x86/cpufeatures: Clean up Spectre v2 related CPUID flags
authorDavid Woodhouse <dwmw@amazon.co.uk>
Sat, 27 Jan 2018 16:24:32 +0000 (16:24 +0000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 7 Feb 2018 19:12:20 +0000 (11:12 -0800)
commit7f3e0daa9e125d3d4d7720136370303009edbdeb
treeba0f9e7a090183baec5c298b0d79c129b2fbc6dc
parent249b1f7a7f09c9c5243f8c592ea7fb13871968bc
x86/cpufeatures: Clean up Spectre v2 related CPUID flags

commit 2961298efe1ea1b6fc0d7ee8b76018fa6c0bcef2

We want to expose the hardware features simply in /proc/cpuinfo as "ibrs",
"ibpb" and "stibp". Since AMD has separate CPUID bits for those, use them
as the user-visible bits.

When the Intel SPEC_CTRL bit is set which indicates both IBRS and IBPB
capability, set those (AMD) bits accordingly. Likewise if the Intel STIBP
bit is set, set the AMD STIBP that's used for the generic hardware
capability.

Hide the rest from /proc/cpuinfo by putting "" in the comments. Including
RETPOLINE and RETPOLINE_AMD which shouldn't be visible there. There are
patches to make the sysfs vulnerabilities information non-readable by
non-root, and the same should apply to all information about which
mitigations are actually in use. Those *shouldn't* appear in /proc/cpuinfo.

The feature bit for whether IBPB is actually used, which is needed for
ALTERNATIVEs, is renamed to X86_FEATURE_USE_IBPB.

Originally-by: Borislav Petkov <bp@suse.de>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: ak@linux.intel.com
Cc: dave.hansen@intel.com
Cc: karahmed@amazon.de
Cc: arjan@linux.intel.com
Cc: torvalds@linux-foundation.org
Cc: peterz@infradead.org
Cc: bp@alien8.de
Cc: pbonzini@redhat.com
Cc: tim.c.chen@linux.intel.com
Cc: gregkh@linux-foundation.org
Link: https://lkml.kernel.org/r/1517070274-12128-2-git-send-email-dwmw@amazon.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/x86/include/asm/cpufeatures.h
arch/x86/include/asm/nospec-branch.h
arch/x86/kernel/cpu/bugs.c
arch/x86/kernel/cpu/intel.c