On Wed, Jan 23, 2019 at 02:00:47AM +0200, Oded Gabbay wrote:
> This patch adds the CB module, which allows the user to create and
> destroy CBs and to map them to the user's process address-space.

Can you please spell "command buffer" at least first time it's mentioned?
 
> A command buffer is a memory blocks that reside in DMA-able address-space
> and is physically contiguous so it can be accessed by the device without
> MMU translation. The command buffer memory is allocated using the
> coherent DMA API.
> 
> When creating a new CB, the IOCTL returns a handle of it, and the
> user-space process needs to use that handle to mmap the buffer to get a VA
> in the user's address-space.
> 
> Before destroying (freeing) a CB, the user must unmap the CB's VA using the
> CB handle.
> 
> Each CB has a reference counter, which tracks its usage in command
> submissions and also its mmaps (only a single mmap is allowed).
> 
> The driver maintains a pool of pre-allocated CBs in order to reduce
> latency during command submissions. In case the pool is empty, the driver
> will go to the slow-path of allocating a new CB, i.e. calling
> dma_alloc_coherent.
> 
> Signed-off-by: Oded Gabbay <oded.gab...@gmail.com>
> ---
>  drivers/misc/habanalabs/Makefile           |   3 +-
>  drivers/misc/habanalabs/command_buffer.c   | 414 +++++++++++++++++++++
>  drivers/misc/habanalabs/device.c           |  43 ++-
>  drivers/misc/habanalabs/goya/goya.c        |  28 ++
>  drivers/misc/habanalabs/habanalabs.h       |  95 ++++-
>  drivers/misc/habanalabs/habanalabs_drv.c   |   2 +
>  drivers/misc/habanalabs/habanalabs_ioctl.c | 102 +++++
>  include/uapi/misc/habanalabs.h             |  62 +++
>  8 files changed, 746 insertions(+), 3 deletions(-)
>  create mode 100644 drivers/misc/habanalabs/command_buffer.c
>  create mode 100644 drivers/misc/habanalabs/habanalabs_ioctl.c
>  create mode 100644 include/uapi/misc/habanalabs.h
> 
> diff --git a/drivers/misc/habanalabs/Makefile 
> b/drivers/misc/habanalabs/Makefile
> index 3ffbadc2ca01..2530c9b78ca4 100644
> --- a/drivers/misc/habanalabs/Makefile
> +++ b/drivers/misc/habanalabs/Makefile
> @@ -4,7 +4,8 @@
>  
>  obj-m        := habanalabs.o
>  
> -habanalabs-y := habanalabs_drv.o device.o context.o asid.o
> +habanalabs-y := habanalabs_drv.o device.o context.o asid.o 
> habanalabs_ioctl.o \
> +             command_buffer.o
>  
>  include $(src)/goya/Makefile
>  habanalabs-y += $(HL_GOYA_FILES)
> diff --git a/drivers/misc/habanalabs/command_buffer.c 
> b/drivers/misc/habanalabs/command_buffer.c
> new file mode 100644
> index 000000000000..535ed6cc5bda
> --- /dev/null
> +++ b/drivers/misc/habanalabs/command_buffer.c
> @@ -0,0 +1,414 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * Copyright 2016-2018 HabanaLabs, Ltd.
> + * All Rights Reserved.
> + */
> +
> +#include <uapi/misc/habanalabs.h>
> +#include "habanalabs.h"
> +
> +#include <linux/dma-mapping.h>
> +
> +static void cb_fini(struct hl_device *hdev, struct hl_cb *cb)
> +{
> +     hdev->asic_funcs->dma_free_coherent(hdev, cb->size,
> +                     (void *) cb->kernel_address, cb->bus_address);

As it seems, ASIC specific dma_free_coherent is a shortcut for a generic
dma_free_coherent. Why not use it directly?

> +     kfree(cb);
> +}
> +
> +static void cb_do_release(struct hl_device *hdev, struct hl_cb *cb)
> +{
> +     if (cb->is_pool) {
> +             spin_lock(&hdev->cb_pool_lock);
> +             list_add(&cb->pool_list, &hdev->cb_pool);
> +             spin_unlock(&hdev->cb_pool_lock);
> +     } else {
> +             cb_fini(hdev, cb);
> +     }
> +}
> +
> +static void cb_release(struct kref *ref)
> +{
> +     struct hl_device *hdev;
> +     struct hl_cb *cb;
> +
> +     cb = container_of(ref, struct hl_cb, refcount);
> +     hdev = cb->hdev;
> +
> +     cb_do_release(hdev, cb);
> +}
> +
> +static struct hl_cb *hl_cb_alloc(struct hl_device *hdev, u32 cb_size,
> +                                     int ctx_id)
> +{
> +     struct hl_cb *cb;
> +     void *p;
> +
> +     if (ctx_id == HL_KERNEL_ASID_ID)
> +             cb = kzalloc(sizeof(*cb), GFP_ATOMIC);

The GFP_ATOMIC should be used when the caller cannot tolerate reclaim or
sleep and it does not seem to be the case here.

