RE: [PATCH][v2] KVM: x86/mmu: fix counting of rmap entries in pte_list_add

["Li,Rongqing" <lirongqing@baidu.com>]

> -----Original Message-----
> From: Sean Christopherson [mailto:sean.j.christopherson@intel.com]
> Sent: Saturday, September 26, 2020 12:44 AM
> To: Li,Rongqing <lirongqing@baidu.com>
> Cc: kvm@vger.kernel.org; x86@kernel.org
> Subject: Re: [PATCH][v2] KVM: x86/mmu: fix counting of rmap entries in
> pte_list_add
> 
> On Wed, Sep 23, 2020 at 12:58:58PM +0800, Li RongQing wrote:
> > counting of rmap entries was missed when desc->sptes is full and
> > desc->more is NULL
> >
> > and merging two PTE_LIST_EXT-1 check as one, to avoids the extra
> > comparison to give slightly optimization
> 
> Please write complete sentences, and use proper capitalization and
> punctuation.
> It's not a big deal for short changelogs, but it's crucial for readability of larger
> changelogs.
> 
> E.g.
> 
>   Fix an off-by-one style bug in pte_list_add() where it failed to account
>   the last full set of SPTEs, i.e. when desc->sptes is full and desc->more
>   is NULL.
> 
>   Merge the two "PTE_LIST_EXT-1" checks as part of the fix to avoid an
>   extra comparison.
> 
> > Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
> 
> No need to give me credit, I just nitpicked the code, identifying the bug and the
> fix was all you. :-)
> 
> Thanks for the fix!
> 
> > Signed-off-by: Li RongQing <lirongqing@baidu.com>
> 
> Paolo,
> 
> Although it's a bug fix, I don't think this needs a Fixes / Cc:stable.  The bug
> only results in rmap recycling being delayed by one rmap.  Stable kernels can
> probably live with an off-by-one bug given that RMAP_RECYCLE_THRESHOLD is
> completely arbitrary. :-)
> 
> Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
> 

Thank you very much , I will send V3

-Li