From b14fd309e7cc28d6a151fde2fe413506a4178e1c Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 4 Dec 2017 15:07:33 +0100 Subject: [PATCH 055/131] x86/cpufeatures: Add X86_BUG_CPU_INSECURE CVE-2017-5715 (Spectre v2 retpoline) commit a89f040fa34ec9cd682aed98b8f04e3c47d998bd upstream. Many x86 CPUs leak information to user space due to missing isolation of user space and kernel space page tables. There are many well documented ways to exploit that. The upcoming software migitation of isolating the user and kernel space page tables needs a misfeature flag so code can be made runtime conditional. Add the BUG bits which indicates that the CPU is affected and add a feature bit which indicates that the software migitation is enabled. Assume for now that _ALL_ x86 CPUs are affected by this. Exceptions can be made later. Signed-off-by: Thomas Gleixner Cc: Andy Lutomirski Cc: Boris Ostrovsky Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: David Laight Cc: Denys Vlasenko Cc: Eduardo Valentin Cc: Greg KH Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Will Deacon Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Signed-off-by: Ingo Molnar Signed-off-by: David Woodhouse Signed-off-by: Greg Kroah-Hartman (backported from commit 07c7aa5e7e8ac83768246822b61ebffbdea61ff7) Signed-off-by: Andy Whitcroft --- arch/x86/include/asm/cpufeature.h | 1 + arch/x86/kernel/cpu/common.c | 3 +++ 2 files changed, 4 insertions(+) diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index a6efb544138f..05689045b7d3 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -239,6 +239,7 @@ #define X86_BUG_COMA X86_BUG(2) /* Cyrix 6x86 coma */ #define X86_BUG_AMD_TLB_MMATCH X86_BUG(3) /* AMD Erratum 383 */ #define X86_BUG_AMD_APIC_C1E X86_BUG(4) /* AMD Erratum 400 */ +#define X86_BUG_CPU_INSECURE X86_BUG(14) /* CPU is insecure and needs kernel page table isolation */ #if defined(__KERNEL__) && !defined(__ASSEMBLY__) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index f7b9f1c7b21e..efacdb176261 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -800,6 +800,9 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c) this_cpu->c_bsp_init(c); setup_force_cpu_cap(X86_FEATURE_ALWAYS); + + /* Assume for now that ALL x86 CPUs are insecure */ + setup_force_cpu_bug(X86_BUG_CPU_INSECURE); } void __init early_cpu_init(void) -- 2.15.1