From: Borislav Petkov <bp@suse.de>
Date: Thu, 7 Sep 2017 17:08:21 +0000 (+0200)
Subject: x86/cpu/AMD: Fix erratum 1076 (CPB bit)
X-Git-Tag: Ubuntu-4.13.0-45.50~24
X-Git-Url: https://git.proxmox.com/?p=mirror_ubuntu-artful-kernel.git;a=commitdiff_plain;h=44fccfc084ff4ec9bf7e51800d323f7919973d10

x86/cpu/AMD: Fix erratum 1076 (CPB bit)

CPUID Fn8000_0007_EDX[CPB] is wrongly 0 on models up to B1. But they do
support CPB (AMD's Core Performance Boosting cpufreq CPU feature), so fix that.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sherry Hurwitz <sherry.hurwitz@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170907170821.16021-1-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

CVE-2018-3639 (x86)

(cherry picked from commit f7f3dc00f61261cdc9ccd8b886f21bc4dffd6fd9)
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
---

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 3bdd6ef99771..71225dba26c4 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -749,6 +749,16 @@ static void init_amd_bd(struct cpuinfo_x86 *c)
 	}
 }
 
+static void init_amd_zn(struct cpuinfo_x86 *c)
+{
+	/*
+	 * Fix erratum 1076: CPB feature bit not being set in CPUID. It affects
+	 * all up to and including B1.
+	 */
+	if (c->x86_model <= 1 && c->x86_mask <= 1)
+		set_cpu_cap(c, X86_FEATURE_CPB);
+}
+
 static void init_amd(struct cpuinfo_x86 *c)
 {
 	u32 dummy;
@@ -779,6 +789,7 @@ static void init_amd(struct cpuinfo_x86 *c)
 	case 0x10: init_amd_gh(c); break;
 	case 0x12: init_amd_ln(c); break;
 	case 0x15: init_amd_bd(c); break;
+	case 0x17: init_amd_zn(c); break;
 	}
 
 	/*