Re: [Qemu-devel] [PATCH 04/15] memory: MemoryRegion topology must be stable when updating

[Blue Swirl <blauwirbel@gmail.com>]

On Wed, Aug 8, 2012 at 6:25 AM, Liu Ping Fan <qemulist@gmail.com> wrote:
> From: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
>
> Using mem_map_lock to protect among updaters. So we can get the intact
> snapshot of mem topology -- FlatView & radix-tree.
>
> Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
> ---
>  exec.c   |    3 +++
>  memory.c |   22 ++++++++++++++++++++++
>  memory.h |    2 ++
>  3 files changed, 27 insertions(+), 0 deletions(-)
>
> diff --git a/exec.c b/exec.c
> index 8244d54..0e29ef9 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -210,6 +210,8 @@ static unsigned phys_map_nodes_nb, phys_map_nodes_nb_alloc;
>     The bottom level has pointers to MemoryRegionSections.  */
>  static PhysPageEntry phys_map = { .ptr = PHYS_MAP_NODE_NIL, .is_leaf = 0 };
>
> +QemuMutex mem_map_lock;
> +
>  static void io_mem_init(void);
>  static void memory_map_init(void);
>
> @@ -637,6 +639,7 @@ void cpu_exec_init_all(void)
>  #if !defined(CONFIG_USER_ONLY)
>      memory_map_init();
>      io_mem_init();
> +    qemu_mutex_init(&mem_map_lock);

I'd move this and the mutex to memory.c since there are no other uses.
The mutex could be static then.

