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Re: [PATCH 1/2] x86/shadow: slightly consolidate sh_unshadow_for_p2m_change()


  • To: George Dunlap <George.Dunlap@xxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Mon, 27 Jun 2022 08:26:15 +0200
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  • Cc: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Roger Pau Monne <roger.pau@xxxxxxxxxx>, "Tim (Xen.org)" <tim@xxxxxxx>
  • Delivery-date: Mon, 27 Jun 2022 06:26:21 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 24.06.2022 21:16, George Dunlap wrote:
> 
> 
>> On 9 Dec 2021, at 11:26, Jan Beulich <jbeulich@xxxxxxxx> wrote:
>>
>> In preparation for reactivating the presently dead 2M page path of the
>> function,
>> - also deal with the case of replacing an L1 page table all in one go,
>> - pull common checks out of the switch(). This includes extending a
>>  _PAGE_PRESENT check to L1 as well, which presumably was deemed
>>  redundant with p2m_is_valid() || p2m_is_grant(), but I think we are
>>  better off being explicit in all cases,
>> - replace a p2m_is_ram() check in the 2M case by an explicit
>>  _PAGE_PRESENT one, to make more obvious that the subsequent
>>  l1e_get_mfn() actually retrieves something that is actually an MFN.
> 
> Each of these changes requires careful checking to make sure there aren’t any 
> bugs introduced.  I’d feel much more comfortable giving an R-b of they were 
> broken out into separate patches.

I'll see what I can do. It has been quite some time, but iirc trying
to do things separately didn't work out very well.

Jan



 


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