Il 08/05/2013 08:20, liu ping fan ha scritto: > 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.
You mean in hostmem, or in general as in this patch? Note that this patch releases the old FlatView at the end of all MemoryListener operations. Paolo > 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 >>
