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

["Tao Wu(吴涛@Eng)" <lepton@google.com>]

Thanks. Sent out a new version add comments to say that we rely on
pixman create_bits to fail.

On Thu, Nov 9, 2017 at 2:34 AM, Marc-André Lureau
<marcandre.lureau@redhat.com> wrote:
> 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>
>
>>