Re: [PATCH 4/6] drm/amdkfd: Export DMABufs from KFD using GEM handles

[Christian König <christian.koenig@xxxxxxx>]

Am 16.11.23 um 22:53 schrieb Felix Kuehling:
> On 2023-11-07 11:58, Felix Kuehling wrote:
> > Create GEM handles for exporting DMABufs using GEM-Prime APIs. The GEM
> > handles are created in a drm_client_dev context to avoid exposing them
> > in user mode contexts through a DMABuf import.
> This patch (and the next one) won't apply upstream because Thomas 
> Zimmerman just made drm_gem_prime_fd_to_handle and 
> drm_gem_prime_handle_to_fd private because nobody was using them. 
> (drm/prime: Unexport helpers for fd/handle conversion)
>
> Is it OK to export those APIs again? Or is there a better way for 
> drivers to export/import DMABufs without using the GEM ioctls?

Well let me say so: I think it's the least evil approach :)

So yeah, propose a patch to export them again.

Regards,
Christian.

> Regards,
>   Felix
>
>
> > Signed-off-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
> > ---
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c    | 11 +++++++
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h    |  5 +++
> >   .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c  | 33 +++++++++++++++----
> >   drivers/gpu/drm/amd/amdkfd/kfd_chardev.c      |  4 +--
> >   4 files changed, 44 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
> > index 6ab17330a6ed..b0a67f16540a 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
> > @@ -142,6 +142,7 @@ void amdgpu_amdkfd_device_init(struct 
> > amdgpu_device *adev)
> >   {
> >       int i;
> >       int last_valid_bit;
> > +    int ret;
> >         amdgpu_amdkfd_gpuvm_init_mem_limits();
> >   @@ -160,6 +161,12 @@ void amdgpu_amdkfd_device_init(struct 
> > amdgpu_device *adev)
> >               .enable_mes = adev->enable_mes,
> >           };
> >   +        ret = drm_client_init(&adev->ddev, &adev->kfd.client, 
> > "kfd", NULL);
> > +        if (ret) {
> > +            dev_err(adev->dev, "Failed to init DRM client: %d\n", ret);
> > +            return;
> > +        }
> > +
> >           /* this is going to have a few of the MSBs set that we need to
> >            * clear
> >            */
> > @@ -198,6 +205,10 @@ void amdgpu_amdkfd_device_init(struct 
> > amdgpu_device *adev)
> >             adev->kfd.init_complete = kgd2kfd_device_init(adev->kfd.dev,
> >                               &gpu_resources);
> > +        if (adev->kfd.init_complete)
> > +            drm_client_register(&adev->kfd.client);
> > +        else
> > +            drm_client_release(&adev->kfd.client);
> >             amdgpu_amdkfd_total_mem_size += adev->gmc.real_vram_size;
> >   diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> > index 68d534a89942..4caf8cece028 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> > @@ -32,6 +32,7 @@
> >   #include <linux/mmu_notifier.h>
> >   #include <linux/memremap.h>
> >   #include <kgd_kfd_interface.h>
> > +#include <drm/drm_client.h>
> >   #include <drm/ttm/ttm_execbuf_util.h>
> >   #include "amdgpu_sync.h"
> >   #include "amdgpu_vm.h"
> > @@ -84,6 +85,7 @@ struct kgd_mem {
> >         struct amdgpu_sync sync;
> >   +    uint32_t gem_handle;
> >       bool aql_queue;
> >       bool is_imported;
> >   };
> > @@ -106,6 +108,9 @@ struct amdgpu_kfd_dev {
> >         /* HMM page migration MEMORY_DEVICE_PRIVATE mapping */
> >       struct dev_pagemap pgmap;
> > +
> > +    /* Client for KFD BO GEM handle allocations */
> > +    struct drm_client_dev client;
> >   };
> >     enum kgd_engine_type {
