Re: [Qemu-devel] [PATCH v2 06/11] memory: add ref/unref calls

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2013-06-28 18:58, Paolo Bonzini wrote:
> Add ref/unref calls at the following places:
> 
> - places where memory regions are stashed by a listener and
>   used outside the BQL (including in Xen or KVM).
> 
> - memory_region_find callsites

You missed some recently added ones. Check hw/acpi/piix4.c and
hw/isa/lpc_ich9.c (both will require some refactorings for this).

> 
> - creation of aliases and containers (only the aliased/contained
>   region gets a reference to avoid loops)
> 
> - around calls to del_subregion/add_subregion, where the region
>   could disappear after the first call
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  exec.c                                |  3 +++
>  hw/core/loader.c                      |  1 +
>  hw/display/exynos4210_fimd.c          |  6 ++++++
>  hw/display/framebuffer.c              | 12 +++++++-----
>  hw/i386/kvmvapic.c                    |  1 +
>  hw/misc/vfio.c                        |  2 ++
>  hw/virtio/dataplane/hostmem.c         |  7 +++++++
>  hw/virtio/vhost.c                     |  2 ++
>  hw/virtio/virtio-balloon.c            |  1 +
>  hw/xen/xen_pt.c                       |  4 ++++
>  include/hw/virtio/dataplane/hostmem.h |  1 +
>  kvm-all.c                             |  2 ++
>  memory.c                              | 20 ++++++++++++++++++++
>  target-arm/kvm.c                      |  2 ++
>  target-sparc/mmu_helper.c             |  1 +
>  xen-all.c                             |  2 ++
>  16 files changed, 62 insertions(+), 5 deletions(-)
> 
> diff --git a/exec.c b/exec.c
> index 9c77285..8722420 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -771,11 +771,14 @@ static uint16_t phys_section_add(MemoryRegionSection *section)
>                                  phys_sections_nb_alloc);
>      }
>      phys_sections[phys_sections_nb] = *section;
> +    memory_region_ref(section->mr);
>      return phys_sections_nb++;
>  }
> 
>  static void phys_section_destroy(MemoryRegion *mr)
>  {
> +    memory_region_unref(mr);
> +
>      if (mr->subpage) {
>          subpage_t *subpage = container_of(mr, subpage_t, iomem);
>          memory_region_destroy(&subpage->iomem);
> diff --git a/hw/core/loader.c b/hw/core/loader.c
> index d569636..44311ff 100644
> --- a/hw/core/loader.c
> +++ b/hw/core/loader.c
> @@ -727,6 +727,7 @@ int rom_load_all(void)
>          addr += rom->romsize;
>          section = memory_region_find(get_system_memory(), rom->addr, 1);
>          rom->isrom = int128_nz(section.size) && memory_region_is_rom(section.mr);
> +        memory_region_unref(section.mr);
>      }
>      qemu_register_reset(rom_reset, NULL);
>      roms_loaded = 1;
> diff --git a/hw/display/exynos4210_fimd.c b/hw/display/exynos4210_fimd.c
> index d9088d9..b520f52 100644
> --- a/hw/display/exynos4210_fimd.c
> +++ b/hw/display/exynos4210_fimd.c
> @@ -1126,6 +1126,11 @@ static void fimd_update_memory_section(Exynos4210fimdState *s, unsigned win)
>      /* Total number of bytes of virtual screen used by current window */
>      w->fb_len = fb_mapped_len = (w->virtpage_width + w->virtpage_offsize) *
>              (w->rightbot_y - w->lefttop_y + 1);
> +
> +    /* TODO: add .exit and unref the region there.  Not needed yet since sysbus
> +     * does not support hot-unplug.
> +     */
> +    memory_region_unref(w->mem_section.mr);
>      w->mem_section = memory_region_find(sysbus_address_space(&s->busdev),
>              fb_start_addr, w->fb_len);
>      assert(w->mem_section.mr);
> @@ -1154,6 +1159,7 @@ static void fimd_update_memory_section(Exynos4210fimdState *s, unsigned win)
>      return;
> 
>  error_return:
> +    memory_region_unref(w->mem_section.mr);
>      w->mem_section.mr = NULL;
>      w->mem_section.size = int128_zero();
>      w->host_fb_addr = NULL;
