[PATCH v4 00/14] RFC Support hot device unplug in amdgpu
Andrey Grodzovsky
Andrey.Grodzovsky at amd.com
Mon Feb 8 05:59:10 UTC 2021
On 1/20/21 10:59 AM, Daniel Vetter wrote:
> On Wed, Jan 20, 2021 at 3:20 PM Andrey Grodzovsky
> <Andrey.Grodzovsky at amd.com> wrote:
>>
>> On 1/20/21 4:05 AM, Daniel Vetter wrote:
>>> On Tue, Jan 19, 2021 at 01:18:15PM -0500, Andrey Grodzovsky wrote:
>>>> On 1/19/21 1:08 PM, Daniel Vetter wrote:
>>>>> On Tue, Jan 19, 2021 at 6:31 PM Andrey Grodzovsky
>>>>> <Andrey.Grodzovsky at amd.com> wrote:
>>>>>> On 1/19/21 9:16 AM, Daniel Vetter wrote:
>>>>>>> On Mon, Jan 18, 2021 at 04:01:09PM -0500, Andrey Grodzovsky wrote:
>>>>>>>> Until now extracting a card either by physical extraction (e.g. eGPU with
>>>>>>>> thunderbolt connection or by emulation through syfs -> /sys/bus/pci/devices/device_id/remove)
>>>>>>>> would cause random crashes in user apps. The random crashes in apps were
>>>>>>>> mostly due to the app having mapped a device backed BO into its address
>>>>>>>> space was still trying to access the BO while the backing device was gone.
>>>>>>>> To answer this first problem Christian suggested to fix the handling of mapped
>>>>>>>> memory in the clients when the device goes away by forcibly unmap all buffers the
>>>>>>>> user processes has by clearing their respective VMAs mapping the device BOs.
>>>>>>>> Then when the VMAs try to fill in the page tables again we check in the fault
>>>>>>>> handlerif the device is removed and if so, return an error. This will generate a
>>>>>>>> SIGBUS to the application which can then cleanly terminate.This indeed was done
>>>>>>>> but this in turn created a problem of kernel OOPs were the OOPSes were due to the
>>>>>>>> fact that while the app was terminating because of the SIGBUSit would trigger use
>>>>>>>> after free in the driver by calling to accesses device structures that were already
>>>>>>>> released from the pci remove sequence.This was handled by introducing a 'flush'
>>>>>>>> sequence during device removal were we wait for drm file reference to drop to 0
>>>>>>>> meaning all user clients directly using this device terminated.
>>>>>>>>
>>>>>>>> v2:
>>>>>>>> Based on discussions in the mailing list with Daniel and Pekka [1] and based on the document
>>>>>>>> produced by Pekka from those discussions [2] the whole approach with returning SIGBUS and
>>>>>>>> waiting for all user clients having CPU mapping of device BOs to die was dropped.
>>>>>>>> Instead as per the document suggestion the device structures are kept alive until
>>>>>>>> the last reference to the device is dropped by user client and in the meanwhile all existing and new CPU mappings of the BOs
>>>>>>>> belonging to the device directly or by dma-buf import are rerouted to per user
>>>>>>>> process dummy rw page.Also, I skipped the 'Requirements for KMS UAPI' section of [2]
>>>>>>>> since i am trying to get the minimal set of requirements that still give useful solution
>>>>>>>> to work and this is the'Requirements for Render and Cross-Device UAPI' section and so my
>>>>>>>> test case is removing a secondary device, which is render only and is not involved
>>>>>>>> in KMS.
>>>>>>>>
>>>>>>>> v3:
>>>>>>>> More updates following comments from v2 such as removing loop to find DRM file when rerouting
>>>>>>>> page faults to dummy page,getting rid of unnecessary sysfs handling refactoring and moving
>>>>>>>> prevention of GPU recovery post device unplug from amdgpu to scheduler layer.
>>>>>>>> On top of that added unplug support for the IOMMU enabled system.
>>>>>>>>
>>>>>>>> v4:
>>>>>>>> Drop last sysfs hack and use sysfs default attribute.
>>>>>>>> Guard against write accesses after device removal to avoid modifying released memory.
>>>>>>>> Update dummy pages handling to on demand allocation and release through drm managed framework.
>>>>>>>> Add return value to scheduler job TO handler (by Luben Tuikov) and use this in amdgpu for prevention
>>>>>>>> of GPU recovery post device unplug
>>>>>>>> Also rebase on top of drm-misc-mext instead of amd-staging-drm-next
>>>>>>>>
>>>>>>>> With these patches I am able to gracefully remove the secondary card using sysfs remove hook while glxgears
>>>>>>>> is running off of secondary card (DRI_PRIME=1) without kernel oopses or hangs and keep working
>>>>>>>> with the primary card or soft reset the device without hangs or oopses
>>>>>>>>
>>>>>>>> TODOs for followup work:
>>>>>>>> Convert AMDGPU code to use devm (for hw stuff) and drmm (for sw stuff and allocations) (Daniel)
>>>>>>>> Support plugging the secondary device back after unplug - currently still experiencing HW error on plugging back.
