Vitaly Kuznetsov e525cd364c ACPI: processor: Fix CPU0 wakeup in acpi_idle_play_dead() ... commit 8cdddd182bd7befae6af49c5fd612893f55d6ccb upstream. Commit 496121c021 ("ACPI: processor: idle: Allow probing on platforms with one ACPI C-state") broke CPU0 hotplug on certain systems, e.g. I'm observing the following on AWS Nitro (e.g r5b.xlarge but other instance types are affected as well): # echo 0 > /sys/devices/system/cpu/cpu0/online # echo 1 > /sys/devices/system/cpu/cpu0/online <10 seconds delay> -bash: echo: write error: Input/output error In fact, the above mentioned commit only revealed the problem and did not introduce it. On x86, to wakeup CPU an NMI is being used and hlt_play_dead()/mwait_play_dead() loops are prepared to handle it: /* * If NMI wants to wake up CPU0, start CPU0. */ if (wakeup_cpu0()) start_cpu0(); cpuidle_play_dead() -> acpi_idle_play_dead() (which is now being called on systems where it wasn't called before the above mentioned commit) serves the same purpose but it doesn't have a path for CPU0. What happens now on wakeup is: - NMI is sent to CPU0 - wakeup_cpu0_nmi() works as expected - we get back to while (1) loop in acpi_idle_play_dead() - safe_halt() puts CPU0 to sleep again. The straightforward/minimal fix is add the special handling for CPU0 on x86 and that's what the patch is doing. Fixes: 496121c021 ("ACPI: processor: idle: Allow probing on platforms with one ACPI C-state") Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: 5.10+ <stable@vger.kernel.org> # 5.10+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2021-04-07 15:00:08 +02:00
..
boot	A set of fixes for x86:	2020-12-06 11:22:39 -08:00
configs
crypto	crypto: x86/aes-ni-xts - use direct calls to and 4-way stride	2021-03-20 10:43:43 +01:00
entry	x86/entry: Fix entry/exit mismatch on failed fast 32-bit syscalls	2021-03-17 17:06:36 +01:00
events	perf/x86/intel: Fix unchecked MSR access error caused by VLBR_EVENT	2021-03-25 09:04:16 +01:00
hyperv	x86/hyperv: Fix kexec panic/hang issues	2021-01-27 11:54:57 +01:00
ia32
include	ACPI: processor: Fix CPU0 wakeup in acpi_idle_play_dead()	2021-04-07 15:00:08 +02:00
kernel	ACPI: processor: Fix CPU0 wakeup in acpi_idle_play_dead()	2021-04-07 15:00:08 +02:00
kvm	KVM: x86: Protect userspace MSR filter with SRCU, and set atomically-ish	2021-03-30 14:31:53 +02:00
lib	x86/sev-es: Use __copy_from_user_inatomic()	2021-03-17 17:06:36 +01:00
math-emu
mm	x86/mem_encrypt: Correct physical address calculation in __set_clr_pte_enc()	2021-03-30 14:32:07 +02:00
net	bpf: Fix fexit trampoline.	2021-04-07 15:00:03 +02:00
oprofile
pci	x86/pci: Create PCI/MSI irqdomain after x86_init.pci.arch_init()	2021-02-17 11:02:28 +01:00
platform	x86/efi: Remove EFI PGD build time checks	2021-02-17 11:02:24 +01:00
power
purgatory	treewide: Convert macro and uses of __section(foo) to __section("foo")	2020-10-25 14:51:49 -07:00
ras
realmode
tools	x86/build: Treat R_386_PLT32 relocation as R_386_PC32	2021-03-07 12:34:04 +01:00
um	arch/um: partially revert the conversion to __section() macro	2020-10-26 15:39:37 -07:00
video
xen	Revert "xen: fix p2m size in dom0 for disabled memory hotplug case"	2021-03-30 14:32:08 +02:00
.gitignore
Kbuild
Kconfig	fanotify: Fix sys_fanotify_mark() on native x86-32	2021-01-17 14:16:59 +01:00
Kconfig.assembler
Kconfig.cpu
Kconfig.debug
Makefile	x86/build: Disable CET instrumentation in the kernel for 32-bit too	2021-02-17 11:02:27 +01:00
Makefile_32.cpu
Makefile.um