Potentially false positive VUID-VkVertexInputBindingDivisorDescription-divisor-01870

[TheMostDiligent]

Environment:

• OS: Windows 10
• GPU and driver version: NVIDIA GeForce RTX 2070 Super
• SDK or header version if building from repo: 1.4.304

Describe the Issue

In the latest SDK version, we started observing the following error:

Vulkan debug message (validation): VUID-VkVertexInputBindingDivisorDescription-divisor-01870
                 Validation Error: [ VUID-VkVertexInputBindingDivisorDescription-divisor-01870 ] | MessageID = 0xf7312938 | vkCreateGraphicsPipelines(): pCreateInfos[0].pVertexInputState->pNext<VkVertexInputBindingDivisorDescription>.pVertexBindingDivisors[0].divisor (2) exceeds device maxVertexAttribDivisor (0).
The Vulkan spec states: divisor must be a value between 0 and VkPhysicalDeviceVertexAttributeDivisorProperties::maxVertexAttribDivisor, inclusive (https://vulkan.lunarg.com/doc/view/1.4.304.0/windows/1.4-extensions/vkspec.html#VUID-VkVertexInputBindingDivisorDescription-divisor-01870)

We don't enable the VK_KHR_vertex_attribute_divisor extension, but do enable the VK_EXT_vertex_attribute_divisor, and there was no error in prior versions.

Expected behavior

I believe there should be no validation error if VK_EXT_vertex_attribute_divisor is enabled.

[spencer-lunarg]

We have a test (PositiveVertexInput.VertexAttributeDivisorFirstInstance https://github.com/KhronosGroup/Vulkan-ValidationLayers/blob/main/tests/unit/vertex_input_positive.cpp#L563C7-L605)

when I look at it, I see it correctly using VkPhysicalDeviceVertexAttributeDivisorPropertiesEXT to get the value for maxVertexAttribDivisor (

Vulkan-ValidationLayers/layers/state_tracker/state_tracker.cpp

Lines 995 to 998 in b18ee98

	if (dev_ext.vk_ext_vertex_attribute_divisor) {
	VkPhysicalDeviceVertexAttributeDivisorPropertiesEXT vtx_attrib_divisor_props_ext;
	GetPhysicalDeviceExtProperties(physical_device, dev_ext.vk_ext_vertex_attribute_divisor, &vtx_attrib_divisor_props_ext);
	phys_dev_props_core14.maxVertexAttribDivisor = vtx_attrib_divisor_props_ext.maxVertexAttribDivisor;

)

So I am not quite sure what is happening our you device that you are getting a value of zero

[artem-lunarg]

This part of the specification might explain zero divisor values:

The maximum value of divisor is implementation-dependent and can be queried using VkPhysicalDeviceVertexAttributeDivisorPropertiesEXT::maxVertexAttribDivisor. A value of 0 can be used for the divisor if the vertexAttributeInstanceRateZeroDivisor feature is enabled. In this case, the same vertex attribute will be applied to all instances.

[spencer-lunarg]

so here is saying in the spec that VkVertexInputBindingDescription2EXT::divisor can be zero

The property limit needs to be 2^16 - 1 and no one exposes a value of zero https://www.vulkan.gpuinfo.org/displayextensionproperty.php?extensionname=VK_EXT_vertex_attribute_divisor&extensionproperty=maxVertexAttribDivisor&platform=all

The issue is how we are tracking the EXT and KHR (and now 1.4 promoted) version of that limit, and it should be working as I can't reproduce the issue with any combination of the Test ICD and/or devices I have on me

[TheMostDiligent]

The value of maxVertexAttribDivisor returned in VkPhysicalDeviceVertexAttributeDivisorPropertiesEXT is 4294967295

[spencer-lunarg]

@TheMostDiligent one more question, is your app a 1.4 app now?

[TheMostDiligent]

It is 1.3: Using physical device 'NVIDIA GeForce RTX 2070 Super', API version 1.3.289, Driver version 54.144.0.