Participants: Christopher Dall, Marc Zyngier, Paolo Bonzini, Suraj Jitindar Singh, Frediano Ziglio, Sean Christopherson, Radim Krcmar, Janosch Frank, Christian Borntraeger +some more - Discussion about common code for different architectures - initiated by my talk https://schd.ws/hosted_files/kvmforum2018/a0/Christian-Borntraegercrossarch.pdf - We agreed that we as architecture maintainers should teach people during review about making things generic when applicable - Problem: we do not understand "the other side" at all, e.g. one example in x86 code was: does spte means shadow page table or also nested pages (EPT) - maybe we need a hack-a-thon to sit together and talk about this - other idea: To see if we can factor out things, just provide a header file with "needed" interfaces and the pass that along to the other side Things to look at: - dirty log, now 2 common code variante (and arch specific ones) - ordering of ioctl (e.g. qemu vs native kvm tool) triggered sometimes bugs on ARM - can we test this better and maybe also refactor some of the common checks - api tests should be extended to all architectures - rmap code for nested virtualization -> x86, power and now arm. All private copies (s390 uses radix to make it a 4th variant) - can we avoid compiling virt/kvm/ from arch folders? - Christopher also wants to look at nested page table faults (stage 2 faults on Arm), where on the Arm side we have a lot of code which is not arch-specific, but related to finding a page to back the fault, figuring out if the page is hugetlbfs, thp, page size, permission of page, and so on. This could expand to functionality for shadow page tables which we'll use for nested virt on Arm as well. Things such as managing caches of shadow page tables for certain guest contexts, handling emulated TLB invalidations, etc. should have some commonality at least between x86 and Arm. we agreed to have a meeting of arch maintainers either before or after next KVM forum or independently. This will be discussed separately. Christian Borntraeger will kick of that discussion.
