[linux-next:master 14650/16300] arch/riscv/kernel/kernel_mode_vector.c:27:13: sparse: sparse: cast removes address space '__rcu' of expression

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   5453bc3279e9f8578ac3e534d476240e40c879e1
commit: b5060a4aa33d7d78a8c1837ab08ef0c81ea96650 [14650/16300] RISC-V: KVM: fix vcpu vector context handling for kernel-mode vector
config: riscv-randconfig-r131-20260819 (https://download.01.org/0day-ci/archive/20260819/[email protected]/config)
compiler: riscv64-linux-gcc (GCC) 16.1.0
sparse: v0.6.5-rc1
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260819/[email protected]/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
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

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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