arch/riscv/kernel/kernel_mode_vector.c:27:13: sparse: sparse: cast removes address space '__rcu' of expression

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   5fc5768c7ca92895ccd1de94dc521e5a55ae7896
commit: b5060a4aa33d7d78a8c1837ab08ef0c81ea96650 RISC-V: KVM: fix vcpu vector context handling for kernel-mode vector
date:   6 weeks ago
config: riscv-randconfig-r1309-20260925 (https://download.01.org/0day-ci/archive/20260925/202609251807.X3jcxqyP-lkp@intel.com/config)
compiler: clang version 24.0.0git (https://github.com/llvm/llvm-project 6e714c8d91116794cb699cdf80c26afe9cda3ef3)
sparse: v0.6.5-rc1
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260925/202609251807.X3jcxqyP-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Fixes: b5060a4aa33d ("RISC-V: KVM: fix vcpu vector context handling for kernel-mode vector")
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202609251807.X3jcxqyP-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
   WARNING: invalid argument to '-march': '_zacas_zabha'
>> arch/riscv/kernel/kernel_mode_vector.c:27:13: sparse: sparse: cast removes address space '__rcu' of expression
   arch/riscv/kernel/kernel_mode_vector.c:27:13: sparse: sparse: incompatible types in comparison expression (different address spaces):
   arch/riscv/kernel/kernel_mode_vector.c:27:13: sparse:    void ( [noderef] __rcu * )( ... )
   arch/riscv/kernel/kernel_mode_vector.c:27:13: sparse:    void ( * )( ... )
   arch/riscv/kernel/kernel_mode_vector.c:30:9: sparse: sparse: incompatible types in comparison expression (different address spaces):
   arch/riscv/kernel/kernel_mode_vector.c:30:9: sparse:    void ( [noderef] __rcu * )( ... )
   arch/riscv/kernel/kernel_mode_vector.c:30:9: sparse:    void ( * )( ... )
   arch/riscv/kernel/kernel_mode_vector.c:36:9: sparse: sparse: incompatible types in comparison expression (different address spaces):
   arch/riscv/kernel/kernel_mode_vector.c:36:9: sparse:    void ( [noderef] __rcu * )( ... )
   arch/riscv/kernel/kernel_mode_vector.c:36:9: sparse:    void ( * )( ... )
   arch/riscv/kernel/kernel_mode_vector.c:111:41: sparse: sparse: cast removes address space '__rcu' of expression
   arch/riscv/kernel/kernel_mode_vector.c:111:41: sparse: sparse: incompatible types in comparison expression (different address spaces):
   arch/riscv/kernel/kernel_mode_vector.c:111:41: sparse:    void ( [noderef] __rcu * )( ... )
   arch/riscv/kernel/kernel_mode_vector.c:111:41: sparse:    void ( * )( ... )

vim +/__rcu +27 arch/riscv/kernel/kernel_mode_vector.c

    24	
    25	void kvm_riscv_register_vctx_callback(void (*func)(void))
    26	{
  > 27		if (WARN_ON_ONCE(rcu_access_pointer(kvm_flush_vector_ctx_callback)))
    28			return;
    29	
    30		rcu_assign_pointer(kvm_flush_vector_ctx_callback, func);
    31	}
    32	EXPORT_SYMBOL_GPL(kvm_riscv_register_vctx_callback);
    33	

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