From: Dave Martin Date: Fri, 5 Apr 2019 15:35:50 +0000 (+0100) Subject: KVM: arm64/sve: sys_regs: Demote redundant vcpu_has_sve() checks to WARNs X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=700698a8a9741063c9804c7bce2dbec6c8d69f3d;p=openwrt%2Fstaging%2Fblogic.git KVM: arm64/sve: sys_regs: Demote redundant vcpu_has_sve() checks to WARNs Because of the logic in kvm_arm_sys_reg_{get,set}_reg() and sve_id_visibility(), we should never call {get,set}_id_aa64zfr0_el1() for a vcpu where !vcpu_has_sve(vcpu). To avoid the code giving the impression that it is valid for these functions to be called in this situation, and to help the compiler make the right optimisation decisions, this patch adds WARN_ON() for these cases. Given the way the logic is spread out, this seems preferable to dropping the checks altogether. Suggested-by: Andrew Jones Signed-off-by: Dave Martin Reviewed-by: Andrew Jones Signed-off-by: Marc Zyngier --- diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 09e9b0625911..7046c7686321 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1144,7 +1144,7 @@ static int get_id_aa64zfr0_el1(struct kvm_vcpu *vcpu, { u64 val; - if (!vcpu_has_sve(vcpu)) + if (WARN_ON(!vcpu_has_sve(vcpu))) return -ENOENT; val = guest_id_aa64zfr0_el1(vcpu); @@ -1159,7 +1159,7 @@ static int set_id_aa64zfr0_el1(struct kvm_vcpu *vcpu, int err; u64 val; - if (!vcpu_has_sve(vcpu)) + if (WARN_ON(!vcpu_has_sve(vcpu))) return -ENOENT; err = reg_from_user(&val, uaddr, id);