> +     else
> +             cb = kzalloc(sizeof(*cb), GFP_KERNEL);
> +
> +     if (!cb)
> +             return NULL;
> +
> +     if (ctx_id == HL_KERNEL_ASID_ID)
> +             p = hdev->asic_funcs->dma_alloc_coherent(hdev, cb_size,
> +                                             &cb->bus_address, GFP_ATOMIC);

GFP_KERNEL?

> +     else
> +             p = hdev->asic_funcs->dma_alloc_coherent(hdev, cb_size,
> +                                             &cb->bus_address,
> +                                             GFP_USER | __GFP_ZERO);
> +     if (!p) {
> +             dev_err(hdev->dev,
> +                     "failed to allocate %d of dma memory for CB\n",
> +                     cb_size);
> +             kfree(cb);
> +             return NULL;
> +     }
> +
> +     cb->kernel_address = (u64) p;
> +     cb->size = cb_size;
> +
> +     return cb;
> +}
> +
> +int hl_cb_create(struct hl_device *hdev, struct hl_cb_mgr *mgr,
> +                     u32 cb_size, u64 *handle, int ctx_id)
> +{
> +     struct hl_cb *cb;
> +     bool alloc_new_cb = true;
> +     int rc;
> +
> +     if (hdev->disabled) {
> +             dev_warn_ratelimited(hdev->dev,
> +                     "Device is disabled !!! Can't create new CBs\n");
> +             rc = -EBUSY;
> +             goto out_err;
> +     }
> +
> +     /* Minimum allocation must be PAGE SIZE */
> +     if (cb_size < PAGE_SIZE)
> +             cb_size = PAGE_SIZE;
> +
> +     if (ctx_id == HL_KERNEL_ASID_ID &&
> +                     cb_size <= hdev->asic_prop.cb_pool_cb_size) {
> +
> +             spin_lock(&hdev->cb_pool_lock);
> +             if (!list_empty(&hdev->cb_pool)) {
> +                     cb = list_first_entry(&hdev->cb_pool, typeof(*cb),
> +                                     pool_list);
> +                     list_del(&cb->pool_list);
> +                     spin_unlock(&hdev->cb_pool_lock);
> +                     alloc_new_cb = false;
> +             } else {
> +                     spin_unlock(&hdev->cb_pool_lock);
> +                     dev_warn_once(hdev->dev, "CB pool is empty\n");

Isn't it going to be a false alarm when you allocate the cb for the first
time?

> +             }
> +     }
> +
> +     if (alloc_new_cb) {
> +             cb = hl_cb_alloc(hdev, cb_size, ctx_id);
> +             if (!cb) {
> +                     rc = -ENOMEM;
> +                     goto out_err;
> +             }
> +     }
> +
> +     cb->hdev = hdev;
> +     cb->ctx_id = ctx_id;
> +
> +     spin_lock(&mgr->cb_lock);
> +     rc = idr_alloc(&mgr->cb_handles, cb, 1, 0, GFP_ATOMIC);

It seems the ID will remain dangling if the cb is reused.

> +     spin_unlock(&mgr->cb_lock);
> +
> +     if (rc < 0) {
> +             dev_err(hdev->dev, "Failed to allocate IDR for a new CB\n");
> +             goto release_cb;
> +     }
> +
> +     cb->id = rc;
> +
> +     kref_init(&cb->refcount);
> +     spin_lock_init(&cb->lock);
> +
> +     /*
> +      * idr is 32-bit so we can safely OR it with a mask that is above
> +      * 32 bit
> +      */
> +     *handle = cb->id | HL_MMAP_CB_MASK;
> +     *handle <<= PAGE_SHIFT;
> +
> +     return 0;
> +
> +release_cb:
> +     cb_do_release(hdev, cb);
> +out_err:
> +     *handle = 0;
> +
> +     return rc;
> +}
> +
> +int hl_cb_destroy(struct hl_device *hdev, struct hl_cb_mgr *mgr, u64 
> cb_handle)
> +{
> +     struct hl_cb *cb;
> +     u32 handle;
> +     int rc = 0;
> +
> +     /*
> +      * handle was given to user to do mmap, I need to shift it back to
> +      * how the idr module gave it to me
> +      */
> +     cb_handle >>= PAGE_SHIFT;
> +     handle = (u32) cb_handle;
> +
> +     spin_lock(&mgr->cb_lock);
> +
> +     cb = idr_find(&mgr->cb_handles, handle);
> +     if (cb) {
> +             idr_remove(&mgr->cb_handles, handle);
> +             spin_unlock(&mgr->cb_lock);
> +             kref_put(&cb->refcount, cb_release);
> +     } else {
> +             spin_unlock(&mgr->cb_lock);
> +             dev_err(hdev->dev,
> +                     "CB destroy failed, no match to handle 0x%x\n", handle);
> +             rc = -EINVAL;
> +     }
> +
> +     return rc;
> +}
> +
> +int hl_cb_ioctl(struct hl_fpriv *hpriv, void *data)
> +{
> +     union hl_cb_args *args = data;
> +     struct hl_device *hdev = hpriv->hdev;
> +     u64 handle;
> +     int rc;
> +
> +     switch (args->in.op) {
> +     case HL_CB_OP_CREATE:
> +             rc = hl_cb_create(hdev, &hpriv->cb_mgr, args->in.cb_size,
> +                                     &handle, hpriv->ctx->asid);
> +             memset(args, 0, sizeof(*args));
> +             args->out.cb_handle = handle;
> +             break;
> +     case HL_CB_OP_DESTROY:
> +             rc = hl_cb_destroy(hdev, &hpriv->cb_mgr,
> +                                     args->in.cb_handle);
> +             memset(args, 0, sizeof(*args));
> +             break;
> +     default:
> +             rc = -EINVAL;
> +             break;
> +     }
> +
> +     return rc;
> +}
> +
> +static void cb_vm_close(struct vm_area_struct *vma)
> +{
> +     struct hl_cb *cb = (struct hl_cb *) vma->vm_private_data;
> +
> +     hl_cb_put(cb);
> +
> +     spin_lock(&cb->lock);
> +     cb->mmap = false;
> +     cb->vm_start = 0;
> +     cb->vm_end = 0;
> +     spin_unlock(&cb->lock);
> +
> +     vma->vm_private_data = NULL;
> +}
> +
> +static const struct vm_operations_struct cb_vm_ops = {
> +     .close = cb_vm_close
> +};
> +
> +int hl_cb_mmap(struct hl_fpriv *hpriv, struct vm_area_struct *vma)
> +{
> +     struct hl_device *hdev = hpriv->hdev;
> +     struct hl_cb *cb;
> +     phys_addr_t address;
> +     u32 handle;
> +     int rc;
> +
> +     handle = vma->vm_pgoff;
> +
> +     /* reference was taken here */
> +     cb = hl_cb_get(hdev, &hpriv->cb_mgr, handle);
> +     if (!cb) {
> +             dev_err(hdev->dev,
> +                     "CB mmap failed, no match to handle %d\n", handle);
> +             goto err_out;

