linux/arch/x86
Waiman Long 64870ed1b1 x86/speculation: Fix incorrect MDS/TAA mitigation status
For MDS vulnerable processors with TSX support, enabling either MDS or
TAA mitigations will enable the use of VERW to flush internal processor
buffers at the right code path. IOW, they are either both mitigated
or both not. However, if the command line options are inconsistent,
the vulnerabilites sysfs files may not report the mitigation status
correctly.

For example, with only the "mds=off" option:

  vulnerabilities/mds:Vulnerable; SMT vulnerable
  vulnerabilities/tsx_async_abort:Mitigation: Clear CPU buffers; SMT vulnerable

The mds vulnerabilities file has wrong status in this case. Similarly,
the taa vulnerability file will be wrong with mds mitigation on, but
taa off.

Change taa_select_mitigation() to sync up the two mitigation status
and have them turned off if both "mds=off" and "tsx_async_abort=off"
are present.

Update documentation to emphasize the fact that both "mds=off" and
"tsx_async_abort=off" have to be specified together for processors that
are affected by both TAA and MDS to be effective.

 [ bp: Massage and add kernel-parameters.txt change too. ]

Fixes: 1b42f01741 ("x86/speculation/taa: Add mitigation for TSX Async Abort")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: linux-doc@vger.kernel.org
Cc: Mark Gross <mgross@linux.intel.com>
Cc: <stable@vger.kernel.org>
Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191115161445.30809-2-longman@redhat.com
2019-11-16 13:17:49 +01:00
..
boot x86, efi: Never relocate kernel below lowest acceptable address 2019-10-31 09:40:19 +01:00
configs x86/defconfigs: Remove useless UEVENT_HELPER_PATH 2019-06-21 19:22:08 +02:00
crypto crypto: x86/aes-ni - use AES library instead of single-use AES cipher 2019-09-09 23:48:41 +10:00
entry Kbuild updates for v5.4 2019-09-20 08:36:47 -07:00
events perf/x86/uncore: Fix event group support 2019-10-28 11:02:01 +01:00
hyperv x86/hyperv: Make vapic support x2apic mode 2019-10-15 10:57:09 +02:00
ia32 clone: fix CLONE_PIDFD support 2019-07-14 20:36:12 +02:00
include kvm: x86: mmu: Recovery of shattered NX large pages 2019-11-04 20:26:00 +01:00
kernel x86/speculation: Fix incorrect MDS/TAA mitigation status 2019-11-16 13:17:49 +01:00
kvm kvm: x86: mmu: Recovery of shattered NX large pages 2019-11-04 20:26:00 +01:00
lib x86/asm: Fix MWAITX C-state hint value 2019-10-08 13:25:24 +02:00
math-emu x86/fpu/math-emu: Address fallthrough warnings 2019-08-12 20:35:05 +02:00
mm Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
net bpf: fix x64 JIT code generation for jmp to 1st insn 2019-08-01 13:12:09 -07:00
oprofile
pci dma-mapping updates for 5.4: 2019-09-19 13:27:23 -07:00
platform efi/x86: Do not clean dummy variable in kexec path 2019-10-07 15:24:36 +02:00
power Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-09-17 12:04:39 -07:00
purgatory Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-09-28 13:37:41 -07:00
ras RAS/CEC: Add CONFIG_RAS_CEC_DEBUG and move CEC debug features there 2019-06-08 17:39:24 +02:00
realmode x86/realmode: Remove trampoline_status 2019-07-22 11:30:18 +02:00
tools Merge branch 'x86-paravirt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-07-08 17:34:44 -07:00
um um: Use real DMA barriers 2019-09-15 21:37:14 +02:00
video treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
xen xen: patch for 5.4-rc5 2019-10-26 06:32:12 -04:00
.gitignore
Kbuild treewide: Add SPDX license identifier - Kbuild 2019-05-30 11:32:33 -07:00
Kconfig x86/tsx: Add config options to set tsx=on|off|auto 2019-10-28 09:12:18 +01:00
Kconfig.cpu x86/cpu: Create Zhaoxin processors architecture support file 2019-06-22 11:45:57 +02:00
Kconfig.debug x86, perf: Fix the dependency of the x86 insn decoder selftest 2019-09-02 20:05:58 +02:00
Makefile x86/build: Add -Wnoaddress-of-packed-member to REALMODE_CFLAGS, to silence GCC9 build warning 2019-08-28 17:31:31 +02:00
Makefile_32.cpu
Makefile.um