Re: [RFC PATCH 0/4] DirectX on Linux
On Tue, May 19, 2020 at 2:36 PM Sasha Levin wrote: > > Hi Daniel, > > On Tue, May 19, 2020 at 09:21:15PM +0200, Daniel Vetter wrote: > >Hi Sasha > > > >So obviously great that Microsoft is trying to upstream all this, and > >very much welcome and all that. > > > >But I guess there's a bunch of rather fundamental issues before we > >look into any kind of code details. And that might make this quite a > >hard sell for upstream to drivers/gpu subsystem: > > Let me preface my answers by saying that speaking personally I very much > dislike that the userspace is closed and wish I could do something about > it. > > >- From the blog it sounds like the userspace is all closed. That > >includes the hw specific part and compiler chunks, all stuff we've > >generally expected to be able to look in the past for any kind of > >other driver. It's event documented here: > > > >https://dri.freedesktop.org/docs/drm/gpu/drm-uapi.html#open-source-userspace-requirements > > > >What's your plan here? > > Let me answer with a (genuine) question: does this driver have anything > to do with DRM even after we enable graphics on it? I'm still trying to > figure it out. > > There is an open source DX12 Galluim driver (that lives here: > https://gitlab.freedesktop.org/kusma/mesa/-/tree/msclc-d3d12) with open > source compiler and so on. > > The plan is for Microsoft to provide shims to allow the existing Linux > userspace interact with DX12; I'll explain below why we had to pipe DX12 > all the way into the Linux guest, but this is *not* to introduce DX12 > into the Linux world as competition. There is no intent for anyone in > the Linux world to start coding for the DX12 API. If that really is the case why is microsoft recommending developers to break compatibility with native Linux and use the DX12 API's here: https://devblogs.microsoft.com/directx/in-the-works-opencl-and-opengl-mapping-layers-to-directx/ Quote: "Make it easier for developers to port their apps to D3D12. For developers looking to move from older OpenCL and OpenGL API versions to D3D12, the open source mapping layers will provide helpful example code on how to use the D3D12 Translation Layer library." If developers of applications that use OpenCL and OpenGL API's were to follow this advice and transition to D3D12 their applications would no longer work on Linux systems unless using WSL2. Is Microsoft planning on creating a D3D12/DirectML frontend that doesn't depend on WSL2? > > This is why I'm not sure whether this touches DRM on the Linux side of > things. Nothing is actually rendered on Linux but rather piped to > Windows to be done there. > > >btw since the main goal here (at least at first) seems to be get > >compute and ML going the official work-around here is to relabel your > >driver as an accelerator driver (just sed -e s/vGPU/vaccel/ over the > >entire thing or so) and then Olof and Greg will take it into > >drivers/accel ... > > This submission is not a case of "we want it upstream NOW" but rather > "let's work together to figure out how to do it right" :) > > I thought about placing this driver in drivers/hyper-v/ given that it's > basically just a pipe between the host and the guest. There is no fancy > logic in this drivers. Maybe the right place is indeed drivers/accel or > drivers/hyper-v but I'd love if we agree on that rather than doing that > as a workaround and 6 months down the road enabling graphics. > > >- Next up (but that's not really a surprise for a fresh vendor driver) > >at a more technical level, this seems to reinvent the world, from > >device enumeration (why is this not exposed as /dev/dri/card0 so it > >better integrates with existing linux desktop stuff, in case that > >becomes a goal ever) down to reinvented kref_put_mutex (and please > >look at drm_device->struct_mutex for an example of how bad of a > >nightmare that locking pattern is and how many years it took us to > >untangle that one. > > I'd maybe note that neither of us here at Microsoft is an expert in the > Linux DRM world. Stuff might have been done in a certain way because we > didn't know better. > > >- Why DX12 on linux? Looking at this feels like classic divide and > > There is a single usecase for this: WSL2 developer who wants to run > machine learning on his GPU. The developer is working on his laptop, > which is running Windows and that laptop has a single GPU that Windows > is using. > > Since the GPU is being used by Windows, we can't assign it directly to > the Linux guest, but instead we can use GPU Partitioning to give the > guest access to the GPU. This means that the guest needs to be able to > "speak" DX12, which is why we pulled DX12 into Linux. > > >conquer (or well triple E from the 90s), we have vk, we have > >drm_syncobj, we have an entire ecosystem of winsys layers that work > >across vendors. Is the plan here that we get a dx12 driver for other > >hw mesa drivers from you guys, so this is all consistent and we have a > >nice linux platform? How
Re: [RFC PATCH 0/4] DirectX on Linux
On Tue, Jun 16, 2020 at 04:41:22PM +0200, Pavel Machek wrote: On Tue 2020-06-16 09:28:19, Sasha Levin wrote: On Tue, Jun 16, 2020 at 12:51:13PM +0200, Pavel Machek wrote: > Hi! > > > > The driver creates the /dev/dxg device, which can be opened by user mode > > > application and handles their ioctls. The IOCTL interface to the driver > > > is defined in dxgkmthk.h (Dxgkrnl Graphics Port Driver ioctl > > > definitions). The interface matches the D3DKMT interface on Windows. > > > Ioctls are implemented in ioctl.c. > > > > Echoing what others said, you're not making a DRM driver. The driver should live outside > > of the DRM code. > > > > Actually, this sounds to me like "this should not be merged into linux kernel". I mean, > we already have DRM API on Linux. We don't want another one, do we? This driver doesn't have any display functionality. Graphics cards without displays connected are quite common. I may be wrong, but I believe we normally handle them using DRM... This is more similar to the accelerators that live in drivers/misc/ right now. > And at the very least... this misses API docs for /dev/dxg. Code can't really > be reviewed without that. The docs live here: https://docs.microsoft.com/en-us/windows-hardware/drivers/ddi/d3dkmthk/ I don't see "/dev/dxg" being metioned there. Plus, kernel API Right, this is because this entire codebase is just a pipe to the API I've linked, it doesn't implement anything new on it's own. documentation should really go to Documentation, and be suitably licensed. While I don't mind copying the docs into Documentation, I'm concerned that over time they will diverge from the docs on the website. This is similar to how other documentation (such as the virtio spec) live out of tree to avoid these issues. w.r.t the licensing, again: this was sent under GPL2 (note the SPDX tags in each file), and the patches carry a S-O-B by someone who was a Microsoft employee at the time the patches were sent. -- Thanks, Sasha
Re: [RFC PATCH 0/4] DirectX on Linux
On Tue 2020-06-16 09:28:19, Sasha Levin wrote: > On Tue, Jun 16, 2020 at 12:51:13PM +0200, Pavel Machek wrote: > > Hi! > > > > > > The driver creates the /dev/dxg device, which can be opened by user mode > > > > application and handles their ioctls. The IOCTL interface to the driver > > > > is defined in dxgkmthk.h (Dxgkrnl Graphics Port Driver ioctl > > > > definitions). The interface matches the D3DKMT interface on Windows. > > > > Ioctls are implemented in ioctl.c. > > > > > > Echoing what others said, you're not making a DRM driver. The driver > > > should live outside > > > of the DRM code. > > > > > > > Actually, this sounds to me like "this should not be merged into linux > > kernel". I mean, > > we already have DRM API on Linux. We don't want another one, do we? > > This driver doesn't have any display functionality. Graphics cards without displays connected are quite common. I may be wrong, but I believe we normally handle them using DRM... > > And at the very least... this misses API docs for /dev/dxg. Code can't > > really > > be reviewed without that. > > The docs live here: > https://docs.microsoft.com/en-us/windows-hardware/drivers/ddi/d3dkmthk/ I don't see "/dev/dxg" being metioned there. Plus, kernel API documentation should really go to Documentation, and be suitably licensed. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html signature.asc Description: PGP signature
