54 lines
2 KiB
Diff
54 lines
2 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Tom Lendacky <thomas.lendacky@amd.com>
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Date: Tue, 26 Dec 2017 23:43:54 -0600
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Subject: [PATCH] x86/cpu, x86/pti: Do not enable PTI on AMD processors
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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CVE-2017-5754
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AMD processors are not subject to the types of attacks that the kernel
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page table isolation feature protects against. The AMD microarchitecture
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does not allow memory references, including speculative references, that
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access higher privileged data when running in a lesser privileged mode
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when that access would result in a page fault.
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Disable page table isolation by default on AMD processors by not setting
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the X86_BUG_CPU_INSECURE feature, which controls whether X86_FEATURE_PTI
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is set.
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Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Reviewed-by: Borislav Petkov <bp@suse.de>
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Cc: Dave Hansen <dave.hansen@linux.intel.com>
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Cc: Andy Lutomirski <luto@kernel.org>
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Cc: stable@vger.kernel.org
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Link: https://lkml.kernel.org/r/20171227054354.20369.94587.stgit@tlendack-t1.amdoffice.net
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(cherry picked from commit 694d99d40972f12e59a3696effee8a376b79d7c8)
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Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
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(cherry picked from commit 9d334f48f017b9c6457c6ba321e5a53a1cc6a5c7)
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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arch/x86/kernel/cpu/common.c | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
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index 99f37d1636ff..1854dd8071a6 100644
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--- a/arch/x86/kernel/cpu/common.c
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+++ b/arch/x86/kernel/cpu/common.c
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@@ -899,8 +899,8 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
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setup_force_cpu_cap(X86_FEATURE_ALWAYS);
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- /* Assume for now that ALL x86 CPUs are insecure */
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- setup_force_cpu_bug(X86_BUG_CPU_INSECURE);
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+ if (c->x86_vendor != X86_VENDOR_AMD)
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+ setup_force_cpu_bug(X86_BUG_CPU_INSECURE);
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fpu__init_system(c);
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}
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--
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2.14.2
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