[PATCH v7 4/4] winevulkan: Implement VK_KHR_external_memory_win32 for images.

[Zebediah Figura (she/her)]

On 6/5/21 10:53 AM, Georg Lehmann wrote:
> 
> 
> On 05.06.21 01:23, Zebediah Figura (she/her) wrote:
>> On 6/1/21 10:17 AM, Derek Lesho wrote:
>>>
>>> On 5/31/21 10:43 AM, Zebediah Figura (she/her) wrote:
>>>> On 5/26/21 9:21 AM, Derek Lesho wrote:
>>>>> On 5/25/21 10:07 PM, Zebediah Figura (she/her) wrote:
>>>>>
>>>>>>
>>>>>>>>
>>>>>>>> * Shared resources in d3d9-11, when using the OpenGL backend
>>>>>>>
>>>>>>> As mentioned, the EXT_external_objects extension exists, (
>>>>>>> https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_external_objects.txt
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> ), which accepts and produces file descriptors compatible with the
>>>>>>> ones
>>>>>>> Vulkan produces and accepts.  The interactions here seem to be well
>>>>>>> defined.
>>>>>>
>>>>>> According to my reading, neither GL_EXT_external_objects nor
>>>>>> GL_EXT_external_objects_fd provide for export of an object from an
>>>>>> OpenGL context; they only allow importing objects created by Vulkan.
>>>>>
>>>>> Yeah, from what I can see, openGL has no standard way to share memory
>>>>> across processes without the use of this extension and Vulkan. I
>>>>> suspect this would be difficult due to all the user mode driver code
>>>>> protecting against invalid use of resources.  I think the most
>>>>> reasonable path forward is to create a Vulkan dummy object in wined3d,
>>>>> then import it into GL.  Of course, this would make shared resources
>>>>> unsupported for old GPUs and systems that don't support Vulkan, but the
>>>>> API is half a decade old at this point, and only GPUs from almost a
>>>>> decade ago don't support it.
>>>>
>>>> There is no free software NVidia Vulkan driver, which is a rather
>>>> glaring hole. There also exist cards released as recently as 2014 that
>>>> don't support Vulkan. And in general, although it's sometimes
>>>> convenient for the implementer to require the latest hardware, it's a
>>>> rather mean thing to do to users.
>>>>
>>>> Keep in mind that we need Direct3D shared resources for bug 44985,
>>>> which affects a very long list of applications.
>>>>
>>>> Now, with that in mind, two options I immediately see are:
>>>>
>>>> * Create all contexts as shared. It's not clear to me whether this has
>>>> negative consequences, however. It's also not clear to me whether this
>>>> can be done across processes.
>>>>
>>>> * Try to introduce an OpenGL extension that allows exporting file
>>>> descriptors.
>>>
>>> The second option definitely sounds better, as with the first you're
>>> still limited to in-process sharing, if my understanding is correct.
>>> Additionally, the case where you're using wined3d's d3d9 for example,
>>> create a shared resource, then try importing it into DXVK for d3d10/11,
>>> would only work with the second solution from what I can see.  I imagine
>>> that we could cover the vast majority of users by implementing the
>>> "vulkan helper" path that I suggested before, and quite easily
>>> transition into using an extension if/when needed.
>>>>
>>>>>
>>>>> Alternatively we could get try to use platform-specific buffer sharing
>>>>> APIs like EGLStreams or GBM, or just support in-process shared
>>>>> resources
>>>>> through the eglCreateContext API, which allows the creation of "shared
>>>>> contexts", in which the GPU resources are shared.
>>>>>
>>>>>>>>
>>>>>>>> * Shared resources between d3d9-12 devices, when using wined3d or
>>>>>>>> libvkd3d on Windows
>>>>>>> Putting aside how rare and questionable of a use-case this must be, I
>>>>>>> don't think this concerns any of my patches.  My future patches would
>>>>>>> provide a way for translation layers on wine to store metadata
>>>>>>> alongside
>>>>>>> the host handlers, it doesn't have any correspondence to Windows.  If
>>>>>>> you really wanted to (why?), you could probably create your own
>>>>>>> backing
>>>>>>> storage in a shared memory object and accept the caveats that come
>>>>>>> along
>>>>>>> with that.
>>>>>>
>>>>>> I suspect those of us who have worked with Direct3D for multiple
>>>>>> decades would take issue with "rare and questionable", but regardless,
>>>>>> part of the point here is to ask: *is* it possible to use a native set
>>>>>> of APIs, like perhaps the D3DKMT*() functions from gdi32, to share
>>>>>> resources? I.e. should the implementation live in gdi32 instead of
>>>>>> winevulkan/opengl32/wined3d? Just from a quick scan I see several
>>>>>> which look like the ones we want, and they're even documented.
>>>>>
>>>>> Could you link these APIs so I can look further into them?  I conferred
>>>>> with Josh and he didn't find anything.
>>>>
>>>> Sure, here are some APIs that look promising, and are documented:
>>>>
>>>> * D3DKMTCreateAllocation()
>>>> * D3DKMTOpenResource()
>>>> * D3DKMTOpenResourceFromNtHandle()
>>>> * D3DKMTQueryResourceInfo()
>>>> * D3DKMTQueryResourceInfoFromNtHandle()
>>>
>>> So I discussed this with Josh and Georg, and the problems with these
>>> APIs for our usecases are
>>>
>>> 1) In order to interface with any of these APIs, you need a KMT device
>>> handle.  This roughly corresponds to a Vulkan device object or OpenGL
>>> context, but according to Josh they don't have to map 1:1.
>>
>> It's a bit unfortunate that this discussion still isn't happening in a
>> public place,
> 
> I'm sorry, but I get very annoyed by comments like these when at the
> same time most of wine's development happens behind closed doors inside
> codeweavers. It's not like wine-devel is used for architecture
> discussion or anything like that, no it's just patches and sometimes
> reviews. And somehow you now criticize me (well, us, but I can only
> speak for myself) for not communicating only via wine-devel? I send
> patches via wine-devel and I review patches on wine-devel, just like
> everyone else.

So for what it's worth—and I'm not speaking for CodeWeavers here—I don't 
think "most of wine's development" happens anywhere at all. Large-scale 
architectural decisions aren't really discussed often. But if they are, 
they're usually discussed on wine-devel, Bugzilla, #winehackers, 
WineConf, or privately via e-mail.

The last is a bit unfortunate, but it's also not specific to 
CodeWeavers—I can think of two people with whom I'm currently engaged in 
architectural discussion, and only one of those is a CodeWeavers employee.

And I get the impression that CodeWeavers, or at least its employees, 
try to encourage discussing things openly where possible (not 
constrained by NDA, etc.) And when it comes to patches, we *are* 
encouraged and even expected to explain ourselves from the point of view 
of an outsider; see [2] for example.

By contrast, when I tried to get the VKx community to discuss things 
openly, it was made quickly clear to me that they were not interested in 
using official Wine channels or coöperating with upstream Wine 
developers, but rather wanted Wine developers to use their channels (and 
their development practices, and their forks, etc...)

So I'm being more than a little passive-aggressive, and I'm sorry for 
that. But I also really do want to point out that the people most 
involved in Direct3D/GPU work in Wine have not been involved in this 
discussion at all, and before some point in this reply chain they/we had 
no idea it was even happening. And as a result when a submitter acts 
like some fact is obvious, to the point of not explaining it at all, 
just because they discussed it privately with someone else, it's more 
than a little frustrating.

The bottom line is: it's really not clear that this patch set is taking 
the right approach. Not "it's taking the wrong approach", but it's 
really not clear that it's taking the right one. And most of that 
unclarity comes from a lack of public discussion, or even private 
discussion with the Wine contributors involved in Direct3D/GPU APIs.

[2] https://www.winehq.org/pipermail/wine-devel/2019-June/147452.html

> 
> Anyway, back to the actual discussion.
> 
>> but anyway, we already use KMT device handles; see e.g.
>> wined3d_output_init().
>>
>>>
>>> 2) There's no way to update the private runtime data once the resource
>>> is created.  In the current and simpler flow, the host graphics API will
>>> create the object, and the translation layer will then attach the needed
>>> private data.  For this to work on windows, the translation layers would
>>> have to agree on some way to get Vulkan to set the desired private data,
>>> and that's assuming that no Windows drivers already use this for their
>>> own purposes.
>>
>> Part of my point here is that, ideally, we shouldn't need to. Presumably
>> if a Win32 application creates a Vulkan resource and tries to import it
>> into Direct3D, the Microsoft Direct3D runtime will call such functions
>> to get information from it. It seems at least plausible that we could do
>> the same.
>>
> 
> You can *not* import a Vulkan resource into Direct3D.
> The vulkan specification [1] says:
> 
> VK_EXTERNAL_MEMORY_HANDLE_TYPE_OPAQUE_WIN32_BIT specifies an NT handle
> that has only limited valid usage outside of Vulkan and other compatible
> APIs. It must be compatible with the functions DuplicateHandle,
> CloseHandle, CompareObjectHandles, GetHandleInformation, and
> SetHandleInformation.
> 
> VK_EXTERNAL_MEMORY_HANDLE_TYPE_OPAQUE_WIN32_KMT_BIT specifies a global
> share handle that has only limited valid usage outside of Vulkan and
> other compatible APIs. It is not compatible with any native APIs.
> 
> 
> Note the "outside of Vulkan and other compatible APIs" part, which to my
> knowledge means Vulkan and the OpenGL import extension.
> 
> These handles also can *not* include the info needed for e.g. D3D11
> because they are memory objects, not image/buffer objects. If you bind
> e.g. a 2D image to the memory, you don't know the width, the height or
> the format on import because it's *just* memory.
> 
> 
> [1]
> https://www.khronos.org/registry/vulkan/specs/1.2-extensions/html/vkspec.html#VkExternalMemoryHandleTypeFlagBits

That may be true for the OPAQUE bit, but that's not the only bit. E.g. 
as far as I can tell from my reading of the Vulkan specification, 
VK_EXTERNAL_MEMORY_HANDLE_TYPE_D3D11_TEXTURE_BIT isn't forbidden from 
being specified in VkExportMemoryAllocateInfo, and the language even 
seems to "explicitly imply", as it were, that it's allowed. See the 
Vulkan 1.2 specification § 11.2.4 in particular.

Granted, the documentation for 
VK_EXTERNAL_MEMORY_HANDLE_TYPE_D3D11_TEXTURE_BIT itself (no section 
number, I guess?) says "VK_EXTERNAL_MEMORY_HANDLE_TYPE_D3D11_TEXTURE_BIT 
specifies an NT handle returned by IDXGIResource1::CreateSharedHandle 
referring to a Direct3D 10 or 11 texture resource," which is a bit 
unclear. I haven't actually tested whether it works in practice, either, 
although of course even if it doesn't now it might in the future.

> 
>> There may be any number of foreseen and unforeseen pitfalls along the
>> way, which could prevent this approach from working at all, but my point
>> is, it's worth testing—and I mean actually testing, not just theorizing
>> about what we can and can't do. And even if it doesn't work on Windows,
>> it still bears asking whether we should use these APIs for Wine.
>>
> 
> Sorry, I just fail to see what's the point of using D3DKMT is. Unless I
> miss some detail, this won't make any of this work on windows, and if
> you somehow found a way to do make it work (which I think does not
> exists), you would violate the vulkan specification and rely on
> undefined behavior.
> 
> And then that makes me ask the question: Why should we use this API in
> Wine, what's the benefit?
> 
>> And, if the answer ends up being yes, we should start there when
>> implementing them. It's far better to plan out the final architecture
>> and implement things accordingly, when possible, rather than to start
>> implementing things one way and then have to reorganize them later.
>>
> 
> This patch set is 99% setting up winevulkan for translation of the Win32
> external memory extension to the Unix fd external memory extension. You
> have to do that either way, and it won't change regardless of how
> ultimately get your NT handle for a Unix fd. It's also just vulkan <->
> vulkan sharing (and I guess OpenGl if someone wants to implement the
> import extension in Wine), it does *not* relate to Direct3D at all.

