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Re: [Xen-devel] [PATCH] vunmap: let vunmap align virtual address by itself
- To: Andrii Anisov <andrii.anisov@xxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- From: Jan Beulich <JBeulich@xxxxxxxx>
- Date: Fri, 19 Jul 2019 09:37:14 +0000
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- Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Andrii Anisov <andrii_anisov@xxxxxxxx>, Wei Liu <wl@xxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, George Dunlap <George.Dunlap@xxxxxxxxxxxxx>, Tim Deegan <tim@xxxxxxx>, Ian Jackson <ian.jackson@xxxxxxxxxxxxx>, Julien Grall <julien.grall@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
- Delivery-date: Fri, 19 Jul 2019 09:38:00 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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- Thread-topic: [PATCH] vunmap: let vunmap align virtual address by itself
On 18.07.2019 19:11, Andrii Anisov wrote:
> Let vunmap align passed virtual address by PAGE_SIZE.
Despite seeing Andrew's R-b you've already got I'd like to point out
that this increases the risk of some code passing the wrong pointer
into here. {,un}map_domain_page() act on single pages only, so there's
no ambiguity. When talking about multi-page regions though, not undoing
arithmetic previously done may mean actually pointing at other than the
first page of the mapping.
> This also makes it consistent with how {,un}map_domain_page()
> currently works.
>
> With the main change, also:
> - strip all existing vunmap() calls from prior masking
_If_ we are to go this route, then unmap_domain_page_global()
callers should also be adjusted. There, as for unmap_domain_page(),
I agree it would make sense to be more tolerant.
Jan
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