We already have hyp_alternate_select() to define a function pointer
that gets changed by a kernel feature or workaround.
It would be useful to have a similar feature that resolves in a
direct value, without requiring a function call. For this purpose,
introduce hyp_alternate_value(), which returns one of two values
depending on the state of the alternative.
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
arch/arm64/kvm/hyp/hyp.h | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/arch/arm64/kvm/hyp/hyp.h b/arch/arm64/kvm/hyp/hyp.h
index 44eaff7..dc75fdb 100644
--- a/arch/arm64/kvm/hyp/hyp.h
+++ b/arch/arm64/kvm/hyp/hyp.h
@@ -144,6 +144,17 @@ typeof(orig) * __hyp_text fname(void) \
return val; \
}
+#define hyp_alternate_value(fname, orig, alt, cond) \
+typeof(orig) __hyp_text fname(void) \
+{ \
+ typeof(alt) val = orig; \
+ asm volatile(ALTERNATIVE("nop \n", \
+ "mov %0, %1 \n", \
+ cond) \
+ : "+r" (val) : "r" ((typeof(orig))alt)); \
+ return val; \
+}
+
void __vgic_v2_save_state(struct kvm_vcpu *vcpu);
void __vgic_v2_restore_state(struct kvm_vcpu *vcpu);
--
2.1.4
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