> From: Thomas Gleixner
> Sent: Thursday, July 18, 2019 12:56 AM
> To: Dexuan Cui
>
> On Thu, 18 Jul 2019, Dexuan Cui wrote:
> >
> > The concept of the "overlay page" seems weird, and frankly speaking,
> > I don't really understand why the Hyper-V guys invented it, but as far
> > as this patch h
On Thu, 18 Jul 2019, Dexuan Cui wrote:
>
> The concept of the "overlay page" seems weird, and frankly speaking,
> I don't really understand why the Hyper-V guys invented it, but as far
> as this patch here is concerned, I think the patch is safe and it can
> indeed fix the CPU offlining issue I d
> From: Thomas Gleixner
> Sent: Thursday, July 18, 2019 12:01 AM
> ...
> Those are two different things. The GPF_ZERO allocation makes sense on its
> own but it _cannot_ prevent the following scenario:
Hi tglx,
The scenario can be prevented.
The VP ASSIST PAGE is an "overlay" page (please see H
On Thu, 18 Jul 2019, Dexuan Cui wrote:
> > On Thu, 4 Jul 2019, Dexuan Cui wrote:
> > This is the allocation when the CPU is brought online for the first
> > time. So what effect has zeroing at allocation time vs. offlining and
> > potentially receiving IPIs? That allocation is never freed.
> >
> >
> From: Thomas Gleixner
> Sent: Wednesday, July 17, 2019 4:04 PM
> To: Dexuan Cui
> ...
> On Thu, 4 Jul 2019, Dexuan Cui wrote:
> > When a CPU is being offlined, the CPU usually still receives a few
> > interrupts (e.g. reschedule IPIs), after hv_cpu_die() disables the
> > HV_X64_MSR_VP_ASSIST_PA
Dexuan,
On Thu, 4 Jul 2019, Dexuan Cui wrote:
> When a CPU is being offlined, the CPU usually still receives a few
> interrupts (e.g. reschedule IPIs), after hv_cpu_die() disables the
> HV_X64_MSR_VP_ASSIST_PAGE, so hv_apic_eoi_write() may not write the EOI
> MSR, if the apic_assist field's bit0
From: Dexuan Cui Sent: Wednesday, July 3, 2019 6:46 PM
>
> When a CPU is being offlined, the CPU usually still receives a few
> interrupts (e.g. reschedule IPIs), after hv_cpu_die() disables the
> HV_X64_MSR_VP_ASSIST_PAGE, so hv_apic_eoi_write() may not write the EOI
> MSR, if the apic_assist fi
When a CPU is being offlined, the CPU usually still receives a few
interrupts (e.g. reschedule IPIs), after hv_cpu_die() disables the
HV_X64_MSR_VP_ASSIST_PAGE, so hv_apic_eoi_write() may not write the EOI
MSR, if the apic_assist field's bit0 happens to be 1; as a result, Hyper-V
may not be able to
