Re: [Qemu-devel] [PATCH] virtio-gpu: fix bug in host memory calculation.

["Marc-André Lureau" <marcandre.lureau@redhat.com>]

Hi

----- Original Message -----
> The old code treats bits as bytes when calculating host memory usage.
> Change it to be consistent with allocation logic in pixman library.
> 

Good catch

> Signed-off-by: Tao Wu <lepton@google.com>
> ---
>  hw/display/virtio-gpu.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
> index 43bbe09ea0..428786f291 100644
> --- a/hw/display/virtio-gpu.c
> +++ b/hw/display/virtio-gpu.c
> @@ -322,6 +322,15 @@ static pixman_format_code_t get_pixman_format(uint32_t
> virtio_gpu_format)
>      }
>  }
>  
> +static uint32_t calc_image_hostmem(pixman_format_code_t pformat,
> +                                   uint32_t width, uint32_t height)
> +{
> +    /* copied from pixman/pixman-bits-image.c, skip integer overflow check.
> */

So we rely on pixman create_bits() to fail if overflow happened? perhaps it's worth a comment.
 
> +    int bpp = PIXMAN_FORMAT_BPP(pformat);
> +    int stride = ((width * bpp + 0x1f) >> 5) * sizeof(uint32_t);
> +    return height * stride;
> +}
> +
>  static void virtio_gpu_resource_create_2d(VirtIOGPU *g,
>                                            struct virtio_gpu_ctrl_command
>                                            *cmd)
>  {
> @@ -366,7 +375,7 @@ static void virtio_gpu_resource_create_2d(VirtIOGPU *g,
>          return;
>      }
>  
> -    res->hostmem = PIXMAN_FORMAT_BPP(pformat) * c2d.width * c2d.height;
> +    res->hostmem = calc_image_hostmem(pformat, c2d.width, c2d.height);
>      if (res->hostmem + g->hostmem < g->conf.max_hostmem) {
>          res->image = pixman_image_create_bits(pformat,
>                                                c2d.width,
> @@ -1087,7 +1096,7 @@ static int virtio_gpu_load(QEMUFile *f, void *opaque,
> size_t size,
>              return -EINVAL;
>          }
>  
> -        res->hostmem = PIXMAN_FORMAT_BPP(pformat) * res->width *
> res->height;
> +        res->hostmem = calc_image_hostmem(pformat, res->width, res->height);
>  
>          res->addrs = g_new(uint64_t, res->iov_cnt);
>          res->iov = g_new(struct iovec, res->iov_cnt);
> --
> 2.15.0.403.gc27cc4dac6-goog
> 

looks good otherwise,

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

>