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> > index 0c1cb6048259..4bb8b5fd7598 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> > @@ -25,6 +25,7 @@
> >   #include <linux/pagemap.h>
> >   #include <linux/sched/mm.h>
> >   #include <linux/sched/task.h>
> > +#include <linux/fdtable.h>
> >   #include <drm/ttm/ttm_tt.h>
> >     #include "amdgpu_object.h"
> > @@ -804,13 +805,22 @@ kfd_mem_dmaunmap_attachment(struct kgd_mem *mem,
> >   static int kfd_mem_export_dmabuf(struct kgd_mem *mem)
> >   {
> >       if (!mem->dmabuf) {
> > -        struct dma_buf *ret = amdgpu_gem_prime_export(
> > -            &mem->bo->tbo.base,
> > +        struct amdgpu_device *bo_adev;
> > +        struct dma_buf *dmabuf;
> > +        int r, fd;
> > +
> > +        bo_adev = amdgpu_ttm_adev(mem->bo->tbo.bdev);
> > +        r = drm_gem_prime_handle_to_fd(&bo_adev->ddev, 
> > bo_adev->kfd.client.file,
> > +                           mem->gem_handle,
> >               mem->alloc_flags & KFD_IOC_ALLOC_MEM_FLAGS_WRITABLE ?
> > -                DRM_RDWR : 0);
> > -        if (IS_ERR(ret))
> > -            return PTR_ERR(ret);
> > -        mem->dmabuf = ret;
> > +                           DRM_RDWR : 0, &fd);
> > +        if (r)
> > +            return r;
> > +        dmabuf = dma_buf_get(fd);
> > +        close_fd(fd);
> > +        if (WARN_ON_ONCE(IS_ERR(dmabuf)))
> > +            return PTR_ERR(dmabuf);
> > +        mem->dmabuf = dmabuf;
> >       }
> >         return 0;
> > @@ -1826,6 +1836,9 @@ int amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu(
> >           pr_debug("Failed to allow vma node access. ret %d\n", ret);
> >           goto err_node_allow;
> >       }
> > +    ret = drm_gem_handle_create(adev->kfd.client.file, gobj, 
> > &(*mem)->gem_handle);
> > +    if (ret)
> > +        goto err_gem_handle_create;
> >       bo = gem_to_amdgpu_bo(gobj);
> >       if (bo_type == ttm_bo_type_sg) {
> >           bo->tbo.sg = sg;
> > @@ -1877,6 +1890,8 @@ int amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu(
> >   err_pin_bo:
> >   err_validate_bo:
> >       remove_kgd_mem_from_kfd_bo_list(*mem, avm->process_info);
> > +    drm_gem_handle_delete(adev->kfd.client.file, (*mem)->gem_handle);
> > +err_gem_handle_create:
> >       drm_vma_node_revoke(&gobj->vma_node, drm_priv);
> >   err_node_allow:
> >       /* Don't unreserve system mem limit twice */
> > @@ -1991,8 +2006,12 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
> >         /* Free the BO*/
> >       drm_vma_node_revoke(&mem->bo->tbo.base.vma_node, drm_priv);
> > -    if (mem->dmabuf)
> > +    if (!mem->is_imported)
> > +        drm_gem_handle_delete(adev->kfd.client.file, mem->gem_handle);
> > +    if (mem->dmabuf) {
> >           dma_buf_put(mem->dmabuf);
> > +        mem->dmabuf = NULL;
> > +    }
> >       mutex_destroy(&mem->lock);
> >         /* If this releases the last reference, it will end up calling
> > diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c 
> > b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> > index 06988cf1db51..4417a9863cd0 100644
> > --- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> > @@ -1855,8 +1855,8 @@ static uint32_t get_process_num_bos(struct 
> > kfd_process *p)
> >       return num_of_bos;
> >   }
> >   -static int criu_get_prime_handle(struct kgd_mem *mem, int flags,
> > -                      u32 *shared_fd)
> > +static int criu_get_prime_handle(struct kgd_mem *mem,
> > +                 int flags, u32 *shared_fd)
> >   {
> >       struct dma_buf *dmabuf;
> >       int ret;