On 27.10.2022 14:22, Julien Grall wrote: > On 26/10/2022 03:03, Henry Wang wrote: >>> -----Original Message----- >>> From: Jan Beulich <[email protected]> >>> Sent: Wednesday, October 26, 2022 12:07 AM >>> To: Henry Wang <[email protected]> >>> Cc: [email protected]; Andrew Cooper >>> <[email protected]>; George Dunlap <[email protected]>; >>> Julien Grall <[email protected]>; Stefano Stabellini <[email protected]>; >>> Wei Liu <[email protected]>; Roger Pau Monné <[email protected]> >>> Subject: [4.17?] Re: [PATCH] common: map_vcpu_info() wants to unshare >>> the underlying page >>> >>> On 25.10.2022 17:42, Roger Pau Monné wrote: >>>> On Tue, Oct 11, 2022 at 10:48:38AM +0200, Jan Beulich wrote: >>>>> Not passing P2M_UNSHARE to get_page_from_gfn() means there won't >>> even be >>>>> an attempt to unshare the referenced page, without any indication to the >>>>> caller (e.g. -EAGAIN). Note that guests have no direct control over >>>>> which of their pages are shared (or paged out), and hence they have no >>>>> way to make sure all on their own that the subsequent obtaining of a >>>>> writable type reference can actually succeed. >>>>> >>>>> Signed-off-by: Jan Beulich <[email protected]> >>>> >>>> Reviewed-by: Roger Pau Monné <[email protected]> >>> >>> I didn't Cc you on the initial submission because mem-sharing isn't a >>> supported feature, but upon reconsideration I thought I'd at least ask >>> whether you would want to give this a release-ack. I don't really see >>> any risk associated with it. >> >> By looking at the patch itself, this change seems ok to me, so I think >> I will not block it, but I think Arm maintainers' approval might be needed >> because of the discussion in [1], so I added them for their information. >> If Arm maintainers do not object the change, you can have my release-ack.
I'll take the liberty then to translate this into an actual tag, with ... > The P2M query type is so far ignored on Arm as we neither support > populate-on-demand nor memsharing. > > I am assuming that if we ever introduce any those of features, we would > follow the same behavior as x86. So: > > Acked-by: Julien Grall <[email protected]> ... this now in place (thanks Julien). Jan
