Re: [Qemu-devel] [PATCH 05/29] memory: differentiate memory_region_is_logging and memory_region_get_dirty_log_mask

[Fam Zheng <famz@redhat.com>]

On Mon, 04/27 18:28, Paolo Bonzini wrote:
> For now memory regions only track DIRTY_MEMORY_VGA individually, but
> this will change soon.  To support this, split memory_region_is_logging
> in two functions: one that returns a given bit from dirty_log_mask,
> and one that returns the entire mask.  memory_region_is_logging gets an
> extra parameter so that the compiler flags misuse.
> 
> While VGA-specific users (including the Xen listener!) will want to keep
> checking that bit, KVM and vhost check for "any bit except migration"
> (because migration is handled via the global start/stop listener
> callbacks).
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  hw/display/vmware_vga.c     |  2 +-
>  hw/virtio/dataplane/vring.c |  2 +-
>  hw/virtio/vhost.c           |  3 ++-
>  include/exec/memory.h       | 17 +++++++++++++++--
>  kvm-all.c                   |  3 ++-
>  memory.c                    |  7 ++++++-
>  xen-hvm.c                   |  2 +-
>  7 files changed, 28 insertions(+), 8 deletions(-)
> 
> diff --git a/hw/display/vmware_vga.c b/hw/display/vmware_vga.c
> index c17ddd1..7f397d3 100644
> --- a/hw/display/vmware_vga.c
> +++ b/hw/display/vmware_vga.c
> @@ -1124,7 +1124,7 @@ static void vmsvga_update_display(void *opaque)
>       * Is it more efficient to look at vram VGA-dirty bits or wait
>       * for the driver to issue SVGA_CMD_UPDATE?
>       */
> -    if (memory_region_is_logging(&s->vga.vram)) {
> +    if (memory_region_is_logging(&s->vga.vram, DIRTY_MEMORY_VGA)) {
>          vga_sync_dirty_bitmap(&s->vga);
>          dirty = memory_region_get_dirty(&s->vga.vram, 0,
>              surface_stride(surface) * surface_height(surface),
> diff --git a/hw/virtio/dataplane/vring.c b/hw/virtio/dataplane/vring.c
> index 5c7b8c2..e378733 100644
> --- a/hw/virtio/dataplane/vring.c
> +++ b/hw/virtio/dataplane/vring.c
> @@ -42,7 +42,7 @@ static void *vring_map(MemoryRegion **mr, hwaddr phys, hwaddr len,
>      }
>  
>      /* Ignore regions with dirty logging, we cannot mark them dirty */
> -    if (memory_region_is_logging(section.mr)) {
> +    if (memory_region_get_dirty_log_mask(section.mr)) {
>          goto out;
>      }
>  
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 54851b7..5f698a1 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -377,7 +377,8 @@ static void vhost_set_memory(MemoryListener *listener,
>                                           memory_listener);
>      hwaddr start_addr = section->offset_within_address_space;
>      ram_addr_t size = int128_get64(section->size);
> -    bool log_dirty = memory_region_is_logging(section->mr);
> +    bool log_dirty =
> +        memory_region_get_dirty_log_mask(section->mr) & ~(1 << DIRTY_MEMORY_MIGRATION);

Too long a line.

>      int s = offsetof(struct vhost_memory, regions) +
>          (dev->mem->nregions + 1) * sizeof dev->mem->regions[0];
>      void *ram;
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 081f7d6..229733e 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -569,11 +569,24 @@ const char *memory_region_name(const MemoryRegion *mr);
>  /**
>   * memory_region_is_logging: return whether a memory region is logging writes
>   *
> - * Returns %true if the memory region is logging writes
> + * Returns %true if the memory region is logging writes for the given client
> + * a bitmap of clients for which the memory region is logging writes.

I can't parse this sentence, rephrase a bit?

>   *
>   * @mr: the memory region being queried
> + * @client: the client being queried
>   */
> -bool memory_region_is_logging(MemoryRegion *mr);
> +bool memory_region_is_logging(MemoryRegion *mr, uint8_t client);
> +
> +/**
> + * memory_region_get_dirty_log_mask: return the clients for which a

s/which a/ which the/ ?

> + * memory region is logging writes.
> + *
> + * Returns a bitmap of clients for which the memory region is logging writes.

Why repeat?

All questions are trivial enough that once you fix them or if they don't need
fixing:

Reviewed-by: Fam Zheng <famz@redhat.com>

> + * Right now this will be either 0 or (1 << DIRTY_MEMORY_VGA).
> + *
> + * @mr: the memory region being queried
> + */
> +uint8_t memory_region_get_dirty_log_mask(MemoryRegion *mr);
>  
>  /**
>   * memory_region_is_rom: check whether a memory region is ROM
> diff --git a/kvm-all.c b/kvm-all.c
> index dd44f8c..bd1f910 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -663,7 +663,8 @@ static void kvm_set_phys_mem(MemoryRegionSection *section, bool add)
>      KVMSlot *mem, old;
>      int err;
>      MemoryRegion *mr = section->mr;
> -    bool log_dirty = memory_region_is_logging(mr);
> +    bool log_dirty =
> +        memory_region_get_dirty_log_mask(mr) & ~(1 << DIRTY_MEMORY_MIGRATION);
>      bool writeable = !mr->readonly && !mr->rom_device;
>      bool readonly_flag = mr->readonly || memory_region_is_romd(mr);
>      hwaddr start_addr = section->offset_within_address_space;
> diff --git a/memory.c b/memory.c
> index e688f5e..a982d99 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1318,11 +1318,16 @@ bool memory_region_is_skip_dump(MemoryRegion *mr)
>      return mr->skip_dump;
>  }
>  
> -bool memory_region_is_logging(MemoryRegion *mr)
> +uint8_t memory_region_get_dirty_log_mask(MemoryRegion *mr)
>  {
>      return mr->dirty_log_mask;
>  }
>  
> +bool memory_region_is_logging(MemoryRegion *mr, uint8_t client)
> +{
> +    return memory_region_get_dirty_log_mask(mr) & (1 << client);
> +}
> +
>  bool memory_region_is_rom(MemoryRegion *mr)
>  {
>      return mr->ram && mr->readonly;
> diff --git a/xen-hvm.c b/xen-hvm.c
> index 315864c..338ab29 100644
> --- a/xen-hvm.c
> +++ b/xen-hvm.c
> @@ -488,7 +488,7 @@ static void xen_set_memory(struct MemoryListener *listener,
>      XenIOState *state = container_of(listener, XenIOState, memory_listener);
>      hwaddr start_addr = section->offset_within_address_space;
>      ram_addr_t size = int128_get64(section->size);
> -    bool log_dirty = memory_region_is_logging(section->mr);
> +    bool log_dirty = memory_region_is_logging(section->mr, DIRTY_MEMORY_VGA);
>      hvmmem_type_t mem_type;
>  
>      if (section->mr == &ram_memory) {
> -- 
> 1.8.3.1
> 
>