linux-stable.git/arch/x86/kernel/cpu/bugs.c, branch linux-5.0.y

x86/speculation/mds: Add 'mitigations=' support for MDS

2019-05-14T17:17:13+00:00

commit 5c14068f87d04adc73ba3f41c2a303d3c3d1fa12 upstream

Add MDS to the new 'mitigations=' cmdline option.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

x86/speculation: Support 'mitigations=' cmdline option

2019-05-14T17:17:13+00:00

commit d68be4c4d31295ff6ae34a8ddfaa4c1a8ff42812 upstream

Configure x86 runtime CPU speculation bug mitigations in accordance with
the 'mitigations=' cmdline option.  This affects Meltdown, Spectre v2,
Speculative Store Bypass, and L1TF.

The default behavior is unchanged.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Thomas Gleixner 
Tested-by: Jiri Kosina  (on x86)
Reviewed-by: Jiri Kosina 
Cc: Borislav Petkov 
Cc: "H . Peter Anvin" 
Cc: Andy Lutomirski 
Cc: Peter Zijlstra 
Cc: Jiri Kosina 
Cc: Waiman Long 
Cc: Andrea Arcangeli 
Cc: Jon Masters 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Michael Ellerman 
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: linux-s390@vger.kernel.org
Cc: Catalin Marinas 
Cc: Will Deacon 
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-arch@vger.kernel.org
Cc: Greg Kroah-Hartman 
Cc: Tyler Hicks 
Cc: Linus Torvalds 
Cc: Randy Dunlap 
Cc: Steven Price 
Cc: Phil Auld 
Link: https://lkml.kernel.org/r/6616d0ae169308516cfdf5216bedd169f8a8291b.1555085500.git.jpoimboe@redhat.com
Signed-off-by: Greg Kroah-Hartman

x86/speculation/mds: Print SMT vulnerable on MSBDS with mitigations off

2019-05-14T17:17:13+00:00

commit e2c3c94788b08891dcf3dbe608f9880523ecd71b upstream

This code is only for CPUs which are affected by MSBDS, but are *not*
affected by the other two MDS issues.

For such CPUs, enabling the mds_idle_clear mitigation is enough to
mitigate SMT.

However if user boots with 'mds=off' and still has SMT enabled, we should
not report that SMT is mitigated:

$cat /sys//devices/system/cpu/vulnerabilities/mds
Vulnerable; SMT mitigated

But rather:
Vulnerable; SMT vulnerable

Signed-off-by: Konrad Rzeszutek Wilk 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Tyler Hicks 
Reviewed-by: Josh Poimboeuf 
Link: https://lkml.kernel.org/r/20190412215118.294906495@localhost.localdomain
Signed-off-by: Greg Kroah-Hartman

x86/speculation/mds: Fix comment

2019-05-14T17:17:12+00:00

commit cae5ec342645746d617dd420d206e1588d47768a upstream

s/L1TF/MDS/

Signed-off-by: Boris Ostrovsky 
Signed-off-by: Konrad Rzeszutek Wilk 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Tyler Hicks 
Reviewed-by: Josh Poimboeuf 
Signed-off-by: Greg Kroah-Hartman

x86/speculation/mds: Add SMT warning message

2019-05-14T17:17:12+00:00

commit 39226ef02bfb43248b7db12a4fdccb39d95318e3 upstream

MDS is vulnerable with SMT.  Make that clear with a one-time printk
whenever SMT first gets enabled.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Tyler Hicks 
Acked-by: Jiri Kosina 
Signed-off-by: Greg Kroah-Hartman

x86/speculation: Move arch_smt_update() call to after mitigation decisions

2019-05-14T17:17:12+00:00

commit 7c3658b20194a5b3209a143f63bc9c643c6a3ae2 upstream

arch_smt_update() now has a dependency on both Spectre v2 and MDS
mitigations.  Move its initial call to after all the mitigation decisions
have been made.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Tyler Hicks 
Acked-by: Jiri Kosina 
Signed-off-by: Greg Kroah-Hartman

x86/speculation/mds: Add mds=full,nosmt cmdline option

2019-05-14T17:17:12+00:00

commit d71eb0ce109a124b0fa714832823b9452f2762cf upstream

Add the mds=full,nosmt cmdline option.  This is like mds=full, but with
SMT disabled if the CPU is vulnerable.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Tyler Hicks 
Acked-by: Jiri Kosina 
Signed-off-by: Greg Kroah-Hartman

Documentation: Move L1TF to separate directory

2019-05-14T17:17:12+00:00

commit 65fd4cb65b2dad97feb8330b6690445910b56d6a upstream

Move L!TF to a separate directory so the MDS stuff can be added at the
side. Otherwise the all hardware vulnerabilites have their own top level
entry. Should have done that right away.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Jon Masters 
Signed-off-by: Greg Kroah-Hartman

x86/speculation/mds: Add mitigation mode VMWERV

2019-05-14T17:17:11+00:00

commit 22dd8365088b6403630b82423cf906491859b65e upstream

In virtualized environments it can happen that the host has the microcode
update which utilizes the VERW instruction to clear CPU buffers, but the
hypervisor is not yet updated to expose the X86_FEATURE_MD_CLEAR CPUID bit
to guests.

Introduce an internal mitigation mode VMWERV which enables the invocation
of the CPU buffer clearing even if X86_FEATURE_MD_CLEAR is not set. If the
system has no updated microcode this results in a pointless execution of
the VERW instruction wasting a few CPU cycles. If the microcode is updated,
but not exposed to a guest then the CPU buffers will be cleared.

That said: Virtual Machines Will Eventually Receive Vaccine

Signed-off-by: Thomas Gleixner 
Reviewed-by: Borislav Petkov 
Reviewed-by: Jon Masters 
Tested-by: Jon Masters 
Signed-off-by: Greg Kroah-Hartman

x86/speculation/mds: Add sysfs reporting for MDS

2019-05-14T17:17:11+00:00

commit 8a4b06d391b0a42a373808979b5028f5c84d9c6a upstream

Add the sysfs reporting file for MDS. It exposes the vulnerability and
mitigation state similar to the existing files for the other speculative
hardware vulnerabilities.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Borislav Petkov 
Reviewed-by: Jon Masters 
Tested-by: Jon Masters 
Signed-off-by: Greg Kroah-Hartman