** Description changed: [Impact] - * To avoid bugs with newer Hardware and to allow users/admins to control - the KVM guests correctly we usually try to backport major CPU- - detect/control features back to at least the last LTS (currently Focal) - In SRU Terms this is under the second entry in - https://wiki.ubuntu.com/StableReleaseUpdates#Other_safe_cases + * To avoid bugs with newer Hardware and to allow users/admins to control + the KVM guests correctly we usually try to backport major CPU- + detect/control features back to at least the last LTS (currently Focal) + In SRU Terms this is under the second entry in + https://wiki.ubuntu.com/StableReleaseUpdates#Other_safe_cases - * In this particular case it is about Support for EPYC Milan chips - https://en.wikipedia.org/wiki/Epyc#Third_generation_Epyc_(Milan) + * In this particular case it is about Support for EPYC Milan chips + https://en.wikipedia.org/wiki/Epyc#Third_generation_Epyc_(Milan) [Test Plan] - * First of all we'll (and have in advance) run general regression tests + * First of all we'll (and have in advance) run general regression tests - * Second you'd want to run this with host-model and host-passthrough on - Rome / Milan chips to ensure no case is now falling in to a totally - dysfunctional state + * Second you'd want to run this with host-model and host-passthrough on + Rome / Milan chips to ensure no case is now falling in to a totally + dysfunctional state - * Finally migrations between old->new should be checked to work fine. + * Qemu shall show to be aware of the new types + # qemu-system-x86_64 -cpu ? | grep EPYC-Milan + x86 EPYC-Milan (alias configured by machine type) + x86 EPYC-Milan-v1 AMD EPYC-Milan Processor + + * Finally migrations between old->new should be checked to work fine. [Where problems could occur] - * This kind of "add the new type" usually only s a problem in backward- - migratebility which isn't supported anyway. Never the less the areas to - look out for is behavior on various AMD EPYC chips. To ensure that old - chips won't change in a breaking way (they might detect new features - now, but not more) and that new Milan chips are now all detected - properly. + * This kind of "add the new type" usually only s a problem in backward- + migratebility which isn't supported anyway. Never the less the areas to + look out for is behavior on various AMD EPYC chips. To ensure that old + chips won't change in a breaking way (they might detect new features + now, but not more) and that new Milan chips are now all detected + properly. [Other Info] - * This is not the first time new AMD chips need to add their definitions, - for example bug 1887490 was similar + * This is not the first time new AMD chips need to add their definitions, + for example bug 1887490 was similar ---- - QEMU added a separate model for EPYC-Milan in https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg03370.html On the qemu side most bits are already present as far back as focal. The only things missing are the ibrs and svme-addr-chk flag. On the libvirt side the same and fsrm (which is already in qemu) fsrm https://gitlab.com/libvirt/libvirt/-/commit/8c5c660b99101544d8cfcb8edbe48688c04bee25 svme-addr-chk (later patch fixed spelling) https://gitlab.com/libvirt/libvirt/-/commit/5ac6ab2fde63881d3c5cc7372a0d0e59618feb55 ibrs https://gitlab.com/libvirt/libvirt/-/commit/5c17a7ba41670f3182186c06e621995b5d03fc95 EPYC-Milan model https://gitlab.com/libvirt/libvirt/-/commit/f321a4822e9fa6542e48a78611989ecd9acaa83a https://gitlab.com/libvirt/libvirt/-/commit/d3de79dbfc20dc4dfc19154b16079861c542b71e spelling fix for svme-addr-chk https://gitlab.com/libvirt/libvirt/-/commit/b5abf9a192248b1005f63a7102d2627375d70fe5 Please consider adding/backporting these. Of course there are a number of kernel commits, some/most listed in the qemu commit, that would need to be backported to enable all features. But even without them, this already works for the most part (tested on focal kernel 5.4.0-70).
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1921880 Title: Add EPYC-Milan model To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1921880/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
