KVM: arm64/sve: Fix vq_present() macro to yield a bool

The original implementation of vq_present() relied on aggressive inlining in order for the compiler to know that the code is correct, due to some const-casting issues. This was causing sparse and clang to complain, while GCC compiled cleanly. Commit 0c529ff789bc addressed this problem, but since vq_present() is no longer a function, there is now no implicit casting of the returned value to the return type (bool). In set_sve_vls(), this uncast bit value is compared against a bool, and so may spuriously compare as unequal when both are nonzero. As a result, KVM may reject valid SVE vector length configurations as invalid, and vice versa. Fix it by forcing the returned value to a bool.

ZLZhang Lei committed 7 years ago