kernel/linux.git/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.h, branch v6.12.80

drm/amdgpu: Replace Mutex with Spinlock for RLCG register access to avoid Priority Inversion in SRIOV

2025-07-17T16:37:01+00:00

commit dc0297f3198bd60108ccbd167ee5d9fa4af31ed0 upstream. RLCG Register Access is a way for virtual functions to safely access GPU registers in a virtualized environment., including TLB flushes and register reads. When multiple threads or VFs try to access the same registers simultaneously, it can lead to race conditions. By using the RLCG interface, the driver can serialize access to the registers. This means that only one thread can access the registers at a time, preventing conflicts and ensuring that operations are performed correctly. Additionally, when a low-priority task holds a mutex that a high-priority task needs, ie., If a thread holding a spinlock tries to acquire a mutex, it can lead to priority inversion. register access in amdgpu_virt_rlcg_reg_rw especially in a fast code path is critical. The call stack shows that the function amdgpu_virt_rlcg_reg_rw is being called, which attempts to acquire the mutex. This function is invoked from amdgpu_sriov_wreg, which in turn is called from gmc_v11_0_flush_gpu_tlb. The [ BUG: Invalid wait context ] indicates that a thread is trying to acquire a mutex while it is in a context that does not allow it to sleep (like holding a spinlock). Fixes the below: [ 253.013423] ============================= [ 253.013434] [ BUG: Invalid wait context ] [ 253.013446] 6.12.0-amdstaging-drm-next-lol-050225 #14 Tainted: G U OE [ 253.013464] ----------------------------- [ 253.013475] kworker/0:1/10 is trying to lock: [ 253.013487] ffff9f30542e3cf8 (&adev->virt.rlcg_reg_lock){+.+.}-{3:3}, at: amdgpu_virt_rlcg_reg_rw+0xf6/0x330 [amdgpu] [ 253.013815] other info that might help us debug this: [ 253.013827] context-{4:4} [ 253.013835] 3 locks held by kworker/0:1/10: [ 253.013847] #0: ffff9f3040050f58 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x3f5/0x680 [ 253.013877] #1: ffffb789c008be40 ((work_completion)(&wfc.work)){+.+.}-{0:0}, at: process_one_work+0x1d6/0x680 [ 253.013905] #2: ffff9f3054281838 (&adev->gmc.invalidate_lock){+.+.}-{2:2}, at: gmc_v11_0_flush_gpu_tlb+0x198/0x4f0 [amdgpu] [ 253.014154] stack backtrace: [ 253.014164] CPU: 0 UID: 0 PID: 10 Comm: kworker/0:1 Tainted: G U OE 6.12.0-amdstaging-drm-next-lol-050225 #14 [ 253.014189] Tainted: [U]=USER, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE [ 253.014203] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 11/18/2024 [ 253.014224] Workqueue: events work_for_cpu_fn [ 253.014241] Call Trace: [ 253.014250] [ 253.014260] dump_stack_lvl+0x9b/0xf0 [ 253.014275] dump_stack+0x10/0x20 [ 253.014287] __lock_acquire+0xa47/0x2810 [ 253.014303] ? srso_alias_return_thunk+0x5/0xfbef5 [ 253.014321] lock_acquire+0xd1/0x300 [ 253.014333] ? amdgpu_virt_rlcg_reg_rw+0xf6/0x330 [amdgpu] [ 253.014562] ? __lock_acquire+0xa6b/0x2810 [ 253.014578] __mutex_lock+0x85/0xe20 [ 253.014591] ? amdgpu_virt_rlcg_reg_rw+0xf6/0x330 [amdgpu] [ 253.014782] ? sched_clock_noinstr+0x9/0x10 [ 253.014795] ? srso_alias_return_thunk+0x5/0xfbef5 [ 253.014808] ? local_clock_noinstr+0xe/0xc0 [ 253.014822] ? amdgpu_virt_rlcg_reg_rw+0xf6/0x330 [amdgpu] [ 253.015012] ? srso_alias_return_thunk+0x5/0xfbef5 [ 253.015029] mutex_lock_nested+0x1b/0x30 [ 253.015044] ? mutex_lock_nested+0x1b/0x30 [ 253.015057] amdgpu_virt_rlcg_reg_rw+0xf6/0x330 [amdgpu] [ 253.015249] amdgpu_sriov_wreg+0xc5/0xd0 [amdgpu] [ 253.015435] gmc_v11_0_flush_gpu_tlb+0x44b/0x4f0 [amdgpu] [ 253.015667] gfx_v11_0_hw_init+0x499/0x29c0 [amdgpu] [ 253.015901] ? __pfx_smu_v13_0_update_pcie_parameters+0x10/0x10 [amdgpu] [ 253.016159] ? srso_alias_return_thunk+0x5/0xfbef5 [ 253.016173] ? smu_hw_init+0x18d/0x300 [amdgpu] [ 253.016403] amdgpu_device_init+0x29ad/0x36a0 [amdgpu] [ 253.016614] amdgpu_driver_load_kms+0x1a/0xc0 [amdgpu] [ 253.017057] amdgpu_pci_probe+0x1c2/0x660 [amdgpu] [ 253.017493] local_pci_probe+0x4b/0xb0 [ 253.017746] work_for_cpu_fn+0x1a/0x30 [ 253.017995] process_one_work+0x21e/0x680 [ 253.018248] worker_thread+0x190/0x330 [ 253.018500] ? __pfx_worker_thread+0x10/0x10 [ 253.018746] kthread+0xe7/0x120 [ 253.018988] ? __pfx_kthread+0x10/0x10 [ 253.019231] ret_from_fork+0x3c/0x60 [ 253.019468] ? __pfx_kthread+0x10/0x10 [ 253.019701] ret_from_fork_asm+0x1a/0x30 [ 253.019939] v2: s/spin_trylock/spin_lock_irqsave to be safe (Christian). Fixes: e864180ee49b ("drm/amdgpu: Add lock around VF RLCG interface") Cc: lin cao Cc: Jingwen Chen Cc: Victor Skvortsov Cc: Zhigang Luo Cc: Christian König Cc: Alex Deucher Signed-off-by: Srinivasan Shanmugam Suggested-by: Alex Deucher Reviewed-by: Christian König Signed-off-by: Alex Deucher [ Minor context change fixed. ] Signed-off-by: Wenshan Lan Signed-off-by: Greg Kroah-Hartman

