linux.git/arch/x86/kernel/cpu/bugs.c, branch v4.16

x86/speculation: Use IBRS if available before calling into firmware

2018-02-20T08:38:33+00:00

Retpoline means the kernel is safe because it has no indirect branches.
But firmware isn't, so use IBRS for firmware calls if it's available.

Block preemption while IBRS is set, although in practice the call sites
already had to be doing that.

Ignore hpwdt.c for now. It's taking spinlocks and calling into firmware
code, from an NMI handler. I don't want to touch that with a bargepole.

Signed-off-by: David Woodhouse 
Reviewed-by: Thomas Gleixner 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: arjan.van.de.ven@intel.com
Cc: bp@alien8.de
Cc: dave.hansen@intel.com
Cc: jmattson@google.com
Cc: karahmed@amazon.de
Cc: kvm@vger.kernel.org
Cc: pbonzini@redhat.com
Cc: rkrcmar@redhat.com
Link: http://lkml.kernel.org/r/1519037457-7643-2-git-send-email-dwmw@amazon.co.uk
Signed-off-by: Ingo Molnar

x86/spectre: Fix an error message

2018-02-15T00:15:53+00:00

If i == ARRAY_SIZE(mitigation_options) then we accidentally print
garbage from one space beyond the end of the mitigation_options[] array.

Signed-off-by: Dan Carpenter 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: David Woodhouse 
Cc: Greg Kroah-Hartman 
Cc: KarimAllah Ahmed 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: kernel-janitors@vger.kernel.org
Fixes: 9005c6834c0f ("x86/spectre: Simplify spectre_v2 command line parsing")
Link: http://lkml.kernel.org/r/20180214071416.GA26677@mwanda
Signed-off-by: Ingo Molnar

x86/speculation: Clean up various Spectre related details

2018-02-13T08:03:08+00:00

Harmonize all the Spectre messages so that a:

    dmesg | grep -i spectre

... gives us most Spectre related kernel boot messages.

Also fix a few other details:

 - clarify a comment about firmware speculation control

 - s/KPTI/PTI

 - remove various line-breaks that made the code uglier

Acked-by: David Woodhouse 
Cc: Andy Lutomirski 
Cc: Arjan van de Ven 
Cc: Borislav Petkov 
Cc: Dan Williams 
Cc: Dave Hansen 
Cc: David Woodhouse 
Cc: Greg Kroah-Hartman 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

Revert "x86/speculation: Simplify indirect_branch_prediction_barrier()"

2018-02-13T07:59:00+00:00

This reverts commit 64e16720ea0879f8ab4547e3b9758936d483909b.

We cannot call C functions like that, without marking all the
call-clobbered registers as, well, clobbered. We might have got away
with it for now because the __ibp_barrier() function was *fairly*
unlikely to actually use any other registers. But no. Just no.

Signed-off-by: David Woodhouse 
Cc: Andy Lutomirski 
Cc: Arjan van de Ven 
Cc: Borislav Petkov 
Cc: Dan Williams 
Cc: Dave Hansen 
Cc: David Woodhouse 
Cc: Greg Kroah-Hartman 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: arjan.van.de.ven@intel.com
Cc: dave.hansen@intel.com
Cc: jmattson@google.com
Cc: karahmed@amazon.de
Cc: kvm@vger.kernel.org
Cc: pbonzini@redhat.com
Cc: rkrcmar@redhat.com
Cc: sironi@amazon.de
Link: http://lkml.kernel.org/r/1518305967-31356-3-git-send-email-dwmw@amazon.co.uk
Signed-off-by: Ingo Molnar

x86/spectre: Simplify spectre_v2 command line parsing

2018-02-02T11:28:27+00:00

[dwmw2: Use ARRAY_SIZE]

Signed-off-by: KarimAllah Ahmed 
Signed-off-by: David Woodhouse 
Signed-off-by: Thomas Gleixner 
Cc: peterz@infradead.org
Cc: bp@alien8.de
Link: https://lkml.kernel.org/r/1517484441-1420-3-git-send-email-dwmw@amazon.co.uk

x86/spectre: Fix spelling mistake: "vunerable"-> "vulnerable"

2018-01-30T21:08:44+00:00

Trivial fix to spelling mistake in pr_err error message text.

Signed-off-by: Colin Ian King 
Signed-off-by: Thomas Gleixner 
Cc: Andi Kleen 
Cc: Greg Kroah-Hartman 
Cc: kernel-janitors@vger.kernel.org
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: David Woodhouse 
Link: https://lkml.kernel.org/r/20180130193218.9271-1-colin.king@canonical.com

x86/spectre: Report get_user mitigation for spectre_v1

2018-01-30T20:54:32+00:00

Reflect the presence of get_user(), __get_user(), and 'syscall' protections
in sysfs. The expectation is that new and better tooling will allow the
kernel to grow more usages of array_index_nospec(), for now, only claim
mitigation for __user pointer de-references.

Reported-by: Jiri Slaby 
Signed-off-by: Dan Williams 
Signed-off-by: Thomas Gleixner 
Cc: linux-arch@vger.kernel.org
Cc: kernel-hardening@lists.openwall.com
Cc: gregkh@linuxfoundation.org
Cc: torvalds@linux-foundation.org
Cc: alan@linux.intel.com
Link: https://lkml.kernel.org/r/151727420158.33451.11658324346540434635.stgit@dwillia2-desk3.amr.corp.intel.com

x86/spectre: Check CONFIG_RETPOLINE in command line parser

2018-01-30T14:30:35+00:00

The spectre_v2 option 'auto' does not check whether CONFIG_RETPOLINE is
enabled. As a consequence it fails to emit the appropriate warning and sets
feature flags which have no effect at all.

Add the missing IS_ENABLED() check.

Fixes: da285121560e ("x86/spectre: Add boot time option to select Spectre v2 mitigation")
Signed-off-by: Dou Liyang 
Signed-off-by: Thomas Gleixner 
Cc: ak@linux.intel.com
Cc: peterz@infradead.org
Cc: Tomohiro" 
Cc: dave.hansen@intel.com
Cc: bp@alien8.de
Cc: arjan@linux.intel.com
Cc: dwmw@amazon.co.uk
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/f5892721-7528-3647-08fb-f8d10e65ad87@cn.fujitsu.com

x86/speculation: Simplify indirect_branch_prediction_barrier()

2018-01-27T18:10:45+00:00

Make it all a function which does the WRMSR instead of having a hairy
inline asm.

[dwmw2: export it, fix CONFIG_RETPOLINE issues]

Signed-off-by: Borislav Petkov 
Signed-off-by: David Woodhouse 
Signed-off-by: Thomas Gleixner 
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/1517070274-12128-4-git-send-email-dwmw@amazon.co.uk

x86/cpufeatures: Clean up Spectre v2 related CPUID flags

2018-01-27T18:10:44+00:00

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 
Signed-off-by: David Woodhouse 
Signed-off-by: Thomas Gleixner 
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