I was hoping this would be evident by now, but Vulkan does not exist in 
a vacuum, as far as Wine is concerned. Neither does 
VK_KHR_external_memory_win32. Vulkan can at the very least import 
resources from Direct3D, and export resources to OpenGL. Those in turn 
have more interop and intra-op (as it were) capabilities. And even if 
there were no interop, it's not unlikely that we'd want to consider how 
to make intra-op work in a generic way. Even the initial version of this 
patch set was submitted with that in mind.

Yes, it's a hard problem, and a lot of the hard things about it come 
from making *all* of the interop and intra-op work at once. It would be 
much easier if we could just submit this patch series and claim we're 
done, if only for now. But Wine doesn't really follow this development 
model: we much prefer to get the design right from the beginning, no 
matter how long it takes, so that we don't have to fix it much later, 
when it'll be much more painful.

>>>>> Also, if there are APIs which allow registering resources retrieved
>>>>> from
>>>>> Vulkan with certain metadata, winevulkan would still have roughly the
>>>>> same role.  The only difference would be in the translation layers,
>>>>> where instead of using IOCTLs on the HANDLEs to shared resources they
>>>>> have to get/set metadata, they would use some D3DKMT API you've found.
>>>>
>>>> Well, broadly, yes, but it changes the way that this patch series
>>>> should be structured and sent.
>>>
>>> This patch's main focus is just setting up the winevulkan infrastructure
>>> for shared resources.  If we decide to still use D3DKMT for one reason
>>> or another, the only change to the current patchset would be to the tiny
>>> function create_gpu_resource to get the HANDLE through KMT APIs instead
>>> of wine_server_fd_to_handle.
>>>>
>>>>>
>>>>>>
>>>>>>>>
>>>>>>>> I note your tests also don't seem very interesting; they only share
>>>>>>>> objects within the same device. Sharing objects across multiple
>>>>>>>> devices, and across multiple processes, strikes me as more
>>>>>>>> interesting.
>>>>>>>
>>>>>>> In my opinion, given that the semantics for VK_KHR_external_memory_fd
>>>>>>> and VK_KHR_external_memory_win32 are so similar, I wonder how
>>>>>>> relevant
>>>>>>> such tests would be, it seems like the kind of thing the Vulkan CTS
>>>>>>> should add for testing drivers.
>>>>>>>
>>>>>>> I think the tests should be more for testing the properties of the
>>>>>>> HANDLEs we get, as this is what we are implementing ourselves.
>>>>>>> Maybe I
>>>>>>> should add more tests looking at the locations of the named
>>>>>>> objects in
>>>>>>> the NT directory, or tests relating to types of the objects and their
>>>>>>> access permissions.
>>>>>>>
>>>>>>>
>>>>>>
>>>>>> The point is more of a smoke test, because it's easy to get it wrong,
>>>>>> and not too hard to verify that we got it right.
>>>>>>
>>>>>> It'd also be nice to demonstrate what the behaviour of KMT handles is
>>>>>> across processes.
>>>>>>
>>>>> An in-process intra-device test tests the same amount of winevulkan
>>>>> behavior as a cross-process inter-device test.  All the implementation
>>>>> details of cross-process and cross-device sharing are handled on the
>>>>> host and through wineserver's well established HANDLE<->FD mapping.
>>>>>
>>>>
>>>> Is it really that hard just to add a test?
>>>
>>>
>>> No, but I just think it would be a waste of time and lines of code,
>>> especially for testing cross-process when it makes no difference which
>>> processes the two devices are made on.  Given that you said "a test", do
>>> you mean you think it would be fine if I were to just add a test testing
>>> shared resources across devices in the same process?
>>>
>>>
>>
>> It's not that hard to write a cross-process test; see kernel32:pipe for
>> an example. We have infrastructure for it.
>>
>> For a rationale: even if the code path isn't significantly different
>> now, it might be in the future, especially when this patch series seems
>> far from maturity. And, like I said, we have no tests for KMT handles
>> across processes.
>>
> 
> FWIW since this patch set only implements NT handles, it might be better
> to just not add any KMT handle tests in this patch set at all.
>