Re: [RFC PATCH 0/4] DirectX on Linux
On Tue, Jun 16, 2020 at 12:51:13PM +0200, Pavel Machek wrote: Hi! > The driver creates the /dev/dxg device, which can be opened by user mode > application and handles their ioctls. The IOCTL interface to the driver > is defined in dxgkmthk.h (Dxgkrnl Graphics Port Driver ioctl > definitions). The interface matches the D3DKMT interface on Windows. > Ioctls are implemented in ioctl.c. Echoing what others said, you're not making a DRM driver. The driver should live outside of the DRM code. Actually, this sounds to me like "this should not be merged into linux kernel". I mean, we already have DRM API on Linux. We don't want another one, do we? This driver doesn't have any display functionality. And at the very least... this misses API docs for /dev/dxg. Code can't really be reviewed without that. The docs live here: https://docs.microsoft.com/en-us/windows-hardware/drivers/ddi/d3dkmthk/ -- Thanks, Sasha
Re: [RFC PATCH 0/4] DirectX on Linux
On Tue, Jun 16, 2020 at 12:51:56PM +0200, Pavel Machek wrote: > Having said that, I hit one stumbling block: > "Further, at this time there are no presentation integration. " > > If we upstream this driver as-is into some hyperv specific place, and > you decide to add presentation integration this is more than likely > going to mean you will want to interact with dma-bufs and dma-fences. > If the driver is hidden away in a hyperv place it's likely we won't > even notice that feature landing until it's too late. > > I would like to see a coherent plan for presentation support (not > code, just an architectural diagram), because I think when you > contemplate how that works it will change the picture of how this > driver looks and intergrates into the rest of the Linux graphics > ecosystem. > > As-is I'd rather this didn't land under my purview, since I don't see > the value this adds to the Linux ecosystem at all, and I think it's > important when putting a burden on upstream that you provide some > value. I also have another concern from a legal standpoint I'd rather not review the ioctl part of this. I'd probably request under DRI developers abstain as well. This is a Windows kernel API being smashed into a Linux driver. I don't want to be tainted by knowledge of an API that I've no idea of the legal status of derived works. (it this all covered patent wise under OIN?) If you can't look onto it, perhaps it is not suitable to merge into kernel...? What would be legal requirements so this is "safe to look at"? We should really require submitter to meet them... Could you walk me through your view on what the function of the "Signed-off-by" tag is? -- Thanks, Sasha
Re: [RFC PATCH 0/4] DirectX on Linux
Hi! > > The driver creates the /dev/dxg device, which can be opened by user mode > > application and handles their ioctls. The IOCTL interface to the driver > > is defined in dxgkmthk.h (Dxgkrnl Graphics Port Driver ioctl > > definitions). The interface matches the D3DKMT interface on Windows. > > Ioctls are implemented in ioctl.c. > > Echoing what others said, you're not making a DRM driver. The driver should > live outside > of the DRM code. > Actually, this sounds to me like "this should not be merged into linux kernel". I mean, we already have DRM API on Linux. We don't want another one, do we? And at the very least... this misses API docs for /dev/dxg. Code can't really be reviewed without that. Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
Re: [RFC PATCH 0/4] DirectX on Linux
> > Having said that, I hit one stumbling block: > > "Further, at this time there are no presentation integration. " > > > > If we upstream this driver as-is into some hyperv specific place, and > > you decide to add presentation integration this is more than likely > > going to mean you will want to interact with dma-bufs and dma-fences. > > If the driver is hidden away in a hyperv place it's likely we won't > > even notice that feature landing until it's too late. > > > > I would like to see a coherent plan for presentation support (not > > code, just an architectural diagram), because I think when you > > contemplate how that works it will change the picture of how this > > driver looks and intergrates into the rest of the Linux graphics > > ecosystem. > > > > As-is I'd rather this didn't land under my purview, since I don't see > > the value this adds to the Linux ecosystem at all, and I think it's > > important when putting a burden on upstream that you provide some > > value. > > I also have another concern from a legal standpoint I'd rather not > review the ioctl part of this. I'd probably request under DRI > developers abstain as well. > > This is a Windows kernel API being smashed into a Linux driver. I don't want > to be > tainted by knowledge of an API that I've no idea of the legal status of > derived works. > (it this all covered patent wise under OIN?) If you can't look onto it, perhaps it is not suitable to merge into kernel...? What would be legal requirements so this is "safe to look at"? We should really require submitter to meet them... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
Re: [EXTERNAL] Re: [RFC PATCH 0/4] DirectX on Linux
Hi! > Thanks for the discussion. I may not be able to immediately answer all of > your questions, but I'll do my best . > Could you do something with your email settings? Because this is not how you should use email on lkml. "[EXTERNAL]" in the subject, top-posting, unwrapped lines... Thank you, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
RE: [EXTERNAL] Re: [RFC PATCH 0/4] DirectX on Linux
[resending as plain text, sorry about that] Thanks Daniel, more below. From: Daniel Vetter <mailto:dan...@ffwll.ch> Sent: Wednesday, May 20, 2020 12:41 AM To: Steve Pronovost <mailto:spron...@microsoft.com> Cc: Dave Airlie <mailto:airl...@gmail.com>; Sasha Levin <mailto:sas...@kernel.org>; mailto:linux-hyp...@vger.kernel.org; Stephen Hemminger <mailto:sthem...@microsoft.com>; Ursulin, Tvrtko <mailto:tvrtko.ursu...@intel.com>; Greg Kroah-Hartman <mailto:gre...@linuxfoundation.org>; Haiyang Zhang <mailto:haiya...@microsoft.com>; LKML <mailto:linux-kernel@vger.kernel.org>; dri-devel <mailto:dri-de...@lists.freedesktop.org>; Chris Wilson <mailto:ch...@chris-wilson.co.uk>; Linux Fbdev development list <mailto:linux-fb...@vger.kernel.org>; Iouri Tarassov <mailto:iou...@microsoft.com>; Deucher, Alexander <mailto:alexander.deuc...@amd.com>; KY Srinivasan <mailto:k...@microsoft.com>; Wei Liu <mailto:wei....@kernel.org>; Hawking Zhang <mailto:hawking.zh...@amd.com> Subject: Re: [EXTERNAL] Re: [RFC PATCH 0/4] DirectX on Linux Hi Steve, Sounds all good, some more comments and details below. On Wed, May 20, 2020 at 5:47 AM Steve Pronovost <mailto:spron...