Navin Patel
2012-Sep-16 15:52 UTC
4.2.0-rc4 bug: memory events for CR3 register are broken (working in 4.1.3)
Greetings, I have tested some of my research code watching for CR3 memory events on Xen 4.2.0-rc4, and I have discovered that CR3 events are not being delivered. This did work properly in 4.1.3, so I think 4.2.0-rc4 may has a bug. This feature has been removed maybe? Crude test to confirm this can be had by changing tools/tests/xen-access/xen-access.c : replace HVM_PARAM_MEMORY_EVENT_INT3 with HVM_PARAM_MEMORY_EVENT_CR3 and rebuild (line 569 and 571 in 4.2.0-rc4). Then (while domU is scheduling programs/launching new processes) run like int3 were still the constant value: ./xen-access $DOMID int3 4.1.3: In the switch/case, printf will show "UNKNOWN REASON CODE $C", with c == 3 == MEM_EVENT_REASON_CR3 (no case built to detect CR3 evnets). 4.2.0-rc4: In the switch/case, printf will never show "UNKNOWN REASON CODE 3" Cheers, Navin _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
Keir Fraser
2012-Sep-16 16:35 UTC
Re: 4.2.0-rc4 bug: memory events for CR3 register are broken (working in 4.1.3)
This issue is known and a fix has been proposed. It¹s too late for 4.2.0 unfortunately, but will be fixed for 4.2.1. -- Keir On 16/09/2012 16:52, "Navin Patel" <navinjpatel336@gmail.com> wrote:> Greetings, > > I have tested some of my research code watching for CR3 memory events on Xen > 4.2.0-rc4, and I have discovered that CR3 events are not being delivered. > This did work properly in 4.1.3, so I think 4.2.0-rc4 may has a bug. > > This feature has been removed maybe? > > Crude test to confirm this can be had by changing > tools/tests/xen-access/xen-access.c : replace HVM_PARAM_MEMORY_EVENT_INT3 with > HVM_PARAM_MEMORY_EVENT_CR3 and rebuild (line 569 and 571 in 4.2.0-rc4). > > Then (while domU is scheduling programs/launching new processes) run like int3 > were still the constant value: ./xen-access $DOMID int3 > > 4.1.3: In the switch/case, printf will show "UNKNOWN REASON CODE $C", with c > == 3 == MEM_EVENT_REASON_CR3 (no case built to detect CR3 evnets). > > 4.2.0-rc4: In the switch/case, printf will never show "UNKNOWN REASON CODE 3" > > Cheers, > Navin > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel_______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
Navin Patel
2012-Sep-16 18:35 UTC
Re: 4.2.0-rc4 bug: memory events for CR3 register are broken (working in 4.1.3)
On Sun, Sep 16, 2012 at 12:35 PM, Keir Fraser <keir.xen@gmail.com> wrote:> This issue is known and a fix has been proposed. It’s too late for 4.2.0 > unfortunately, but will be fixed for 4.2.1. > > -- Keir > > > On 16/09/2012 16:52, "Navin Patel" <navinjpatel336@gmail.com> wrote: > > Greetings, > > I have tested some of my research code watching for CR3 memory events on > Xen 4.2.0-rc4, and I have discovered that CR3 events are not being > delivered. This did work properly in 4.1.3, so I think 4.2.0-rc4 may has a > bug. > > This feature has been removed maybe? > > Crude test to confirm this can be had by changing > tools/tests/xen-access/xen-access.c : replace HVM_PARAM_MEMORY_EVENT_INT3 > with HVM_PARAM_MEMORY_EVENT_CR3 and rebuild (line 569 and 571 in 4.2.0-rc4). > > Then (while domU is scheduling programs/launching new processes) run like > int3 were still the constant value: ./xen-access $DOMID int3 > > 4.1.3: In the switch/case, printf will show "UNKNOWN REASON CODE $C", with > c == 3 == MEM_EVENT_REASON_CR3 (no case built to detect CR3 evnets). > > 4.2.0-rc4: In the switch/case, printf will never show "UNKNOWN REASON CODE > 3" > > Cheers, > Navin > > ------------------------------ > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel > > Keir and Steven,Thank you for your work. The proposed patch solved the bug! After 4.2.0 is officially released this week, I very much hope that this patch is backported to the 4.2.0 tree. Several distributions like Debian are already building upon 4.2.0 and will not wait for 4.2.1, and without the patch being backported, researchers like me will not be able to use the supported Xen from package repository. We can compile from source, but if we have a supported version it is better for everyone. (And it is such a simple patch! ) Is this something I can request in formal manner? Cheers, Navin _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
