Re: [PATCH v3 7/9] hvf: use GTree to store memory slots instead of fixed-size array

[Peter Maydell]

On Wed, 2 Mar 2022 at 13:04, Yan-Jie Wang <ubzeme@gmail.com> wrote:
>
> Currently, there are only 32 memory slots in the fixed size array.
> It is not scalable. Instead of using fixed size array, use GTree
> (from glib library) and dynamically-allocated structures to store
> memory slots.
>
> Signed-off-by: Yan-Jie Wang <ubzeme@gmail.com>
> ---
>  accel/hvf/hvf-mem.c | 63 +++++++++++++++++++++++----------------------
>  1 file changed, 32 insertions(+), 31 deletions(-)
>
> diff --git a/accel/hvf/hvf-mem.c b/accel/hvf/hvf-mem.c
> index 081029ba98..2f70ceb307 100644
> --- a/accel/hvf/hvf-mem.c
> +++ b/accel/hvf/hvf-mem.c
> @@ -28,8 +28,6 @@
>
>  /* Memory slots */
>
> -#define HVF_NUM_SLOTS 32
> -
>  /* HVFSlot flags */
>  #define HVF_SLOT_LOG (1 << 0)
>  #define HVF_SLOT_READONLY (1 << 1)
> @@ -42,35 +40,24 @@ typedef struct HVFSlot {
>      MemoryRegion *region;
>  } HVFSlot;
>
> -static HVFSlot memslots[HVF_NUM_SLOTS];
> +static GTree *memslots;
>  static QemuMutex memlock;
>
>  static HVFSlot *hvf_find_overlap_slot(hwaddr start, hwaddr size)
>  {
> -    HVFSlot *slot;
> -    int x;
> -    for (x = 0; x < HVF_NUM_SLOTS; ++x) {
> -        slot = &memslots[x];
> -        if (slot->size && start < (slot->start + slot->size) &&
> -            (start + size) > slot->start) {
> -            return slot;
> -        }
> -    }
> -    return NULL;
> +    HVFSlot key = {.start = start, .size = 1};

Doesn't using a size of 1 mean that this function no longer
finds an overlapping slot which starts somewhere above
our 'start' address ?

> +    return g_tree_lookup(memslots, &key);
>  }
>

-- PMM