why no simply return -EINVAL?

> +     }
> +
> +     /* Validation check */
> +     if (vma->vm_end - vma->vm_start != cb->size) {
> +             dev_err(hdev->dev,
> +                     "CB mmap failed, mmap size 0x%lx != 0x%x cb size\n",
> +                     vma->vm_end - vma->vm_start, cb->size);
> +             goto put_cb;
> +     }
> +
> +     spin_lock(&cb->lock);
> +
> +     if (cb->mmap) {
> +             dev_err(hdev->dev,
> +                     "CB mmap failed, CB already mmaped to user\n");
> +             goto release_lock;
> +     }
> +
> +     cb->mmap = true;
> +
> +     spin_unlock(&cb->lock);
> +
> +     vma->vm_ops = &cb_vm_ops;
> +
> +     /*
> +      * Note: We're transferring the cb reference to
> +      * vma->vm_private_data here.
> +      */
> +
> +     vma->vm_private_data = cb;
> +
> +     /* Calculate address for CB */
> +     address = virt_to_phys((void *) cb->kernel_address);
> +
> +     rc = hdev->asic_funcs->cb_mmap(hdev, vma, cb->kernel_address,
> +                                     address, cb->size);
> +
> +     if (rc) {
> +             spin_lock(&cb->lock);
> +             cb->mmap = false;
> +             goto release_lock;
> +     }
> +
> +     cb->vm_start = vma->vm_start;
> +     cb->vm_end = vma->vm_end;
> +
> +     return 0;
> +
> +release_lock:
> +     spin_unlock(&cb->lock);
> +put_cb:
> +     hl_cb_put(cb);
> +err_out:
> +     return -EINVAL;
> +}
> +
> +struct hl_cb *hl_cb_get(struct hl_device *hdev, struct hl_cb_mgr *mgr,
> +                     u32 handle)
> +{
> +     struct hl_cb *cb;
> +
> +     spin_lock(&mgr->cb_lock);
> +     cb = idr_find(&mgr->cb_handles, handle);
> +
> +     if (!cb) {
> +             spin_unlock(&mgr->cb_lock);
> +             dev_warn(hdev->dev,
> +                     "CB get failed, no match to handle %d\n", handle);
> +             return NULL;
> +     }
> +
> +     kref_get(&cb->refcount);
> +
> +     spin_unlock(&mgr->cb_lock);
> +
> +     return cb;
> +
> +}
> +
> +void hl_cb_put(struct hl_cb *cb)
> +{
> +     kref_put(&cb->refcount, cb_release);
> +}
> +
> +void hl_cb_mgr_init(struct hl_cb_mgr *mgr)
> +{
> +     spin_lock_init(&mgr->cb_lock);
> +     idr_init(&mgr->cb_handles);
> +}
> +
> +void hl_cb_mgr_fini(struct hl_device *hdev, struct hl_cb_mgr *mgr)
> +{
> +     struct hl_cb *cb;
> +     struct idr *idp;
> +     u32 id;
> +
> +     idp = &mgr->cb_handles;
> +
> +     idr_for_each_entry(idp, cb, id) {
> +             if (kref_put(&cb->refcount, cb_release) != 1)
> +                     dev_err(hdev->dev,
> +                             "CB %d for CTX ID %d is still alive\n",
> +                             id, cb->ctx_id);
> +     }
> +
> +     idr_destroy(&mgr->cb_handles);
> +}
> +
> +struct hl_cb *hl_cb_kernel_create(struct hl_device *hdev, u32 cb_size)
> +{
> +     u64 cb_handle;
> +     struct hl_cb *cb;
> +     int rc;
> +
> +     rc = hl_cb_create(hdev, &hdev->kernel_cb_mgr, cb_size, &cb_handle,
> +                     HL_KERNEL_ASID_ID);
> +     if (rc) {
> +             dev_err(hdev->dev, "Failed to allocate CB for KMD %d\n", rc);
> +             return NULL;
> +     }
> +
> +     cb_handle >>= PAGE_SHIFT;
> +     cb = hl_cb_get(hdev, &hdev->kernel_cb_mgr, (u32) cb_handle);
> +     /* hl_cb_get should never fail here so use kernel WARN */
> +     WARN(!cb, "Kernel CB handle invalid 0x%x\n", (u32) cb_handle);
> +     if (!cb)
> +             goto destroy_cb;
> +
> +     return cb;
> +
> +destroy_cb:
> +     hl_cb_destroy(hdev, &hdev->kernel_cb_mgr, cb_handle << PAGE_SHIFT);
> +
> +     return NULL;
> +}
> +
> +int hl_cb_pool_init(struct hl_device *hdev)
> +{
> +     struct hl_cb *cb;
> +     int i;
> +
> +     INIT_LIST_HEAD(&hdev->cb_pool);
> +     spin_lock_init(&hdev->cb_pool_lock);
> +
> +     for (i = 0 ; i < hdev->asic_prop.cb_pool_cb_cnt ; i++) {
> +             cb = hl_cb_alloc(hdev, hdev->asic_prop.cb_pool_cb_size,
> +                             HL_KERNEL_ASID_ID);