@microsoft.com> wrote: Hey guys, Thanks for the discussion. I may not be able to immediately answer all of your questions, but I'll do my best . drivers/hyperv sounds like it could be a better location. We weren't too sure where to put this, we though /drivers/gpu would be appropriate given this deal with GPUs, but I get your point... this is a vGPU driver that really only works when being run under Hyper-V, so drivers/hyperv is likely more appropriate. I think "it's a virtual gpu" is the wrong sales pitch, as is "only runs on $platform". We have lots of drm drivers in drivers/gpu that fit that bill. The better pitch I think is "it's a not a gpu, it's a dx12 protocol pipe" and "we actually do not want to integrate with the linux gpu ecosystem and primitives, we want to integrate with dx12 ecosystem and primitives to make the seamless rdp/rail/vail stuff work nicely". Below some more thoughts on the technical said. [spronovo] Agreed. As I mentioned in another reply, that protocol isn’t tied to DX… but the point you are making is still valid. This is really a projection of the Windows native abstraction of a GPU that windows user mode driver (dx, gl, cl, vulkan, cuda, etc…) are familiar with and use to communicate with the GPU… This effectively enable porting of these user mode driver to Linux inside of WSL and allow them to share the GPU with the host. Our goal is to offer CL/EGL/GLX/CUDA/… API support for applications running inside of WSL and integrate their output on the Windows desktop through the Wayland compositor we are building. The fact that we are using layer to implement some of these APIs (to reduce our partners work among other thing) is just an implementation details that most application shouldn’t have to worry about… “it just works” . From that perspective we’re fine moving the driver under a different node than /driver/gpu . In term of presentation, I need to clarify a few things. We announced today that we're also adding support for Linux GUI applications. The way this will work is roughly as follow. We're writing a Wayland compositor that will essentially bridge over RDP-RAIL (RAIL=Remote Application Integrated Locally). We're starting from a Weston base. Weston already has an RDP Backend, but that's for a full desktop remoting scheme. Weston draws a desktop and remote it over RDP... and then you can peek at that desktop using an rdp client on the Windows side. RAIL works differently. In that case our wayland compositor no longer paint a desktop... instead it simply forward individual visual / wl_surface over the RDP RAIL channel such that these visual can be displayed on the Windows desktop. The RDP client create proxy window for each of these top level visual and their content is filled with the data coming over the RDP channel. All pixels are owned by the RDP server/WSL... so these windows looks different than native window are they are painted and themed by WSL. The proxy window on the host gather input and inject back over RDP... This is essentially how application remoting works on windows and this is all publicly documented as part of the various RDP protocol specification. As a matter of fact, for the RDP server on the Weston side we are looking at continue to leverage FreeRDP (and provide fixes/enhancement as needed to the public project). Further, we're looking at further improvement down this path to avoid having to copy the content over the RAIL channel and instead just share/swap buffer between the guest and the host. We have extension to the RDP protocol, called VAIL (Virtualized Application Integrated Locally)
Re: [EXTERNAL] Re: [RFC PATCH 0/4] DirectX on Linux
Hi Steve, thank you for the fast reply. Am 20.05.20 um 09:42 schrieb Steve Pronovost: >> Echoing what others said, you're not making a DRM driver. The driver should >> live outside of the DRM code. > > Agreed, please see my earlier reply. We'll be moving the driver to > drivers/hyperv node or something similar. Apology for the confusion here. > >> I have one question about the driver API: on Windows, DirectX versions are >> loosly tied to Windows releases. So I guess you can change the kernel >> interface among DirectX versions? >> If so, how would this work on Linux in the long term? If there ever is a >> DirectX 13 or 14 with incompatible kernel interfaces, how would you plan to >> update the Linux driver? > > You should think of the communication over the VM Bus for the vGPU projection > as a strongly versioned interface. We will be keeping compatibility with > older version of that interface as it evolves over time so we can continue to > run older guest (we already do). This protocol isn't actually tied to the DX > API. It is a generic abstraction for the GPU that can be used for any APIs > (for example the NVIDIA CUDA driver that we announced is going over the same > protocol to access the GPU). > > New version of user mode DX can either take advantage or sometime require new > services from this kernel abstraction. This mean that pulling a new version > of user mode DX can mean having to also pull a new version of this vGPU > kernel driver. For WSL, these essentially ships together. The kernel driver > ships as part of our WSL2 Linux Kernel integration. User mode DX bits ships > with Windows. Just a friendly advise: maintaining a proprietary component within a Linux environment is tough. You will need a good plan for long-term interface stability and compatibility with the other components. Best regards Thomas > > -Original Message- > From: Thomas Zimmermann > Sent: Wednesday, May 20, 2020 12:11 AM > To: Sasha Levin ; alexander.deuc...@amd.com; > ch...@chris-wilson.co.uk; ville.syrj...@linux.intel.com; > hawking.zh...@amd.com; tvrtko.ursu...@intel.com > Cc: linux-kernel@vger.kernel.org; linux-hyp...@vger.kernel.org; KY Srinivasan > ; Haiyang Zhang ; Stephen > Hemminger ; wei@kernel.org; Steve Pronovost > ; Iouri Tarassov ; > dri-de...@lists.freedesktop.org; linux-fb...@vger.kernel.org; > gre...@linuxfoundation.org > Subject: [EXTERNAL] Re: [RFC PATCH 0/4] DirectX on Linux > > Hi > > Am 19.05.20 um 18:32 schrieb Sasha Levin: >> There is a blog post that goes into more detail about the bigger >> picture, and walks through all the required pieces to make this work. >> It is available here: >> https://devblogs.microsoft.com/directx/directx-heart-linux . The rest >> of this cover letter will focus on the Linux Kernel bits. > > That's quite a surprise. Thanks for your efforts to contribute. > >> >> Overview >> >> >> This is the first draft of the Microsoft Virtual GPU (vGPU) driver. >> The driver exposes a paravirtualized GPU to user mode applications >> running in a virtual machine on a Windows host. This enables hardware >> acceleration in environment such as WSL (Windows Subsystem for Linux) >> where the Linux virtual machine is able to share the GPU with the >> Windows host. >> >> The projection is accomplished by exposing the WDDM (Windows Display >> Driver Model) interface as a set of IOCTL. This allows APIs and user >> mode driver written against the WDDM GPU abstraction on Windows to be >> ported to run within a Linux environment. This enables the port of the >> D3D12 and DirectML APIs as well as their associated user mode driver >> to Linux. This also enables third party APIs, such as the popular >> NVIDIA Cuda compute API, to be hardware accelerated within a WSL environment. >> >> Only the rendering/compute aspect of the GPU are projected to the >> virtual machine, no display functionality is exposed. Further, at this >> time there are no presentation integration. So although the D3D12 API >> can be use to render graphics offscreen, there is no path (yet) for >> pixel to flow from the Linux environment back onto the Windows host >> desktop. This GPU stack is effectively side-by-side with the native >> Linux graphics stack. >> >> The driver creates the /dev/dxg device, which can be opened by user >> mode application and handles their ioctls. The IOCTL interface to the >> driver is defined in dxgkmthk.h (Dxgkrnl Graphics Port Driver ioctl >> definitions). The interface matches the D3DKMT interface on Windows. >> Ioctls
Re: [RFC PATCH 0/4] DirectX on Linux
On Tuesday 2020-05-19 22:36, Sasha Levin wrote: > >> - Why DX12 on linux? Looking at this feels like classic divide and > > There is a single usecase for this: WSL2 developer who wants to run > machine learning on his GPU. The developer is working on his laptop, > which is running Windows and that laptop has a single GPU that Windows > is using. It does not feel right conceptually. If the target is a Windows API (DX12/ML), why bother with Linux environments? Make it a Windows executable, thereby skipping the WSL translation layer and passthrough.
