On 17.12.19 21:40, Sean Christopherson wrote: > The end goal of this series is to dynamically size the memslot array so > that KVM allocates memory based on the number of memslots in use, as > opposed to unconditionally allocating memory for the maximum number of > memslots. On x86, each memslot consumes 88 bytes, and so with 2 address > spaces of 512 memslots, each VM consumes ~90k bytes for the memslots. > E.g. given a VM that uses a total of 30 memslots, dynamic sizing reduces > the memory footprint from 90k to ~2.6k bytes. > > The changes required to support dynamic sizing are relatively small, > e.g. are essentially contained in patches 17/19 and 18/19. > > Patches 2-16 clean up the memslot code, which has gotten quite crusty, > especially __kvm_set_memory_region(). The clean up is likely not strictly > necessary to switch to dynamic sizing, but I didn't have a remotely > reasonable level of confidence in the correctness of the dynamic sizing > without first doing the clean up. > > The only functional change in v4 is the addition of an x86-specific bug > fix in x86's handling of KVM_MR_MOVE. The bug fix is not directly related > to dynamically allocating memslots, but it has subtle and hidden conflicts > with the cleanup patches, and the fix is higher priority than anything > else in the series, i.e. should be merged first. > > On non-x86 architectures, v3 and v4 should be functionally equivalent, > the only non-x86 change in v4 is the dropping of a "const" in > kvm_arch_commit_memory_region(). I gave this series a quick spin and it still seems to work on s390 (minus the selftest).
