Re: [Qemu-devel] [PATCH] vhost: Add vhost_commit callback for SeaBIOS ROM region re-mapping

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Apr 03, 2013 at 09:15:11AM +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> 
> This patch follows MST's recommendation to move checks for
> vhost_verify_ring_mappings() -> cpu_physical_memory_map() operations
> from MemoryListener->region_[add,del]() -> vhost_set_memory() into
> final MemoryListener->commit() -> vhost_commit() callback.
> 
> It addresses the case where virtio-scsi vq ioport RAM re-mapping
> to read-only SeaBIOS ROM triggers a cpu_physical_memory_map()
> NIL MemoryRegionSection pointer failure.
> 
> Also save vhost_dev->mem_changed_[start,end]_addr values in
> vhost_set_memory() for final ranges_overlap checks.  (Thanks Paolo!)
> 
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Asias He <asias@redhat.com>
> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

Looks good.
Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  hw/vhost.c |   53 ++++++++++++++++++++++++++++++++++++++---------------
>  hw/vhost.h |    3 +++
>  2 files changed, 41 insertions(+), 15 deletions(-)
> 
> diff --git a/hw/vhost.c b/hw/vhost.c
> index 832cc89..00345f2 100644
> --- a/hw/vhost.c
> +++ b/hw/vhost.c
> @@ -385,8 +385,6 @@ static void vhost_set_memory(MemoryListener *listener,
>      bool log_dirty = memory_region_is_logging(section->mr);
>      int s = offsetof(struct vhost_memory, regions) +
>          (dev->mem->nregions + 1) * sizeof dev->mem->regions[0];
> -    uint64_t log_size;
> -    int r;
>      void *ram;
>  
>      dev->mem = g_realloc(dev->mem, s);
> @@ -419,12 +417,47 @@ static void vhost_set_memory(MemoryListener *listener,
>          /* Remove old mapping for this memory, if any. */
>          vhost_dev_unassign_memory(dev, start_addr, size);
>      }
> +    dev->mem_changed_start_addr = MIN(dev->mem_changed_start_addr, start_addr);
> +    dev->mem_changed_end_addr = MAX(dev->mem_changed_end_addr, start_addr + size - 1);
> +    dev->memory_changed = true;
> +}
> +
> +static bool vhost_section(MemoryRegionSection *section)
> +{
> +    return memory_region_is_ram(section->mr);
> +}
> +
> +static void vhost_begin(MemoryListener *listener)
> +{
> +    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
> +                                         memory_listener);
> +    dev->mem_changed_end_addr = 0;
> +    dev->mem_changed_start_addr = -1;
> +}
>  
> +static void vhost_commit(MemoryListener *listener)
> +{
> +    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
> +                                         memory_listener);
> +    hwaddr start_addr = 0;
> +    ram_addr_t size = 0;
> +    uint64_t log_size;
> +    int r;
> +
> +    if (!dev->memory_changed) {
> +        return;
> +    }
>      if (!dev->started) {
>          return;
>      }
> +    if (dev->mem_changed_start_addr > dev->mem_changed_end_addr) {
> +        return;
> +    }
>  
>      if (dev->started) {
> +        start_addr = dev->mem_changed_start_addr;
> +        size = dev->mem_changed_end_addr - dev->mem_changed_start_addr + 1;
> +
>          r = vhost_verify_ring_mappings(dev, start_addr, size);
>          assert(r >= 0);
>      }
> @@ -432,6 +465,7 @@ static void vhost_set_memory(MemoryListener *listener,
>      if (!dev->log_enabled) {
>          r = ioctl(dev->control, VHOST_SET_MEM_TABLE, dev->mem);
>          assert(r >= 0);
> +        dev->memory_changed = false;
>          return;
>      }
>      log_size = vhost_get_log_size(dev);
> @@ -448,19 +482,7 @@ static void vhost_set_memory(MemoryListener *listener,
>      if (dev->log_size > log_size + VHOST_LOG_BUFFER) {
>          vhost_dev_log_resize(dev, log_size);
>      }
> -}
> -
> -static bool vhost_section(MemoryRegionSection *section)
> -{
> -    return memory_region_is_ram(section->mr);
> -}
> -
> -static void vhost_begin(MemoryListener *listener)
> -{
> -}
> -
> -static void vhost_commit(MemoryListener *listener)
> -{
> +    dev->memory_changed = false;
>  }
>  
>  static void vhost_region_add(MemoryListener *listener,
> @@ -854,6 +876,7 @@ int vhost_dev_init(struct vhost_dev *hdev, int devfd, const char *devpath,
>      hdev->log_size = 0;
>      hdev->log_enabled = false;
>      hdev->started = false;
> +    hdev->memory_changed = false;
>      memory_listener_register(&hdev->memory_listener, &address_space_memory);
>      hdev->force = force;
>      return 0;
> diff --git a/hw/vhost.h b/hw/vhost.h
> index f062d48..adb40c3 100644
> --- a/hw/vhost.h
> +++ b/hw/vhost.h
> @@ -45,6 +45,9 @@ struct vhost_dev {
>      vhost_log_chunk_t *log;
>      unsigned long long log_size;
>      bool force;
> +    bool memory_changed;
> +    hwaddr mem_changed_start_addr;
> +    hwaddr mem_changed_end_addr;
>  };
>  
>  int vhost_dev_init(struct vhost_dev *hdev, int devfd, const char *devpath,
> -- 
> 1.7.2.5