[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] x86/HVM: honor p2m_ram_ro in hvm_map_guest_frame_rw()
On Fri, Jul 24, 2015 at 04:37:25AM -0600, Jan Beulich wrote: > >>> On 24.07.15 at 12:26, <wei.liu2@xxxxxxxxxx> wrote: > > On Fri, Jul 24, 2015 at 03:41:26AM -0600, Jan Beulich wrote: > >> @@ -3618,7 +3618,12 @@ static void *__hvm_map_guest_frame(unsig > >> } > >> > >> if ( writable ) > > > > I don't claim I know this piece of code, but checking the pointer but > > not the content looks suspicious. > > > >> - paging_mark_dirty(d, page_to_mfn(page)); > >> + { > >> + if ( !p2m_is_discard_write(p2mt) ) > >> + paging_mark_dirty(d, page_to_mfn(page)); > >> + else > >> + *writable = 0; > > > > You then set *writable here, which makes it even more suspicious. > > Why? A caller _wanting_ a writable mapping passes non-NULL as > the pointer argument (pre-initialized to point to a variable holding > TRUE aka 1). Upon return the variable will have got set to FALSE > aka 0 if the page shouldn't be written to. > If this is the convention for using this function then the code you write is of course fine. Wei. > Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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