RE: [EXTERNAL] Re: [RFC PATCH 0/4] DirectX on Linux
>Echoing what others said, you're not making a DRM driver. The driver should >live outside of the DRM code. Agreed, please see my earlier reply. We'll be moving the driver to drivers/hyperv node or something similar. Apology for the confusion here. > I have one question about the driver API: on Windows, DirectX versions are > loosly tied to Windows releases. So I guess you can change the kernel > interface among DirectX versions? > If so, how would this work on Linux in the long term? If there ever is a > DirectX 13 or 14 with incompatible kernel interfaces, how would you plan to > update the Linux driver? You should think of the communication over the VM Bus for the vGPU projection as a strongly versioned interface. We will be keeping compatibility with older version of that interface as it evolves over time so we can continue to run older guest (we already do). This protocol isn't actually tied to the DX API. It is a generic abstraction for the GPU that can be used for any APIs (for example the NVIDIA CUDA driver that we announced is going over the same protocol to access the GPU). New version of user mode DX can either take advantage or sometime require new services from this kernel abstraction. This mean that pulling a new version of user mode DX can mean having to also pull a new version of this vGPU kernel driver. For WSL, these essentially ships together. The kernel driver ships as part of our WSL2 Linux Kernel integration. User mode DX bits ships with Windows. -Original Message- From: Thomas Zimmermann Sent: Wednesday, May 20, 2020 12:11 AM To: Sasha Levin ; alexander.deuc...@amd.com; ch...@chris-wilson.co.uk; ville.syrj...@linux.intel.com; hawking.zh...@amd.com; tvrtko.ursu...@intel.com Cc: linux-kernel@vger.kernel.org; linux-hyp...@vger.kernel.org; KY Srinivasan ; Haiyang Zhang ; Stephen Hemminger ; wei@kernel.org; Steve Pronovost ; Iouri Tarassov ; dri-de...@lists.freedesktop.org; linux-fb...@vger.kernel.org; gre...@linuxfoundation.org Subject: [EXTERNAL] Re: [RFC PATCH 0/4] DirectX on Linux Hi Am 19.05.20 um 18:32 schrieb Sasha Levin: > There is a blog post that goes into more detail about the bigger > picture, and walks through all the required pieces to make this work. > It is available here: > https://devblogs.microsoft.com/directx/directx-heart-linux . The rest > of this cover letter will focus on the Linux Kernel bits. That's quite a surprise. Thanks for your efforts to contribute. > > Overview > > > This is the first draft of the Microsoft Virtual GPU (vGPU) driver. > The driver exposes a paravirtualized GPU to user mode applications > running in a virtual machine on a Windows host. This enables hardware > acceleration in environment such as WSL (Windows Subsystem for Linux) > where the Linux virtual machine is able to share the GPU with the > Windows host. > > The projection is accomplished by exposing the WDDM (Windows Display > Driver Model) interface as a set of IOCTL. This allows APIs and user > mode driver written against the WDDM GPU abstraction on Windows to be > ported to run within a Linux environment. This enables the port of the > D3D12 and DirectML APIs as well as their associated user mode driver > to Linux. This also enables third party APIs, such as the popular > NVIDIA Cuda compute API, to be hardware accelerated within a WSL environment. > > Only the rendering/compute aspect of the GPU are projected to the > virtual machine, no display functionality is exposed. Further, at this > time there are no presentation integration. So although the D3D12 API > can be use to render graphics offscreen, there is no path (yet) for > pixel to flow from the Linux environment back onto the Windows host > desktop. This GPU stack is effectively side-by-side with the native > Linux graphics stack. > > The driver creates the /dev/dxg device, which can be opened by user > mode application and handles their ioctls. The IOCTL interface to the > driver is defined in dxgkmthk.h (Dxgkrnl Graphics Port Driver ioctl > definitions). The interface matches the D3DKMT interface on Windows. > Ioctls are implemented in ioctl.c. Echoing what others said, you're not making a DRM driver. The driver should live outside of the DRM code. I have one question about the driver API: on Windows, DirectX versions are loosly tied to Windows releases. So I guess you can change the kernel interface among DirectX versions? If so, how would this work on Linux in the long term? If there ever is a DirectX 13 or 14 with incompatible kernel interfaces, how would you plan to update the Linux driver? Best regards Thomas > > When a VM starts, hyper-v on the host adds virtual GPU devices to the > VM via the hyper-v driver. The host offers several VM bus channels to > the > VM: the g
Re: [RFC PATCH 0/4] DirectX on Linux
Hi Am 19.05.20 um 18:32 schrieb Sasha Levin: > There is a blog post that goes into more detail about the bigger > picture, and walks through all the required pieces to make this work. It > is available here: > https://devblogs.microsoft.com/directx/directx-heart-linux . The rest of > this cover letter will focus on the Linux Kernel bits. That's quite a surprise. Thanks for your efforts to contribute. > > Overview > > > This is the first draft of the Microsoft Virtual GPU (vGPU) driver. The > driver exposes a paravirtualized GPU to user mode applications running > in a virtual machine on a Windows host. This enables hardware > acceleration in environment such as WSL (Windows Subsystem for Linux) > where the Linux virtual machine is able to share the GPU with the > Windows host. > > The projection is accomplished by exposing the WDDM (Windows Display > Driver Model) interface as a set of IOCTL. This allows APIs and user > mode driver written against the WDDM GPU abstraction on Windows to be > ported to run within a Linux environment. This enables the port of the > D3D12 and DirectML APIs as well as their associated user mode driver to > Linux. This also enables third party APIs, such as the popular NVIDIA > Cuda compute API, to be hardware accelerated within a WSL environment. > > Only the rendering/compute aspect of the GPU are projected to the > virtual machine, no display functionality is exposed. Further, at this > time there are no presentation integration. So although the D3D12 API > can be use to render graphics offscreen, there is no path (yet) for > pixel to flow from the Linux environment back onto the Windows host > desktop. This GPU stack is effectively side-by-side with the native > Linux graphics stack. > > The driver creates the /dev/dxg device, which can be opened by user mode > application and handles their ioctls. The IOCTL interface to the driver > is defined in dxgkmthk.h (Dxgkrnl Graphics Port Driver ioctl > definitions). The interface matches the D3DKMT interface on Windows. > Ioctls are implemented in ioctl.c. Echoing what others said, you're not making a DRM driver. The driver should live outside of the DRM code. I have one question about the driver API: on Windows, DirectX versions are loosly tied to Windows releases. So I guess you can change the kernel interface among DirectX versions? If so, how would this work on Linux in the long term? If there ever is a DirectX 13 or 14 with incompatible kernel interfaces, how would you plan to