Hi all, just as a clarification, this patch series implements the frontend driver for the "vdispl" protocol, which was reviewed, approved and committed in xen.git back in April: https://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/include/public/io/displif.h As Xen maintainer, if a competing PV DRM protocol proposal will come up, I'll try to steer it into evolving the existing vdispl protocol, as we like to have only one protocol per device class. I am really looking forward to having this driver upstream in Linux. Thanks Oleksandr! Cheers, Stefano On Wed, 21 Feb 2018, Oleksandr Andrushchenko wrote: > From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx> > > Hello! > > This patch series adds support for Xen [1] para-virtualized > frontend display driver. It implements the protocol from > include/xen/interface/io/displif.h [2]. > Accompanying backend [3] is implemented as a user-space application > and its helper library [4], capable of running as a Weston client > or DRM master. > Configuration of both backend and frontend is done via > Xen guest domain configuration options [5]. > > ******************************************************************************* > * Driver limitations > ******************************************************************************* > 1. Configuration options 1.1 (contiguous display buffers) and 2 (backend > allocated buffers) below are not supported at the same time. > > 2. Only primary plane without additional properties is supported. > > 3. Only one video mode supported which resolution is configured via XenStore. > > 4. All CRTCs operate at fixed frequency of 60Hz. > > ******************************************************************************* > * Driver modes of operation in terms of display buffers used > ******************************************************************************* > Depending on the requirements for the para-virtualized environment, namely > requirements dictated by the accompanying DRM/(v)GPU drivers running in both > host and guest environments, number of operating modes of para-virtualized > display driver are supported: > - display buffers can be allocated by either frontend driver or backend > - display buffers can be allocated to be contiguous in memory or not > > Note! Frontend driver itself has no dependency on contiguous memory for > its operation. > > ******************************************************************************* > * 1. Buffers allocated by the frontend driver. > ******************************************************************************* > > The below modes of operation are configured at compile-time via > frontend driver's kernel configuration. > > 1.1. Front driver configured to use GEM CMA helpers > This use-case is useful when used with accompanying DRM/vGPU driver in > guest domain which was designed to only work with contiguous buffers, > e.g. DRM driver based on GEM CMA helpers: such drivers can only import > contiguous PRIME buffers, thus requiring frontend driver to provide > such. In order to implement this mode of operation para-virtualized > frontend driver can be configured to use GEM CMA helpers. > > 1.2. Front driver doesn't use GEM CMA > If accompanying drivers can cope with non-contiguous memory then, to > lower pressure on CMA subsystem of the kernel, driver can allocate > buffers from system memory. > > Note! If used with accompanying DRM/(v)GPU drivers this mode of operation > may require IOMMU support on the platform, so accompanying DRM/vGPU > hardware can still reach display buffer memory while importing PRIME > buffers from the frontend driver. > > ******************************************************************************* > * 2. Buffers allocated by the backend > ******************************************************************************* > > This mode of operation is run-time configured via guest domain configuration > through XenStore entries. > > For systems which do not provide IOMMU support, but having specific > requirements for display buffers it is possible to allocate such buffers > at backend side and share those with the frontend. > For example, if host domain is 1:1 mapped and has DRM/GPU hardware expecting > physically contiguous memory, this allows implementing zero-copying > use-cases. > > > I would like to thank at least, but not at last the following > people/communities who helped this driver to happen ;) > > 1. My team at EPAM for continuous support > 2. Xen community for answering tons of questions on different > modes of operation of the driver with respect to virtualized > environment. > 3. Rob Clark for "GEM allocation for para-virtualized DRM driver" [6] > 4. Maarten Lankhorst for "Atomic driver and old remove FB behavior" [7] > 5. Ville Syrjälä for "Questions on page flips and atomic modeset" [8] > > Thank you, > Oleksandr Andrushchenko > > P.S. There are two dependencies for this driver limiting some of the > use-cases which are on review now: > 1. "drm/simple_kms_helper: Add {enable|disable}_vblank callback support" [9] > 2. "drm/simple_kms_helper: Fix NULL pointer dereference with no active CRTC" [10] > > [1] https://wiki.xen.org/wiki/Paravirtualization_(PV)#PV_IO_Drivers > [2] https://elixir.bootlin.com/linux/v4.16-rc2/source/include/xen/interface/io/displif.h > [3] https://github.com/xen-troops/displ_be > [4] https://github.com/xen-troops/libxenbe > [5] https://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=docs/man/xl.cfg.pod.5.in;h=a699367779e2ae1212ff8f638eff0206ec1a1cc9;hb=refs/heads/master#l1257 > [6] https://lists.freedesktop.org/archives/dri-devel/2017-March/136038.html > [7] https://www.spinics.net/lists/dri-devel/msg164102.html > [8] https://www.spinics.net/lists/dri-devel/msg164463.html > [9] https://patchwork.freedesktop.org/series/38073/ > [10] https://patchwork.freedesktop.org/series/38139/ > > Oleksandr Andrushchenko (9): > drm/xen-front: Introduce Xen para-virtualized frontend driver > drm/xen-front: Implement Xen bus state handling > drm/xen-front: Read driver configuration from Xen store > drm/xen-front: Implement Xen event channel handling > drm/xen-front: Implement handling of shared display buffers > drm/xen-front: Introduce DRM/KMS virtual display driver > drm/xen-front: Implement KMS/connector handling > drm/xen-front: Implement GEM operations > drm/xen-front: Implement communication with backend > > drivers/gpu/drm/Kconfig | 2 + > drivers/gpu/drm/Makefile | 1 + > drivers/gpu/drm/xen/Kconfig | 30 ++ > drivers/gpu/drm/xen/Makefile | 17 + > drivers/gpu/drm/xen/xen_drm_front.c | 712 ++++++++++++++++++++++++++++ > drivers/gpu/drm/xen/xen_drm_front.h | 154 ++++++ > drivers/gpu/drm/xen/xen_drm_front_cfg.c | 84 ++++ > drivers/gpu/drm/xen/xen_drm_front_cfg.h | 45 ++ > drivers/gpu/drm/xen/xen_drm_front_conn.c | 125 +++++ > drivers/gpu/drm/xen/xen_drm_front_conn.h | 35 ++ > drivers/gpu/drm/xen/xen_drm_front_drv.c | 294 ++++++++++++ > drivers/gpu/drm/xen/xen_drm_front_drv.h | 73 +++ > drivers/gpu/drm/xen/xen_drm_front_evtchnl.c | 399 ++++++++++++++++ > drivers/gpu/drm/xen/xen_drm_front_evtchnl.h | 89 ++++ > drivers/gpu/drm/xen/xen_drm_front_gem.c | 360 ++++++++++++++ > drivers/gpu/drm/xen/xen_drm_front_gem.h | 46 ++ > drivers/gpu/drm/xen/xen_drm_front_gem_cma.c | 93 ++++ > drivers/gpu/drm/xen/xen_drm_front_kms.c | 299 ++++++++++++ > drivers/gpu/drm/xen/xen_drm_front_kms.h | 30 ++ > drivers/gpu/drm/xen/xen_drm_front_shbuf.c | 430 +++++++++++++++++ > drivers/gpu/drm/xen/xen_drm_front_shbuf.h | 80 ++++ > 21 files changed, 3398 insertions(+) > create mode 100644 drivers/gpu/drm/xen/Kconfig > create mode 100644 drivers/gpu/drm/xen/Makefile > create mode 100644 drivers/gpu/drm/xen/xen_drm_front.c > create mode 100644 drivers/gpu/drm/xen/xen_drm_front.h > create mode 100644 drivers/gpu/drm/xen/xen_drm_front_cfg.c > create mode 100644 drivers/gpu/drm/xen/xen_drm_front_cfg.h > create mode 100644 drivers/gpu/drm/xen/xen_drm_front_conn.c > create mode 100644 drivers/gpu/drm/xen/xen_drm_front_conn.h > create mode 100644 drivers/gpu/drm/xen/xen_drm_front_drv.c > create mode 100644 drivers/gpu/drm/xen/xen_drm_front_drv.h > create mode 100644 drivers/gpu/drm/xen/xen_drm_front_evtchnl.c > create mode 100644 drivers/gpu/drm/xen/xen_drm_front_evtchnl.h > create mode 100644 drivers/gpu/drm/xen/xen_drm_front_gem.c > create mode 100644 drivers/gpu/drm/xen/xen_drm_front_gem.h > create mode 100644 drivers/gpu/drm/xen/xen_drm_front_gem_cma.c > create mode 100644 drivers/gpu/drm/xen/xen_drm_front_kms.c > create mode 100644 drivers/gpu/drm/xen/xen_drm_front_kms.h > create mode 100644 drivers/gpu/drm/xen/xen_drm_front_shbuf.c > create mode 100644 drivers/gpu/drm/xen/xen_drm_front_shbuf.h > > -- > 2.7.4 >
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