>>> On 25.06.15 at 15:08, <paul.durr...@citrix.com> wrote: >> -----Original Message----- >> From: Jan Beulich [mailto:jbeul...@suse.com] >> Sent: 25 June 2015 13:46 >> To: Andrew Cooper >> Cc: Paul Durrant; xen-de...@lists.xenproject.org; Keir (Xen.org) >> Subject: Re: [PATCH v4 07/17] x86/hvm: add length to mmio check op >> >> >>> On 25.06.15 at 14:21, <andrew.coop...@citrix.com> wrote: >> > On 24/06/15 12:24, Paul Durrant wrote: >> >> When memory mapped I/O is range checked by internal handlers, the >> length >> >> of the access should be taken into account. >> >> >> >> Signed-off-by: Paul Durrant <paul.durr...@citrix.com> >> >> Cc: Keir Fraser <k...@xen.org> >> >> Cc: Jan Beulich <jbeul...@suse.com> >> >> Cc: Andrew Cooper <andrew.coop...@citrix.com> >> >> >> > >> > For what purpose? The length of the access doesn't affect which handler >> > should accept the IO. >> > >> > This length check now causes an MMIO handler to not claim an access >> > which straddles the upper boundary. >> > >> > It is probably fine to terminate such an access early, but it isn't fine >> > to pass such a straddled access to the default ioreq server. >> >> No, without involving the length in the check we can end up with >> check() saying "Yes, mine" but read() or write() saying "Not me". >> What I would agree with is for the generic handler to split the >> access if the first byte fits, but the final byte doesn't. > > That's not a trivial thing to do. Could we, for now, have the check claim > based on address but domain_crash() if length does not fit?
Would seem acceptable to me; if problems arise we could drop that domain_crash() later on with a trivial patch. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
