drm/virtio: Add option to disable KMS support

Add a build option to disable modesetting support. This is useful in
cases where the guest only needs to use the GPU in a headless mode, or
(such as in the CrOS usage) window surfaces are proxied to a host
compositor.

As the modesetting ioctls are a big surface area for potential security
bugs to be found (it's happened in the past, we should assume it will
again in the future), it makes sense to have a build option to disable
those ioctls in cases where they serve no legitimate purpose.

v2: Use more if (IS_ENABLED(...))
v3: Also permit the host to advertise no scanouts
v4: Spiff out commit msg
v5: Make num_scanouts==0 and DRM_VIRTIO_GPU_KMS=n behave the same
v6: Drop conditionally building virtgpu_display.c and early-out of
it's init/fini fxns instead

Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230302233506.3146290-1-robdclark@gmail.com

drivers: gpu: drm: virtio: fix dependency of DRM_VIRTIO_GPU on VIRTIO

VIRTIO itself has no dependencies and therefore can easily be just
select'ed, instead of depending on it. The current depends on causes
any others trying to select VIRTIO to fail like this:

drivers/gpu/drm/Kconfig:74:error: recursive dependency detected!
drivers/gpu/drm/Kconfig:74: symbol DRM_KMS_HELPER is selected by DRM_VIRTIO_GPU
drivers/gpu/drm/virtio/Kconfig:2: symbol DRM_VIRTIO_GPU depends on VIRTIO
drivers/virtio/Kconfig:2: symbol VIRTIO is selected by GPIO_VIRTIO
drivers/gpio/Kconfig:1618: symbol GPIO_VIRTIO depends on GPIOLIB
drivers/gpio/Kconfig:14: symbol GPIOLIB is selected by I2C_MUX_LTC4306
drivers/i2c/muxes/Kconfig:47: symbol I2C_MUX_LTC4306 depends on I2C
drivers/i2c/Kconfig:8: symbol I2C is selected by FB_DDC
drivers/video/fbdev/Kconfig:63: symbol FB_DDC depends on FB
drivers/video/fbdev/Kconfig:12: symbol FB is selected by DRM_KMS_FB_HELPER
drivers/gpu/drm/Kconfig:80: symbol DRM_KMS_FB_HELPER depends on DRM_KMS_HELPER

It seems that having both 'depends on' as well as 'select' on the same symbol
sends us into big trouble, and Kconfig can't break up the circular dependency
(note that in the tested configuration, neither I2C, FB or DRM are enabled at
all). Perhaps we could consider this a bug in Kconfig, but the trouble can
easily be circumvented by changing 'depends on' into 'select'.

DRM_VIRTIO_GPU also depends on VIRTIO_MENU, so even after this change, that
option will only show up if the user already enabled virtio in the config.

This change didn't cause any changes in the .config after menuconfig run,
so we should be completely safe here.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Reviewed-by: Anthoine Bourgeois <anthoine.bourgeois@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20201204131221.2827-1-info@metux.net
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

drm: virtio: fix kconfig dependency warning

Fix kconfig dependency warning by using a different Kconfig symbol.

WARNING: unmet direct dependencies detected for VIRTIO_DMA_SHARED_BUFFER
Depends on [n]: VIRTIO_MENU [=n] && DMA_SHARED_BUFFER [=y]
Selected by [y]:
- DRM_VIRTIO_GPU [=y] && HAS_IOMEM [=y] && DRM [=y] && VIRTIO [=y] && MMU [=y]

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: http://patchwork.freedesktop.org/patch/msgid/7481fb88-6b04-3726-57e0-0f513245c657@infradead.org
Cc: David Airlie <airlied@linux.ie>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

virtio: fix build for configs without dma-bufs

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: David Stevens <stevensd@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20200819031011.310180-1-stevensd@chromium.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

drm/virtio: switch from ttm to gem shmem helpers

virtio-gpu basically needs a sg_table for the bo, to tell the host where
the backing pages for the object are. So the gem shmem helpers are a
perfect fit. Some drm_gem_object_funcs need thin wrappers to update the
host state, but otherwise the helpers handle everything just fine.

Once the fencing was sorted the switch was surprisingly easy and for the
most part just removing the ttm code.

v4: fix drm_gem_object_funcs name.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20190829103301.3539-15-kraxel@redhat.com

treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drm: fix compilations issues introduced by "drm: allow to use mmuless SoC"

Removing MMU configuration flag from DRM make few automatic
build failed when they answer yes to all flags.

Add asm/vga.h file on Blackfin architecture to not broke compilation.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Fixes: 62a0d98a188c ("drm: allow to use mmuless SoC")
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1483789151-6603-1-git-send-email-benjamin.gaignard@linaro.org

drm/virtio: kconfig: Fixup white space.

Use tabs instead of spaces.

Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1475913318-12275-1-git-send-email-peter.griffin@linaro.org
Link: http://patchwork.freedesktop.org/patch/msgid/1476238699-25820-1-git-send-email-jiang.biao2@zte.com.cn

drm/virtio: make fbdev support really optional

Currently enabling VirtIO DRM support automatically pulls in
fbdev dependency. However this dep is unnecessary since
DRM core already handles this for us (DRM_FBDEV_EMULATION).

Signed-off-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1468586897-32298-19-git-send-email-tjakobi@math.uni-bielefeld.de

Add virtio gpu driver.

This patch adds a kms driver for the virtio gpu. The xorg modesetting
driver can handle the device just fine, the framebuffer for fbcon is
there too.

Qemu patches for the host side are under review currently.

The pci version of the device comes in two variants: with and without
vga compatibility. The former has a extra memory bar for the vga
framebuffer, the later is a pure virtio device. The only concern for
this driver is that in the virtio-vga case we have to kick out the
firmware framebuffer.

Initial revision has only 2d support, 3d (virgl) support requires
some more work on the qemu side and will be added later.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>