Re: [QEMU PATCH v5 09/13] virtio-gpu: Handle resource blob commands

[Akihiko Odaki <akihiko.odaki@xxxxxxxxxx>]

On 2023/09/20 14:50, Huang Rui wrote:
> On Sat, Sep 16, 2023 at 12:37:29AM +0800, Akihiko Odaki wrote:
> > On 2023/09/16 1:04, Akihiko Odaki wrote:
> > > On 2023/09/15 20:11, Huang Rui wrote:
> > > > From: Antonio Caggiano <antonio.caggiano@xxxxxxxxxxxxx>
> > > >
> > > > Support BLOB resources creation, mapping and unmapping by calling the
> > > > new stable virglrenderer 0.10 interface. Only enabled when available and
> > > > via the blob config. E.g. -device virtio-vga-gl,blob=true
> > > >
> > > > Signed-off-by: Antonio Caggiano <antonio.caggiano@xxxxxxxxxxxxx>
> > > > Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
> > > > Signed-off-by: Xenia Ragiadakou <xenia.ragiadakou@xxxxxxx>
> > > > Signed-off-by: Huang Rui <ray.huang@xxxxxxx>
> > > > ---
> > > >
> > > > V4 -> V5:
> > > >       - Use memory_region_init_ram_ptr() instead of
> > > >         memory_region_init_ram_device_ptr() (Akihiko)
> > > >
> > > >    hw/display/virtio-gpu-virgl.c  | 213 +++++++++++++++++++++++++++++++++
> > > >    hw/display/virtio-gpu.c        |   4 +-
> > > >    include/hw/virtio/virtio-gpu.h |   5 +
> > > >    meson.build                    |   4 +
> > > >    4 files changed, 225 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/hw/display/virtio-gpu-virgl.c
> > > > b/hw/display/virtio-gpu-virgl.c
> > > > index 312953ec16..563a6f2f58 100644
> > > > --- a/hw/display/virtio-gpu-virgl.c
> > > > +++ b/hw/display/virtio-gpu-virgl.c
> > > > @@ -17,6 +17,7 @@
> > > >    #include "trace.h"
> > > >    #include "hw/virtio/virtio.h"
> > > >    #include "hw/virtio/virtio-gpu.h"
> > > > +#include "hw/virtio/virtio-gpu-bswap.h"
> > > >    #include "ui/egl-helpers.h"
> > > > @@ -78,9 +79,24 @@ static void virgl_cmd_create_resource_3d(VirtIOGPU *g,
> > > >        virgl_renderer_resource_create(&args, NULL, 0);
> > > >    }
> > > > +static void virgl_resource_destroy(VirtIOGPU *g,
> > > > +                                   struct virtio_gpu_simple_resource
> > > > *res)
> > > > +{
> > > > +    if (!res)
> > > > +        return;
> > > > +
> > > > +    QTAILQ_REMOVE(&g->reslist, res, next);
> > > > +
> > > > +    virtio_gpu_cleanup_mapping_iov(g, res->iov, res->iov_cnt);
> > > > +    g_free(res->addrs);
> > > > +
> > > > +    g_free(res);
> > > > +}
> > > > +
> > > >    static void virgl_cmd_resource_unref(VirtIOGPU *g,
> > > >                                         struct virtio_gpu_ctrl_command
> > > > *cmd)
> > > >    {
> > > > +    struct virtio_gpu_simple_resource *res;
> > > >        struct virtio_gpu_resource_unref unref;
> > > >        struct iovec *res_iovs = NULL;
> > > >        int num_iovs = 0;
> > > > @@ -88,13 +104,22 @@ static void virgl_cmd_resource_unref(VirtIOGPU *g,
> > > >        VIRTIO_GPU_FILL_CMD(unref);
> > > >        trace_virtio_gpu_cmd_res_unref(unref.resource_id);
> > > > +    res = virtio_gpu_find_resource(g, unref.resource_id);
> > > > +
> > > >        virgl_renderer_resource_detach_iov(unref.resource_id,
> > > >                                           &res_iovs,
> > > >                                           &num_iovs);
> > > >        if (res_iovs != NULL && num_iovs != 0) {
> > > >            virtio_gpu_cleanup_mapping_iov(g, res_iovs, num_iovs);
> > > > +        if (res) {
> > > > +            res->iov = NULL;
> > > > +            res->iov_cnt = 0;
> > > > +        }
> > > >        }
> > > > +
> > > >        virgl_renderer_resource_unref(unref.resource_id);
> > > > +
> > > > +    virgl_resource_destroy(g, res);
> > This may leak memory region.
> The memory region should be freed under virgl_cmd_resource_unmap_blob()
> which is calling memory_region_del_subregion(&b->hostmem, res->region).
> Because this region is created by map_blob(). Do we have the case to call
> virgl_cmd_resource_unref() without calling virgl_cmd_resource_unmap_blob()
> for blob memory?
Calling virgl_cmd_resource_unmap_blob() and virgl_cmd_resource_unref() 
in order is a guest's responsibility, and we are required to prepare for 
broken guests.