From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A6556C25B08 for ; Sun, 7 Aug 2022 20:26:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231393AbiHGUZ7 (ORCPT ); Sun, 7 Aug 2022 16:25:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45642 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230386AbiHGUZ5 (ORCPT ); Sun, 7 Aug 2022 16:25:57 -0400 Received: from alexa-out.qualcomm.com (alexa-out.qualcomm.com [129.46.98.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EAB5364C4; Sun, 7 Aug 2022 13:25:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1659903953; x=1691439953; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=eQ5vUTIVjFaJOW49JpDtCqaTs+jr2jaJBCrYgnxt4dI=; b=N5EVe6SWkfIjMBYqNx9tkukCc/lPhO+mzjPh/cSqxKf4hP1wa5WrfskT AA0Sc2CNxrgSaTwnShlmB/AEXz7WnnpKDF0QkO7Ska/ltxnXJDC9dCjO/ EwQz28V+6HG7DZeWgrs6LNtdDtBgySnPcZBvCE74AS9LZUaHdLhFu+5qs M=; Received: from ironmsg09-lv.qualcomm.com ([10.47.202.153]) by alexa-out.qualcomm.com with ESMTP; 07 Aug 2022 13:25:52 -0700 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg09-lv.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Aug 2022 13:25:52 -0700 Received: from nalasex01a.na.qualcomm.com (10.47.209.196) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Sun, 7 Aug 2022 13:25:51 -0700 Received: from [10.216.42.249] (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Sun, 7 Aug 2022 13:25:48 -0700 Message-ID: <62afe47a-1a50-80ef-400d-8c238f1cb332@quicinc.com> Date: Mon, 8 Aug 2022 01:55:45 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.3.2 Subject: Re: [Freedreno] [PATCH 1/3] dma-buf: Add ioctl to query mmap info Content-Language: en-US To: Rob Clark , CC: Rob Clark , =?UTF-8?B?SsOpcsO0bWUgUG91aWxsZXI=?= , open list , =?UTF-8?Q?Christian_K=c3=b6nig?= , "moderated list:DMA BUFFER SHARING FRAMEWORK" , , Sumit Semwal , "open list:DMA BUFFER SHARING FRAMEWORK" References: <20220729170744.1301044-1-robdclark@gmail.com> <20220729170744.1301044-2-robdclark@gmail.com> From: Akhil P Oommen In-Reply-To: <20220729170744.1301044-2-robdclark@gmail.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01a.na.qualcomm.com (10.47.209.196) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/29/2022 10:37 PM, Rob Clark wrote: > From: Rob Clark > > This is a fairly narrowly focused interface, providing a way for a VMM > in userspace to tell the guest kernel what pgprot settings to use when > mapping a buffer to guest userspace. > > For buffers that get mapped into guest userspace, virglrenderer returns > a dma-buf fd to the VMM (crosvm or qemu). In addition to mapping the > pages into the guest VM, it needs to report to drm/virtio in the guest > the cache settings to use for guest userspace. In particular, on some > architectures, creating aliased mappings with different cache attributes > is frowned upon, so it is important that the guest mappings have the > same cache attributes as any potential host mappings. > > Signed-off-by: Rob Clark > --- > drivers/dma-buf/dma-buf.c | 26 ++++++++++++++++++++++++++ > include/linux/dma-buf.h | 7 +++++++ > include/uapi/linux/dma-buf.h | 28 ++++++++++++++++++++++++++++ > 3 files changed, 61 insertions(+) > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c > index 32f55640890c..d02d6c2a3b49 100644 > --- a/drivers/dma-buf/dma-buf.c > +++ b/drivers/dma-buf/dma-buf.c > @@ -326,6 +326,29 @@ static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf) > return 0; > } > > +static long dma_buf_info(struct dma_buf *dmabuf, const void __user *uarg) > +{ > + struct dma_buf_info arg; > + > + if (copy_from_user(&arg, uarg, sizeof(arg))) > + return -EFAULT; > + > + switch (arg.param) { > + case DMA_BUF_INFO_VM_PROT: > + if (!dmabuf->ops->mmap_info) > + return -ENOSYS; > + arg.value = dmabuf->ops->mmap_info(dmabuf); > + break; > + default: > + return -EINVAL; > + } > + > + if (copy_to_user(uarg, &arg, sizeof(arg))) > + return -EFAULT; > + > + return 0; > +} > + > static long dma_buf_ioctl(struct file *file, > unsigned int cmd, unsigned long arg) > { > @@ -369,6 +392,9 @@ static long dma_buf_ioctl(struct file *file, > case DMA_BUF_SET_NAME_B: > return dma_buf_set_name(dmabuf, (const char __user *)arg); > > + case DMA_BUF_IOCTL_INFO: > + return dma_buf_info(dmabuf, (const void __user *)arg); > + > default: > return -ENOTTY; > } > diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h > index 71731796c8c3..6f4de64a5937 100644 > --- a/include/linux/dma-buf.h > +++ b/include/linux/dma-buf.h > @@ -283,6 +283,13 @@ struct dma_buf_ops { > */ > int (*mmap)(struct dma_buf *, struct vm_area_struct *vma); > > + /** > + * @mmap_info: > + * > + * Return mmapping info for the buffer. See DMA_BUF_INFO_VM_PROT. > + */ > + int (*mmap_info)(struct dma_buf *); > + > int (*vmap)(struct dma_buf *dmabuf, struct iosys_map *map); > void (*vunmap)(struct dma_buf *dmabuf, struct iosys_map *map); > }; > diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h > index b1523cb8ab30..a41adac0f46a 100644 > --- a/include/uapi/linux/dma-buf.h > +++ b/include/uapi/linux/dma-buf.h > @@ -85,6 +85,32 @@ struct dma_buf_sync { > > #define DMA_BUF_NAME_LEN 32 > > + > +/** > + * struct dma_buf_info - Query info about the buffer. > + */ > +struct dma_buf_info { > + > +#define DMA_BUF_INFO_VM_PROT 1 > +# define DMA_BUF_VM_PROT_WC 0 > +# define DMA_BUF_VM_PROT_CACHED 1 > + > + /** > + * @param: Which param to query > + * > + * DMA_BUF_INFO_BM_PROT: Is there a typo here? BM -> VM ? -Akhil. > + * Query the access permissions of userspace mmap's of this buffer. > + * Returns one of DMA_BUF_VM_PROT_x > + */ > + __u32 param; > + __u32 pad; > + > + /** > + * @value: Return value of the query. > + */ > + __u64 value; > +}; > + > #define DMA_BUF_BASE 'b' > #define DMA_BUF_IOCTL_SYNC _IOW(DMA_BUF_BASE, 0, struct dma_buf_sync) > > @@ -95,4 +121,6 @@ struct dma_buf_sync { > #define DMA_BUF_SET_NAME_A _IOW(DMA_BUF_BASE, 1, __u32) > #define DMA_BUF_SET_NAME_B _IOW(DMA_BUF_BASE, 1, __u64) > > +#define DMA_BUF_IOCTL_INFO _IOWR(DMA_BUF_BASE, 2, struct dma_buf_info) > + > #endif