lkml.org 
[lkml]   [2014]   [Jul]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 4/4] kvm, mem-hotplug: Update apic access page when it is migrated.
On Mon, Jul 07, 2014 at 03:10:23PM +0300, Nadav Amit wrote:
> On 7/7/14, 2:54 PM, Gleb Natapov wrote:
> >On Mon, Jul 07, 2014 at 02:42:27PM +0300, Nadav Amit wrote:
> >>Tang,
> >>
> >>Running some (unrelated) tests I see that KVM does not handle APIC base
> >>relocation correctly. When the base is changed, kvm_lapic_set_base just
> >>changes lapic->base_address without taking further action (i.e., modifying
> >>the VMCS apic address in VMX).
> >>
> >>This patch follows KVM bad behavior by using the constant
> >>VMX_APIC_ACCESS_PAGE_ADDR instead of lapic->base_address.
> >There is no OS out there that relocates APIC base (in fact it was not always
> >relocatable on real HW), so there is not point in complicating the code to support
> >it. In fact current APIC_ACCESS_ADDR handling relies on the fact that all vcpus
> >has apic mapped at the same address.
> >
> >>
> >>Anyhow, I didn't see anything that would make my life (in fixing the lapic
> >>base issue) too difficult. Yet, feel free in making it more "fix-friendly".
> >>
> >Why would you want to fix it?
> >
> If there is no general need, I will not send a fix. However, I think the
It is much more works that it may look like for no apparent gain.

> very least a warning message should be appear if the guest relocates the
> APIC base.
>
Warning is fine. Make it _once().

--
Gleb.


\
 
 \ /
  Last update: 2014-07-07 15:01    [W:0.299 / U:0.200 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site