Keir Fraser
2012-Sep-16 18:38 UTC
Re: 4.2.0-rc4 bug: memory events for CR3 register are broken (working in 4.1.3)
Keep an eye on xen-unstable and make sure the patch, or equivalent, goes in in the next week or two. Once it¹s in you can request it be backported. -- Keir On 16/09/2012 19:35, "Navin Patel" <navinjpatel336@gmail.com> wrote:> Keir and Steven, > > Thank you for your work. The proposed patch solved the bug! > > After 4.2.0 is officially released this week, I very much hope that this patch > is backported to the 4.2.0 tree. Several distributions like Debian are already > building upon 4.2.0 and will not wait for 4.2.1, and without the patch being > backported, researchers like me will not be able to use the supported Xen from > package repository. We can compile from source, but if we have a supported > version it is better for everyone. (And it is such a simple patch! ) > > Is this something I can request in formal manner?_______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
Navin Patel
2012-Sep-18 14:30 UTC
Re: 4.2.0-rc4 bug: memory events for CR3 register are broken (working in 4.1.3)
Keir, On Sun, Sep 16, 2012 at 2:38 PM, Keir Fraser <keir@xen.org> wrote:> Keep an eye on xen-unstable and make sure the patch, or equivalent, goes > in in the next week or two. Once it’s in you can request it be backported. > > -- Keir > > > On 16/09/2012 19:35, "Navin Patel" <navinjpatel336@gmail.com> wrote: > > Keir and Steven, > > Thank you for your work. The proposed patch solved the bug! > > After 4.2.0 is officially released this week, I very much hope that this > patch is backported to the 4.2.0 tree. Several distributions like Debian > are already building upon 4.2.0 and will not wait for 4.2.1, and without > the patch being backported, researchers like me will not be able to use the > supported Xen from package repository. We can compile from source, but if > we have a supported version it is better for everyone. (And it is such a > simple patch! ) > > Is this something I can request in formal manner? > > Now that this patch is in xen-unstable.hg, I would like to request thatit be backported to 4.2.0 as we discussed. Thank you! Navin _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
Jan Beulich
2012-Sep-19 10:23 UTC
Re: 4.2.0-rc4 bug: memory events for CR3 register are broken (working in 4.1.3)
>>> On 18.09.12 at 16:30, Navin Patel <navinjpatel336@gmail.com> wrote: > Keir, > > On Sun, Sep 16, 2012 at 2:38 PM, Keir Fraser <keir@xen.org> wrote: > >> Keep an eye on xen-unstable and make sure the patch, or equivalent, goes >> in in the next week or two. Once it’s in you can request it be backported. >> >> -- Keir >> >> >> On 16/09/2012 19:35, "Navin Patel" <navinjpatel336@gmail.com> wrote: >> >> Keir and Steven, >> >> Thank you for your work. The proposed patch solved the bug! >> >> After 4.2.0 is officially released this week, I very much hope that this >> patch is backported to the 4.2.0 tree. Several distributions like Debian >> are already building upon 4.2.0 and will not wait for 4.2.1, and without >> the patch being backported, researchers like me will not be able to use the >> supported Xen from package repository. We can compile from source, but if >> we have a supported version it is better for everyone. (And it is such a >> simple patch! ) >> >> Is this something I can request in formal manner? >> >> Now that this patch is in xen-unstable.hg, I would like to request that > it be backported to 4.2.0 as we discussed.I'll take care of this shortly (assuming it's 25918:7ab899e46347 you're talking about), but obviously this is only going to be for 4.2.1 (despite your hopes/wishes), as Keir already indicated. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel