Re: [PATCH v2 07/29] drm/xe: Add SVM init / close / fini to faulting VMs

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

On Tue, 2024-10-15 at 20:24 -0700, Matthew Brost wrote:
> Add SVM init / close / fini to faulting VMs. Minimual implementation.
> 
> v2:
>  - Add close function
> 
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> ---
>  drivers/gpu/drm/xe/Makefile      |  1 +
>  drivers/gpu/drm/xe/xe_svm.c      | 46
> ++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_svm.h      | 15 +++++++++++
>  drivers/gpu/drm/xe/xe_vm.c       | 12 +++++++++
>  drivers/gpu/drm/xe/xe_vm_types.h |  7 +++++
>  5 files changed, 81 insertions(+)
>  create mode 100644 drivers/gpu/drm/xe/xe_svm.c
>  create mode 100644 drivers/gpu/drm/xe/xe_svm.h
> 
> diff --git a/drivers/gpu/drm/xe/Makefile
> b/drivers/gpu/drm/xe/Makefile
> index 8d991d4a92a5..c3e85bcfd4d1 100644
> --- a/drivers/gpu/drm/xe/Makefile
> +++ b/drivers/gpu/drm/xe/Makefile
> @@ -96,6 +96,7 @@ xe-y += drm_gpusvm.o \
>  	xe_sa.o \
>  	xe_sched_job.o \
>  	xe_step.o \
> +	xe_svm.o \
>  	xe_sync.o \
>  	xe_tile.o \
>  	xe_tile_sysfs.o \
> diff --git a/drivers/gpu/drm/xe/xe_svm.c
> b/drivers/gpu/drm/xe/xe_svm.c
> new file mode 100644
> index 000000000000..57b740367843
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_svm.c
> @@ -0,0 +1,46 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2024 Intel Corporation
> + */
> +
> +#include "drm_gpusvm.h"
> +
> +#include "xe_svm.h"
> +#include "xe_vm.h"
> +#include "xe_vm_types.h"
> +
> +static void xe_svm_invalidate(struct drm_gpusvm *gpusvm,
> +			      struct drm_gpusvm_notifier *notifier,
> +			      const struct mmu_notifier_range
> *mmu_range)
> +{
> +	/* TODO: Implement */
> +}
> +
> +static const struct drm_gpusvm_ops gpusvm_ops = {
> +	.invalidate = xe_svm_invalidate,
> +};
> +
> +static const u64 fault_chunk_sizes[] = {
> +	SZ_2M,
> +	SZ_64K,
> +	SZ_4K,
> +};
> +
> +int xe_svm_init(struct xe_vm *vm)
Kerneldoc + other undocumented extern funcs

> +{
> +	return drm_gpusvm_init(&vm->svm.gpusvm, "Xe SVM", &vm->xe-
> >drm,
> +			       current->mm, NULL, 0, vm->size,
> +			       SZ_512M, &gpusvm_ops,
> fault_chunk_sizes,
> +			       ARRAY_SIZE(fault_chunk_sizes));
> +}
> +
> +void xe_svm_close(struct xe_vm *vm)

> +{
> +}
> +
> +void xe_svm_fini(struct xe_vm *vm)
> +{
> +	xe_assert(vm->xe, xe_vm_is_closed(vm));
> +
> +	drm_gpusvm_fini(&vm->svm.gpusvm);
> +}
> diff --git a/drivers/gpu/drm/xe/xe_svm.h
> b/drivers/gpu/drm/xe/xe_svm.h
> new file mode 100644
> index 000000000000..979f2322eeba
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_svm.h
> @@ -0,0 +1,15 @@
> +/* SPDX-License-Identifier: MIT */
> +/*
> + * Copyright © 2024 Intel Corporation
> + */
> +
> +#ifndef _XE_SVM_H_
> +#define _XE_SVM_H_
> +
> +struct xe_vm;
> +
> +int xe_svm_init(struct xe_vm *vm);
> +void xe_svm_fini(struct xe_vm *vm);
> +void xe_svm_close(struct xe_vm *vm);
> +
> +#endif
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index 0d887fb9de59..b11fb0ac9520 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -35,6 +35,7 @@
>  #include "xe_preempt_fence.h"
>  #include "xe_pt.h"
>  #include "xe_res_cursor.h"
> +#include "xe_svm.h"
>  #include "xe_sync.h"
>  #include "xe_trace_bo.h"
>  #include "xe_wa.h"
> @@ -1503,6 +1504,12 @@ struct xe_vm *xe_vm_create(struct xe_device
> *xe, u32 flags)
>  		}
>  	}
>  
> +	if (flags & XE_VM_FLAG_FAULT_MODE) {
> +		err = xe_svm_init(vm);
> +		if (err)
> +			goto err_close;
> +	}
> +
>  	if (number_tiles > 1)
>  		vm->composite_fence_ctx =
> dma_fence_context_alloc(1);
>  
> @@ -1548,6 +1555,8 @@ void xe_vm_close_and_put(struct xe_vm *vm)
>  	xe_vm_close(vm);
>  	if (xe_vm_in_preempt_fence_mode(vm))
>  		flush_work(&vm->preempt.rebind_work);
> +	if (xe_vm_in_fault_mode(vm))
> +		xe_svm_close(vm);
>  
>  	down_write(&vm->lock);
>  	for_each_tile(tile, xe, id) {
> @@ -1616,6 +1625,9 @@ void xe_vm_close_and_put(struct xe_vm *vm)
>  		xe_vma_destroy_unlocked(vma);
>  	}
>  
> +	if (xe_vm_in_fault_mode(vm))
> +		xe_svm_fini(vm);
> +
>  	up_write(&vm->lock);
>  
>  	down_write(&xe->usm.lock);
> diff --git a/drivers/gpu/drm/xe/xe_vm_types.h
> b/drivers/gpu/drm/xe/xe_vm_types.h
> index 1764781c376b..bd1c0e368238 100644
> --- a/drivers/gpu/drm/xe/xe_vm_types.h
> +++ b/drivers/gpu/drm/xe/xe_vm_types.h
> @@ -6,6 +6,7 @@
>  #ifndef _XE_VM_TYPES_H_
>  #define _XE_VM_TYPES_H_
>  
> +#include "drm_gpusvm.h"
>  #include <drm/drm_gpuvm.h>
>  
>  #include <linux/dma-resv.h>
> @@ -140,6 +141,12 @@ struct xe_vm {
>  	/** @gpuvm: base GPUVM used to track VMAs */
>  	struct drm_gpuvm gpuvm;
>  
> +	/** @svm: Shared virtual memory state */
> +	struct {
> +		/** @svm.gpusvm: base GPUSVM used to track fault
> allocations */
> +		struct drm_gpusvm gpusvm;
> +	} svm;
> +
>  	struct xe_device *xe;
>  
>  	/* exec queue used for (un)binding vma's */

Thanks,
Thomas