:17:11 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     <linux-arch@...r.kernel.org>, <linux-efi@...r.kernel.org>,
        <kvm@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <x86@...nel.org>, <kexec@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <kasan-dev@...glegroups.com>,
        <linux-mm@...ck.org>, <iommu@...ts.linux-foundation.org>
CC:     Rik van Riel <riel@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Toshimitsu Kani <toshi.kani@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Jonathan Corbet <corbet@....net>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Larry Woodman <lwoodman@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dave Young <dyoung@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: [PATCH v5 05/32] 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.

Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 arch/x86/kernel/cpu/amd.c |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 5fc5232..35eeeb1 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -613,8 +613,10 @@ 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)
+	 * BIOS support is required for SME. If BIOS has enabld 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).
 	 */
 	if (c->extended_cpuid_level >= 0x8000001f) {
 		if (cpu_has(c, X86_FEATURE_SME)) {
@@ -622,8 +624,14 @@ static void early_init_amd(struct cpuinfo_x86 *c)
 
 			/* Check if SME is enabled */
 			rdmsrl(MSR_K8_SYSCFG, msr);
-			if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT))
+			if (msr & MSR_K8_SYSCFG_MEM_ENCRYPT) {
+				unsigned int ebx;
+
+				ebx = cpuid_ebx(0x8000001f);
+				c->x86_phys_bits -= (ebx >> 6) & 0x3f;
+			} else {
 				clear_cpu_cap(c, X86_FEATURE_SME);
+			}
 		}
 	}
 }