[PATCH 02/25] KVM: arm64: Add feature checking helpers

[Marc Zyngier <maz@kernel.org>]

In order to make it easier to check whether a particular feature
is exposed to a guest, add a new set of helpers, with kvm_has_feat()
being the most useful.

Follow-up work will make heavy use of these.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/include/asm/kvm_host.h | 53 +++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 21c57b812569..c0cf9c5f5e8d 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -1233,4 +1233,57 @@ static inline void kvm_hyp_reserve(void) { }
 void kvm_arm_vcpu_power_off(struct kvm_vcpu *vcpu);
 bool kvm_arm_vcpu_stopped(struct kvm_vcpu *vcpu);
 
+#define __expand_field_sign_unsigned(id, fld, val)			\
+	((u64)(id##_##fld##_##val))
+
+#define __expand_field_sign_signed(id, fld, val)			\
+	({								\
+		s64 __val = id##_##fld##_##val;				\
+		__val <<= 64 - id##_##fld##_WIDTH;			\
+		__val >>= 64 - id##_##fld##_SHIFT - id##_##fld##_WIDTH;	\
+									\
+		__val;							\
+	})
+
+#define expand_field_sign(id, fld, val)					\
+	(id##_##fld##_SIGNED ?						\
+	 __expand_field_sign_signed(id, fld, val) :			\
+	 __expand_field_sign_unsigned(id, fld, val))
+
+#define get_idreg_field_unsigned(kvm, id, fld)				\
+	({								\
+		u64 __val = IDREG(kvm, SYS_##id);			\
+		__val &= id##_##fld##_MASK;				\
+		__val >>= id##_##fld##_SHIFT;				\
+									\
+		__val;							\
+	})
+
+#define get_idreg_field_signed(kvm, id, fld)				\
+	({								\
+		s64 __val = IDREG(kvm, SYS_##id);			\
+		__val <<= 64 - id##_##fld##_SHIFT - id##_##fld##_WIDTH;	\
+		__val >>= id##_##fld##_SHIFT;				\
+									\
+		__val;							\
+	})
+
+#define get_idreg_field_enum(kvm, id, fld)				\
+	get_idreg_field_unsigned(kvm, id, fld)
+
+#define get_idreg_field(kvm, id, fld)					\
+	(id##_##fld##_SIGNED ?						\
+	 get_idreg_field_signed(kvm, id, fld) :				\
+	 get_idreg_field_unsigned(kvm, id, fld))
+
+#define kvm_has_feat(kvm, id, fld, limit)				\
+	(get_idreg_field((kvm), id, fld) >= expand_field_sign(id, fld, limit))
+
+#define kvm_has_feat_enum(kvm, id, fld, limit)				\
+	(get_idreg_field_unsigned((kvm), id, fld) == id##_##fld##_##limit)
+
+#define kvm_has_feat_range(kvm, id, fld, min, max)			\
+	(get_idreg_field((kvm), id, fld) >= expand_field_sign(id, fld, min) && \
+	 get_idreg_field((kvm), id, fld) <= expand_field_sign(id, fld, max))
+
 #endif /* __ARM64_KVM_HOST_H__ */
-- 
2.39.2


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