Patch "arm64: efi: Make efi_rt_lock a raw_spinlock" has been added to the 6.2-stable tree

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This is a note to let you know that I've just added the patch titled

    arm64: efi: Make efi_rt_lock a raw_spinlock

to the 6.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     arm64-efi-make-efi_rt_lock-a-raw_spinlock.patch
and it can be found in the queue-6.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 0e68b5517d3767562889f1d83fdb828c26adb24f Mon Sep 17 00:00:00 2001
From: Pierre Gondois <pierre.gondois@xxxxxxx>
Date: Wed, 15 Feb 2023 17:10:47 +0100
Subject: arm64: efi: Make efi_rt_lock a raw_spinlock

From: Pierre Gondois <pierre.gondois@xxxxxxx>

commit 0e68b5517d3767562889f1d83fdb828c26adb24f upstream.

Running a rt-kernel base on 6.2.0-rc3-rt1 on an Ampere Altra outputs
the following:
  BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
  in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 9, name: kworker/u320:0
  preempt_count: 2, expected: 0
  RCU nest depth: 0, expected: 0
  3 locks held by kworker/u320:0/9:
  #0: ffff3fff8c27d128 ((wq_completion)efi_rts_wq){+.+.}-{0:0}, at: process_one_work (./include/linux/atomic/atomic-long.h:41)
  #1: ffff80000861bdd0 ((work_completion)(&efi_rts_work.work)){+.+.}-{0:0}, at: process_one_work (./include/linux/atomic/atomic-long.h:41)
  #2: ffffdf7e1ed3e460 (efi_rt_lock){+.+.}-{3:3}, at: efi_call_rts (drivers/firmware/efi/runtime-wrappers.c:101)
  Preemption disabled at:
  efi_virtmap_load (./arch/arm64/include/asm/mmu_context.h:248)
  CPU: 0 PID: 9 Comm: kworker/u320:0 Tainted: G        W          6.2.0-rc3-rt1
  Hardware name: WIWYNN Mt.Jade Server System B81.03001.0005/Mt.Jade Motherboard, BIOS 1.08.20220218 (SCP: 1.08.20220218) 2022/02/18
  Workqueue: efi_rts_wq efi_call_rts
  Call trace:
  dump_backtrace (arch/arm64/kernel/stacktrace.c:158)
  show_stack (arch/arm64/kernel/stacktrace.c:165)
  dump_stack_lvl (lib/dump_stack.c:107 (discriminator 4))
  dump_stack (lib/dump_stack.c:114)
  __might_resched (kernel/sched/core.c:10134)
  rt_spin_lock (kernel/locking/rtmutex.c:1769 (discriminator 4))
  efi_call_rts (drivers/firmware/efi/runtime-wrappers.c:101)
  [...]

This seems to come from commit ff7a167961d1 ("arm64: efi: Execute
runtime services from a dedicated stack") which adds a spinlock. This
spinlock is taken through:
efi_call_rts()
\-efi_call_virt()
  \-efi_call_virt_pointer()
    \-arch_efi_call_virt_setup()

Make 'efi_rt_lock' a raw_spinlock to avoid being preempted.

[ardb: The EFI runtime services are called with a different set of
       translation tables, and are permitted to use the SIMD registers.
       The context switch code preserves/restores neither, and so EFI
       calls must be made with preemption disabled, rather than only
       disabling migration.]

Fixes: ff7a167961d1 ("arm64: efi: Execute runtime services from a dedicated stack")
Signed-off-by: Pierre Gondois <pierre.gondois@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v6.1+
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/arm64/include/asm/efi.h |    6 +++---
 arch/arm64/kernel/efi.c      |    2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -33,7 +33,7 @@ int efi_set_mapping_permissions(struct m
 ({									\
 	efi_virtmap_load();						\
 	__efi_fpsimd_begin();						\
-	spin_lock(&efi_rt_lock);					\
+	raw_spin_lock(&efi_rt_lock);					\
 })
 
 #undef arch_efi_call_virt
@@ -42,12 +42,12 @@ int efi_set_mapping_permissions(struct m
 
 #define arch_efi_call_virt_teardown()					\
 ({									\
-	spin_unlock(&efi_rt_lock);					\
+	raw_spin_unlock(&efi_rt_lock);					\
 	__efi_fpsimd_end();						\
 	efi_virtmap_unload();						\
 })
 
-extern spinlock_t efi_rt_lock;
+extern raw_spinlock_t efi_rt_lock;
 extern u64 *efi_rt_stack_top;
 efi_status_t __efi_rt_asm_wrapper(void *, const char *, ...);
 
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -146,7 +146,7 @@ asmlinkage efi_status_t efi_handle_corru
 	return s;
 }
 
-DEFINE_SPINLOCK(efi_rt_lock);
+DEFINE_RAW_SPINLOCK(efi_rt_lock);
 
 asmlinkage u64 *efi_rt_stack_top __ro_after_init;
 


Patches currently in stable-queue which might be from pierre.gondois@xxxxxxx are

queue-6.2/arm64-efi-make-efi_rt_lock-a-raw_spinlock.patch
queue-6.2/cacheinfo-fix-shared_cpu_map-to-handle-shared-caches.patch



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