update the Linux driver? Best regards Thomas > > When a VM starts, hyper-v on the host adds virtual GPU devices to the VM > via the hyper-v driver. The host offers several VM bus channels to the > VM: the global channel and one channel per virtual GPU, assigned to the > VM. > > The driver registers with the hyper-v driver (hv_driver) for the arrival > of VM bus channels. dxg_probe_device recognizes the vGPU channels and > creates the corresponding objects (dxgadapter for vGPUs and dxgglobal > for the global channel). > > The driver uses the hyper-V VM bus interface to communicate with the > host. dxgvmbus.c implements the communication interface. > > The global channel has 8GB of IO space assigned by the host. This space > is managed by the host and used to give the guest direct CPU access to > some allocations. Video memory is allocated on the host except in the > case of existing_sysmem allocations. The Windows host allocates memory > for the GPU on behalf of the guest. The Linux guest can access that > memory by mapping GPU virtual address to allocations and then > referencing those GPU virtual address from within GPU command buffers > submitted to the GPU. For allocations which require CPU access, the > allocation is mapped by the host into a location in the 8GB of IO space > reserved in the guest for that purpose. The Windows host uses the nested > CPU page table to ensure that this guest IO space always map to the > correct location for the allocation as it may migrate between dedicated > GPU memory (e.g. VRAM, firmware reserved DDR) and shared system memory > (regular DDR) over its lifetime. The Linux guest maps a user mode CPU > virtual address to an allocation IO space range for direct access by > user mode APIs and drivers. > > > > Implementation of LX_DXLOCK2 ioctl > == > > We would appreciate your feedback on the implementation of the > LX_DXLOCK2 ioctl. > > This ioctl is used to get a CPU address to an allocation, which is > resident in video/system memory on the host. The way it works: > > 1. The driver sends the Lock message to the host > > 2. The host allocates space in the VM IO space and maps it to the > allocation memory > > 3. The host returns the address in IO space for the mapped allocation > > 4. The driver (in dxg_map_iospace) allocates a user mode virtual address > range using vm_mmap and maps it to the IO space using > io_remap_ofn_range) > > 5. The VA is
RE: [EXTERNAL] Re: [RFC PATCH 0/4] DirectX on Linux
Hey guys, Thanks for the discussion. I may not be able to immediately answer all of your questions, but I'll do my best . drivers/hyperv sounds like it could be a better location. We weren't too sure where to put this, we though /drivers/gpu would be appropriate given this deal with GPUs, but I get your point... this is a vGPU driver that really only works when being run under Hyper-V, so drivers/hyperv is likely more appropriate. In term of presentation, I need to clarify a few things. We announced today that we're also adding support for Linux GUI applications. The way this will work is roughly as follow. We're writing a Wayland compositor that will essentially bridge over RDP-RAIL (RAIL=Remote Application Integrated Locally). We're starting from a Weston base. Weston already has an RDP Backend, but that's for a full desktop remoting scheme. Weston draws a desktop and remote it over RDP... and then you can peek at that desktop using an rdp client on the Windows side. RAIL works differently. In that case our wayland compositor no longer paint a desktop... instead it simply forward individual visual / wl_surface over the RDP RAIL channel such that these visual can be displayed on the Windows desktop. The RDP client create proxy window for each of these top level visual and their content is filled with the data coming over the RDP channel. All pixels are owned by the RDP server/WSL... so these windows looks different than native window are they are painted and themed by WSL. The proxy window on the host gather input and inject back over RDP... This is essentially how application remoting works on windows and this is all publicly documented as part of the various RDP protocol specification. As a matter of fact, for the RDP server on the Weston side we are looking at continue to leverage FreeRDP (and provide fixes/enhancement as needed to the public project). Further, we're looking at further improvement down this path to avoid having to copy the content over the RAIL channel and instead just share/swap buffer between the guest and the host. We have extension to the RDP protocol, called VAIL (Virtualized Application Integrated Locally) which does that today. Today this is only use in Windows on Windows for very specific scenario. We're looking at extending the public RDP protocol with these VAIL extension to make this an official Microsoft supported protocol which would allow us to target this in WSL. We have finished designing this part in details. Our goal would be to leverage something along the line of wl_drm, dma-buf, dma-fence, etc... This compositor and all our contribution to FreeRDP will be fully open source, including our design doc. We're not quite sure yet whether this will be offered as a separate project entirely distinct from it's Weston root... or if we'll propose an extension to Weston to operate in this mode. We would like to build it such that in theory any Wayland compositor could add support for this mode of operation if they want to remote application to a Windows host (over the network, or on the same box). We see /dev/dxg really as a projection of the GPU when running in WSL such that the GPU can be shared between WSL and the host... not something that would coexist "at the same time" with a real DRM GPU. We have consider the possibility of bringing DX to Linux with no Windows cord attached. I'm not ready to discuss this at this time ... but in the hypothetical that we were do this, DX would be running on top of DRI/DRM on native Linux. We likely would be contributing some changes to DRM to address area of divergence and get better mapping for our user mode driver, but we wouldn't try to shoehorn /dev/dxg into the picture. In that hypothetical world, we would essentially have DX target DRM on native Linux and DX continue to target DXG in WSL to share the GPU with the host. I think this further reinforce the point you guys were making that the right place for our current dxgkrnl driver to live in would be /drivers/hyperv/dxgkrnl. In insight, I totally agree . I think this cover all questions, let me know if I missed anything. Thanks, Steve -Original Message- From: Daniel Vetter Sent: Tuesday, May 19, 2020 4:01 PM To: Dave Airlie Cc: Sasha Levin ; linux-hyp...@vger.kernel.org; Stephen Hemminger ; Ursulin, Tvrtko ; Greg Kroah-Hartman ; Haiyang Zhang ; LKML ; dri-devel ; Chris Wilson ; Steve Pronovost ; Linux Fbdev development list ; Iouri Tarassov ; Deucher, Alexander ; KY Srinivasan ; Wei Liu ; Hawking Zhang Subject: [EXTERNAL] Re: [RFC PATCH 0/4] DirectX on Linux On Wed, May 20, 2020 at 12:42 AM Dave Airlie wrote: > > On Wed, 20 May 2020 at 02:33, Sasha Levin wrote: > > > > There is a blog post that goes into more detail about the bigger > > picture, and walks through all the required pieces to make this > > work. It is available here: > > https://nam06.
