[Public]
> -----Original Message-----
> From: Kuehling, Felix <felix.kuehl...@amd.com>
> Sent: Thursday, April 24, 2025 9:56 PM
> To: Xiao, Shane <shane.x...@amd.com>; amd-gfx@lists.freedesktop.org;
> Koenig, Christian <christian.koe...@amd.com>; Yang, Philip
> <philip.y...@amd.com>
> Subject: Re: [PATCH 2/2] amd/amdkfd: Trigger segfault for early userptr
> unmmapping
>
>
> On 2025-04-24 0:54, Shane Xiao wrote:
> > If applications unmap the memory before destroying the userptr, it
> > needs trigger a segfault to notify user space to correct the free
> > sequence in VM debug mode.
> >
> > v2: Send GPU access fault to user space
>
> See some comments inline.
>
>
> >
> > Signed-off-by: Shane Xiao <shane.x...@amd.com>
> > ---
> > .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 14 +++++++++++++
> > drivers/gpu/drm/amd/amdkfd/kfd_events.c | 20 +++++++++++++++++++
> > drivers/gpu/drm/amd/amdkfd/kfd_priv.h | 3 +++
> > 3 files changed, 37 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> > index d2ec4130a316..876e9df34adf 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> > @@ -2496,6 +2496,7 @@ static int update_invalid_user_pages(struct
> amdkfd_process_info *process_info,
> > struct ttm_operation_ctx ctx = { false, false };
> > uint32_t invalid;
> > int ret = 0;
> > + uint64_t userptr = 0;
> >
> > mutex_lock(&process_info->notifier_lock);
> >
> > @@ -2559,6 +2560,19 @@ static int update_invalid_user_pages(struct
> amdkfd_process_info *process_info,
> > if (ret != -EFAULT)
> > return ret;
> >
> > + /* If applications unmap memory before destroying the
> userptr
> > + * from the KFD, trigger a segmentation fault in VM
> debug mode.
> > + */
> > + if (amdgpu_ttm_adev(bo->tbo.bdev)-
> >debug_vm_userptr) {
> > + amdgpu_ttm_tt_get_userptr(&bo->tbo,
> userptr);
>
> I think you meant &userptr. But this will get you the CPU address of the
> userptr,
> not the GPU address. For reporting a GPU fault it would make more sense to use
> the GPU address in mem->va.
Yes, will use gpu address to notify user space.
>
>
> > + pr_err("User space unmap memory before
> destroying a userptr that refers to it\n");
> > + pr_err("The unmap userptr address is
> 0x%llx\n", userptr);
> > +
> > + // Send GPU VM fault to user space
> > +
> kfd_signal_vm_fault_event_with_userptr(kfd_lookup_process_by_pid(pr
> ocess_info->pid),
> > + amdgpu_ttm_adev(bo-
> >tbo.bdev)->kfd.dev, userptr);
> > + }
> > +
> > ret = 0;
> > }
> >
> > diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_events.c
> > b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
> > index fecdb6794075..89943d2146a4 100644
> > --- a/drivers/gpu/drm/amd/amdkfd/kfd_events.c
> > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
> > @@ -1177,6 +1177,26 @@ void kfd_signal_hw_exception_event(u32 pasid)
> > kfd_unref_process(p);
> > }
> >
> > +void kfd_signal_vm_fault_event_with_userptr(struct kfd_process *p,
> > + struct kfd_dev *dev , uint64_t userptr)
>
> dev seems to be unused. You can remove that parameter.
Sure, will update it accordingly.
Best Regards,
Shane
>
> Regards,
> Felix
>
>
> > +{
> > + struct kfd_process_device *pdd;
> > + struct kfd_hsa_memory_exception_data exception_data;
> > + int i;
> > +
> > + memset(&exception_data, 0, sizeof(exception_data));
> > + exception_data.va = userptr;
> > + exception_data.failure.NotPresent = 1;
> > +
> > + // Send VM seg fault to all kfd process device
> > + for (i = 0; i < p->n_pdds; i++) {
> > + pdd = p->pdds[i];
> > + exception_data.gpu_id = pdd->user_gpu_id;
> > + kfd_evict_process_device(pdd);
> > + kfd_signal_vm_fault_event(pdd, NULL, &exception_data);
> > + }
> > +}
> > +
> > void kfd_signal_vm_fault_event(struct kfd_process_device *pdd,
> > struct kfd_vm_fault_info *info,
> > struct kfd_hsa_memory_exception_data *data)
> diff --git
> > a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> > b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> > index f6aedf69c644..34f47dc1cbbd 100644
> > --- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> > @@ -1507,6 +1507,9 @@ int kfd_event_create(struct file *devkfd, struct
> > kfd_process *p, int kfd_get_num_events(struct kfd_process *p); int
> > kfd_event_destroy(struct kfd_process *p, uint32_t event_id);
> >
> > +void kfd_signal_vm_fault_event_with_userptr(struct kfd_process *p,
> > + struct kfd_dev *dev , uint64_t userptr);
> > +
> > void kfd_signal_vm_fault_event(struct kfd_process_device *pdd,
> > struct kfd_vm_fault_info *info,
> > struct kfd_hsa_memory_exception_data
> *data);