> +             if (cb) {
> +                     cb->is_pool = true;
> +                     list_add(&cb->pool_list, &hdev->cb_pool);
> +             } else {
> +                     hl_cb_pool_fini(hdev);
> +                     return -ENOMEM;
> +             }
> +     }
> +
> +     return 0;
> +}
> +
> +int hl_cb_pool_fini(struct hl_device *hdev)
> +{
> +     struct hl_cb *cb, *tmp;
> +
> +     list_for_each_entry_safe(cb, tmp, &hdev->cb_pool, pool_list) {
> +             list_del(&cb->pool_list);
> +             cb_fini(hdev, cb);
> +     }
> +
> +     return 0;
> +}
> diff --git a/drivers/misc/habanalabs/device.c 
> b/drivers/misc/habanalabs/device.c
> index 84ce9fcb52da..0bd86a7d34db 100644
> --- a/drivers/misc/habanalabs/device.c
> +++ b/drivers/misc/habanalabs/device.c
> @@ -53,6 +53,7 @@ static int hl_device_release(struct inode *inode, struct 
> file *filp)
>  {
>       struct hl_fpriv *hpriv = filp->private_data;
>  
> +     hl_cb_mgr_fini(hpriv->hdev, &hpriv->cb_mgr);
>       hl_ctx_mgr_fini(hpriv->hdev, &hpriv->ctx_mgr);
>  
>       filp->private_data = NULL;
> @@ -62,10 +63,34 @@ static int hl_device_release(struct inode *inode, struct 
> file *filp)
>       return 0;
>  }
>  
> +/**
> + * hl_mmap - mmap function for habanalabs device
> + *
> + * @*filp: pointer to file structure
> + * @*vma: pointer to vm_area_struct of the process
> + *
> + * Called when process does an mmap on habanalabs device. Call the device's 
> mmap
> + * function at the end of the common code.
> + */
> +static int hl_mmap(struct file *filp, struct vm_area_struct *vma)
> +{
> +     struct hl_fpriv *hpriv = filp->private_data;
> +
> +     if ((vma->vm_pgoff & HL_MMAP_CB_MASK) == HL_MMAP_CB_MASK) {
> +             vma->vm_pgoff ^= HL_MMAP_CB_MASK;
> +             return hl_cb_mmap(hpriv, vma);
> +     }
> +
> +     return hpriv->hdev->asic_funcs->mmap(hpriv, vma);
> +}
> +
>  static const struct file_operations hl_ops = {
>       .owner = THIS_MODULE,
>       .open = hl_device_open,
> -     .release = hl_device_release
> +     .release = hl_device_release,
> +     .mmap = hl_mmap,
> +     .unlocked_ioctl = hl_ioctl,
> +     .compat_ioctl = hl_ioctl
>  };
>  
>  /**
> @@ -145,6 +170,8 @@ static int device_early_init(struct hl_device *hdev)
>       if (rc)
>               goto early_fini;
>  
> +     hl_cb_mgr_init(&hdev->kernel_cb_mgr);
> +
>       mutex_init(&hdev->device_open);
>       atomic_set(&hdev->fd_open_cnt, 0);
>  
> @@ -166,6 +193,8 @@ static int device_early_init(struct hl_device *hdev)
>  static void device_early_fini(struct hl_device *hdev)
>  {
>  
> +     hl_cb_mgr_fini(hdev, &hdev->kernel_cb_mgr);
> +
>       hl_asid_fini(hdev);
>  
>       if (hdev->asic_funcs->early_fini)
> @@ -280,11 +309,21 @@ int hl_device_init(struct hl_device *hdev, struct class 
> *hclass)
>               goto free_ctx;
>       }
>  
> +     rc = hl_cb_pool_init(hdev);
> +     if (rc) {
> +             dev_err(hdev->dev, "failed to initialize CB pool\n");
> +             goto release_ctx;
> +     }
> +
>       dev_notice(hdev->dev,
>               "Successfully added device to habanalabs driver\n");
>  
>       return 0;
>  
> +release_ctx:
> +     if (hl_ctx_put(hdev->kernel_ctx) != 1)
> +             dev_err(hdev->dev,
> +                     "kernel ctx is still alive on initialization 
> failure\n");
>  free_ctx:
>       kfree(hdev->kernel_ctx);
>  sw_fini:
> @@ -321,6 +360,8 @@ void hl_device_fini(struct hl_device *hdev)
>       /* Mark device as disabled */
>       hdev->disabled = true;
>  
> +     hl_cb_pool_fini(hdev);
> +
>       /* Release kernel context */
>       if ((hdev->kernel_ctx) && (hl_ctx_put(hdev->kernel_ctx) != 1))
>               dev_err(hdev->dev, "kernel ctx is still alive\n");
> diff --git a/drivers/misc/habanalabs/goya/goya.c 
> b/drivers/misc/habanalabs/goya/goya.c
> index b2952296b890..341ac085af82 100644
> --- a/drivers/misc/habanalabs/goya/goya.c
> +++ b/drivers/misc/habanalabs/goya/goya.c
> @@ -92,6 +92,9 @@
>  
>  #define GOYA_MAX_INITIATORS          20
>  
> +#define GOYA_CB_POOL_CB_CNT          512
> +#define GOYA_CB_POOL_CB_SIZE         0x20000         /* 128KB */
> +
>  static void goya_get_fixed_properties(struct hl_device *hdev)
>  {
>       struct asic_fixed_properties *prop = &hdev->asic_prop;
> @@ -119,6 +122,8 @@ static void goya_get_fixed_properties(struct hl_device 
> *hdev)
>       prop->tpc_enabled_mask = TPC_ENABLED_MASK;
>  
>       prop->high_pll = PLL_HIGH_DEFAULT;
> +     prop->cb_pool_cb_cnt = GOYA_CB_POOL_CB_CNT;
> +     prop->cb_pool_cb_size = GOYA_CB_POOL_CB_SIZE;
>  }
>  
>  /**
> @@ -598,6 +603,27 @@ int goya_resume(struct hl_device *hdev)
>       return 0;
>  }
>  
> +int goya_mmap(struct hl_fpriv *hpriv, struct vm_area_struct *vma)
> +{
> +     return -EINVAL;
> +}
> +
> +int goya_cb_mmap(struct hl_device *hdev, struct vm_area_struct *vma,
> +             u64 kaddress, phys_addr_t paddress, u32 size)
> +{
> +     int rc;
> +
> +     vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP |
> +                     VM_DONTCOPY | VM_NORESERVE;
> +
> +     rc = remap_pfn_range(vma, vma->vm_start, paddress >> PAGE_SHIFT,
> +                             size, vma->vm_page_prot);
> +     if (rc)
> +             dev_err(hdev->dev, "remap_pfn_range error %d", rc);
> +
> +     return rc;
> +}
> +
>  void *goya_dma_alloc_coherent(struct hl_device *hdev, size_t size,
>                                       dma_addr_t *dma_handle, gfp_t flags)
>  {
> @@ -617,6 +643,8 @@ static const struct hl_asic_funcs goya_funcs = {
>       .sw_fini = goya_sw_fini,
>       .suspend = goya_suspend,
>       .resume = goya_resume,
> +     .mmap = goya_mmap,
> +     .cb_mmap = goya_cb_mmap,
>       .dma_alloc_coherent = goya_dma_alloc_coherent,
>       .dma_free_coherent = goya_dma_free_coherent,
>  };
> diff --git a/drivers/misc/habanalabs/habanalabs.h 
> b/drivers/misc/habanalabs/habanalabs.h
> index d003a6af2131..6ad476df65b0 100644
> --- a/drivers/misc/habanalabs/habanalabs.h
> +++ b/drivers/misc/habanalabs/habanalabs.h
> @@ -21,10 +21,12 @@
>  
>  #define HL_NAME                              "habanalabs"
>  
> +#define HL_MMAP_CB_MASK                      (0x8000000000000000ull >> 
> PAGE_SHIFT)
> +
>  #define HL_MAX_QUEUES                        128
>  
>  struct hl_device;
> -
> +struct hl_fpriv;
>  
>  
>  
> @@ -53,6 +55,8 @@ struct hl_device;
>   * @max_asid: maximum number of open contexts (ASIDs).
>   * @completion_queues_count: number of completion queues.
>   * @high_pll: high PLL frequency used by the device.
> + * @cb_pool_cb_cnt: number of CBs in the CB pool.
> + * @cb_pool_cb_size: size of each CB in the CB pool.
>   * @tpc_enabled_mask: which TPCs are enabled.
>   */
>  struct asic_fixed_properties {
> @@ -73,11 +77,68 @@ struct asic_fixed_properties {
>       u32                     sram_size;
>       u32                     max_asid;
>       u32                     high_pll;
> +     u32                     cb_pool_cb_cnt;
> +     u32                     cb_pool_cb_size;
>       u8                      completion_queues_count;
>       u8                      tpc_enabled_mask;
>  };
>  
>  
> +
> +
> +
> +
> +/*
> + * Command Buffers
> + */
> +
> +/**
> + * struct hl_cb_mgr - describes a Command Buffer Manager.
> + * @cb_lock: protects cb_handles.
> + * @cb_handles: an idr to hold all command buffer handles.
> + */
> +struct hl_cb_mgr {
> +     spinlock_t              cb_lock;
> +     struct idr              cb_handles; /* protected by cb_lock */
> +};
> +
> +/**
> + * struct hl_cb - describes a Command Buffer.
> + * @refcount: reference counter for usage of the CB.
> + * @hdev: pointer to device this CB belongs to.
> + * @lock: spinlock to protect mmap/cs flows.
> + * @pool_list: node in pool list of command buffers.
> + * @kernel_address: Holds the CB's kernel virtual address.
