From: Paolo Bonzini <pbonzini@redhat.com>
To: Yang Weijiang <weijiang.yang@intel.com>
Cc: kvm@vger.kernel.org
Subject: Re: Migration for SPP(Sub-Page Protection) bitmaps
Date: Sat, 27 Apr 2019 03:37:39 -0400 (EDT) [thread overview]
Message-ID: <1936609002.15679158.1556350659850.JavaMail.zimbra@redhat.com> (raw)
In-Reply-To: <20190426085723.GA32222@local-michael-cet-test>
> > The destination userspace should simply call KVM_SUBPAGES_SET_ACCESS,
> > and KVM will process it just like it would on the source. In other
> > words, it shouldn't matter if the ioctl is done as part of migration or
> > the first time a VM is setup. And in both cases, lazy setup should be
> > fine.
>
> The problem is in current patch (as in link), it assumes
> the target pages are there in EPT, but in migration case, these pages
> are not setup in ETP, so KVM_SUBPAGES_SET_ACCESS during migration or
> destination bootup will fail, should I modify the patch to setup the
> ETP in lazy mode?
Yes, definitely. Remember that EPT page tables come and go (pages could
be swapped out, or moved from one host physical address to another; there
is also a shrinker that will release EPT page tables if memory is low),
so SPP support should be ready for that. Migration is just a special case.
Paolo
next prev parent reply other threads:[~2019-04-27 7:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-17 9:59 Migration for SPP(Sub-Page Protection) bitmaps Yang Weijiang
2019-04-26 8:06 ` Paolo Bonzini
2019-04-26 8:57 ` Yang Weijiang
2019-04-27 7:37 ` Paolo Bonzini [this message]
2019-04-28 2:31 ` Yang Weijiang
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