RE: [PATCH v2 2/2] habanalabs: add support for dma-buf exporter

[Tomer Tayar]

On 16/06/2021 17:59, Gal Pressman wrote:
> On 15/06/2021 11:53, Oded Gabbay wrote:
> > @@ -1346,9 +1372,11 @@ struct hl_ctx {
> >  	struct mutex			mem_hash_lock;
> >  	struct mutex			mmu_lock;
> >  	struct mutex			hw_block_list_lock;
> > +	struct mutex			dmabuf_list_lock;
> >  	struct list_head		debugfs_list;
> >  	struct list_head		pending_cb_list;
> >  	struct list_head		hw_block_mem_list;
> > +	struct list_head		dmabuf_list;
> 
> Am I missing where this list is used? I only see insertions and deletions, but
> what is it used for?

You are right, we will remove it.

> > +static int export_dmabuf_from_addr(struct hl_ctx *ctx, u64 device_addr,
> > +					u64 size, int flags, int *dmabuf_fd) {
> > +	struct hl_device *hdev = ctx->hdev;
> > +	struct asic_fixed_properties *prop = &hdev->asic_prop;
> > +	struct hl_dmabuf_wrapper *hl_dmabuf;
> > +	int rc;
> > +
> > +	dev_dbg(hdev->dev, "exporting dma-buf for addr 0x%llx, size
> 0x%llx\n",
> > +			device_addr, size);
> > +
> > +	if (!IS_ALIGNED(device_addr,
> DMA_BUF_MEM_ADDR_ALIGNMENT)) {
> > +		dev_err(hdev->dev,
> > +			"address of exported device memory should be
> aligned to 0x%x, address 0x%llx\n",
> > +			DMA_BUF_MEM_ADDR_ALIGNMENT, device_addr);
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (!size) {
> > +		dev_err(hdev->dev,
> > +			"size of exported device memory should be greater
> than 0\n");
> 
> These cases can be caused by user providing wrong input, right? Maybe
> debug level is more appropriate to prevent spamming dmesg.

As in other places in the driver, we do want to have these dev_err prints.
However it is true that we should at least use the *_ratelimited version.
Will modify it.

> > +		return -EINVAL;
> > +	}
> > +
> > +	if (!IS_ALIGNED(size, DMA_BUF_MEM_SIZE_ALIGNMENT)) {
> > +		dev_err(hdev->dev,
> > +			"size of exported device memory should be aligned
> to 0x%x, size 0x%llx\n",
> > +			DMA_BUF_MEM_SIZE_ALIGNMENT, device_addr);
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (device_addr < prop->dram_user_base_address ||
> > +			device_addr + size > prop->dram_end_address) {
> > +		dev_err(hdev->dev,
> > +			"DRAM memory range is outside of DRAM
> boundaries, address 0x%llx, size 0x%llx\n",
> > +			device_addr, size);
> > +		return -EINVAL;
> > +	}
> > +
> > +	hl_dmabuf = kzalloc(sizeof(*hl_dmabuf), GFP_KERNEL);
> > +	if (!hl_dmabuf)
> > +		return -ENOMEM;
> > +
> > +	hl_dmabuf->handle = device_addr;
> > +	hl_dmabuf->total_size = size;
> > +
> > +	rc = export_dmabuf_common(ctx, hl_dmabuf, &device_addr, 1, size,
> flags,
> > +					dmabuf_fd);
> > +	if (rc)
> > +		goto err_free_dmabuf_wrapper;
> > +
> > +	return 0;
> > +
> > +err_free_dmabuf_wrapper:
> > +	kfree(hl_dmabuf);
> > +	return rc;
> > +}
> > +
> > +/**
> > + * export_dmabuf_from_handle() - export a dma-buf object for the given
> memory
> > + *                               handle.
> > + * @ctx: pointer to the context structure.
> > + * @handle: device memory allocation handle.
> > + * @flags: DMA-BUF file/FD flags.
> > + * @dmabuf_fd: pointer to result FD that represents the dma-buf object.
> > + *
> > + * Create and export a dma-buf object for an existing memory
> > +allocation inside
> > + * the device memory, and return a FD which is associated with the
> > +dma-buf
> > + * object.
> > + *
> > + * Return: 0 on success, non-zero for failure.
> > + */
> > +static int export_dmabuf_from_handle(struct hl_ctx *ctx, u64 handle, int
> flags,
> > +					int *dmabuf_fd)
> > +{
> > +	struct hl_device *hdev = ctx->hdev;
> > +	struct hl_vm_phys_pg_pack *phys_pg_pack;
> > +	struct hl_dmabuf_wrapper *hl_dmabuf;
> > +	struct hl_vm *vm = &hdev->vm;
> > +	enum vm_type_t *vm_type;
> > +	u32 idr_handle;
> > +	int rc;
> > +
> > +	dev_dbg(hdev->dev, "exporting dma-buf for handle 0x%llx\n",
> handle);
> > +
> > +	idr_handle = lower_32_bits(handle);
> > +
> > +	spin_lock(&vm->idr_lock);
> > +
> > +	phys_pg_pack = idr_find(&vm->phys_pg_pack_handles,
> idr_handle);
> > +	if (!phys_pg_pack) {
> > +		spin_unlock(&vm->idr_lock);
> > +		dev_err(hdev->dev, "no match for handle 0x%x\n",
> idr_handle);
> > +		return -EINVAL;
> > +	}
> > +
> > +	/* increment now to avoid freeing device memory while exporting */
> > +	atomic_inc(&phys_pg_pack->exporting_cnt);
> > +
> > +	spin_unlock(&vm->idr_lock);
> > +
> > +	vm_type = (enum vm_type_t *) phys_pg_pack;
> 
> Why is this casting a struct instead of accessing its first field?