>  #endif
>  }
>
> diff --git a/memory.c b/memory.c
> index aab4a31..5986532 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -761,7 +761,9 @@ void memory_region_transaction_commit(void)
>      assert(memory_region_transaction_depth);
>      --memory_region_transaction_depth;
>      if (!memory_region_transaction_depth && memory_region_update_pending) {
> +        qemu_mutex_lock(&mem_map_lock);
>          memory_region_update_topology(NULL);
> +        qemu_mutex_unlock(&mem_map_lock);
>      }
>  }
>
> @@ -1069,8 +1071,10 @@ void memory_region_set_log(MemoryRegion *mr, bool log, unsigned client)
>  {
>      uint8_t mask = 1 << client;
>
> +    qemu_mutex_lock(&mem_map_lock);
>      mr->dirty_log_mask = (mr->dirty_log_mask & ~mask) | (log * mask);
>      memory_region_update_topology(mr);
> +    qemu_mutex_unlock(&mem_map_lock);
>  }
>
>  bool memory_region_get_dirty(MemoryRegion *mr, target_phys_addr_t addr,
> @@ -1103,8 +1107,10 @@ void memory_region_sync_dirty_bitmap(MemoryRegion *mr)
>  void memory_region_set_readonly(MemoryRegion *mr, bool readonly)
>  {
>      if (mr->readonly != readonly) {
> +        qemu_mutex_lock(&mem_map_lock);
>          mr->readonly = readonly;
>          memory_region_update_topology(mr);
> +        qemu_mutex_unlock(&mem_map_lock);
>      }
>  }
>
> @@ -1112,7 +1118,9 @@ void memory_region_rom_device_set_readable(MemoryRegion *mr, bool readable)
>  {
>      if (mr->readable != readable) {
>          mr->readable = readable;
> +        qemu_mutex_lock(&mem_map_lock);
>          memory_region_update_topology(mr);
> +        qemu_mutex_unlock(&mem_map_lock);
>      }
>  }
>
> @@ -1206,6 +1214,7 @@ void memory_region_add_eventfd(MemoryRegion *mr,
>      };
>      unsigned i;
>
> +    qemu_mutex_lock(&mem_map_lock);
>      for (i = 0; i < mr->ioeventfd_nb; ++i) {
>          if (memory_region_ioeventfd_before(mrfd, mr->ioeventfds[i])) {
>              break;
> @@ -1218,6 +1227,7 @@ void memory_region_add_eventfd(MemoryRegion *mr,
>              sizeof(*mr->ioeventfds) * (mr->ioeventfd_nb-1 - i));
>      mr->ioeventfds[i] = mrfd;
>      memory_region_update_topology(mr);
> +    qemu_mutex_unlock(&mem_map_lock);
>  }
>
>  void memory_region_del_eventfd(MemoryRegion *mr,
> @@ -1236,6 +1246,7 @@ void memory_region_del_eventfd(MemoryRegion *mr,
>      };
>      unsigned i;
>
> +    qemu_mutex_lock(&mem_map_lock);
>      for (i = 0; i < mr->ioeventfd_nb; ++i) {
>          if (memory_region_ioeventfd_equal(mrfd, mr->ioeventfds[i])) {
>              break;
> @@ -1248,6 +1259,7 @@ void memory_region_del_eventfd(MemoryRegion *mr,
>      mr->ioeventfds = g_realloc(mr->ioeventfds,
>                                    sizeof(*mr->ioeventfds)*mr->ioeventfd_nb + 1);
>      memory_region_update_topology(mr);
> +    qemu_mutex_unlock(&mem_map_lock);
>  }
>
>  static void memory_region_add_subregion_common(MemoryRegion *mr,
> @@ -1259,6 +1271,8 @@ static void memory_region_add_subregion_common(MemoryRegion *mr,
>      assert(!subregion->parent);
>      subregion->parent = mr;
>      subregion->addr = offset;
> +
> +    qemu_mutex_lock(&mem_map_lock);
>      QTAILQ_FOREACH(other, &mr->subregions, subregions_link) {
>          if (subregion->may_overlap || other->may_overlap) {
>              continue;
> @@ -1289,6 +1303,7 @@ static void memory_region_add_subregion_common(MemoryRegion *mr,
>      QTAILQ_INSERT_TAIL(&mr->subregions, subregion, subregions_link);
>  done:
>      memory_region_update_topology(mr);
> +    qemu_mutex_unlock(&mem_map_lock);
>  }
>
>
> @@ -1316,8 +1331,11 @@ void memory_region_del_subregion(MemoryRegion *mr,
>  {
>      assert(subregion->parent == mr);
>      subregion->parent = NULL;
> +
> +    qemu_mutex_lock(&mem_map_lock);
>      QTAILQ_REMOVE(&mr->subregions, subregion, subregions_link);
>      memory_region_update_topology(mr);
> +    qemu_mutex_unlock(&mem_map_lock);
>  }
>
>  void memory_region_set_enabled(MemoryRegion *mr, bool enabled)
> @@ -1325,8 +1343,10 @@ void memory_region_set_enabled(MemoryRegion *mr, bool enabled)
>      if (enabled == mr->enabled) {
>          return;
>      }
> +    qemu_mutex_lock(&mem_map_lock);
>      mr->enabled = enabled;
>      memory_region_update_topology(NULL);
> +    qemu_mutex_unlock(&mem_map_lock);
>  }
>
>  void memory_region_set_address(MemoryRegion *mr, target_phys_addr_t addr)
> @@ -1361,7 +1381,9 @@ void memory_region_set_alias_offset(MemoryRegion *mr, target_phys_addr_t offset)
>          return;
>      }
>
> +    qemu_mutex_lock(&mem_map_lock);
>      memory_region_update_topology(mr);
> +    qemu_mutex_unlock(&mem_map_lock);
>  }
>
>  ram_addr_t memory_region_get_ram_addr(MemoryRegion *mr)
> diff --git a/memory.h b/memory.h
> index 740c48e..fe6aefa 100644
> --- a/memory.h
> +++ b/memory.h
> @@ -25,6 +25,7 @@
>  #include "iorange.h"
>  #include "ioport.h"
>  #include "int128.h"
> +#include "qemu-thread.h"
>
>  typedef struct MemoryRegionOps MemoryRegionOps;
>  typedef struct MemoryRegion MemoryRegion;
> @@ -207,6 +208,7 @@ struct MemoryListener {
>      QTAILQ_ENTRY(MemoryListener) link;
>  };
>
> +extern QemuMutex mem_map_lock;
>  /**
>   * memory_region_init: Initialize a memory region
>   *
> --
> 1.7.4.4
>