drm/amdgpu: Disable dpm_enabled flag while VF is in reset

2024-08-13T16:12:52+00:00

VFs do not perform HW fini/suspend in FLR, so the dpm_enabled is incorrectly kept enabled. Add interface to disable it in virt_pre_reset call. v2: Made implementation generic for all asics v3: Re-order conditionals so PP_MP1_STATE_FLR is only evaluated on VF Signed-off-by: Victor Skvortsov Reviewed-by: Lijo Lazar Signed-off-by: Alex Deucher

drm/amdgpu: process RAS fatal error MB notification

2024-06-27T21:31:37+00:00

For RAS error scenario, VF guest driver will check mailbox and set fed flag to avoid unnecessary HW accesses. additionally, poll for reset completion message first to avoid accidentally spamming multiple reset requests to host. v2: add another mailbox check for handling case where kfd detects timeout first v3: set host_flr bit and use wait_for_reset Signed-off-by: Vignesh Chander Reviewed-by: Zhigang Luo Signed-off-by: Alex Deucher

drm/amdgpu: fix sriov host flr handler

2024-06-14T20:15:58+00:00

We send back the ready to reset message before we stop anything. This is wrong. Move it to when we are actually ready for the FLR to happen. In the current state since we take tens of seconds to stop everything, it is very likely that host would give up waiting and reset the GPU before we send ready, so it would be the same as before. But this gets rid of the hack with reset_domain locking and also let us tell how slow ready to reset actually is from the host. The ready to reset speed can be improved later. Signed-off-by: Yunxiang Li Acked-by: Christian König Reviewed-by: Emily Deng Signed-off-by: Alex Deucher

drm/amdgpu: Add lock around VF RLCG interface

2024-05-29T18:48:30+00:00

flush_gpu_tlb may be called from another thread while device_gpu_recover is running. Both of these threads access registers through the VF RLCG interface during VF Full Access. Add a lock around this interface to prevent race conditions between these threads. Signed-off-by: Victor Skvortsov Reviewed-by: Zhigang Luo Signed-off-by: Alex Deucher

amd/amdgpu: improve VF recover time

2024-04-10T02:14:30+00:00

1. change AMDGPU_VF2PF_UPDATE_MAX_RETRY_LIMIT from 30 to 5. 2. set fatel error detected flag. Signed-off-by: Zhigang Luo Reviewed-by: Lijo Lazar Signed-off-by: Alex Deucher

drm/amd/amdgpu: support MES command SET_HW_RESOURCE1 in sriov

2024-04-10T02:08:53+00:00

support MES command SET_HW_RESOURCE1 in sriov Signed-off-by: chongli2 Reviewed-by: Jingwen Chen Acked-by: Jingwen Chen Signed-off-by: Alex Deucher

drm/amdgpu: trigger flr_work if reading pf2vf data failed

2024-03-20T17:38:13+00:00

if reading pf2vf data failed 30 times continuously, it means something is wrong. Need to trigger flr_work to recover the issue. also use dev_err to print the error message to get which device has issue and add warning message if waiting IDH_FLR_NOTIFICATION_CMPL timeout. Signed-off-by: Zhigang Luo Acked-by: Hawking Zhang Signed-off-by: Alex Deucher

drm/amdgpu: Improve error checking in amdgpu_virt_rlcg_reg_rw (v2)

2024-02-22T15:27:23+00:00

The current error detection only looks for a timeout. This should be changed to also check scratch_reg1 for any errors returned from RLCG. v2: remove new error value Signed-off-by: Victor Lu Acked-by: Alex Deucher Signed-off-by: Alex Deucher

drm/amdgpu: Support passing poison consumption ras block to SRIOV

2024-01-25T19:58:03+00:00

Support passing poison consumption ras blocks to SRIOV. Signed-off-by: YiPeng Chai Reviewed-by: Hawking Zhang Signed-off-by: Alex Deucher