linux_dsm_epyc7002/arch/x86
Borislav Petkov bb8c13d61a x86/microcode: Fix CPU synchronization routine
Emanuel reported an issue with a hang during microcode update because my
dumb idea to use one atomic synchronization variable for both rendezvous
- before and after update - was simply bollocks:

  microcode: microcode_reload_late: late_cpus: 4
  microcode: __reload_late: cpu 2 entered
  microcode: __reload_late: cpu 1 entered
  microcode: __reload_late: cpu 3 entered
  microcode: __reload_late: cpu 0 entered
  microcode: __reload_late: cpu 1 left
  microcode: Timeout while waiting for CPUs rendezvous, remaining: 1

CPU1 above would finish, leave and the others will still spin waiting for
it to join.

So do two synchronization atomics instead, which makes the code a lot more
straightforward.

Also, since the update is serialized and it also takes quite some time per
microcode engine, increase the exit timeout by the number of CPUs on the
system.

That's ok because the moment all CPUs are done, that timeout will be cut
short.

Furthermore, panic when some of the CPUs timeout when returning from a
microcode update: we can't allow a system with not all cores updated.

Also, as an optimization, do not do the exit sync if microcode wasn't
updated.

Reported-by: Emanuel Czirai <xftroxgpx@protonmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Emanuel Czirai <xftroxgpx@protonmail.com>
Tested-by: Ashok Raj <ashok.raj@intel.com>
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lkml.kernel.org/r/20180314183615.17629-2-bp@alien8.de
2018-03-16 20:55:51 +01:00
..
boot Merge branch 'next-tpm' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2018-01-31 13:12:31 -08:00
configs x86/unwind: Rename unwinder config options to 'CONFIG_UNWINDER_*' 2017-10-14 10:12:12 +02:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-02-12 08:57:21 -08:00
entry x86/vsyscall/64: Drop "native" vsyscalls 2018-03-08 06:48:15 +01:00
events Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-02-14 17:02:15 -08:00
hyperv KVM changes for 4.16 2018-02-10 13:16:35 -08:00
ia32 x86/entry: Do not special-case clone(2) in compat entry 2018-03-07 07:57:31 +01:00
include x86/microcode: Attempt late loading only when new microcode is present 2018-03-16 20:55:51 +01:00
kernel x86/microcode: Fix CPU synchronization routine 2018-03-16 20:55:51 +01:00
kvm KVM/VMX: Optimize vmx_vcpu_run() and svm_vcpu_run() by marking the RDMSR path as unlikely() 2018-02-23 08:24:36 +01:00
lib Revert "x86/retpoline: Simplify vmexit_fill_RSB()" 2018-02-20 09:38:26 +01:00
math-emu License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mm x86/pti: Fix a comment typo 2018-03-08 12:33:21 +01:00
net bpf, x86_64: remove obsolete exception handling from div/mod 2018-01-26 16:42:06 -08:00
oprofile Modules updates for v4.15 2017-11-15 13:46:33 -08:00
pci pci-v4.16-changes 2018-02-06 09:59:40 -08:00
platform Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-02-14 17:02:15 -08:00
power x86: hibernate: fix swsusp_arch_resume() prototype 2018-02-07 12:18:23 +01:00
purgatory License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ras License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
realmode x86-64/realmode: Add instruction suffix 2018-02-20 09:33:41 +01:00
tools x86/tools: Standardize output format of insn_decode_test 2017-12-12 13:27:47 +01:00
um Merge commit 'upstream-x86-entry' into WIP.x86/mm 2017-12-17 12:58:53 +01:00
video
xen x86/xen: Zero MSR_IA32_SPEC_CTRL before suspend 2018-02-28 16:03:19 +01:00
.gitignore
Kbuild Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-07 09:25:15 -07:00
Kconfig x86/vsyscall/64: Drop "native" vsyscalls 2018-03-08 06:48:15 +01:00
Kconfig.cpu License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig.debug Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-30 13:01:09 -08:00
Makefile objtool, retpolines: Integrate objtool with retpoline support more closely 2018-02-21 16:54:32 +01:00
Makefile_32.cpu License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Makefile.um License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00