> + * @bus_address: Holds the CB's DMA address.
> + * @vm_start: Holds the CB's user start virtual address (when mmaped).
> + * @vm_end: Holds the CB's user end virtual address (when mmaped).
> + * @size: holds the CB's size.
> + * @id: the CB's ID.
> + * @ctx_id: holds the ID of the owner's context.
> + * @mmap: true if the CB is currently mmaped to user.
> + * @is_pool: true if CB was acquired from the pool, false otherwise.
> + */
> +struct hl_cb {
> +     struct kref             refcount;
> +     struct hl_device        *hdev;
> +     spinlock_t              lock;
> +     struct list_head        pool_list;
> +     u64                     kernel_address;
> +     dma_addr_t              bus_address;
> +     u64                     vm_start;
> +     u64                     vm_end;
> +     u32                     size;
> +     u32                     id;
> +     u32                     ctx_id;
> +     u8                      mmap;
> +     u8                      is_pool;
> +};
> +
> +
> +
> +
> +
> +
>  #define HL_QUEUE_LENGTH                      256
>  
>  
> @@ -109,6 +170,8 @@ enum hl_asic_type {
>   * @sw_fini: tears down driver state, does not configure H/W.
>   * @suspend: handles IP specific H/W or SW changes for suspend.
>   * @resume: handles IP specific H/W or SW changes for resume.
> + * @mmap: mmap function, does nothing.
> + * @cb_mmap: maps a CB.
>   * @dma_alloc_coherent: DMA allocate coherent memory.
>   * @dma_free_coherent: free DMA allocation.
>   */
> @@ -119,6 +182,9 @@ struct hl_asic_funcs {
>       int (*sw_fini)(struct hl_device *hdev);
>       int (*suspend)(struct hl_device *hdev);
>       int (*resume)(struct hl_device *hdev);
> +     int (*mmap)(struct hl_fpriv *hpriv, struct vm_area_struct *vma);
> +     int (*cb_mmap)(struct hl_device *hdev, struct vm_area_struct *vma,
> +                     u64 kaddress, phys_addr_t paddress, u32 size);
>       void* (*dma_alloc_coherent)(struct hl_device *hdev, size_t size,
>                                       dma_addr_t *dma_handle, gfp_t flag);
>       void (*dma_free_coherent)(struct hl_device *hdev, size_t size,
> @@ -175,6 +241,7 @@ struct hl_ctx_mgr {
>   * @taskpid: current process ID.
>   * @ctx: current executing context.
>   * @ctx_mgr: context manager to handle multiple context for this FD.
> + * @cb_mgr: command buffer manager to handle multiple buffers for this FD.
>   * @refcount: number of related contexts.
>   */
>  struct hl_fpriv {
> @@ -183,6 +250,7 @@ struct hl_fpriv {
>       struct pid              *taskpid;
>       struct hl_ctx           *ctx; /* TODO: remove for multiple ctx */
>       struct hl_ctx_mgr       ctx_mgr;
> +     struct hl_cb_mgr        cb_mgr;
>       struct kref             refcount;
>  };
>  
> @@ -239,6 +307,7 @@ void hl_wreg(struct hl_device *hdev, u32 reg, u32 val);
>   * @asic_name: ASIC specific nmae.
>   * @asic_type: ASIC specific type.
>   * @kernel_ctx: KMD context structure.
> + * @kernel_cb_mgr: command buffer manager for creating/destroying/handling 
> CGs.
>   * @dma_pool: DMA pool for small allocations.
>   * @cpu_accessible_dma_mem: KMD <-> ArmCP shared memory CPU address.
>   * @cpu_accessible_dma_address: KMD <-> ArmCP shared memory DMA address.
> @@ -249,6 +318,8 @@ void hl_wreg(struct hl_device *hdev, u32 reg, u32 val);
>   * @asic_prop: ASIC specific immutable properties.
>   * @asic_funcs: ASIC specific functions.
>   * @asic_specific: ASIC specific information to use only from ASIC files.
> + * @cb_pool: list of preallocated CBs.
> + * @cb_pool_lock: protects the CB pool.
>   * @user_ctx: current user context executing.
>   * @fd_open_cnt: number of open context executing.
>   * @major: habanalabs KMD major.
> @@ -264,6 +335,7 @@ struct hl_device {
>       char                            asic_name[16];
>       enum hl_asic_type               asic_type;
>       struct hl_ctx                   *kernel_ctx;
