On Mon, Mar 01, 2021, David Woodhouse wrote:
> From: David Woodhouse <dwmw@xxxxxxxxxxxx>
>
> When clearing the per-vCPU shared regions, set the return value to zero
> to indicate success. This was causing spurious errors to be returned to
> userspace on soft reset.
>
> Also add a paranoid BUILD_BUG_ON() for compat structure compatibility.
>
> Fixes: 0c165b3c01fe ("KVM: x86/xen: Allow reset of Xen attributes")
> Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
> ---
> arch/x86/kvm/xen.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
> index af8f6562fce4..77b20ff09078 100644
> --- a/arch/x86/kvm/xen.c
> +++ b/arch/x86/kvm/xen.c
> @@ -187,9 +187,12 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data)
To avoid similar issues in the future, might be worth throwing "r = -ENOENT" in
the default case and have "r" be initialized to '0', or uninitialized to trigger
compiler warnings. For any which way:
Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> /* No compat necessary here. */
> BUILD_BUG_ON(sizeof(struct vcpu_info) !=
> sizeof(struct compat_vcpu_info));
> + BUILD_BUG_ON(offsetof(struct vcpu_info, time) !=
> + offsetof(struct compat_vcpu_info, time));
>
> if (data->u.gpa == GPA_INVALID) {
> vcpu->arch.xen.vcpu_info_set = false;
> + r = 0;
> break;
> }
>
> @@ -206,6 +209,7 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data)
> case KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO:
> if (data->u.gpa == GPA_INVALID) {
> vcpu->arch.xen.vcpu_time_info_set = false;
> + r = 0;
> break;
> }
>
> --
> 2.29.2
>
