From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-lf0-f68.google.com ([209.85.215.68]:44211 "EHLO mail-lf0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935905AbeE3Gru (ORCPT ); Wed, 30 May 2018 02:47:50 -0400 Subject: Re: [PATCH 4/8] xen/gntdev: Allow mappings for DMA buffers To: Boris Ostrovsky , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, jgross@suse.com, konrad.wilk@oracle.com Cc: daniel.vetter@intel.com, dongwon.kim@intel.com, matthew.d.roper@intel.com, Oleksandr Andrushchenko References: <20180525153331.31188-1-andr2000@gmail.com> <20180525153331.31188-5-andr2000@gmail.com> <9f2999a8-7786-5811-bdf0-ff7f30301cf2@oracle.com> From: Oleksandr Andrushchenko Message-ID: Date: Wed, 30 May 2018 09:47:46 +0300 MIME-Version: 1.0 In-Reply-To: <9f2999a8-7786-5811-bdf0-ff7f30301cf2@oracle.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-media-owner@vger.kernel.org List-ID: On 05/30/2018 12:52 AM, Boris Ostrovsky wrote: > On 05/25/2018 11:33 AM, Oleksandr Andrushchenko wrote: >> >> struct unmap_notify { >> @@ -96,10 +104,28 @@ struct grant_map { >> struct gnttab_unmap_grant_ref *kunmap_ops; >> struct page **pages; >> unsigned long pages_vm_start; >> + >> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC >> + /* >> + * If dmabuf_vaddr is not NULL then this mapping is backed by DMA >> + * capable memory. >> + */ >> + >> + /* Device for which DMA memory is allocated. */ >> + struct device *dma_dev; >> + /* Flags used to create this DMA buffer: GNTDEV_DMABUF_FLAG_XXX. */ >> + bool dma_flags; > Again, I think most of the comments here can be dropped. Except possibly > for the flags. will drop most of those >> + /* Virtual/CPU address of the DMA buffer. */ >> + void *dma_vaddr; >> + /* Bus address of the DMA buffer. */ >> + dma_addr_t dma_bus_addr; >> +#endif >> }; >> >> static int unmap_grant_pages(struct grant_map *map, int offset, int pages); >> >> +static struct miscdevice gntdev_miscdev; >> + >> /* ------------------------------------------------------------------ */ >> >> static void gntdev_print_maps(struct gntdev_priv *priv, >> @@ -121,8 +147,26 @@ static void gntdev_free_map(struct grant_map *map) >> if (map == NULL) >> return; >> >> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC >> + if (map->dma_vaddr) { >> + struct gnttab_dma_alloc_args args; >> + >> + args.dev = map->dma_dev; >> + args.coherent = map->dma_flags & GNTDEV_DMA_FLAG_COHERENT; >> + args.nr_pages = map->count; >> + args.pages = map->pages; >> + args.vaddr = map->dma_vaddr; >> + args.dev_bus_addr = map->dma_bus_addr; >> + >> + gnttab_dma_free_pages(&args); >> + } else if (map->pages) { >> + gnttab_free_pages(map->count, map->pages); >> + } >> +#else >> if (map->pages) >> gnttab_free_pages(map->count, map->pages); >> +#endif >> + > } else > #endif >     if (map->pages) >         gnttab_free_pages(map->count, map->pages); > > > (and elsewhere) ok, just wasn't sure if it is ok to violate kernel coding style here ;) >> kfree(map->pages); >> kfree(map->grants); >> kfree(map->map_ops); > > >> >> diff --git a/include/uapi/xen/gntdev.h b/include/uapi/xen/gntdev.h >> index 6d1163456c03..2d5a4672f07c 100644 >> --- a/include/uapi/xen/gntdev.h >> +++ b/include/uapi/xen/gntdev.h >> @@ -200,4 +200,19 @@ struct ioctl_gntdev_grant_copy { >> /* Send an interrupt on the indicated event channel */ >> #define UNMAP_NOTIFY_SEND_EVENT 0x2 >> >> +/* >> + * Flags to be used while requesting memory mapping's backing storage >> + * to be allocated with DMA API. >> + */ >> + >> +/* >> + * The buffer is backed with memory allocated with dma_alloc_wc. >> + */ >> +#define GNTDEV_DMA_FLAG_WC (1 << 1) > > Is there a reason you are not using bit 0? No reason for that, will start from 0 > > -boris Thank you, Oleksandr >> + >> +/* >> + * The buffer is backed with memory allocated with dma_alloc_coherent. >> + */ >> +#define GNTDEV_DMA_FLAG_COHERENT (1 << 2) >> + >> #endif /* __LINUX_PUBLIC_GNTDEV_H__ */