> +     struct hl_cb_mgr                kernel_cb_mgr;
>       struct dma_pool                 *dma_pool;
>       void                            *cpu_accessible_dma_mem;
>       dma_addr_t                      cpu_accessible_dma_address;
> @@ -275,6 +347,10 @@ struct hl_device {
>       struct asic_fixed_properties    asic_prop;
>       const struct hl_asic_funcs      *asic_funcs;
>       void                            *asic_specific;
> +
> +     struct list_head                cb_pool;
> +     spinlock_t                      cb_pool_lock;
> +
>       /* TODO: The following fields should be moved for multi-context */
>       struct hl_ctx                   *user_ctx;
>       atomic_t                        fd_open_cnt;
> @@ -345,6 +421,23 @@ int hl_device_resume(struct hl_device *hdev);
>  void hl_hpriv_get(struct hl_fpriv *hpriv);
>  void hl_hpriv_put(struct hl_fpriv *hpriv);
>  
> +int hl_cb_create(struct hl_device *hdev, struct hl_cb_mgr *mgr, u32 cb_size,
> +             u64 *handle, int ctx_id);
> +int hl_cb_destroy(struct hl_device *hdev, struct hl_cb_mgr *mgr, u64 
> cb_handle);
> +int hl_cb_mmap(struct hl_fpriv *hpriv, struct vm_area_struct *vma);
> +struct hl_cb *hl_cb_get(struct hl_device *hdev,      struct hl_cb_mgr *mgr,
> +                     u32 handle);
> +void hl_cb_put(struct hl_cb *cb);
> +void hl_cb_mgr_init(struct hl_cb_mgr *mgr);
> +void hl_cb_mgr_fini(struct hl_device *hdev, struct hl_cb_mgr *mgr);
> +struct hl_cb *hl_cb_kernel_create(struct hl_device *hdev, u32 cb_size);
> +int hl_cb_pool_init(struct hl_device *hdev);
> +int hl_cb_pool_fini(struct hl_device *hdev);
> +
>  void goya_set_asic_funcs(struct hl_device *hdev);
>  
> +/* IOCTLs */
> +long hl_ioctl(struct file *filep, unsigned int cmd, unsigned long arg);
> +int hl_cb_ioctl(struct hl_fpriv *hpriv, void *data);
> +
>  #endif /* HABANALABSP_H_ */
> diff --git a/drivers/misc/habanalabs/habanalabs_drv.c 
> b/drivers/misc/habanalabs/habanalabs_drv.c
> index 0646da83eb53..5c312dd3aa50 100644
> --- a/drivers/misc/habanalabs/habanalabs_drv.c
> +++ b/drivers/misc/habanalabs/habanalabs_drv.c
> @@ -123,6 +123,7 @@ int hl_device_open(struct inode *inode, struct file *filp)
>       kref_init(&hpriv->refcount);
>       nonseekable_open(inode, filp);
>  
> +     hl_cb_mgr_init(&hpriv->cb_mgr);
>       hl_ctx_mgr_init(&hpriv->ctx_mgr);
>  
>       rc = hl_ctx_create(hdev, hpriv);
> @@ -138,6 +139,7 @@ int hl_device_open(struct inode *inode, struct file *filp)
>  out_err:
>       filp->private_data = NULL;
>       hl_ctx_mgr_fini(hpriv->hdev, &hpriv->ctx_mgr);
> +     hl_cb_mgr_fini(hpriv->hdev, &hpriv->cb_mgr);
>       kfree(hpriv);
>  
>  close_device:
> diff --git a/drivers/misc/habanalabs/habanalabs_ioctl.c 
> b/drivers/misc/habanalabs/habanalabs_ioctl.c
> new file mode 100644
> index 000000000000..fa2287569e0e
> --- /dev/null
> +++ b/drivers/misc/habanalabs/habanalabs_ioctl.c
> @@ -0,0 +1,102 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * Copyright 2016-2018 HabanaLabs, Ltd.
> + * All Rights Reserved.
> + */
> +
> +#include <uapi/misc/habanalabs.h>
> +#include "habanalabs.h"
> +
> +#include <linux/fs.h>
> +#include <linux/uaccess.h>
> +#include <linux/cred.h>
> +
> +#define HL_IOCTL_DEF(ioctl, _func) \
> +     [_IOC_NR(ioctl)] = {.cmd = ioctl, .func = _func}
> +
> +static const struct hl_ioctl_desc hl_ioctls[] = {
> +     HL_IOCTL_DEF(HL_IOCTL_CB, hl_cb_ioctl)
> +};
> +
> +#define HL_CORE_IOCTL_COUNT  ARRAY_SIZE(hl_ioctls)
> +
> +long hl_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
> +{
> +     struct hl_fpriv *hpriv = filep->private_data;
> +     struct hl_device *hdev = hpriv->hdev;
> +     hl_ioctl_t *func;
> +     const struct hl_ioctl_desc *ioctl = NULL;
> +     unsigned int nr = _IOC_NR(cmd);
> +     char stack_kdata[128];
> +     char *kdata = NULL;
> +     unsigned int usize, asize;
> +     int retcode = -EINVAL;
> +
> +     if (nr >= HL_CORE_IOCTL_COUNT)

