linux/arch/x86
Bandan Das bae3a8d330 x86/apic: Do not initialize LDR and DFR for bigsmp
Legacy apic init uses bigsmp for smp systems with 8 and more CPUs. The
bigsmp APIC implementation uses physical destination mode, but it
nevertheless initializes LDR and DFR. The LDR even ends up incorrectly with
multiple bit being set.

This does not cause a functional problem because LDR and DFR are ignored
when physical destination mode is active, but it triggered a problem on a
32-bit KVM guest which jumps into a kdump kernel.

The multiple bits set unearthed a bug in the KVM APIC implementation. The
code which creates the logical destination map for VCPUs ignores the
disabled state of the APIC and ends up overwriting an existing valid entry
and as a result, APIC calibration hangs in the guest during kdump
initialization.

Remove the bogus LDR/DFR initialization.

This is not intended to work around the KVM APIC bug. The LDR/DFR
ininitalization is wrong on its own.

The issue goes back into the pre git history. The fixes tag is the commit
in the bitkeeper import which introduced bigsmp support in 2003.

  git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git

Fixes: db7b9e9f26b8 ("[PATCH] Clustered APIC setup for >8 CPU systems")
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190826101513.5080-2-bsd@redhat.com
2019-08-26 20:00:56 +02:00
..
boot x86/boot/compressed/64: Fix boot on machines with broken E820 table 2019-08-19 15:59:13 +02:00
configs x86/defconfigs: Remove useless UEVENT_HELPER_PATH 2019-06-21 19:22:08 +02:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2019-07-08 20:57:08 -07:00
entry Merge branch master from git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 2019-07-28 22:22:40 +02:00
events perf/x86/intel: Mark expected switch fall-throughs 2019-07-25 20:10:05 -05:00
hyperv x86/hyper-v: Zero out the VP ASSIST PAGE on allocation 2019-07-19 09:48:15 +02:00
ia32 clone: fix CLONE_PIDFD support 2019-07-14 20:36:12 +02:00
include x86/retpoline: Don't clobber RFLAGS during CALL_NOSPEC on i386 2019-08-23 17:38:13 +02:00
kernel x86/apic: Do not initialize LDR and DFR for bigsmp 2019-08-26 20:00:56 +02:00
kvm KVM/arm fixes for 5.3 2019-08-09 16:53:39 +02:00
lib x86/lib/cpu: Address missing prototypes warning 2019-08-08 08:25:53 +02:00
math-emu x86/fpu/math-emu: Address fallthrough warnings 2019-08-12 20:35:05 +02:00
mm x86/mm: Sync also unmappings in vmalloc_sync_all() 2019-07-22 10:18:30 +02:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-07-08 19:48:57 -07:00
oprofile
pci treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 387 2019-06-05 17:37:11 +02:00
platform platform-drivers-x86 for v5.3-1 2019-07-14 16:51:47 -07:00
power x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h 2019-08-19 19:42:52 +02:00
purgatory x86/purgatory: Use CFLAGS_REMOVE rather than reset KBUILD_CFLAGS 2019-08-08 08:25:53 +02:00
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: Make set_real_mode_mem() static inline 2019-03-29 10:16:27 +01:00
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 Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2019-07-08 21:48:15 -07:00
video treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
xen Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-07-20 11:24:49 -07:00
.gitignore
Kbuild treewide: Add SPDX license identifier - Kbuild 2019-05-30 11:32:33 -07:00
Kconfig dma-mapping fixes for 5.3-rc1 2019-07-20 12:09:52 -07:00
Kconfig.cpu x86/cpu: Create Zhaoxin processors architecture support file 2019-06-22 11:45:57 +02:00
Kconfig.debug It's been a relatively busy cycle for docs: 2019-07-09 12:34:26 -07:00
Makefile x86/build: Keep local relocations with ld.lld 2019-04-05 12:34:35 +02:00
Makefile_32.cpu
Makefile.um x86, powerpc: Remove -funit-at-a-time compiler option entirely 2018-12-09 11:55:32 +01:00