[PATCH] KVM: arm64: Stop sparse from moaning at __hyp_this_cpu_ptr

Marc Zyngier
2020-06-08T08:57:39Z

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 | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 0c9b5fc4ba0a..82691406d493 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -81,12 +81,17 @@ 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); \
__ptr += read_sysreg(tpidr_el2); \
- (typeof(&sym))__ptr; \
+ (typeof(sym) __kernel __force *)__ptr; \
})

#define __hyp_this_cpu_read(sym) \
--
2.26.2