KVM: arm64: Stop sparse from moaning at __hyp_this_cpu_ptr

Sparse complains that __hyp_this_cpu_ptr() returns something
that is flagged noderef and not in the correct address space
(both being the result of the __percpu annotation).

Pretend that __hyp_this_cpu_ptr() knows what it is doing by
forcefully casting the pointer with __kernel __force.

Signed-off-by: Marc Zyngier <maz@kernel.org>

arch/arm64/include/asm/kvm_asm.h

@@ -81,12 +81,19 @@ extern u32 __kvm_get_mdcr_el2(void);
 
 extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ];
 
-/* Home-grown __this_cpu_{ptr,read} variants that always work at HYP */
+/*
+ * Home-grown __this_cpu_{ptr,read} variants that always work at HYP,
+ * provided that sym is really a *symbol* and not a pointer obtained from
+ * a data structure. As for SHIFT_PERCPU_PTR(), the creative casting keeps
+ * sparse quiet.
+ */
 #define __hyp_this_cpu_ptr(sym)						\
 	({								\
-		void *__ptr = hyp_symbol_addr(sym);			\
+		void *__ptr;						\
+		__verify_pcpu_ptr(&sym);				\
+		__ptr = hyp_symbol_addr(sym);				\
 		__ptr += read_sysreg(tpidr_el2);			\
-		(typeof(&sym))__ptr;					\
+		(typeof(sym) __kernel __force *)__ptr;			\
 	 })
 
 #define __hyp_this_cpu_read(sym)					\