Re: [RFC PATCH 0/4] DirectX on Linux
On Wed, 20 May 2020 at 08:42, Dave Airlie wrote: > > On Wed, 20 May 2020 at 02:33, Sasha Levin wrote: > > > > There is a blog post that goes into more detail about the bigger > > picture, and walks through all the required pieces to make this work. It > > is available here: > > https://devblogs.microsoft.com/directx/directx-heart-linux . The rest of > > this cover letter will focus on the Linux Kernel bits. > > > > Overview > > > > > > This is the first draft of the Microsoft Virtual GPU (vGPU) driver. The > > driver exposes a paravirtualized GPU to user mode applications running > > in a virtual machine on a Windows host. This enables hardware > > acceleration in environment such as WSL (Windows Subsystem for Linux) > > where the Linux virtual machine is able to share the GPU with the > > Windows host. > > > > The projection is accomplished by exposing the WDDM (Windows Display > > Driver Model) interface as a set of IOCTL. This allows APIs and user > > mode driver written against the WDDM GPU abstraction on Windows to be > > ported to run within a Linux environment. This enables the port of the > > D3D12 and DirectML APIs as well as their associated user mode driver to > > Linux. This also enables third party APIs, such as the popular NVIDIA > > Cuda compute API, to be hardware accelerated within a WSL environment. > > > > Only the rendering/compute aspect of the GPU are projected to the > > virtual machine, no display functionality is exposed. Further, at this > > time there are no presentation integration. So although the D3D12 API > > can be use to render graphics offscreen, there is no path (yet) for > > pixel to flow from the Linux environment back onto the Windows host > > desktop. This GPU stack is effectively side-by-side with the native > > Linux graphics stack. > > Okay I've had some caffiene and absorbed some more of this. > > This is a driver that connects a binary blob interface in the Windows > kernel drivers to a binary blob that you run inside a Linux guest. > It's a binary transport between two binary pieces. Personally this > holds little of interest to me, I can see why it might be nice to have > this upstream, but I don't forsee any other Linux distributor ever > enabling it or having to ship it, it's purely a WSL2 pipe. I'm not > saying I'd be happy to see this in the tree, since I don't see the > value of maintaining it upstream, but it probably should just exists > in a drivers/hyperv type area. > > Having said that, I hit one stumbling block: > "Further, at this time there are no presentation integration. " > > If we upstream this driver as-is into some hyperv specific place, and > you decide to add presentation integration this is more than likely > going to mean you will want to interact with dma-bufs and dma-fences. > If the driver is hidden away in a hyperv place it's likely we won't > even notice that feature landing until it's too late. > > I would like to see a coherent plan for presentation support (not > code, just an architectural diagram), because I think when you > contemplate how that works it will change the picture of how this > driver looks and intergrates into the rest of the Linux graphics > ecosystem. > > As-is I'd rather this didn't land under my purview, since I don't see > the value this adds to the Linux ecosystem at all, and I think it's > important when putting a burden on upstream that you provide some > value. I also have another concern from a legal standpoint I'd rather not review the ioctl part of this. I'd probably request under DRI developers abstain as well. This is a Windows kernel API being smashed into a Linux driver. I don't want to be tainted by knowledge of an API that I've no idea of the legal status of derived works. (it this all covered patent wise under OIN?) I don't want to ever be accused of designing a Linux kernel API with illgotten D3DKMT knowledge, I feel tainting myself with knowledge of a properietary API might cause derived work issues. Dave.
