On 19/10/2022 8:41 am, Jan Beulich wrote:
> --- a/xen/arch/x86/time.c
> +++ b/xen/arch/x86/time.c
> @@ -1462,12 +1462,34 @@ static void __update_vcpu_system_time(st
> v->arch.pv.pending_system_time = _u;
> }
>
> +static void write_time_guest_area(struct vcpu_time_info *map,
> + const struct vcpu_time_info *src)
> +{
> + /* 1. Update userspace version. */
> + write_atomic(&map->version, src->version);
version_update_begin()
~Andrew
> + smp_wmb();
> +
> + /* 2. Update all other userspace fields. */
> + *map = *src;
> +
> + /* 3. Update userspace version again. */
> + smp_wmb();
> + write_atomic(&map->version, version_update_end(src->version));
> +}
> +
> bool update_secondary_system_time(struct vcpu *v,
> struct vcpu_time_info *u)
> {
> XEN_GUEST_HANDLE(vcpu_time_info_t) user_u = v->arch.time_info_guest;
> + struct vcpu_time_info *map = v->arch.time_guest_area.map;
> struct guest_memory_policy policy = { .nested_guest_mode = false };
>
> + if ( map )
> + {
> + write_time_guest_area(map, u);
> + return true;
> + }
> +
> if ( guest_handle_is_null(user_u) )
> return true;
>
>
