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

e644fa18 · Zhang Lei <[email protected]> · 2019-07-03 18:42:50 +01:00

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.

Signed-off-by: Zhang Lei <[email protected]>
Fixes: 0c529ff789bc ("KVM: arm64: Implement vq_present() as a macro")
Signed-off-by: Dave Martin <[email protected]> [commit message rewrite]
Cc: Viresh Kumar <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

Commit: e644fa18e2ffc8895ca30dade503ae10128573a6
Parents: bb34e690

Changes

1 files changed · +1 −1

File	Status	Add	Del	Content
arch/arm64/kvm/guest.c	modified	+1	−1	View file

arch/arm64/kvm/guest.c

View file

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index c2afa79..dfd6264 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -208,7 +208,7 @@ out:
 
 #define vq_word(vq) (((vq) - SVE_VQ_MIN) / 64)
 #define vq_mask(vq) ((u64)1 << ((vq) - SVE_VQ_MIN) % 64)
-#define vq_present(vqs, vq) ((vqs)[vq_word(vq)] & vq_mask(vq))
+#define vq_present(vqs, vq) (!!((vqs)[vq_word(vq)] & vq_mask(vq)))
 
 static int get_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 {