Re: [RFC PATCH 0/4] DirectX on Linux
On Wed, May 20, 2020 at 12:42 AM Dave Airlie wrote: > > On Wed, 20 May 2020 at 02:33, Sasha Levin wrote: > > > > There is a blog post that goes into more detail about the bigger > > picture, and walks through all the required pieces to make this work. It > > is available here: > > https://devblogs.microsoft.com/directx/directx-heart-linux . The rest of > > this cover letter will focus on the Linux Kernel bits. > > > > Overview > > > > > > This is the first draft of the Microsoft Virtual GPU (vGPU) driver. The > > driver exposes a paravirtualized GPU to user mode applications running > > in a virtual machine on a Windows host. This enables hardware > > acceleration in environment such as WSL (Windows Subsystem for Linux) > > where the Linux virtual machine is able to share the GPU with the > > Windows host. > > > > The projection is accomplished by exposing the WDDM (Windows Display > > Driver Model) interface as a set of IOCTL. This allows APIs and user > > mode driver written against the WDDM GPU abstraction on Windows to be > > ported to run within a Linux environment. This enables the port of the > > D3D12 and DirectML APIs as well as their associated user mode driver to > > Linux. This also enables third party APIs, such as the popular NVIDIA > > Cuda compute API, to be hardware accelerated within a WSL environment. > > > > Only the rendering/compute aspect of the GPU are projected to the > > virtual machine, no display functionality is exposed. Further, at this > > time there are no presentation integration. So although the D3D12 API > > can be use to render graphics offscreen, there is no path (yet) for > > pixel to flow from the Linux environment back onto the Windows host > > desktop. This GPU stack is effectively side-by-side with the native > > Linux graphics stack. > > Okay I've had some caffiene and absorbed some more of this. > > This is a driver that connects a binary blob interface in the Windows > kernel drivers to a binary blob that you run inside a Linux guest. > It's a binary transport between two binary pieces. Personally this > holds little of interest to me, I can see why it might be nice to have > this upstream, but I don't forsee any other Linux distributor ever > enabling it or having to ship it, it's purely a WSL2 pipe. I'm not > saying I'd be happy to see this in the tree, since I don't see the > value of maintaining it upstream, but it probably should just exists > in a drivers/hyperv type area. Yup as-is (especially with the goal of this being aimed at ml/compute only) drivers/hyperv sounds a bunch more reasonable than drivers/gpu. > Having said that, I hit one stumbling block: > "Further, at this time there are no presentation integration. " > > If we upstream this driver as-is into some hyperv specific place, and > you decide to add presentation integration this is more than likely > going to mean you will want to interact with dma-bufs and dma-fences. > If the driver is hidden away in a hyperv place it's likely we won't > even notice that feature landing until it's too late. I've recently added regex matches to MAINTAINERS so we'll see dma_buf/fence/anything show up on dri-devel. So that part is solved hopefully. > I would like to see a coherent plan for presentation support (not > code, just an architectural diagram), because I think when you > contemplate how that works it will change the picture of how this > driver looks and intergrates into the rest of the Linux graphics > ecosystem. Yeah once we have the feature-creep to presentation support all the integration fun starts, with all the questions about "why does this not look like any other linux gpu driver". We have that already with nvidia insisting they just can't implement any of the upstream gpu uapi we have, but at least they're not in-tree, so not our problem from an upstream maintainership pov. But once this dx12 pipe is landed and then we want to extend it it's still going to have all the "we can't ever release the sources to any of the parts we usually expect to be open for gpu drivers in upstream" problems. Then we're stuck at a rather awkward point of why one vendor gets an exception and all the others dont. > As-is I'd rather this didn't land under my purview, since I don't see > the value this adds to the Linux ecosystem at all, and I think it's > important when putting a burden on upstream that you provide some > value. Well there is some in the form of "more hw/platform support". But given that gpus evolved rather fast, including the entire integration ecosystem (it's by far not just the hw drivers that move quickly). So that value deprecates a lot faster than for other kernel subsystems. And all that's left is the pain of not breaking anything without actually being able to evolve the overall stack in any meaningful way. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch
Re: [RFC PATCH 0/4] DirectX on Linux
On Wed, 20 May 2020 at 02:33, Sasha Levin wrote: > > There is a blog post that goes into more detail about the bigger > picture, and walks through all the required pieces to make this work. It > is available here: > https://devblogs.microsoft.com/directx/directx-heart-linux . The rest of > this cover letter will focus on the Linux Kernel bits. > > Overview > > > This is the first draft of the Microsoft Virtual GPU (vGPU) driver. The > driver exposes a paravirtualized GPU to user mode applications running > in a virtual machine on a Windows host. This enables hardware > acceleration in environment such as WSL (Windows Subsystem for Linux) > where the Linux virtual machine is able to share the GPU with the > Windows host. > > The projection is accomplished by exposing the WDDM (Windows Display > Driver Model) interface as a set of IOCTL. This allows APIs and user > mode driver written against the WDDM GPU abstraction on Windows to be > ported to run within a Linux environment. This enables the port of the > D3D12 and DirectML APIs as well as their associated user mode driver to > Linux. This also enables third party APIs, such as the popular NVIDIA > Cuda compute API, to be hardware accelerated within a WSL environment. > > Only the rendering/compute aspect of the GPU are projected to the > virtual machine, no display functionality is exposed. Further, at this > time there are no presentation integration. So although the D3D12 API > can be use to render graphics offscreen, there is no path (yet) for > pixel to flow from the Linux environment back onto the Windows host > desktop. This GPU stack is effectively side-by-side with the native > Linux graphics stack. Okay I've had some caffiene and absorbed some more of this. This is a driver that connects a binary blob interface in the Windows kernel drivers to a binary blob that you run inside a Linux guest. It's a binary transport between two binary pieces. Personally this holds little of interest to me, I can see why it might be nice to have this upstream, but I don't forsee any other Linux distributor ever enabling it or having to ship it, it's purely a WSL2 pipe. I'm not saying I'd be happy to see this in the tree, since I don't see the value of maintaining it upstream, but it probably should just exists in a drivers/hyperv type area. Having said that, I hit one stumbling block: "Further, at this time there are no presentation integration. " If we upstream this driver as-is into some hyperv specific place, and you decide to add presentation integration this is more than likely going to mean you will want to interact with dma-bufs and dma-fences. If the driver is hidden away in a hyperv place it's likely we won't even notice that feature landing until it's too late. I would like to see a coherent plan for presentation support (not code, just an architectural diagram), because I think when you contemplate how that works it will change the picture of how this driver looks and intergrates into the rest of the Linux graphics ecosystem. As-is I'd rather this didn't land under my purview, since I don't see the value this adds to the Linux ecosystem at all, and I think it's important when putting a burden on upstream that you provide some value. Dave.