> diff --git a/hw/display/framebuffer.c b/hw/display/framebuffer.c
> index 49c9e59..4546e42 100644
> --- a/hw/display/framebuffer.c
> +++ b/hw/display/framebuffer.c
> @@ -54,11 +54,11 @@ void framebuffer_update_display(
>      src_len = src_width * rows;
> 
>      mem_section = memory_region_find(address_space, base, src_len);
> +    mem = mem_section.mr;
>      if (int128_get64(mem_section.size) != src_len ||
>              !memory_region_is_ram(mem_section.mr)) {
> -        return;
> +        goto out;
>      }
> -    mem = mem_section.mr;
>      assert(mem);
>      assert(mem_section.offset_within_address_space == base);
> 
> @@ -68,10 +68,10 @@ void framebuffer_update_display(
>         but it's not really worth it as dirty flag tracking will probably
>         already have failed above.  */
>      if (!src_base)
> -        return;
> +        goto out;
>      if (src_len != src_width * rows) {
>          cpu_physical_memory_unmap(src_base, src_len, 0, 0);
> -        return;
> +        goto out;
>      }
>      src = src_base;
>      dest = surface_data(ds);
> @@ -102,10 +102,12 @@ void framebuffer_update_display(
>      }
>      cpu_physical_memory_unmap(src_base, src_len, 0, 0);
>      if (first < 0) {
> -        return;
> +        goto out;
>      }
>      memory_region_reset_dirty(mem, mem_section.offset_within_region, src_len,
>                                DIRTY_MEMORY_VGA);
>      *first_row = first;
>      *last_row = last;
> +out:
> +    memory_region_unref(mem);
>  }
> diff --git a/hw/i386/kvmvapic.c b/hw/i386/kvmvapic.c
> index 953fc74..bf2ed91 100644
> --- a/hw/i386/kvmvapic.c
> +++ b/hw/i386/kvmvapic.c
> @@ -605,6 +605,7 @@ static void vapic_map_rom_writable(VAPICROMState *s)
>                               rom_size);
>      memory_region_add_subregion_overlap(as, rom_paddr, &s->rom, 1000);
>      s->rom_mapped_writable = true;
> +    memory_region_unref(section.mr);
>  }
> 
>  static int vapic_prepare(VAPICROMState *s)
> diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
> index e2e957d..675bbfc 100644
> --- a/hw/misc/vfio.c
> +++ b/hw/misc/vfio.c
> @@ -1969,6 +1969,7 @@ static void vfio_listener_region_add(MemoryListener *listener,
>      DPRINTF("region_add %"HWADDR_PRIx" - %"HWADDR_PRIx" [%p]\n",
>              iova, end - 1, vaddr);
> 
> +    memory_region_ref(section->mr);
>      ret = vfio_dma_map(container, iova, end - iova, vaddr, section->readonly);
>      if (ret) {
>          error_report("vfio_dma_map(%p, 0x%"HWADDR_PRIx", "
> @@ -2010,6 +2011,7 @@ static void vfio_listener_region_del(MemoryListener *listener,
>              iova, end - 1);
> 
>      ret = vfio_dma_unmap(container, iova, end - iova);
> +    memory_region_unref(section->mr);
>      if (ret) {
>          error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", "
>                       "0x%"HWADDR_PRIx") = %d (%m)",
> diff --git a/hw/virtio/dataplane/hostmem.c b/hw/virtio/dataplane/hostmem.c
> index 7e46723..901d98b 100644
> --- a/hw/virtio/dataplane/hostmem.c
> +++ b/hw/virtio/dataplane/hostmem.c
> @@ -64,8 +64,12 @@ out:
>  static void hostmem_listener_commit(MemoryListener *listener)
>  {
>      HostMem *hostmem = container_of(listener, HostMem, listener);
> +    int i;
> 
>      qemu_mutex_lock(&hostmem->current_regions_lock);
> +    for (i = 0; i < hostmem->num_current_regions; i++) {
> +        memory_region_unref(hostmem->current_regions[i].mr);
> +    }
>      g_free(hostmem->current_regions);
>      hostmem->current_regions = hostmem->new_regions;
>      hostmem->num_current_regions = hostmem->num_new_regions;
> @@ -92,8 +96,11 @@ static void hostmem_append_new_region(HostMem *hostmem,
>          .guest_addr = section->offset_within_address_space,
>          .size = int128_get64(section->size),
>          .readonly = section->readonly,
> +        .mr = section->mr,
>      };
>      hostmem->num_new_regions++;
> +
> +    memory_region_ref(section->mr);

Hmm, hostmem_append_new_region is also called on region_nop. Don't we
accumulate them? But that's not changed by this patch.

>  }
> 
>  static void hostmem_listener_append_region(MemoryListener *listener,
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index baf84ea..96ab625 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -497,6 +497,7 @@ static void vhost_region_add(MemoryListener *listener,
>      dev->mem_sections = g_renew(MemoryRegionSection, dev->mem_sections,
>                                  dev->n_mem_sections);
>      dev->mem_sections[dev->n_mem_sections - 1] = *section;
> +    memory_region_ref(section->mr);
>      vhost_set_memory(listener, section, true);
>  }
> 
> @@ -512,6 +513,7 @@ static void vhost_region_del(MemoryListener *listener,
>      }
> 
>      vhost_set_memory(listener, section, false);
> +    memory_region_unref(section->mr);
>      for (i = 0; i < dev->n_mem_sections; ++i) {
>          if (dev->mem_sections[i].offset_within_address_space
>              == section->offset_within_address_space) {
> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> index a27051c..3fa72a9 100644
> --- a/hw/virtio/virtio-balloon.c
> +++ b/hw/virtio/virtio-balloon.c
> @@ -205,6 +205,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>              addr = section.offset_within_region;
>              balloon_page(memory_region_get_ram_ptr(section.mr) + addr,
>                           !!(vq == s->dvq));
> +            memory_region_unref(section.mr);
>          }
> 
>          virtqueue_push(vq, &elem, offset);
> diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
> index 15b4896..c06a018 100644
> --- a/hw/xen/xen_pt.c
> +++ b/hw/xen/xen_pt.c
> @@ -606,6 +606,7 @@ static void xen_pt_region_add(MemoryListener *l, MemoryRegionSection *sec)
>      XenPCIPassthroughState *s = container_of(l, XenPCIPassthroughState,
>                                               memory_listener);
> 
> +    memory_region_ref(sec->mr);
>      xen_pt_region_update(s, sec, true);
>  }
> 
> @@ -615,6 +616,7 @@ static void xen_pt_region_del(MemoryListener *l, MemoryRegionSection *sec)
>                                               memory_listener);
> 
>      xen_pt_region_update(s, sec, false);
> +    memory_region_unref(sec->mr);
>  }
> 
>  static void xen_pt_io_region_add(MemoryListener *l, MemoryRegionSection *sec)
> @@ -622,6 +624,7 @@ static void xen_pt_io_region_add(MemoryListener *l, MemoryRegionSection *sec)
>      XenPCIPassthroughState *s = container_of(l, XenPCIPassthroughState,
>                                               io_listener);
> 
> +    memory_region_ref(sec->mr);
>      xen_pt_region_update(s, sec, true);
>  }
> 
> @@ -631,6 +634,7 @@ static void xen_pt_io_region_del(MemoryListener *l, MemoryRegionSection *sec)
>                                               io_listener);
> 
>      xen_pt_region_update(s, sec, false);
> +    memory_region_unref(sec->mr);
>  }
> 
>  static const MemoryListener xen_pt_memory_listener = {
> diff --git a/include/hw/virtio/dataplane/hostmem.h b/include/hw/virtio/dataplane/hostmem.h
> index b2cf093..2810f4b 100644
> --- a/include/hw/virtio/dataplane/hostmem.h
> +++ b/include/hw/virtio/dataplane/hostmem.h
> @@ -18,6 +18,7 @@
>  #include "qemu/thread.h"
> 
>  typedef struct {
> +    MemoryRegion *mr;
>      void *host_addr;
>      hwaddr guest_addr;
>      uint64_t size;
> diff --git a/kvm-all.c b/kvm-all.c
> index e6b262f..91aa7ff 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -788,6 +788,7 @@ static void kvm_set_phys_mem(MemoryRegionSection *section, bool add)
>  static void kvm_region_add(MemoryListener *listener,
>                             MemoryRegionSection *section)
>  {
> +    memory_region_ref(section->mr);
>      kvm_set_phys_mem(section, true);
>  }
> 
> @@ -795,6 +796,7 @@ static void kvm_region_del(MemoryListener *listener,
>                             MemoryRegionSection *section)
>  {
>      kvm_set_phys_mem(section, false);
> +    memory_region_unref(section->mr);
>  }
> 
>  static void kvm_log_sync(MemoryListener *listener,
> diff --git a/memory.c b/memory.c
> index 970c448..688c817 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -148,6 +148,7 @@ static bool memory_listener_match(MemoryListener *listener,
>          }                                                               \
>      } while (0)
> 
> +/* No need to ref/unref .mr, the FlatRange keeps it alive.  */
>  #define MEMORY_LISTENER_UPDATE_REGION(fr, as, dir, callback)            \
>      MEMORY_LISTENER_CALL(callback, dir, (&(MemoryRegionSection) {       \
>          .mr = (fr)->mr,                                                 \
> @@ -263,11 +264,17 @@ static void flatview_insert(FlatView *view, unsigned pos, FlatRange *range)
>      memmove(view->ranges + pos + 1, view->ranges + pos,
>              (view->nr - pos) * sizeof(FlatRange));
>      view->ranges[pos] = *range;
> +    memory_region_ref(range->mr);
>      ++view->nr;
>  }
> 
>  static void flatview_destroy(FlatView *view)
>  {
> +    int i;
> +
> +    for (i = 0; i < view->nr; i++) {
> +        memory_region_unref(view->ranges[i].mr);
> +    }
>      g_free(view->ranges);
>  }
> 
> @@ -709,6 +716,11 @@ static void memory_region_destructor_ram(MemoryRegion *mr)
>      qemu_ram_free(mr->ram_addr);
>  }
> 
> +static void memory_region_destructor_alias(MemoryRegion *mr)
> +{
> +    memory_region_unref(mr->alias);
> +}
> +
>  static void memory_region_destructor_ram_from_ptr(MemoryRegion *mr)
>  {
>      qemu_ram_free_from_ptr(mr->ram_addr);
> @@ -962,6 +974,8 @@ void memory_region_init_alias(MemoryRegion *mr,
>                                uint64_t size)
>  {
>      memory_region_init(mr, owner, name, size);
> +    memory_region_ref(orig);
> +    mr->destructor = memory_region_destructor_alias;
>      mr->alias = orig;
>      mr->alias_offset = offset;
>  }
> @@ -1340,6 +1354,7 @@ static void memory_region_add_subregion_common(MemoryRegion *mr,
>      memory_region_transaction_begin();
> 
>      assert(!subregion->parent);
> +    memory_region_ref(subregion);
>      subregion->parent = mr;
>      subregion->addr = offset;
>      QTAILQ_FOREACH(other, &mr->subregions, subregions_link) {
> @@ -1402,6 +1417,7 @@ void memory_region_del_subregion(MemoryRegion *mr,
>      assert(subregion->parent == mr);
>      subregion->parent = NULL;
>      QTAILQ_REMOVE(&mr->subregions, subregion, subregions_link);
> +    memory_region_unref(subregion);
>      memory_region_update_pending |= mr->enabled && subregion->enabled;
>      memory_region_transaction_commit();
>  }
> @@ -1429,12 +1445,14 @@ void memory_region_set_address(MemoryRegion *mr, hwaddr addr)
>      }
> 
>      memory_region_transaction_begin();
> +    memory_region_ref(mr);
>      memory_region_del_subregion(parent, mr);
>      if (may_overlap) {
>          memory_region_add_subregion_overlap(parent, addr, mr, priority);
>      } else {
>          memory_region_add_subregion(parent, addr, mr);
>      }
> +    memory_region_unref(mr);
>      memory_region_transaction_commit();
>  }
> 
> @@ -1512,6 +1530,8 @@ MemoryRegionSection memory_region_find(MemoryRegion *mr,
>      ret.size = range.size;
>      ret.offset_within_address_space = int128_get64(range.start);
>      ret.readonly = fr->readonly;
> +    memory_region_ref(ret.mr);
> +
>      return ret;
>  }
> 
> diff --git a/target-arm/kvm.c b/target-arm/kvm.c
> index d3937a2..b92e00d 100644
> --- a/target-arm/kvm.c
> +++ b/target-arm/kvm.c
> @@ -233,6 +233,7 @@ static void kvm_arm_machine_init_done(Notifier *notifier, void *data)
>                  abort();
>              }
>          }
> +        memory_region_unref(kd->mr);
>          g_free(kd);
>      }
>  }
> @@ -258,6 +259,7 @@ void kvm_arm_register_device(MemoryRegion *mr, uint64_t devid)
>      kd->kda.id = devid;
>      kd->kda.addr = -1;
>      QSLIST_INSERT_HEAD(&kvm_devices_head, kd, entries);
> +    memory_region_ref(kd->mr);
>  }
> 
>  bool write_kvmstate_to_list(ARMCPU *cpu)
> diff --git a/target-sparc/mmu_helper.c b/target-sparc/mmu_helper.c
> index 3983c96..740cbe8 100644
> --- a/target-sparc/mmu_helper.c
> +++ b/target-sparc/mmu_helper.c
> @@ -845,6 +845,7 @@ hwaddr cpu_get_phys_page_debug(CPUSPARCState *env, target_ulong addr)
>          }
>      }
>      section = memory_region_find(get_system_memory(), phys_addr, 1);
> +    memory_region_unref(section.mr);
>      if (!int128_nz(section.size)) {
>          return -1;
>      }
> diff --git a/xen-all.c b/xen-all.c
> index 1f040c0..21246e0 100644
> --- a/xen-all.c
> +++ b/xen-all.c
> @@ -459,6 +459,7 @@ static void xen_set_memory(struct MemoryListener *listener,
>  static void xen_region_add(MemoryListener *listener,
>                             MemoryRegionSection *section)
>  {
> +    memory_region_ref(section->mr);
>      xen_set_memory(listener, section, true);
>  }
> 
> @@ -466,6 +467,7 @@ static void xen_region_del(MemoryListener *listener,
>                             MemoryRegionSection *section)
>  {
>      xen_set_memory(listener, section, false);
> +    memory_region_unref(section->mr);
>  }
> 
>  static void xen_sync_dirty_bitmap(XenIOState *state,
> --
> 1.8.1.4
> 
> 

Looks good otherwise.

Jan

-- 
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