linux.git/arch/riscv/kernel/cacheinfo.c, branch v6.13 Linux kernel source tree riscv: Prevent a bad reference count on CPU nodes 2024-10-25T13:18:39+00:00 Miquel Sabaté Solà mikisabate@gmail.com 2024-09-13T08:00:52+00:00 37233169a6ea912020c572f870075a63293b786a When populating cache leaves we previously fetched the CPU device node at the very beginning. But when ACPI is enabled we go through a specific branch which returns early and does not call 'of_node_put' for the node that was acquired. Since we are not using a CPU device node for the ACPI code anyways, we can simply move the initialization of it just passed the ACPI block, and we are guaranteed to have an 'of_node_put' call for the acquired node. This prevents a bad reference count of the CPU device node. Moreover, the previous function did not check for errors when acquiring the device node, so a return -ENOENT has been added for that case. Signed-off-by: Miquel Sabaté Solà <mikisabate@gmail.com> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com> Reviewed-by: Sunil V L <sunilvl@ventanamicro.com> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Fixes: 604f32ea6909 ("riscv: cacheinfo: initialize cacheinfo's level and type from ACPI PPTT") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240913080053.36636-1-mikisabate@gmail.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> 
When populating cache leaves we previously fetched the CPU device node
at the very beginning. But when ACPI is enabled we go through a
specific branch which returns early and does not call 'of_node_put' for
the node that was acquired.

Since we are not using a CPU device node for the ACPI code anyways, we
can simply move the initialization of it just passed the ACPI block, and
we are guaranteed to have an 'of_node_put' call for the acquired node.
This prevents a bad reference count of the CPU device node.

Moreover, the previous function did not check for errors when acquiring
the device node, so a return -ENOENT has been added for that case.

Signed-off-by: Miquel Sabaté Solà <mikisabate@gmail.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Fixes: 604f32ea6909 ("riscv: cacheinfo: initialize cacheinfo's level and  type from ACPI PPTT")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240913080053.36636-1-mikisabate@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
riscv: cacheinfo: Add back init_cache_level() function 2024-09-16T03:15:50+00:00 Steffen Persvold spersvold@gmail.com 2024-07-07T00:35:15+00:00 1845d381f28063a3b68e9e148d5a7f01d6be8721 commit 5944ce092b97 (arch_topology: Build cacheinfo from primary CPU) removed the init_cache_level() function from arch/riscv/kernel/cacheinfo.c and relies on the init_cpu_topology() function in drivers/base/arch_topology.c to call fetch_cache_info() which in turn calls init_of_cache_level() to populate the cache hierarchy information. However, init_cpu_topology() is only called from smpboot.c:smp_prepare_cpus() and thus only available when CONFIG_SMP is defined. To support non-SMP enabled kernels to still detect cache hierarchy, we add back the init_cache_level() function. The init_level_allocate_ci() function handles this gracefully on SMP-enabled kernels anyway where fetch_cache_info() is called from init_cpu_topology() earlier in the boot phase. Signed-off-by: Steffen Persvold <spersvold@gmail.com> Link: https://lore.kernel.org/r/20240707003515.5058-1-spersvold@gmail.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> 
commit 5944ce092b97 (arch_topology: Build cacheinfo from primary CPU)
removed the init_cache_level() function from arch/riscv/kernel/cacheinfo.c
and relies on the init_cpu_topology() function in drivers/base/arch_topology.c
to call fetch_cache_info() which in turn calls init_of_cache_level() to
populate the cache hierarchy information. However, init_cpu_topology() is only
called from smpboot.c:smp_prepare_cpus() and thus only available when
CONFIG_SMP is defined.

To support non-SMP enabled kernels to still detect cache hierarchy, we add back
the init_cache_level() function. The init_level_allocate_ci() function handles
this gracefully on SMP-enabled kernels anyway where fetch_cache_info() is
called from init_cpu_topology() earlier in the boot phase.