>>>>>>>> Add support for 'Requirements for KMS UAPI' section of [2] - unplugging primary, display connected card.
>>>>>>>>
>>>>>>>> [1] - Discussions during v3 of the patchset https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.spinics.net%2Flists%2Famd-gfx%2Fmsg55576.html&data=04%7C01%7CAndrey.Grodzovsky%40amd.com%7Cf3fc3c7b55df40e165f408d8bd5c7364%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637467552072067767%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=fjgP9YubHCrILFxWmpVGSmurTJHkWw%2Bv4okyjSNsPxE%3D&reserved=0
>>>>>>>> [2] - drm/doc: device hot-unplug for userspace https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.spinics.net%2Flists%2Fdri-devel%2Fmsg259755.html&data=04%7C01%7CAndrey.Grodzovsky%40amd.com%7Cf3fc3c7b55df40e165f408d8bd5c7364%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637467552072067767%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=11PYyAhOjLDEiNNho8WaMB%2FLkA5AuxK6g9XpbNiPIec%3D&reserved=0
>>>>>>>> [3] - Related gitlab ticket https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.freedesktop.org%2Fdrm%2Famd%2F-%2Fissues%2F1081&data=04%7C01%7CAndrey.Grodzovsky%40amd.com%7Cf3fc3c7b55df40e165f408d8bd5c7364%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637467552072077759%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=q%2F%2FXDKm9LOgw9mq4Ts4JoHR8Ysd8KmoM0NGLD98MsFw%3D&reserved=0
>>>>>>> btw have you tried this out with some of the igts we have? core_hotunplug
>>>>>>> is the one I'm thinking of. Might be worth to extend this for amdgpu
>>>>>>> specific stuff (like run some batches on it while hotunplugging).
>>>>>> No, I mostly used just running glxgears while testing which covers already
>>>>>> exported/imported dma-buf case and a few manually hacked tests in libdrm amdgpu
>>>>>> test suite
>>>>>>
>>>>>>
>>>>>>> Since there's so many corner cases we need to test here (shared dma-buf,
>>>>>>> shared dma_fence) I think it would make sense to have a shared testcase
>>>>>>> across drivers.
>>>>>> Not familiar with IGT too much, is there an easy way to setup shared dma bufs
>>>>>> and fences
>>>>>> use cases there or you mean I need to add them now ?
>>>>> We do have test infrastructure for all of that, but the hotunplug test
>>>>> doesn't have that yet I think.
>>>>>
>>>>>>> Only specific thing would be some hooks to keep the gpu
>>>>>>> busy in some fashion while we yank the driver.
>>>>>> Do you mean like staring X and some active rendering on top (like glxgears)
>>>>>> automatically from within IGT ?
>>>>> Nope, igt is meant to be bare metal testing so you don't have to drag
>>>>> the entire winsys around (which in a wayland world, is not really good
>>>>> for driver testing anyway, since everything is different). We use this
>>>>> for our pre-merge ci for drm/i915.
>>>> So i keep it busy by X/glxgers which is manual operation. What you suggest
>>>> then is some client within IGT which opens the device and starts submitting jobs
>>>> (which is much like what libdrm amdgpu tests already do) ? And this
>>>> part is the amdgou specific code I just need to port from libdrm to here ?
>>> Yup. For i915 tests we have an entire library already for small workloads,
>>> including some that just spin forever (useful for reset testing and could
>>> also come handy for unload testing).
>>> -Daniel
>>
>> Does it mean I would have to drag in the entire infrastructure code from
>> within libdrm amdgpu code that allows for command submissions through
>> our IOCTLs ?
> No it's perfectly fine to use libdrm in igt tests, we do that too. I
> just mean we have some additional helpers to submit specific workloads
> for intel gpu, like rendercpy to move data with the 3d engine (just
> using copy engines only isn't good enough sometimes for testing), or
> the special hanging batchbuffers we use for reset testing, or in
> general for having precise control over race conditions and things
> like that.
>
> One thing that was somewhat annoying for i915 but shouldn't be a
> problem for amdgpu is that igt builds on intel. So we have stub
> functions for libdrm-intel, since libdrm-intel doesn't build on arm.
> Shouldn't be a problem for you.
> -Daniel
Tested with igt hot-unplug test. Passed unbind_rebind, unplug-rescan,
hot-unbind-rebind and hotunplug-rescan
if disabling the rescan part as I don't support plug-back for now. Also added
command submission for amdgpu.
Attached a draft of submitting workload while unbinding the driver or simulating
detach. Catched 2 issues with unpug if command submission in flight during
unplug -
(unsignaled fence causing a hang in amdgpu_cs_sync and hitting a BUG_ON in
gfx_v9_0_ring_emit_patch_cond_exec whic is expected i guess).
Guess glxgears command submissions is at a much slower rate so this was missed.
Is that what you meant for this test ?
Andrey
>
>
>> Andrey
>>
>>>> Andrey
>>>>
>>>>
>>>>>>> But just to get it started
>>>>>>> you can throw in entirely amdgpu specific subtests and just share some of
>>>>>>> the test code.
>>>>>>> -Daniel
>>>>>> Im general, I wasn't aware of this test suite and looks like it does what i test
>>>>>> among other stuff.
>>>>>> I will definitely try to run with it although the rescan part will not work as
>>>>>> plugging
>>>>>> the device back is in my TODO list and not part of the scope for this patchset
>>>>>> and so I will
>>>>>> probably comment the re-scan section out while testing.
>>>>> amd gem has been using libdrm-amd thus far iirc, but for things like
>>>>> this I think it'd be worth to at least consider switching. Display
>>>>> team has already started to use some of the test and contribute stuff
>>>>> (I think the VRR testcase is from amd).
>>>>> -Daniel
>>>>>
>>>>>> Andrey
>>>>>>
>>>>>>
>>>>>>>> Andrey Grodzovsky (13):
>>>>>>>> drm/ttm: Remap all page faults to per process dummy page.
>>>>>>>> drm: Unamp the entire device address space on device unplug
>>>>>>>> drm/ttm: Expose ttm_tt_unpopulate for driver use
>>>>>>>> drm/sched: Cancel and flush all oustatdning jobs before finish.
>>>>>>>> drm/amdgpu: Split amdgpu_device_fini into early and late
>>>>>>>> drm/amdgpu: Add early fini callback
>>>>>>>> drm/amdgpu: Register IOMMU topology notifier per device.
>>>>>>>> drm/amdgpu: Fix a bunch of sdma code crash post device unplug
>>>>>>>> drm/amdgpu: Remap all page faults to per process dummy page.
>>>>>>>> dmr/amdgpu: Move some sysfs attrs creation to default_attr
>>>>>>>> drm/amdgpu: Guard against write accesses after device removal
>>>>>>>> drm/sched: Make timeout timer rearm conditional.
>>>>>>>> drm/amdgpu: Prevent any job recoveries after device is unplugged.
>>>>>>>>
>>>>>>>> Luben Tuikov (1):
>>>>>>>> drm/scheduler: Job timeout handler returns status
>>>>>>>>
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu.h | 11 +-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c | 17 +--
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 149 ++++++++++++++++++++--
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 20 ++-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c | 15 ++-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c | 2 +-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_gart.h | 1 +
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c | 9 ++
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c | 25 ++--
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_irq.c | 26 ++--
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_irq.h | 3 +-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_job.c | 19 ++-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c | 12 +-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 10 ++
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_object.h | 2 +
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c | 53 +++++---
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_psp.h | 3 +
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c | 1 +
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c | 70 ++++++++++
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h | 52 +-------
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 21 ++-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 8 +-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 14 +-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/cik_ih.c | 2 +-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/cz_ih.c | 2 +-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/iceland_ih.c | 2 +-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/navi10_ih.c | 2 +-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/psp_v11_0.c | 16 +--
>>>>>>>> drivers/gpu/drm/amd/amdgpu/psp_v12_0.c | 8 +-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/psp_v3_1.c | 8 +-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/si_ih.c | 2 +-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/tonga_ih.c | 2 +-
>>>>>>>> drivers/gpu/drm/amd/amdgpu/vega10_ih.c | 2 +-
>>>>>>>> drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 12 +-
>>>>>>>> drivers/gpu/drm/amd/include/amd_shared.h | 2 +
>>>>>>>> drivers/gpu/drm/drm_drv.c | 3 +
>>>>>>>> drivers/gpu/drm/etnaviv/etnaviv_sched.c | 10 +-
>>>>>>>> drivers/gpu/drm/lima/lima_sched.c | 4 +-
>>>>>>>> drivers/gpu/drm/panfrost/panfrost_job.c | 9 +-
>>>>>>>> drivers/gpu/drm/scheduler/sched_main.c | 18 ++-
>>>>>>>> drivers/gpu/drm/ttm/ttm_bo_vm.c | 82 +++++++++++-
>>>>>>>> drivers/gpu/drm/ttm/ttm_tt.c | 1 +
>>>>>>>> drivers/gpu/drm/v3d/v3d_sched.c | 32 ++---
>>>>>>>> include/drm/gpu_scheduler.h | 17 ++-
>>>>>>>> include/drm/ttm/ttm_bo_api.h | 2 +
>>>>>>>> 45 files changed, 583 insertions(+), 198 deletions(-)
>>>>>>>>
>>>>>>>> --
>>>>>>>> 2.7.4
>>>>>>>>
>
>
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