On 20/09/18 14:39, Jan Beulich wrote: >>>> On 20.09.18 at 14:41, <andrew.coop...@citrix.com> wrote: >> On 13/09/18 11:12, Jan Beulich wrote: >>> The function does two translations in one go for a single guest access. >>> Any failure of the first translation step (guest linear -> guest >>> physical), resulting in #PF, ought to take precedence over any failure >>> of the second step (guest physical -> host physical). >> Why? What is the basis of this presumption? >> >> As far as what real hardware does... >> >> This test sets up a ballooned page and a read-only page. I.e. a second >> stage fault on the first part of a misaligned access, and a first stage >> fault on the second part of the access. >> >> (d1) --- Xen Test Framework --- >> (d1) Environment: HVM 64bit (Long mode 4 levels) >> (d1) Test splitfault >> (d1) About to read >> (XEN) *** EPT qual 0000000000000181, gpa 000000000011cffc >> (d1) Reading PTR: got 00000000ffffffff >> (d1) About to write >> (XEN) *** EPT qual 0000000000000182, gpa 000000000011cffc >> (d1) ****************************** >> (d1) PANIC: Unhandled exception at 0008:00000000001047e0 >> (d1) Vec 14 #PF[-d-sWP] %cr2 000000000011d000 >> (d1) ****************************** >> >> The second stage fault is recognised first, which is contrary to your >> presumption, i.e. the code in its current form appears to be correct. > But the guest doesn't know about 2nd stage translation. In the > absence of it, the (1st stage / only) fault ought to occur before > any bus level actions would be taken.
You have not answered my question. Why? On what basis do you conclude that the behaviour you describe is "correct", especially now given evidence to the contrary? ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
