Re: [RFC PATCH] subprojects: add a wrapper for libvirglrenderer

["Alex Bennée" <alex.bennee@linaro.org>]

Manos Pitsidianakis <manos.pitsidianakis@linaro.org> writes:

> On Wed, 05 Jun 2024 16:35, Alex Bennée <alex.bennee@linaro.org> wrote:
>>As the latest features for virtio-gpu need a pretty recent version of
>>libvirglrenderer. When it is not available on the system we can use a
>>meson wrapper and provide it when --download is specified in
>>configure.
>>
>>We have to take some additional care as currently QEMU will hang
>>libvirglrenderer fails to exec the render server. As the error isn't
>>back propagated we make sure we at least test we have a path to an
>>executable before tweaking the environment.
>>
>>Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>>Cc: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
>>Cc: Dmitry Osipenko <dmitry.osipenko@collabora.com>
>>Cc: Akihiko Odaki <akihiko.odaki@daynix.com>
>>---
>> meson.build                    |  7 ++++++-
>> hw/display/virtio-gpu-virgl.c  | 24 ++++++++++++++++++++++++
>> subprojects/virglrenderer.wrap |  6 ++++++
>> 3 files changed, 36 insertions(+), 1 deletion(-)
>> create mode 100644 subprojects/virglrenderer.wrap
>>
>>diff --git a/meson.build b/meson.build
>>index 1d7346b703..e4e270df78 100644
>>--- a/meson.build
>>+++ b/meson.build
>>@@ -1203,7 +1203,8 @@ have_vhost_user_gpu = have_tools and host_os == 'linux' and pixman.found()
>> if not get_option('virglrenderer').auto() or have_system or have_vhost_user_gpu
>>   virgl = dependency('virglrenderer',
>>                      method: 'pkg-config',
>>-                     required: get_option('virglrenderer'))
>>+                     required: get_option('virglrenderer'),
>>+                     default_options: ['default_library=static', 'render-server=true', 'venus=true'])
>> endif
>> rutabaga = not_found
>> if not get_option('rutabaga_gfx').auto() or have_system or have_vhost_user_gpu
>>@@ -2314,6 +2315,10 @@ if virgl.version().version_compare('>=1.0.0')
>>   config_host_data.set('HAVE_VIRGL_RESOURCE_BLOB', 1)
>>   config_host_data.set('HAVE_VIRGL_VENUS', 1)
>> endif
>>+if virgl.type_name().contains('internal')
>>+  config_host_data.set('HAVE_BUNDLED_VIRGL_SERVER', 1)
>>+endif
>>+
>> config_host_data.set('CONFIG_VIRTFS', have_virtfs)
>> config_host_data.set('CONFIG_VTE', vte.found())
>> config_host_data.set('CONFIG_XKBCOMMON', xkbcommon.found())
>>diff --git a/hw/display/virtio-gpu-virgl.c b/hw/display/virtio-gpu-virgl.c
>>index c9d20a8a60..53d6742e79 100644
>>--- a/hw/display/virtio-gpu-virgl.c
>>+++ b/hw/display/virtio-gpu-virgl.c
>>@@ -14,6 +14,7 @@
>> #include "qemu/osdep.h"
>> #include "qemu/error-report.h"
>> #include "qemu/iov.h"
>>+#include "qemu/cutils.h"
>> #include "trace.h"
>> #include "hw/virtio/virtio.h"
>> #include "hw/virtio/virtio-gpu.h"
>>@@ -1122,6 +1123,26 @@ void virtio_gpu_virgl_reset(VirtIOGPU *g)
>>     virgl_renderer_reset();
>> }
>> +/*
>>+ * If we fail to spawn the render server things tend to hang so it is
>>+ * important to do our due diligence before then. If QEMU has bundled
>>+ * the virgl server we want to ensure we can run it from the build
>>+ * directory and if installed.
>>+ *
>>+ * The principle way we can override the libvirglrenders behaviour is
>>+ * by setting environment variables.
>>+ */
>>+static void virgl_set_render_env(void)
>>+{
>
> Since it's a few lines we could also inline this in
> virtio_gpu_virgl_init()

I mainly put it in a helper function to avoid putting a big comment
block inline ;-)

>
>>+#ifdef HAVE_BUNDLED_VIRGL_SERVER
>>+    g_autofree char *file = get_relocated_path(CONFIG_QEMU_HELPERDIR "/virgl_render_server");
>>+    if (g_file_test(file, G_FILE_TEST_EXISTS | G_FILE_TEST_IS_EXECUTABLE)) {
>>+        g_setenv("RENDER_SERVER_EXEC_PATH", file, false);
>
>
>  Return value
>
>  Type: gboolean
>
>  FALSE if the environment variable couldn’t be set.
>
> Worth adding a check here.

ok.

> Offtopic, but it feels weird to set our environment without creating
> the process ourselves.

yeah I'm not overly happy with the way the proxy server stuff works
because its a bit spooky action at a distance (as noted by the failure
to detect it not working). Not sure if we want to replicate all the
proxy login in QEMU though.

> There's also an option to launch the server in threads, so that if it
> crashes it pulls qemu down with it. Would that work with our thread
> setup?

Hmm not sure. We could try but I suspect we want to insulate the main
process from the vagaries of the helper.

>
>
>>+    }
>>+#endif
>>+}
>>+
>>+
>> int virtio_gpu_virgl_init(VirtIOGPU *g)
>> {
>>     int ret;
>>@@ -1145,6 +1166,9 @@ int virtio_gpu_virgl_init(VirtIOGPU *g)
>>     }
>> #endif
>> +    /* Ensure we can find the render server */
>>+    virgl_set_render_env();
>>+
>>     ret = virgl_renderer_init(g, flags, &virtio_gpu_3d_cbs);
>>     if (ret != 0) {
>>         error_report("virgl could not be initialized: %d", ret);
>>diff --git a/subprojects/virglrenderer.wrap b/subprojects/virglrenderer.wrap
>>new file mode 100644
>>index 0000000000..3656a478c4
>>--- /dev/null
>>+++ b/subprojects/virglrenderer.wrap
>>@@ -0,0 +1,6 @@
>>+[wrap-git]
>>+url = https://gitlab.freedesktop.org/virgl/virglrenderer.git
>>+revision = virglrenderer-1.0.1
>
>
> Can we say "at least 1.0.1" here? Should we? Dunno.
>
>>+
>>+[provide]
>>+virglrenderer = libvirglrenderer_dep
>> -- 2.39.2
>>

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro