While running the new GPU tests it was noted that the proprietary
nVidia driver barfed when run under the sanitiser:

  2025-02-20 11:13:08,226: [11:13:07.782] Output 'headless' attempts
  EOTF mode SDR and colorimetry mode default.
  2025-02-20 11:13:08,227: [11:13:07.784] Output 'headless' using color
  profile: stock sRGB color profile

  and that's the last thing it outputs.

  The sanitizer reports that when the framework sends the SIGTERM
  because of the timeout we get a write to a NULL pointer (but
  interesting not this time in an atexit callback):

  UndefinedBehaviorSanitizer:DEADLYSIGNAL
  ==471863==ERROR: UndefinedBehaviorSanitizer: SEGV on unknown address
  0x000000000000 (pc 0x7a18ceaafe80 bp 0x000000000000 sp 0x7ffe8e3ff6d0
  T471863)
  ==471863==The signal is caused by a WRITE memory access.
  ==471863==Hint: address points to the zero page.
      #0 0x7a18ceaafe80
  (/lib/x86_64-linux-gnu/libnvidia-eglcore.so.535.183.01+0x16afe80)
  (BuildId: 24b0d0b90369112e3de888a93eb8d7e00304a6db)
      #1 0x7a18ce9e72c0
  (/lib/x86_64-linux-gnu/libnvidia-eglcore.so.535.183.01+0x15e72c0)
  (BuildId: 24b0d0b90369112e3de888a93eb8d7e00304a6db)
      #2 0x7a18ce9f11bb
  (/lib/x86_64-linux-gnu/libnvidia-eglcore.so.535.183.01+0x15f11bb)
  (BuildId: 24b0d0b90369112e3de888a93eb8d7e00304a6db)
      #3 0x7a18ce6dc9d1
  (/lib/x86_64-linux-gnu/libnvidia-eglcore.so.535.183.01+0x12dc9d1)
  (BuildId: 24b0d0b90369112e3de888a93eb8d7e00304a6db)
      #4 0x7a18e7d15326 in vrend_renderer_create_fence
  /usr/src/virglrenderer-1.0.0-1ubuntu2/obj-x86_64-linux-gnu/../src/vrend_renderer.c:10883:26
      #5 0x55bfb6621871 in virtio_gpu_virgl_process_cmd

The #dri-devel channel confirmed:

  <digetx> stsquad: nv driver is known to not work with venus, don't use
      it for testing

So lets implement a blocklist to stop users starting a known bad
setup.

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Cc: Dmitry Osipenko <dmitry.osipenko@collabora.com>
---
 meson.build                               |   4 +
 include/qemu/host-gpu.h                   |  23 +++++
 hw/display/virtio-gpu.c                   |   4 +
 stubs/host-gpu.c                          |  17 ++++
 util/host-gpu.c                           | 102 ++++++++++++++++++++++
 stubs/meson.build                         |   4 +
 tests/functional/test_aarch64_virt_gpu.py |   2 +
 util/meson.build                          |   2 +
 8 files changed, 158 insertions(+)
 create mode 100644 include/qemu/host-gpu.h
 create mode 100644 stubs/host-gpu.c
 create mode 100644 util/host-gpu.c

diff --git a/meson.build b/meson.build
index 4588bfd864..8f4a431445 100644
--- a/meson.build
+++ b/meson.build
@@ -1373,12 +1373,16 @@ if not get_option('qatzip').auto() or have_system
 endif
 
 virgl = not_found
+vulkan = not_found
 
 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'))
+  vulkan = dependency('vulkan',
+                      method: 'pkg-config',
+                      required: get_option('virglrenderer'))
 endif
 rutabaga = not_found
 if not get_option('rutabaga_gfx').auto() or have_system or have_vhost_user_gpu
diff --git a/include/qemu/host-gpu.h b/include/qemu/host-gpu.h
new file mode 100644
index 0000000000..45053c2f77
--- /dev/null
+++ b/include/qemu/host-gpu.h
@@ -0,0 +1,23 @@
+/*
+ * Utility functions to probe host GPU
+ *
+ * Copyright (c) 2025 Linaro Ltd
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#ifndef HOST_GPU_H
+#define HOST_GPU_H
+
+#include "qapi/error.h"
+
+/**
+ * validate_vulkan_backend() - verify working backend
+ *
+ * errp: error pointer
+ *
+ * If the system vulkan implementation is known to not work return
+ * false otherwise true.
+ */
+bool validate_vulkan_backend(Error **errp);
+
+#endif /* HOST_GPU_H */
diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index 11a7a85750..816eedf838 100644
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -32,6 +32,7 @@
 #include "qemu/module.h"
 #include "qapi/error.h"
 #include "qemu/error-report.h"
+#include "qemu/host-gpu.h"
 
 #define VIRTIO_GPU_VM_VERSION 1
 
@@ -1498,6 +1499,9 @@ void virtio_gpu_device_realize(DeviceState *qdev, Error **errp)
             error_setg(errp, "venus requires enabled blob and hostmem options");
             return;
         }
+        if (!validate_vulkan_backend(errp)) {
+            return;
+        }
     #else
         error_setg(errp, "old virglrenderer, venus unsupported");
         return;
diff --git a/stubs/host-gpu.c b/stubs/host-gpu.c
new file mode 100644
index 0000000000..7bf76ee4f6
--- /dev/null
+++ b/stubs/host-gpu.c
@@ -0,0 +1,17 @@
+/*
+ * Stub of utility functions to probe host GPU
+ *
+ * Copyright (c) 2025 Linaro Ltd
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/host-gpu.h"
+
+bool validate_vulkan_backend(Error **errp)
+{
+    error_setg(errp, "No vulkan library present");
+    return false;
+}
diff --git a/util/host-gpu.c b/util/host-gpu.c
new file mode 100644
index 0000000000..5e7bf2557c
--- /dev/null
+++ b/util/host-gpu.c
@@ -0,0 +1,102 @@
+/*
+ * Utility functions to probe host GPU
+ *
+ * Copyright (c) 2025 Linaro Ltd
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/host-gpu.h"
+
+#include <vulkan/vulkan.h>
+
+const char *extensions[] = {
+    /* needed to query the driver details */
+    "VK_KHR_get_physical_device_properties2",
+};
+
+/*
+ * Info for known broken drivers. Sadly driver version info tends to
+ * be in the driverInfo text field which is free form so tricky to
+ * parse.
+ */
+struct VkDriverBlockList {
+    VkDriverId id;
+    const char *reason;
+};
+
+struct VkDriverBlockList vulkan_blocklist[] = {
+    /* at least 535.183.01 is reported to SEGV in libnvidia-eglcore.so */
+    { VK_DRIVER_ID_NVIDIA_PROPRIETARY, "proprietary nVidia driver is broken" },
+};
+
+static bool is_driver_blocked(VkPhysicalDevice dev, Error **errp)
+{
+    VkPhysicalDeviceDriverProperties driverProperties = {
+        .sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_DRIVER_PROPERTIES,
+        .pNext = NULL
+    };
+    VkPhysicalDeviceProperties2 deviceProperties2 = {
+        .sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_PROPERTIES_2,
+        .pNext = &driverProperties
+    };
+    VkPhysicalDeviceProperties *deviceProperties = &deviceProperties2.properties;
+
+    vkGetPhysicalDeviceProperties2(dev, &deviceProperties2);
+
+    for (int i = 0; i < ARRAY_SIZE(vulkan_blocklist); i++) {
+        if (driverProperties.driverID == vulkan_blocklist[i].id) {
+            error_setg(errp, "Blocked GPU %s because %s",
+                       deviceProperties->deviceName,
+                       vulkan_blocklist[i].reason);
+            return true;
+        }
+    }
+
+    return false;
+}
+
+bool validate_vulkan_backend(Error **errp)
+{
+    VkInstanceCreateInfo instance_info = {
+        VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO,
+        NULL, /* pNext extension */
+        0,    /* VkInstanceCreateFlags */
+        NULL, /* Application Info */
+        0, NULL, /* no Enabled Layers */
+        ARRAY_SIZE(extensions), extensions, /* Extensions */
+    };
+
+    VkInstance inst;
+    VkResult res;
+
+    res = vkCreateInstance(&instance_info, NULL, &inst);
+
+    if ( res == VK_SUCCESS ) {
+        uint32_t count;
+        VkPhysicalDevice *devices;
+
+        /* Do the enumeration two-step */
+        vkEnumeratePhysicalDevices(inst, &count, NULL);
+        devices = g_new0(VkPhysicalDevice, count);
+        vkEnumeratePhysicalDevices(inst, &count, devices);
+
+        for (int i = 0; i  < count; i++) {
+            if (is_driver_blocked(devices[i], errp)) {
+                return false;
+            }
+        }
+    } else {
+        error_setg(errp, "Could not initialise a Vulkan instance");
+        return false;
+    }
+
+    /*
+     * It would be nice to g_autofree the instance, but returning
+     * false will abort start-up anyway.
+     */
+    vkDestroyInstance(inst, NULL);
+    return true;
+}
diff --git a/stubs/meson.build b/stubs/meson.build
index b0fee37e05..c18501aa6d 100644
--- a/stubs/meson.build
+++ b/stubs/meson.build
@@ -89,3 +89,7 @@ if have_system or have_user
   stub_ss.add(files('hotplug-stubs.c'))
   stub_ss.add(files('sysbus.c'))
 endif
+
+if not vulkan.found()
+  stubs_ss.add(files('host-gpu.c'))
+endif
diff --git a/tests/functional/test_aarch64_virt_gpu.py b/tests/functional/test_aarch64_virt_gpu.py
index 7a8471d1ca..9a0e694049 100755
--- a/tests/functional/test_aarch64_virt_gpu.py
+++ b/tests/functional/test_aarch64_virt_gpu.py
@@ -79,6 +79,8 @@ def _run_virt_gpu_test(self, gpu_device,  weston_cmd, weston_pattern):
                 self.skipTest("Can't access host DRM render node")
             elif "'type' does not accept value 'egl-headless'" in excp.output:
                 self.skipTest("egl-headless support is not available")
+            elif "Blocked GPU" in excp.output:
+                self.skipTest("GPU is in block list")
             else:
                 self.log.info(f"unhandled launch failure: {excp.output}")
                 raise excp
diff --git a/util/meson.build b/util/meson.build
index 780b5977a8..7c6cc36e07 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -132,3 +132,5 @@ elif cpu in ['ppc', 'ppc64']
 elif cpu in ['riscv32', 'riscv64']
   util_ss.add(files('cpuinfo-riscv.c'))
 endif
+
+util_ss.add(when: vulkan, if_true: files('host-gpu.c'))
-- 
2.39.5

On 21/2/25 17:01, Alex Bennée wrote:
> While running the new GPU tests it was noted that the proprietary
> nVidia driver barfed when run under the sanitiser:
> 
>    2025-02-20 11:13:08,226: [11:13:07.782] Output 'headless' attempts
>    EOTF mode SDR and colorimetry mode default.
>    2025-02-20 11:13:08,227: [11:13:07.784] Output 'headless' using color
>    profile: stock sRGB color profile
> 
>    and that's the last thing it outputs.
> 
>    The sanitizer reports that when the framework sends the SIGTERM
>    because of the timeout we get a write to a NULL pointer (but
>    interesting not this time in an atexit callback):
> 
>    UndefinedBehaviorSanitizer:DEADLYSIGNAL
>    ==471863==ERROR: UndefinedBehaviorSanitizer: SEGV on unknown address
>    0x000000000000 (pc 0x7a18ceaafe80 bp 0x000000000000 sp 0x7ffe8e3ff6d0
>    T471863)
>    ==471863==The signal is caused by a WRITE memory access.
>    ==471863==Hint: address points to the zero page.
>        #0 0x7a18ceaafe80
>    (/lib/x86_64-linux-gnu/libnvidia-eglcore.so.535.183.01+0x16afe80)
>    (BuildId: 24b0d0b90369112e3de888a93eb8d7e00304a6db)
>        #1 0x7a18ce9e72c0
>    (/lib/x86_64-linux-gnu/libnvidia-eglcore.so.535.183.01+0x15e72c0)
>    (BuildId: 24b0d0b90369112e3de888a93eb8d7e00304a6db)
>        #2 0x7a18ce9f11bb
>    (/lib/x86_64-linux-gnu/libnvidia-eglcore.so.535.183.01+0x15f11bb)
>    (BuildId: 24b0d0b90369112e3de888a93eb8d7e00304a6db)
>        #3 0x7a18ce6dc9d1
>    (/lib/x86_64-linux-gnu/libnvidia-eglcore.so.535.183.01+0x12dc9d1)
>    (BuildId: 24b0d0b90369112e3de888a93eb8d7e00304a6db)
>        #4 0x7a18e7d15326 in vrend_renderer_create_fence
>    /usr/src/virglrenderer-1.0.0-1ubuntu2/obj-x86_64-linux-gnu/../src/vrend_renderer.c:10883:26
>        #5 0x55bfb6621871 in virtio_gpu_virgl_process_cmd
> 
> The #dri-devel channel confirmed:
> 
>    <digetx> stsquad: nv driver is known to not work with venus, don't use
>        it for testing
> 
> So lets implement a blocklist to stop users starting a known bad
> setup.
> 
> Reported-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> Cc: Dmitry Osipenko <dmitry.osipenko@collabora.com>
> ---
>   meson.build                               |   4 +
>   include/qemu/host-gpu.h                   |  23 +++++
>   hw/display/virtio-gpu.c                   |   4 +
>   stubs/host-gpu.c                          |  17 ++++
>   util/host-gpu.c                           | 102 ++++++++++++++++++++++
>   stubs/meson.build                         |   4 +
>   tests/functional/test_aarch64_virt_gpu.py |   2 +
>   util/meson.build                          |   2 +
>   8 files changed, 158 insertions(+)
>   create mode 100644 include/qemu/host-gpu.h
>   create mode 100644 stubs/host-gpu.c
>   create mode 100644 util/host-gpu.c
> 
> diff --git a/meson.build b/meson.build
> index 4588bfd864..8f4a431445 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -1373,12 +1373,16 @@ if not get_option('qatzip').auto() or have_system
>   endif
>   
>   virgl = not_found
> +vulkan = not_found
>   
>   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'))
> +  vulkan = dependency('vulkan',
> +                      method: 'pkg-config',
> +                      required: get_option('virglrenderer'))
>   endif
>   rutabaga = not_found
>   if not get_option('rutabaga_gfx').auto() or have_system or have_vhost_user_gpu
> diff --git a/include/qemu/host-gpu.h b/include/qemu/host-gpu.h
> new file mode 100644
> index 0000000000..45053c2f77
> --- /dev/null
> +++ b/include/qemu/host-gpu.h
> @@ -0,0 +1,23 @@
> +/*
> + * Utility functions to probe host GPU
> + *
> + * Copyright (c) 2025 Linaro Ltd
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +#ifndef HOST_GPU_H
> +#define HOST_GPU_H
> +
> +#include "qapi/error.h"
> +
> +/**
> + * validate_vulkan_backend() - verify working backend
> + *
> + * errp: error pointer
> + *
> + * If the system vulkan implementation is known to not work return
> + * false otherwise true.
> + */
> +bool validate_vulkan_backend(Error **errp);
> +
> +#endif /* HOST_GPU_H */
> diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
> index 11a7a85750..816eedf838 100644
> --- a/hw/display/virtio-gpu.c
> +++ b/hw/display/virtio-gpu.c
> @@ -32,6 +32,7 @@
>   #include "qemu/module.h"
>   #include "qapi/error.h"
>   #include "qemu/error-report.h"
> +#include "qemu/host-gpu.h"
>   
>   #define VIRTIO_GPU_VM_VERSION 1
>   
> @@ -1498,6 +1499,9 @@ void virtio_gpu_device_realize(DeviceState *qdev, Error **errp)
>               error_setg(errp, "venus requires enabled blob and hostmem options");
>               return;
>           }

Why don't we check VIRTIO_GPU_FLAG_VENUS_ENABLED in 
virtio_gpu_gl_device_realize()?

> +        if (!validate_vulkan_backend(errp)) {
> +            return;
> +        }
>       #else
>           error_setg(errp, "old virglrenderer, venus unsupported");
>           return;
> diff --git a/stubs/host-gpu.c b/stubs/host-gpu.c
> new file mode 100644
> index 0000000000..7bf76ee4f6
> --- /dev/null
> +++ b/stubs/host-gpu.c
> @@ -0,0 +1,17 @@
> +/*
> + * Stub of utility functions to probe host GPU
> + *
> + * Copyright (c) 2025 Linaro Ltd
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qapi/error.h"
> +#include "qemu/host-gpu.h"
> +
> +bool validate_vulkan_backend(Error **errp)
> +{
> +    error_setg(errp, "No vulkan library present");
> +    return false;

Do we really fail virtio_gpu_device_realize() in this case?

> +}
> diff --git a/util/host-gpu.c b/util/host-gpu.c
> new file mode 100644
> index 0000000000..5e7bf2557c
> --- /dev/null
> +++ b/util/host-gpu.c
> @@ -0,0 +1,102 @@
> +/*
> + * Utility functions to probe host GPU
> + *
> + * Copyright (c) 2025 Linaro Ltd
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qapi/error.h"
> +#include "qemu/host-gpu.h"
> +
> +#include <vulkan/vulkan.h>
> +

static

> +const char *extensions[] = {
> +    /* needed to query the driver details */
> +    "VK_KHR_get_physical_device_properties2",
> +};
> +
> +/*
> + * Info for known broken drivers. Sadly driver version info tends to
> + * be in the driverInfo text field which is free form so tricky to
> + * parse.
> + */
> +struct VkDriverBlockList {
> +    VkDriverId id;
> +    const char *reason;
> +};
> +

static const

> +struct VkDriverBlockList vulkan_blocklist[] = {
> +    /* at least 535.183.01 is reported to SEGV in libnvidia-eglcore.so */
> +    { VK_DRIVER_ID_NVIDIA_PROPRIETARY, "proprietary nVidia driver is broken" },
> +};
> +
> +static bool is_driver_blocked(VkPhysicalDevice dev, Error **errp)
> +{
> +    VkPhysicalDeviceDriverProperties driverProperties = {
> +        .sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_DRIVER_PROPERTIES,
> +        .pNext = NULL
> +    };
> +    VkPhysicalDeviceProperties2 deviceProperties2 = {
> +        .sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_PROPERTIES_2,
> +        .pNext = &driverProperties
> +    };
> +    VkPhysicalDeviceProperties *deviceProperties = &deviceProperties2.properties;
> +
> +    vkGetPhysicalDeviceProperties2(dev, &deviceProperties2);
> +
> +    for (int i = 0; i < ARRAY_SIZE(vulkan_blocklist); i++) {
> +        if (driverProperties.driverID == vulkan_blocklist[i].id) {
> +            error_setg(errp, "Blocked GPU %s because %s",
> +                       deviceProperties->deviceName,
> +                       vulkan_blocklist[i].reason);
> +            return true;
> +        }
> +    }
> +
> +    return false;
> +}
> +
> +bool validate_vulkan_backend(Error **errp)
> +{

static const

> +    VkInstanceCreateInfo instance_info = {
> +        VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO,
> +        NULL, /* pNext extension */
> +        0,    /* VkInstanceCreateFlags */
> +        NULL, /* Application Info */
> +        0, NULL, /* no Enabled Layers */
> +        ARRAY_SIZE(extensions), extensions, /* Extensions */
> +    };
> +
> +    VkInstance inst;
> +    VkResult res;
> +
> +    res = vkCreateInstance(&instance_info, NULL, &inst);
> +
> +    if ( res == VK_SUCCESS ) {
> +        uint32_t count;

g_autofree

> +        VkPhysicalDevice *devices;
> +
> +        /* Do the enumeration two-step */
> +        vkEnumeratePhysicalDevices(inst, &count, NULL);
> +        devices = g_new0(VkPhysicalDevice, count);
> +        vkEnumeratePhysicalDevices(inst, &count, devices);
> +
> +        for (int i = 0; i  < count; i++) {
> +            if (is_driver_blocked(devices[i], errp)) {
> +                return false;
> +            }
> +        }
> +    } else {
> +        error_setg(errp, "Could not initialise a Vulkan instance");
> +        return false;
> +    }
> +
> +    /*
> +     * It would be nice to g_autofree the instance, but returning
> +     * false will abort start-up anyway.
> +     */
> +    vkDestroyInstance(inst, NULL);
> +    return true;
> +}
> diff --git a/stubs/meson.build b/stubs/meson.build
> index b0fee37e05..c18501aa6d 100644
> --- a/stubs/meson.build
> +++ b/stubs/meson.build
> @@ -89,3 +89,7 @@ if have_system or have_user
>     stub_ss.add(files('hotplug-stubs.c'))
>     stub_ss.add(files('sysbus.c'))
>   endif
> +
> +if not vulkan.found()
> +  stubs_ss.add(files('host-gpu.c'))
> +endif
> diff --git a/tests/functional/test_aarch64_virt_gpu.py b/tests/functional/test_aarch64_virt_gpu.py
> index 7a8471d1ca..9a0e694049 100755
> --- a/tests/functional/test_aarch64_virt_gpu.py
> +++ b/tests/functional/test_aarch64_virt_gpu.py
> @@ -79,6 +79,8 @@ def _run_virt_gpu_test(self, gpu_device,  weston_cmd, weston_pattern):
>                   self.skipTest("Can't access host DRM render node")
>               elif "'type' does not accept value 'egl-headless'" in excp.output:
>                   self.skipTest("egl-headless support is not available")
> +            elif "Blocked GPU" in excp.output:
> +                self.skipTest("GPU is in block list")
>               else:
>                   self.log.info(f"unhandled launch failure: {excp.output}")
>                   raise excp
> diff --git a/util/meson.build b/util/meson.build
> index 780b5977a8..7c6cc36e07 100644
> --- a/util/meson.build
> +++ b/util/meson.build
> @@ -132,3 +132,5 @@ elif cpu in ['ppc', 'ppc64']
>   elif cpu in ['riscv32', 'riscv64']
>     util_ss.add(files('cpuinfo-riscv.c'))
>   endif
> +
> +util_ss.add(when: vulkan, if_true: files('host-gpu.c'))