Signed-off-by: Steffen Persvold <spersvold@gmail.com>
Link: https://lore.kernel.org/r/20240707003515.5058-1-spersvold@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
riscv: cacheinfo: initialize cacheinfo's level and type from ACPI PPTT 2024-07-24T14:39:36+00:00 Yunhui Cui cuiyunhui@bytedance.com 2024-06-17T13:14:24+00:00 604f32ea6909b0ebb8ab0bf1ab7dc66ee3dc8955 Before cacheinfo can be built correctly, we need to initialize level and type. Since RISC-V currently does not have a register group that describes cache-related attributes like ARM64, we cannot obtain them directly, so now we obtain cache leaves from the ACPI PPTT table (acpi_get_cache_info()) and set the cache type through split_levels. Suggested-by: Jeremy Linton <jeremy.linton@arm.com> Suggested-by: Sudeep Holla <sudeep.holla@arm.com> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Reviewed-by: Sunil V L <sunilvl@ventanamicro.com> Reviewed-by: Jeremy Linton <jeremy.linton@arm.com> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com> Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com> Link: https://lore.kernel.org/r/20240617131425.7526-2-cuiyunhui@bytedance.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> 
Before cacheinfo can be built correctly, we need to initialize level
and type. Since RISC-V currently does not have a register group that
describes cache-related attributes like ARM64, we cannot obtain them
directly, so now we obtain cache leaves from the ACPI PPTT table
(acpi_get_cache_info()) and set the cache type through split_levels.

Suggested-by: Jeremy Linton <jeremy.linton@arm.com>
Suggested-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>
Reviewed-by: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
Link: https://lore.kernel.org/r/20240617131425.7526-2-cuiyunhui@bytedance.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
riscv: cacheinfo: remove the useless input parameter (node) of ci_leaf_init() 2024-07-24T14:39:35+00:00 Yunhui Cui cuiyunhui@bytedance.com 2024-06-17T13:14:23+00:00 ee3fab10cb1566562aa683f319066eaeecccf918 ci_leaf_init() is a declared static function. The implementation of the function body and the caller do not use the parameter (struct device_node *node) input parameter, so remove it. Fixes: 6a24915145c9 ("Revert "riscv: Set more data to cacheinfo"") Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com> Reviewed-by: Jeremy Linton <jeremy.linton@arm.com> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com> Link: https://lore.kernel.org/r/20240617131425.7526-1-cuiyunhui@bytedance.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> 
ci_leaf_init() is a declared static function. The implementation of the
function body and the caller do not use the parameter (struct device_node
*node) input parameter, so remove it.

Fixes: 6a24915145c9 ("Revert "riscv: Set more data to cacheinfo"")
Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
Reviewed-by: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/20240617131425.7526-1-cuiyunhui@bytedance.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Merge tag 'riscv-for-linus-6.4-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux 2023-04-28T23:55:39+00:00 Linus Torvalds torvalds@linux-foundation.org 2023-04-28T23:55:39+00:00 89d77f71f493a3663b10fa812d17f472935d24be Pull RISC-V updates from Palmer Dabbelt: - Support for runtime detection of the Svnapot extension - Support for Zicboz when clearing pages - We've moved to GENERIC_ENTRY - Support for !MMU on rv32 systems - The linear region is now mapped via huge pages - Support for building relocatable kernels - Support for the hwprobe interface - Various fixes and cleanups throughout the tree * tag 'riscv-for-linus-6.4-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (57 commits) RISC-V: hwprobe: Explicity check for -1 in vdso init RISC-V: hwprobe: There can only be one first riscv: Allow to downgrade paging mode from the command line dt-bindings: riscv: add sv57 mmu-type RISC-V: hwprobe: Remove __init on probe_vendor_features() riscv: Use --emit-relocs in order to move .rela.dyn in init riscv: Check relocations at compile time powerpc: Move script to check relocations at compile time in scripts/ riscv: Introduce CONFIG_RELOCATABLE riscv: Move .rela.dyn outside of init to avoid empty relocations riscv: Prepare EFI header for relocatable kernels riscv: Unconditionnally select KASAN_VMALLOC if KASAN riscv: Fix ptdump when KASAN is enabled riscv: Fix EFI stub usage of KASAN instrumented strcmp function riscv: Move DTB_EARLY_BASE_VA to the kernel address space riscv: Rework kasan population functions riscv: Split early and final KASAN population functions riscv: Use PUD/P4D/PGD pages for the linear mapping riscv: Move the linear mapping creation in its own function riscv: Get rid of riscv_pfn_base variable ... 
Pull RISC-V updates from Palmer Dabbelt:

 - Support for runtime detection of the Svnapot extension

 - Support for Zicboz when clearing pages

 - We've moved to GENERIC_ENTRY

 - Support for !MMU on rv32 systems

 - The linear region is now mapped via huge pages

 - Support for building relocatable kernels

 - Support for the hwprobe interface

 - Various fixes and cleanups throughout the tree

* tag 'riscv-for-linus-6.4-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (57 commits)
  RISC-V: hwprobe: Explicity check for -1 in vdso init
  RISC-V: hwprobe: There can only be one first
  riscv: Allow to downgrade paging mode from the command line
  dt-bindings: riscv: add sv57 mmu-type
  RISC-V: hwprobe: Remove __init on probe_vendor_features()
  riscv: Use --emit-relocs in order to move .rela.dyn in init
  riscv: Check relocations at compile time
  powerpc: Move script to check relocations at compile time in scripts/
  riscv: Introduce CONFIG_RELOCATABLE
  riscv: Move .rela.dyn outside of init to avoid empty relocations
  riscv: Prepare EFI header for relocatable kernels
  riscv: Unconditionnally select KASAN_VMALLOC if KASAN
  riscv: Fix ptdump when KASAN is enabled
  riscv: Fix EFI stub usage of KASAN instrumented strcmp function
  riscv: Move DTB_EARLY_BASE_VA to the kernel address space
  riscv: Rework kasan population functions
  riscv: Split early and final KASAN population functions
  riscv: Use PUD/P4D/PGD pages for the linear mapping
  riscv: Move the linear mapping creation in its own function
  riscv: Get rid of riscv_pfn_base variable
  ...
riscv: cacheinfo: Adjust includes to remove of_device.h 2023-04-13T22:46:34+00:00 Rob Herring robh@kernel.org 2023-03-29T15:52:06+00:00 06d90669769b6fc0a390b2f724457994d247aaae Now that of_cpu_device_node_get() is defined in of.h, of_device.h is just implicitly including other includes, and is no longer needed. Adjust the include files with what was implicitly included by of_device.h (cpu.h and of.h) and drop including of_device.h. Link: https://lore.kernel.org/r/20230329-dt-cpu-header-cleanups-v1-9-581e2605fe47@kernel.org Signed-off-by: Rob Herring <robh@kernel.org> 
Now that of_cpu_device_node_get() is defined in of.h, of_device.h is just
implicitly including other includes, and is no longer needed. Adjust the
include files with what was implicitly included by of_device.h (cpu.h and
of.h) and drop including of_device.h.

Link: https://lore.kernel.org/r/20230329-dt-cpu-header-cleanups-v1-9-581e2605fe47@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Revert "riscv: Set more data to cacheinfo" 2023-04-11T23:07:53+00:00 Song Shuai suagrfillet@gmail.com 2023-03-08T06:47:34+00:00 6a24915145c922b79d3ac78f681137a4c14a6d6b This reverts commit baf7cbd94b5688f167443a2cc3dcea3300132099. There are some duplicate cache attributes populations executed in both ci_leaf_init() and later cache_setup_properties(). Revert the commit baf7cbd94b56 ("riscv: Set more data to cacheinfo") to setup only the level and type attributes at this early place. Signed-off-by: Song Shuai <suagrfillet@gmail.com> Acked-by: Sudeep Holla <sudeep.holla@arm.com> Acked-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20230308064734.512457-1-suagrfillet@gmail.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> 
This reverts commit baf7cbd94b5688f167443a2cc3dcea3300132099.

There are some duplicate cache attributes populations executed
in both ci_leaf_init() and later cache_setup_properties().

Revert the commit baf7cbd94b56 ("riscv: Set more data to cacheinfo")
to setup only the level and type attributes at this early place.

