On Mon, May 6, 2013 at 10:25 PM, Paolo Bonzini <pbonz...@redhat.com> wrote: > Hi, > > this is an alternative approach to refactoring of dataplane's HostMem > code. Here, I take Ping Fan's idea of RCU-style updating of the > region list and apply it to the AddressSpace's FlatView. With this
In fact, I am worrying about the priority of MemoryListener, if it is true, then we should drop RCU-style idea. Also if it is true, there is already a bug with hostmem listener. It should use region_del, not region_nop to reconstruct the local view. But just let me have a deep thinking. Regards, Pingfan > change, dataplane can simply use memory_region_find instead of > hostmem. > > This is a somewhat larger change, but I prefer it for two reasons. > > 1) it splits the task of adding BQL-less memory dispatch in two parts, > tacking memory_region_find first (which is simpler because locking > is left to the caller). > > 2) HostMem duplicates a lot of the FlatView logic, and adding the > RCU-style update in FlatView benefits everyone. > > The missing ingredients here are: > > 1) remember and unreference the MemoryRegions that are used in > a vring entry. In order to implement this, it is probably simpler > to change vring.c to use virtio.c's VirtQueueElement data structure. > We want something like that anyway in order to support migration. > > 2) add an owner field to MemoryRegion, and set it for all MemoryRegions > for hot-unpluggable devices. In this series, ref/unref are stubs. > > For simplicity I based the patches on my IOMMU rebase. I placed the > tree at git://github.com/bonzini/qemu.git, branch iommu. > > Paolo > > Paolo Bonzini (8): > memory: add ref/unref calls > exec: check MRU in qemu_ram_addr_from_host > memory: return MemoryRegion from qemu_ram_addr_from_host > memory: ref/unref memory across address_space_map/unmap > memory: access FlatView from a local variable > memory: use a new FlatView pointer on every topology update > memory: add reference counting to FlatView > dataplane: replace hostmem with memory_region_find > > exec.c | 63 +++++++++--- > hw/core/loader.c | 1 + > hw/display/exynos4210_fimd.c | 6 + > hw/display/framebuffer.c | 10 +- > hw/i386/kvm/ioapic.c | 2 + > hw/i386/kvmvapic.c | 1 + > hw/misc/vfio.c | 2 + > hw/virtio/dataplane/Makefile.objs | 2 +- > hw/virtio/dataplane/hostmem.c | 176 > --------------------------------- > hw/virtio/dataplane/vring.c | 56 +++++++++-- > hw/virtio/vhost.c | 2 + > hw/virtio/virtio-balloon.c | 1 + > hw/xen/xen_pt.c | 4 + > include/exec/cpu-common.h | 2 +- > include/exec/memory.h | 9 ++ > include/hw/virtio/dataplane/hostmem.h | 57 ----------- > include/hw/virtio/dataplane/vring.h | 3 +- > kvm-all.c | 2 + > memory.c | 142 +++++++++++++++++++++----- > target-arm/kvm.c | 2 + > target-i386/kvm.c | 4 +- > target-sparc/mmu_helper.c | 1 + > xen-all.c | 2 + > 23 files changed, 253 insertions(+), 297 deletions(-) > delete mode 100644 hw/virtio/dataplane/hostmem.c > delete mode 100644 include/hw/virtio/dataplane/hostmem.h >