        nr > HL_CORE_IOCTL_COUNT, isn't it?

> +             goto err_i1;

err_i1 is not very meaningfull. Maybe invalid_ioctl?

> +
> +     if ((nr >= HL_COMMAND_START) && (nr < HL_COMMAND_END)) {

The HL_COMMAND_{START,END} do not seem to be defined. 
Besides, this check seem to be overlapped with

        if (nr > HL_CORE_IOCTL_COUNT)

> +             u32 hl_size;
> +
> +             ioctl = &hl_ioctls[nr];
> +
> +             hl_size = _IOC_SIZE(ioctl->cmd);
> +             usize = asize = _IOC_SIZE(cmd);
> +             if (hl_size > asize)
> +                     asize = hl_size;
> +
> +             cmd = ioctl->cmd;
> +     } else {
> +             goto err_i1;
> +     }
> +
> +     /* Do not trust userspace, use our own definition */
> +     func = ioctl->func;
> +
> +     if (unlikely(!func)) {
> +             dev_dbg(hdev->dev, "no function\n");
> +             retcode = -EINVAL;
> +             goto err_i1;
> +     }
> +
> +     if (cmd & (IOC_IN | IOC_OUT)) {
> +             if (asize <= sizeof(stack_kdata)) {
> +                     kdata = stack_kdata;
> +             } else {
> +                     kdata = kmalloc(asize, GFP_KERNEL);
> +                     if (!kdata) {
> +                             retcode = -ENOMEM;
> +                             goto err_i1;
> +                     }
> +             }
> +             if (asize > usize)
> +                     memset(kdata + usize, 0, asize - usize);

Just init stack_kdata to 0 and use kzalloc instead of malloc.

> +     }
> +
> +     if (cmd & IOC_IN) {
> +             if (copy_from_user(kdata, (void __user *)arg, usize)) {
> +                     retcode = -EFAULT;
> +                     goto err_i1;
> +             }
> +     } else if (cmd & IOC_OUT) {
> +             memset(kdata, 0, usize);
> +     }
> +
> +     retcode = func(hpriv, kdata);
> +
> +     if (cmd & IOC_OUT)
> +             if (copy_to_user((void __user *)arg, kdata, usize))
> +                     retcode = -EFAULT;
> +
> +err_i1:
> +     if (!ioctl)
> +             dev_dbg(hdev->dev,
> +                     "invalid ioctl: pid=%d, cmd=0x%02x, nr=0x%02x\n",
> +                       task_pid_nr(current), cmd, nr);

I think this can move right after the 'nr' sanity check and there you can
simple return -EINVAL after dev_dbg().

> +
> +     if (kdata != stack_kdata)
> +             kfree(kdata);
> +
> +     return retcode;
> +}
> diff --git a/include/uapi/misc/habanalabs.h b/include/uapi/misc/habanalabs.h
> new file mode 100644
> index 000000000000..b3f9213d4709
> --- /dev/null
> +++ b/include/uapi/misc/habanalabs.h
> @@ -0,0 +1,62 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note
> + *
> + * Copyright 2016-2018 HabanaLabs, Ltd.
> + * All Rights Reserved.
> + *
> + * Author: Oded Gabbay <oded.gab...@gmail.com>
> + *
> + */
> +
> +#ifndef HABANALABS_H_
> +#define HABANALABS_H_
> +
> +#include <linux/types.h>
> +#include <linux/ioctl.h>
> +
> +/* Opcode to create a new command buffer */
> +#define HL_CB_OP_CREATE              0
> +/* Opcode to destroy previously created command buffer */
> +#define HL_CB_OP_DESTROY     1
> +
> +struct hl_cb_in {
> +     /* Handle of CB or 0 if we want to create one */
> +     __u64 cb_handle;
> +     /* HL_CB_OP_* */
> +     __u32 op;
> +     /* Size of CB. Minimum requested size must be PAGE_SIZE */
> +     __u32 cb_size;
> +     /* Context ID - Currently not in use */
> +     __u32 ctx_id;
> +     __u32 pad;
> +};
> +
> +struct hl_cb_out {
> +     /* Handle of CB */
> +     __u64 cb_handle;
> +};
> +
> +union hl_cb_args {
> +     struct hl_cb_in in;
> +     struct hl_cb_out out;
> +};
> +
> +/*
> + * Command Buffer
> + * - Request a Command Buffer
> + * - Destroy a Command Buffer
> + *
> + * The command buffers are memory blocks that reside in DMA-able address
> + * space and are physically contiguous so they can be accessed by the device
> + * directly. They are allocated using the coherent DMA API.
> + *
> + * When creating a new CB, the IOCTL returns a handle of it, and the 
> user-space
> + * process needs to use that handle to mmap the buffer so it can access them.
> + *
> + */
> +#define HL_IOCTL_CB          \
> +             _IOWR('H', 0x02, union hl_cb_args)
> +
> +#define HL_COMMAND_START     0x02
> +#define HL_COMMAND_END               0x03
> +
> +#endif /* HABANALABS_H_ */
> -- 
> 2.17.1
> 

-- 
Sincerely yours,
Mike.

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