Signed-off-by: Song Shuai <suagrfillet@gmail.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230308064734.512457-1-suagrfillet@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
arch_topology: Build cacheinfo from primary CPU 2023-01-18T09:58:40+00:00 Pierre Gondois pierre.gondois@arm.com 2023-01-04T18:30:29+00:00 5944ce092b97caed5d86d961e963b883b5c44ee2 commit 3fcbf1c77d08 ("arch_topology: Fix cache attributes detection in the CPU hotplug path") adds a call to detect_cache_attributes() to populate the cacheinfo before updating the siblings mask. detect_cache_attributes() allocates memory and can take the PPTT mutex (on ACPI platforms). On PREEMPT_RT kernels, on secondary CPUs, this triggers a: 'BUG: sleeping function called from invalid context' [1] as the code is executed with preemption and interrupts disabled. The primary CPU was previously storing the cache information using the now removed (struct cpu_topology).llc_id: commit 5b8dc787ce4a ("arch_topology: Drop LLC identifier stash from the CPU topology") allocate_cache_info() tries to build the cacheinfo from the primary CPU prior secondary CPUs boot, if the DT/ACPI description contains cache information. If allocate_cache_info() fails, then fallback to the current state for the cacheinfo allocation. [1] will be triggered in such case. When unplugging a CPU, the cacheinfo memory cannot be freed. If it was, then the memory would be allocated early by the re-plugged CPU and would trigger [1]. Note that populate_cache_leaves() might be called multiple times due to populate_leaves being moved up. This is required since detect_cache_attributes() might be called with per_cpu_cacheinfo(cpu) being allocated but not populated. [1]: | BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46 | in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/111 | preempt_count: 1, expected: 0 | RCU nest depth: 1, expected: 1 | 3 locks held by swapper/111/0: | #0: (&pcp->lock){+.+.}-{3:3}, at: get_page_from_freelist+0x218/0x12c8 | #1: (rcu_read_lock){....}-{1:3}, at: rt_spin_trylock+0x48/0xf0 | #2: (&zone->lock){+.+.}-{3:3}, at: rmqueue_bulk+0x64/0xa80 | irq event stamp: 0 | hardirqs last enabled at (0): 0x0 | hardirqs last disabled at (0): copy_process+0x5dc/0x1ab8 | softirqs last enabled at (0): copy_process+0x5dc/0x1ab8 | softirqs last disabled at (0): 0x0 | Preemption disabled at: | migrate_enable+0x30/0x130 | CPU: 111 PID: 0 Comm: swapper/111 Tainted: G W 6.0.0-rc4-rt6-[...] | Call trace: | __kmalloc+0xbc/0x1e8 | detect_cache_attributes+0x2d4/0x5f0 | update_siblings_masks+0x30/0x368 | store_cpu_topology+0x78/0xb8 | secondary_start_kernel+0xd0/0x198 | __secondary_switched+0xb0/0xb4 Signed-off-by: Pierre Gondois <pierre.gondois@arm.com> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com> Acked-by: Palmer Dabbelt <palmer@rivosinc.com> Link: https://lore.kernel.org/r/20230104183033.755668-7-pierre.gondois@arm.com Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> 
commit 3fcbf1c77d08 ("arch_topology: Fix cache attributes detection
in the CPU hotplug path")
adds a call to detect_cache_attributes() to populate the cacheinfo
before updating the siblings mask. detect_cache_attributes() allocates
memory and can take the PPTT mutex (on ACPI platforms). On PREEMPT_RT
kernels, on secondary CPUs, this triggers a:
  'BUG: sleeping function called from invalid context' [1]
as the code is executed with preemption and interrupts disabled.

The primary CPU was previously storing the cache information using
the now removed (struct cpu_topology).llc_id:
commit 5b8dc787ce4a ("arch_topology: Drop LLC identifier stash from
the CPU topology")

allocate_cache_info() tries to build the cacheinfo from the primary
CPU prior secondary CPUs boot, if the DT/ACPI description
contains cache information.
If allocate_cache_info() fails, then fallback to the current state
for the cacheinfo allocation. [1] will be triggered in such case.

When unplugging a CPU, the cacheinfo memory cannot be freed. If it
was, then the memory would be allocated early by the re-plugged
CPU and would trigger [1].

Note that populate_cache_leaves() might be called multiple times
due to populate_leaves being moved up. This is required since
detect_cache_attributes() might be called with per_cpu_cacheinfo(cpu)
being allocated but not populated.

