Re: [Xen-devel] [PATCH v5 3/4] x86/xen/time: setup vcpu 0 time info page

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

> +
> +static void xen_setup_vsyscall_time_info(void)
> +{
> +     struct vcpu_register_time_memory_area t;
> +     struct pvclock_vsyscall_time_info *ti;
> +     int ret;


In the previous version you'd return immediately if
PVCLOCK_TSC_STABLE_BIT was not set. Don't you still need to check this?
Especially give...


> +
> +     ti = (struct pvclock_vsyscall_time_info *)get_zeroed_page(GFP_KERNEL);
> +     if (!ti)
> +             return;
> +
> +     t.addr.v = &ti->pvti;
> +
> +     ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
> +     if (ret) {
> +             pr_notice("xen: VCLOCK_PVCLOCK not supported (err %d)\n", ret);
> +             free_page((unsigned long)ti);
> +             return;
> +     }
> +
> +     /*
> +      * If primary time info had this bit set, secondary should too since

... this comment?

-boris

> +      * it's the same data on both just different memory regions. But we
> +      * still check it in case hypervisor is buggy.
> +      */
> +     if (!(ti->pvti.flags & PVCLOCK_TSC_STABLE_BIT)) {
> +             t.addr.v = NULL;
> +             ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area,
> +                                      0, &t);
> +             if (!ret)
> +                     free_page((unsigned long)ti);
> +
> +             pr_notice("xen: VCLOCK_PVCLOCK not supported (tsc unstable)\n");
> +             return;
> +     }
> +
> +     xen_clock = ti;
> +     pvclock_set_pvti_cpu0_va(xen_clock);
> +
> +     xen_clocksource.archdata.vclock_mode = VCLOCK_PVCLOCK;
> +}
> +
>  


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