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Re: [PATCH] kvm: Take into account the unaligned section size when prepa
From: |
Peter Xu |
Subject: |
Re: [PATCH] kvm: Take into account the unaligned section size when preparing bitmap |
Date: |
Thu, 10 Dec 2020 09:50:06 -0500 |
On Thu, Dec 10, 2020 at 10:53:23AM +0800, zhukeqian wrote:
>
>
> On 2020/12/10 10:08, Peter Xu wrote:
> > Keqian,
> >
> > On Thu, Dec 10, 2020 at 09:46:06AM +0800, zhukeqian wrote:
> >> Hi,
> >>
> >> I see that if start or size is not PAGE aligned, it also clears areas
> >> which beyond caller's expectation, so do we also need to consider this?
> >
> > Could you elaborate?
> >
> > If start_delta != 0, kvm_log_clear_one_slot() should already go the slow
> > path.
> >
> > Thanks,
> >
>
> Hi Peter,
>
> start_delta /= psize;
>
> If start is not PAGE aligned, then start_delta is not PAGE aligned.
> so I think the above code will implicitly extend our start to be PAGE aligned.
>
> I suggest that we should shrink the start and (start + size) to be PAGE
> aligned
> at beginning of this function.
Callers should be with TARGET_PAGE_SIZE aligned on the size, so at least x86_64
should be pretty safe since host/guest page sizes match.
Though indeed I must confess I don't know how it worked in general when host
page size != target page size, at least for migration. For example, I believe
kvm dirty logging is host page size based, though migration should be migrating
pages in guest page size granule when it spots a dirty bit set.
--
Peter Xu
- [PATCH] kvm: Take into account the unaligned section size when preparing bitmap, Zenghui Yu, 2020/12/08
- Re: [PATCH] kvm: Take into account the unaligned section size when preparing bitmap, Peter Xu, 2020/12/08
- Re: [PATCH] kvm: Take into account the unaligned section size when preparing bitmap, Zenghui Yu, 2020/12/08
- Re: [PATCH] kvm: Take into account the unaligned section size when preparing bitmap, zhukeqian, 2020/12/09
- Re: [PATCH] kvm: Take into account the unaligned section size when preparing bitmap, Peter Xu, 2020/12/09
- Re: [PATCH] kvm: Take into account the unaligned section size when preparing bitmap, zhukeqian, 2020/12/09
- Re: [PATCH] kvm: Take into account the unaligned section size when preparing bitmap, Zenghui Yu, 2020/12/09
- Re: [PATCH] kvm: Take into account the unaligned section size when preparing bitmap,
Peter Xu <=
- Re: [PATCH] kvm: Take into account the unaligned section size when preparing bitmap, zhukeqian, 2020/12/10
- Re: [PATCH] kvm: Take into account the unaligned section size when preparing bitmap, Peter Xu, 2020/12/11
- Re: [PATCH] kvm: Take into account the unaligned section size when preparing bitmap, zhukeqian, 2020/12/13
- Re: [PATCH] kvm: Take into account the unaligned section size when preparing bitmap, Peter Xu, 2020/12/14
- Re: [PATCH] kvm: Take into account the unaligned section size when preparing bitmap, zhukeqian, 2020/12/15
- Re: [PATCH] kvm: Take into account the unaligned section size when preparing bitmap, Zenghui Yu, 2020/12/15