[1]:
 | BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
 | in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/111
 | preempt_count: 1, expected: 0
 | RCU nest depth: 1, expected: 1
 | 3 locks held by swapper/111/0:
 |  #0:  (&pcp->lock){+.+.}-{3:3}, at: get_page_from_freelist+0x218/0x12c8
 |  #1:  (rcu_read_lock){....}-{1:3}, at: rt_spin_trylock+0x48/0xf0
 |  #2:  (&zone->lock){+.+.}-{3:3}, at: rmqueue_bulk+0x64/0xa80
 | irq event stamp: 0
 | hardirqs last  enabled at (0):  0x0
 | hardirqs last disabled at (0):  copy_process+0x5dc/0x1ab8
 | softirqs last  enabled at (0):  copy_process+0x5dc/0x1ab8
 | softirqs last disabled at (0):  0x0
 | Preemption disabled at:
 |  migrate_enable+0x30/0x130
 | CPU: 111 PID: 0 Comm: swapper/111 Tainted: G        W          6.0.0-rc4-rt6-[...]
 | Call trace:
 |  __kmalloc+0xbc/0x1e8
 |  detect_cache_attributes+0x2d4/0x5f0
 |  update_siblings_masks+0x30/0x368
 |  store_cpu_topology+0x78/0xb8
 |  secondary_start_kernel+0xd0/0x198
 |  __secondary_switched+0xb0/0xb4

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Link: https://lore.kernel.org/r/20230104183033.755668-7-pierre.gondois@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
cacheinfo: Use RISC-V's init_cache_level() as generic OF implementation 2023-01-17T21:59:52+00:00 Pierre Gondois pierre.gondois@arm.com 2023-01-04T18:30:24+00:00 c3719bd9eeb2edf84bd263d662e36ca0ba262a23 RISC-V's implementation of init_of_cache_level() is following the Devicetree Specification v0.3 regarding caches, cf.: - s3.7.3 'Internal (L1) Cache Properties' - s3.8 'Multi-level and Shared Cache Nodes' Allow reusing the implementation by moving it. Also make 'levels', 'leaves' and 'level' unsigned int. Signed-off-by: Pierre Gondois <pierre.gondois@arm.com> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Acked-by: Palmer Dabbelt <palmer@rivosinc.com> Link: https://lore.kernel.org/r/20230104183033.755668-2-pierre.gondois@arm.com Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> 
RISC-V's implementation of init_of_cache_level() is following
the Devicetree Specification v0.3 regarding caches, cf.:
- s3.7.3 'Internal (L1) Cache Properties'
- s3.8 'Multi-level and Shared Cache Nodes'

Allow reusing the implementation by moving it.

Also make 'levels', 'leaves' and 'level' unsigned int.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Link: https://lore.kernel.org/r/20230104183033.755668-2-pierre.gondois@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
drivers: base: cacheinfo: Get rid of DEFINE_SMP_CALL_CACHE_FUNCTION() 2021-09-01T08:29:10+00:00 Thomas Gleixner tglx@linutronix.de 2021-08-31T11:48:34+00:00 4b92d4add5f6dcf21275185c997d6ecb800054cd DEFINE_SMP_CALL_CACHE_FUNCTION() was usefel before the CPU hotplug rework to ensure that the cache related functions are called on the upcoming CPU because the notifier itself could run on any online CPU. The hotplug state machine guarantees that the callbacks are invoked on the upcoming CPU. So there is no need to have this SMP function call obfuscation. That indirection was missed when the hotplug notifiers were converted. This also solves the problem of ARM64 init_cache_level() invoking ACPI functions which take a semaphore in that context. That's invalid as SMP function calls run with interrupts disabled. Running it just from the callback in context of the CPU hotplug thread solves this. Fixes: 8571890e1513 ("arm64: Add support for ACPI based firmware tables") Reported-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Guenter Roeck <linux@roeck-us.net> Acked-by: Will Deacon <will@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/871r69ersb.ffs@tglx 
DEFINE_SMP_CALL_CACHE_FUNCTION() was usefel before the CPU hotplug rework
to ensure that the cache related functions are called on the upcoming CPU
because the notifier itself could run on any online CPU.

The hotplug state machine guarantees that the callbacks are invoked on the
upcoming CPU. So there is no need to have this SMP function call
obfuscation. That indirection was missed when the hotplug notifiers were
converted.

This also solves the problem of ARM64 init_cache_level() invoking ACPI
functions which take a semaphore in that context. That's invalid as SMP
function calls run with interrupts disabled. Running it just from the
callback in context of the CPU hotplug thread solves this.

Fixes: 8571890e1513 ("arm64: Add support for ACPI based firmware tables")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/871r69ersb.ffs@tglx