While running 3D apps inside a Guest VM with a SRIOV enabled dGPU,
it was noticed that migrating a BO to System RAM before exporting
it as a dmabuf results in considerable performance degradation.
For example, running a simple 3D app such as weston-simple-egl
would yield ~44 FPS instead of ~59 FPS, assuming a mode of
1920x1080@60.
So, fix this issue by not migrating the BO and keep it in LMEM
during export if the P2P test (pci_p2pdma_distance()) succeeds.
However, since the GPU running in PF mode on the Host cannot
effectively access the PCI BAR addresses backing the imported
dmabuf BO, they need to be translated into LMEM addresses (DPAs)
to enable this use-case to work properly.
With this patch series applied, it would become possible to display
(via Qemu GTK UI) Guest VM compositor's framebuffer (created in its
LMEM) on the Host without having to make any copies of it or a
costly roundtrip to System RAM. And, weston-simple-egl can now
achieve ~59 FPS while running with Gnome Wayland in the Guest VM.
Changelog:
v3 -> v4:
- Drop the IS_SRIOV_VF() check in xe_dma_buf_pin() and instead rely
on Qemu's virtual PCI ports to make virtio-gpu P2P compatible
with VF
- Add an additional condition to check for Intel GPU in P2PDMA patch
(Logan)
- Ensure that a reference is taken on VF's backing object in LMEM
(Michal)
- Create a new type to store dma data for external dmabuf BOs
v2 -> v3:
- Rebased (and tested) on kernel 6.17.0-rc4 with B60
- Updated the commit message in the P2PDMA patch and other patches
v1 -> v2:
- Use a dma_addr array instead of SG table to store translated DMA
addresses (Matt)
- Use a cursor to iterate over the entries in the dma_addr array
instead of relying on SG iterator (Matt)
- Rebased and tested this series on top of the one that introduces
drm_pagemap_dma_addr and xe_res_first_dma/__xe_res_dma_next
that this version relies on
Patchset overview:
Patch 1: PCI driver patch to unblock P2P DMA between VF and PF
Patch 2: Prevent BO migration to System RAM while running in VM
Patch 3: Helper function to get VF's backing object in LMEM
Patch 4-5: Create and use a new dma_addr array for LMEM based
dmabuf BOs to store translated addresses (DPAs)
Associated Qemu patch series:
https://lore.kernel.org/qemu-devel/[email protected]/
Associated vfio-pci patch series:
https://lore.kernel.org/linux-mm/[email protected]/
This series is tested using the following method:
- Run Qemu with the following relevant options:
qemu-system-x86_64 -m 4096m ....
-device ioh3420,id=root_port1,bus=pcie.0
-device x3130-upstream,id=upstream1,bus=root_port1
-device xio3130-downstream,id=downstream1,bus=upstream1,chassis=9
-device xio3130-downstream,id=downstream2,bus=upstream1,chassis=10
-device vfio-pci,host=0000:03:00.1,bus=downstream1
-device virtio-gpu,max_outputs=1,blob=true,xres=1920,yres=1080,bus=downstream2
-display gtk,gl=on
-object memory-backend-memfd,id=mem1,size=4096M
-machine q35,accel=kvm,memory-backend=mem1 ...
- Run Gnome Wayland with the following options in the Guest VM:
# cat /usr/lib/udev/rules.d/61-mutter-primary-gpu.rules
ENV{DEVNAME}=="/dev/dri/card1", TAG+="mutter-device-preferred-primary",
TAG+="mutter-device-disable-kms-modifiers"
# XDG_SESSION_TYPE=wayland dbus-run-session -- /usr/bin/gnome-shell --wayland
--no-x11 &
Cc: Lucas De Marchi <[email protected]>
Cc: Thomas Hellström <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Michal Wajdeczko <[email protected]>
Cc: Matthew Brost <[email protected]>
Cc: Matthew Auld <[email protected]>
Cc: Dongwon Kim <[email protected]>
Vivek Kasireddy (5):
PCI/P2PDMA: Don't enforce ACS check for device functions of Intel GPUs
drm/xe/dmabuf: Don't migrate BO to System RAM if P2P check succeeds
drm/xe/pf: Add a helper function to get a VF's backing object in LMEM
drm/xe/bo: Create new dma_addr array for dmabuf BOs associated with
VFs
drm/xe/pt: Add an additional check for dmabuf BOs while doing bind
drivers/gpu/drm/xe/xe_bo.c | 101 ++++++++++++++++++++-
drivers/gpu/drm/xe/xe_bo_types.h | 12 +++
drivers/gpu/drm/xe/xe_dma_buf.c | 5 +-
drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c | 23 +++++
drivers/gpu/drm/xe/xe_gt_sriov_pf_config.h | 1 +
drivers/gpu/drm/xe/xe_pt.c | 8 ++
drivers/gpu/drm/xe/xe_sriov_pf_types.h | 19 ++++
drivers/pci/p2pdma.c | 15 ++-
8 files changed, 180 insertions(+), 4 deletions(-)
--
2.50.1