The casting is not needed ... we will fix it, thanks.
 
> > +	if (*vm_type != VM_TYPE_PHYS_PACK) {
> > +		dev_err(hdev->dev, "handle 0x%llx is not for DRAM
> memory\n",
> > +				handle);
> > +		rc = -EINVAL;
> > +		goto err_dec_exporting_cnt;
> > +	}
> > +
> > +	hl_dmabuf = kzalloc(sizeof(*hl_dmabuf), GFP_KERNEL);
> > +	if (!hl_dmabuf) {
> > +		rc = -ENOMEM;
> > +		goto err_dec_exporting_cnt;
> > +	}
> > +
> > +	hl_dmabuf->phys_pg_pack = phys_pg_pack;
> > +	hl_dmabuf->handle = handle;
> > +	hl_dmabuf->total_size = phys_pg_pack->total_size;
> > +
> > +	rc = export_dmabuf_common(ctx, hl_dmabuf, phys_pg_pack-
> >pages,
> > +				phys_pg_pack->npages, phys_pg_pack-
> >page_size,
> > +				flags, dmabuf_fd);
> > +	if (rc)
> > +		goto err_free_dmabuf_wrapper;
> > +
> > +	return 0;
> > +
> > +err_free_dmabuf_wrapper:
> > +	kfree(hl_dmabuf);
> > +err_dec_exporting_cnt:
> > +	atomic_dec(&phys_pg_pack->exporting_cnt);
> > +	return rc;
> > +}
> > +
> >  static int mem_ioctl_no_mmu(struct hl_fpriv *hpriv, union hl_mem_args
> > *args)  {
> >  	struct hl_device *hdev = hpriv->hdev;
> >  	struct hl_ctx *ctx = hpriv->ctx;
> >  	u64 block_handle, device_addr = 0;
> >  	u32 handle = 0, block_size;
> > -	int rc;
> > +	int rc, dmabuf_fd = -EBADF;
> >
> >  	switch (args->in.op) {
> >  	case HL_MEM_OP_ALLOC:
> > @@ -1471,6 +1863,16 @@ static int mem_ioctl_no_mmu(struct hl_fpriv
> *hpriv, union hl_mem_args *args)
> >  		args->out.block_size = block_size;
> >  		break;
> >
> > +	case HL_MEM_OP_EXPORT_DMABUF_FD:
> > +		rc = export_dmabuf_from_addr(ctx,
> > +				args->in.export_dmabuf_fd.handle,
> > +				args->in.export_dmabuf_fd.mem_size,
> > +				args->in.flags,
> > +				&dmabuf_fd);
> > +		memset(args, 0, sizeof(*args));
> > +		args->out.fd = dmabuf_fd;
> > +		break;
> > +
> >  	default:
> >  		dev_err(hdev->dev, "Unknown opcode for memory
> IOCTL\n");
> >  		rc = -ENOTTY;
> > @@ -1489,7 +1891,7 @@ int hl_mem_ioctl(struct hl_fpriv *hpriv, void
> *data)
> >  	struct hl_ctx *ctx = hpriv->ctx;
> >  	u64 block_handle, device_addr = 0;
> >  	u32 handle = 0, block_size;
> > -	int rc;
> > +	int rc, dmabuf_fd = -EBADF;
> >
> >  	if (!hl_device_operational(hdev, &status)) {
> >  		dev_warn_ratelimited(hdev->dev,
> > @@ -1580,6 +1982,22 @@ int hl_mem_ioctl(struct hl_fpriv *hpriv, void
> *data)
> >  		args->out.block_size = block_size;
> >  		break;
> >
> > +	case HL_MEM_OP_EXPORT_DMABUF_FD:
> > +		if (hdev->asic_prop.dram_supports_virtual_memory)
> > +			rc = export_dmabuf_from_handle(ctx,
> > +					args->in.export_dmabuf_fd.handle,
> > +					args->in.flags,
> > +					&dmabuf_fd);
> > +		else
> > +			rc = export_dmabuf_from_addr(ctx,
> > +					args->in.export_dmabuf_fd.handle,
> > +					args-
> >in.export_dmabuf_fd.mem_size,
> > +					args->in.flags,
> > +					&dmabuf_fd);
> 
> So these devices either work with virtual or physical memory, but the
> memory is pinned regardless?