Re: [RFC PATCH 0/4] DirectX on Linux
Hi Daniel, On Tue, May 19, 2020 at 09:21:15PM +0200, Daniel Vetter wrote: Hi Sasha So obviously great that Microsoft is trying to upstream all this, and very much welcome and all that. But I guess there's a bunch of rather fundamental issues before we look into any kind of code details. And that might make this quite a hard sell for upstream to drivers/gpu subsystem: Let me preface my answers by saying that speaking personally I very much dislike that the userspace is closed and wish I could do something about it. - From the blog it sounds like the userspace is all closed. That includes the hw specific part and compiler chunks, all stuff we've generally expected to be able to look in the past for any kind of other driver. It's event documented here: https://dri.freedesktop.org/docs/drm/gpu/drm-uapi.html#open-source-userspace-requirements What's your plan here? Let me answer with a (genuine) question: does this driver have anything to do with DRM even after we enable graphics on it? I'm still trying to figure it out. There is an open source DX12 Galluim driver (that lives here: https://gitlab.freedesktop.org/kusma/mesa/-/tree/msclc-d3d12) with open source compiler and so on. The plan is for Microsoft to provide shims to allow the existing Linux userspace interact with DX12; I'll explain below why we had to pipe DX12 all the way into the Linux guest, but this is *not* to introduce DX12 into the Linux world as competition. There is no intent for anyone in the Linux world to start coding for the DX12 API. This is why I'm not sure whether this touches DRM on the Linux side of things. Nothing is actually rendered on Linux but rather piped to Windows to be done there. btw since the main goal here (at least at first) seems to be get compute and ML going the official work-around here is to relabel your driver as an accelerator driver (just sed -e s/vGPU/vaccel/ over the entire thing or so) and then Olof and Greg will take it into drivers/accel ... This submission is not a case of "we want it upstream NOW" but rather "let's work together to figure out how to do it right" :) I thought about placing this driver in drivers/hyper-v/ given that it's basically just a pipe between the host and the guest. There is no fancy logic in this drivers. Maybe the right place is indeed drivers/accel or drivers/hyper-v but I'd love if we agree on that rather than doing that as a workaround and 6 months down the road enabling graphics. - Next up (but that's not really a surprise for a fresh vendor driver) at a more technical level, this seems to reinvent the world, from device enumeration (why is this not exposed as /dev/dri/card0 so it better integrates with existing linux desktop stuff, in case that becomes a goal ever) down to reinvented kref_put_mutex (and please look at drm_device->struct_mutex for an example of how bad of a nightmare that locking pattern is and how many years it took us to untangle that one. I'd maybe note that neither of us here at Microsoft is an expert in the Linux DRM world. Stuff might have been done in a certain way because we didn't know better. - Why DX12 on linux? Looking at this feels like classic divide and There is a single usecase for this: WSL2 developer who wants to run machine learning on his GPU. The developer is working on his laptop, which is running Windows and that laptop has a single GPU that Windows is using. Since the GPU is being used by Windows, we can't assign it directly to the Linux guest, but instead we can use GPU Partitioning to give the guest access to the GPU. This means that the guest needs to be able to "speak" DX12, which is why we pulled DX12 into Linux. conquer (or well triple E from the 90s), we have vk, we have drm_syncobj, we have an entire ecosystem of winsys layers that work across vendors. Is the plan here that we get a dx12 driver for other hw mesa drivers from you guys, so this is all consistent and we have a nice linux platform? How does this integrate everywhere else with linux winsys standards, like dma-buf for passing stuff around, dma-fence/sync_file/drm_syncobj for syncing, drm_fourcc/modifiers for some idea how it all meshes together? Let me point you to this blog post that has more information about the graphics side of things: https://www.collabora.com/news-and-blog/news-and-events/introducing-opencl-and-opengl-on-directx.html . The intent is to wrap DX12 with shims to work with the existing ecosystem; DX12 isn't a new player on it's own and thus isn't trying to divide/conquer anything. - There's been a pile of hallway track/private discussions about moving on from the buffer-based memory managed model to something more modern. That relates to your DXLOCK2 question, but there's a lot more to userspace managed gpu memory residency than just that. monitored fences are another part. Also, to avoid a platform split we need to figure out how to tie this back into the dma-buf and dma-fence (including various uapi flavours) or
Re: [RFC PATCH 0/4] DirectX on Linux
Hi Sasha So obviously great that Microsoft is trying to upstream all this, and very much welcome and all that. But I guess there's a bunch of rather fundamental issues before we look into any kind of code details. And that might make this quite a hard sell for upstream to drivers/gpu subsystem: - From the blog it sounds like the userspace is all closed. That includes the hw specific part and compiler chunks, all stuff we've generally expected to be able to look in the past for any kind of other driver. It's event documented here: https://dri.freedesktop.org/docs/drm/gpu/drm-uapi.html#open-source-userspace-requirements What's your plan here? btw since the main goal here (at least at first) seems to be get compute and ML going the official work-around here is to relabel your driver as an accelerator driver (just sed -e s/vGPU/vaccel/ over the entire thing or so) and then Olof and Greg will take it into drivers/accel ... - Next up (but that's not really a surprise for a fresh vendor driver) at a more technical level, this seems to reinvent the world, from device enumeration (why is this not exposed as /dev/dri/card0 so it better integrates with existing linux desktop stuff, in case that becomes a goal ever) down to reinvented kref_put_mutex (and please look at drm_device->struct_mutex for an example of how bad of a nightmare that locking pattern is and how many years it took us to untangle that one. - Why DX12 on linux? Looking at this feels like classic divide and conquer (or well triple E from the 90s), we have vk, we have drm_syncobj, we have an entire ecosystem of winsys layers that work across vendors. Is the plan here that we get a dx12 driver for other hw mesa drivers from you guys, so this is all consistent and we have a nice linux platform? How does this integrate everywhere else with linux winsys standards, like dma-buf for passing stuff around, dma-fence/sync_file/drm_syncobj for syncing, drm_fourcc/modifiers for some idea how it all meshes together? - There's been a pile of hallway track/private discussions about moving on from the buffer-based memory managed model to something more modern. That relates to your DXLOCK2 question, but there's a lot more to userspace managed gpu memory residency than just that. monitored fences are another part. Also, to avoid a platform split we need to figure out how to tie this back into the dma-buf and dma-fence (including various uapi flavours) or it'll be made of fail. dx12 has all that in some form, except 0 integration with the linux stuff we have (no surprise, since linux isn't windows). Finally if we go to the trouble of a completely revamped I think ioctls aren't a great idea, something like iouring (the gossip name is drm_uring) would be a lot better. Also for easier paravirt we'd need 0 cpu pointers in any such new interface. Adding a few people who've been involved in these discussions thus far, mostly under a drm/hmm.ko heading iirc. I think the above are the really big ticket items around what's the plan here and are we solving even the right problem. Cheers, Daniel On Tue, May 19, 2020 at 6:33 PM Sasha Levin wrote: > > There is a blog post that goes into more detail about the bigger > picture, and walks through all the required pieces to make this work. It > is available here: > https://devblogs.microsoft.com/directx/directx-heart-linux . The rest of > this cover letter will focus on the Linux Kernel bits. > > Overview > > > This is the first draft of the Microsoft Virtual GPU (vGPU) driver. The > driver exposes a paravirtualized GPU to user mode applications running > in a virtual machine on a Windows host. This enables hardware > acceleration in environment such as WSL (Windows Subsystem for Linux) > where the Linux virtual machine is able to share the GPU with the > Windows host. > > The projection is accomplished by exposing the WDDM (Windows Display > Driver Model) interface as a set of IOCTL. This allows APIs and user > mode driver written against the WDDM GPU abstraction on Windows to be > ported to run within a Linux environment. This enables the port of the > D3D12 and DirectML APIs as well as their associated user mode driver to > Linux. This also enables third party APIs, such as the popular NVIDIA > Cuda compute API, to be hardware accelerated within a WSL environment. > > Only the rendering/compute aspect of the GPU are projected to the > virtual machine, no display functionality is exposed. Further, at this > time there are no presentation integration. So although the D3D12 API > can be use to render graphics offscreen, there is no path (yet) for > pixel to flow from the Linux environment back onto the Windows host > desktop. This GPU stack is effectively side-by-side with the native > Linux graphics stack. > > The driver creates the /dev/dxg device, which can be opened by user mode > application and handles their ioctls. The IOCTL interface to the driver > is defined in dxgkmthk.h (Dxgkrnl Graphics Port Driver
