[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20200417105558.2jkqq2lih6vvoip2@debian>
Date: Fri, 17 Apr 2020 11:55:58 +0100
From: Wei Liu <wei.liu@...nel.org>
To: Vitaly Kuznetsov <vkuznets@...hat.com>
Cc: Dexuan Cui <decui@...rosoft.com>, bp@...en8.de,
haiyangz@...rosoft.com, hpa@...or.com, kys@...rosoft.com,
linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
mingo@...hat.com, sthemmin@...rosoft.com, tglx@...utronix.de,
x86@...nel.org, mikelley@...rosoft.com, wei.liu@...nel.org,
kvm@...r.kernel.org
Subject: Re: [PATCH] x86/hyperv: Suspend/resume the VP assist page for
hibernation
On Fri, Apr 17, 2020 at 12:03:18PM +0200, Vitaly Kuznetsov wrote:
> Dexuan Cui <decui@...rosoft.com> writes:
>
> > Unlike the other CPUs, CPU0 is never offlined during hibernation. So in the
> > resume path, the "new" kernel's VP assist page is not suspended (i.e.
> > disabled), and later when we jump to the "old" kernel, the page is not
> > properly re-enabled for CPU0 with the allocated page from the old kernel.
> >
> > So far, the VP assist page is only used by hv_apic_eoi_write().
>
> No, not only for that ('git grep hv_get_vp_assist_page')
>
> KVM on Hyper-V also needs VP assist page to use Enlightened VMCS. In
> particular, Enlightened VMPTR is written there.
>
> This makes me wonder: how does hibernation work with KVM in case we use
> Enlightened VMCS and we have VMs running? We need to make sure VP Assist
> page content is preserved.
The page itself is preserved, isn't it?
hv_cpu_die never frees the vp_assit page. It merely disables it.
hv_cpu_init only allocates a new page if necessary.
Wei.
>
> --
> Vitaly
>
Powered by blists - more mailing lists