91 lines
2.8 KiB
Diff
91 lines
2.8 KiB
Diff
From 1b88ea4170f72b4fed72e9235c88b6121f153b21 Mon Sep 17 00:00:00 2001
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From: Andi Kleen <ak@linux.intel.com>
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Date: Fri, 13 Oct 2017 14:56:44 -0700
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Subject: [PATCH 068/232] x86/fpu: Make XSAVE check the base CPUID features
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before enabling
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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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Before enabling XSAVE, not only check the XSAVE specific CPUID bits,
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but also the base CPUID features of the respective XSAVE feature.
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This allows to disable individual XSAVE states using the existing
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clearcpuid= option, which can be useful for performance testing
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and debugging, and also in general avoids inconsistencies.
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Signed-off-by: Andi Kleen <ak@linux.intel.com>
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Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Link: http://lkml.kernel.org/r/20171013215645.23166-5-andi@firstfloor.org
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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(cherry picked from commit ccb18db2ab9d923df07e7495123fe5fb02329713)
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Signed-off-by: Andy Whitcroft <apw@canonical.com>
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Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
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(cherry picked from commit 2efda26f9ee0eeb9919772e90ca30dbe59008dc8)
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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arch/x86/kernel/fpu/xstate.c | 23 +++++++++++++++++++++++
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1 file changed, 23 insertions(+)
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diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
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index c24ac1efb12d..3abe85b08234 100644
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--- a/arch/x86/kernel/fpu/xstate.c
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+++ b/arch/x86/kernel/fpu/xstate.c
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@@ -15,6 +15,7 @@
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#include <asm/fpu/xstate.h>
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#include <asm/tlbflush.h>
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+#include <asm/cpufeature.h>
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/*
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* Although we spell it out in here, the Processor Trace
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@@ -36,6 +37,19 @@ static const char *xfeature_names[] =
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"unknown xstate feature" ,
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};
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+static short xsave_cpuid_features[] __initdata = {
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+ X86_FEATURE_FPU,
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+ X86_FEATURE_XMM,
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+ X86_FEATURE_AVX,
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+ X86_FEATURE_MPX,
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+ X86_FEATURE_MPX,
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+ X86_FEATURE_AVX512F,
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+ X86_FEATURE_AVX512F,
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+ X86_FEATURE_AVX512F,
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+ X86_FEATURE_INTEL_PT,
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+ X86_FEATURE_PKU,
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+};
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+
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/*
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* Mask of xstate features supported by the CPU and the kernel:
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*/
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@@ -702,6 +716,7 @@ void __init fpu__init_system_xstate(void)
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unsigned int eax, ebx, ecx, edx;
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static int on_boot_cpu __initdata = 1;
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int err;
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+ int i;
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WARN_ON_FPU(!on_boot_cpu);
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on_boot_cpu = 0;
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@@ -735,6 +750,14 @@ void __init fpu__init_system_xstate(void)
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goto out_disable;
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}
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+ /*
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+ * Clear XSAVE features that are disabled in the normal CPUID.
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+ */
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+ for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) {
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+ if (!boot_cpu_has(xsave_cpuid_features[i]))
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+ xfeatures_mask &= ~BIT(i);
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+ }
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+
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xfeatures_mask &= fpu__get_supported_xfeatures_mask();
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/* Enable xstate instructions to be able to continue with initialization: */
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--
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2.14.2
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