43 lines
1.7 KiB
Diff
43 lines
1.7 KiB
Diff
From 51786b65797aed683ca72293a3cb86a2cab987c0 Mon Sep 17 00:00:00 2001
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Message-Id: <51786b65797aed683ca72293a3cb86a2cab987c0.1514959852.git.jan.steffens@gmail.com>
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In-Reply-To: <fb89d912d5f7289d3a922c77b671e36e1c740f5e.1514959852.git.jan.steffens@gmail.com>
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References: <fb89d912d5f7289d3a922c77b671e36e1c740f5e.1514959852.git.jan.steffens@gmail.com>
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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 7/7] x86/cpu, x86/pti: Do not enable PTI on AMD processors
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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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Reviewed-by: Borislav Petkov <bp@suse.de>
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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 f2a94dfb434e9a7c..b1be494ab4e8badf 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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2.15.1
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