It is only Gaudi device with which user work with physical addresses and not virtual.
In any case the devices' memory is pinned.

> 
> > +		memset(args, 0, sizeof(*args));
> > +		args->out.fd = dmabuf_fd;
> > +		break;
> > +
> >  	default:
> >  		dev_err(hdev->dev, "Unknown opcode for memory
> IOCTL\n");
> >  		rc = -ENOTTY;
> > diff --git a/drivers/misc/habanalabs/gaudi/gaudi.c
> > b/drivers/misc/habanalabs/gaudi/gaudi.c
> > index a673e404f777..3a66e56d7cd5 100644
> > --- a/drivers/misc/habanalabs/gaudi/gaudi.c
> > +++ b/drivers/misc/habanalabs/gaudi/gaudi.c
> > @@ -685,6 +685,7 @@ static int gaudi_early_init(struct hl_device *hdev)
> >  	}
> >
> >  	prop->dram_pci_bar_size = pci_resource_len(pdev, HBM_BAR_ID);
> > +	hdev->dram_pci_bar_start = pci_resource_start(pdev,
> HBM_BAR_ID);
> >
> >  	/* If FW security is enabled at this point it means no access to ELBI */
> >  	if (hdev->asic_prop.fw_security_enabled) { diff --git
> > a/drivers/misc/habanalabs/goya/goya.c
> > b/drivers/misc/habanalabs/goya/goya.c
> > index 5a837c0b4d76..ad2c6f788030 100644
> > --- a/drivers/misc/habanalabs/goya/goya.c
> > +++ b/drivers/misc/habanalabs/goya/goya.c
> > @@ -617,6 +617,7 @@ static int goya_early_init(struct hl_device *hdev)
> >  	}
> >
> >  	prop->dram_pci_bar_size = pci_resource_len(pdev, DDR_BAR_ID);
> > +	hdev->dram_pci_bar_start = pci_resource_start(pdev,
> DDR_BAR_ID);
> >
> >  	/* If FW security is enabled at this point it means no access to ELBI */
> >  	if (hdev->asic_prop.fw_security_enabled) {
> >
> 
> Pedantic checkpatch has a lot to say about this patch :).
> 
> Reviewed-by: Gal Pressman <galpress@xxxxxxxxxx>

Thanks