From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7D8883CD8D5; Thu, 16 Apr 2026 13:19:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=67.231.153.30 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776345551; cv=none; b=KAYBZ0oT/uqtlAwwJ3uv083UVjBcFsLJiWAuFsK/5YOa1D/jDfjwwIJAsUmEQt6jjcb51/Thkwixk1Cz1LhhccgaNbwkvWVGSbxWyfWIBUr4YA4DYXGIWKFSYryiH067aKWmoktruB4WBCpCjiIT2dZz5HXAETAmOYETtMIuuLk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776345551; c=relaxed/simple; bh=14h1F1VrifsxxJ/TG9PRx84X3spk5+U2yiG+c1NsLTM=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=W4VpJLzfniwX9Cz8tl9LBiGtxhfJfqGqRwXAVdD9CUokXZ5o9CeIys8g4wg2xmr4t/2tlzc80b2UHHscpnnpJFv1upvPBJ3JoukEZL1cQAxNjt0Y8NRJrEXKGmtuy7icBzF3Jzyx+8Nps+jq8sU16DDh2vXmAtVfAvlS+PGgRgU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=meta.com; spf=pass smtp.mailfrom=meta.com; dkim=pass (2048-bit key) header.d=meta.com header.i=@meta.com header.b=fgKuowTf; arc=none smtp.client-ip=67.231.153.30 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=meta.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=meta.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=meta.com header.i=@meta.com header.b="fgKuowTf" Received: from pps.filterd (m0528004.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 63GDClxn292577; Thu, 16 Apr 2026 06:18:55 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=meta.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=s2048-2025-q2; bh=OnXpacRUCWVmj2ZhEhbENFViXZJLK6k7he2hDqU0XWA=; b=fgKuowTfbhMc LpD6qO8c8yeBGBeIuAN712xR/ZRGjstUM7BrwY/5k7kWAfKarMPtnsx5R52+WMfk 69BEruQpJbj/30yDaTt0XB52tbIGNLgz7CNAvsZkMeNh8+qryBSDCKYNLapa76VW 2FDAb/s9iwN+60V98bPHo5x9nQVMIj1W++67kQ4NNIs8qUWykeIn+qJfd9GD2pxg 0LLf32QaC3zYOrjwNqvXO3RNH0Y0bfLRgtMoeNQuySGS+mYnaRN/sDGM786SJAxu dfvouwvFsogFBqgu7bpMxuFYt8V95Nu3HbXJIbUxUIg21YsqP0he7VP/0pTPv+8J cxXt1OafpQ== Received: from maileast.thefacebook.com ([163.114.135.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 4dh84tt06k-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Thu, 16 Apr 2026 06:18:55 -0700 (PDT) Received: from localhost (2620:10d:c0a8:fe::f072) by mail.thefacebook.com (2620:10d:c0a9:6f::8fd4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.2562.37; Thu, 16 Apr 2026 13:18:54 +0000 From: Matt Evans To: Alex Williamson , Leon Romanovsky , Jason Gunthorpe , Alex Mastro , =?UTF-8?q?Christian=20K=C3=B6nig?= CC: Mahmoud Adam , David Matlack , =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= , Sumit Semwal , Kevin Tian , Ankit Agrawal , Pranjal Shrivastava , Alistair Popple , Vivek Kasireddy , , , , , Subject: [PATCH 9/9] vfio/pci: Add mmap() attributes to DMABUF feature Date: Thu, 16 Apr 2026 06:17:52 -0700 Message-ID: <20260416131815.2729131-10-mattev@meta.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260416131815.2729131-1-mattev@meta.com> References: <20260416131815.2729131-1-mattev@meta.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Authority-Analysis: v=2.4 cv=DeknbPtW c=1 sm=1 tr=0 ts=69e0e1bf cx=c_pps a=MfjaFnPeirRr97d5FC5oHw==:117 a=MfjaFnPeirRr97d5FC5oHw==:17 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=7x6HtfJdh03M6CCDgxCd:22 a=GbPsI2Ihf5RTnMjR_gZv:22 a=VabnemYjAAAA:8 a=ZZip-zt6qTTd7FoaoeoA:9 a=gKebqoRLp9LExxC7YDUY:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDE2MDEyNiBTYWx0ZWRfX+tFyEUII+htx zqwYV0dvl9D+Yw505382/FK3ILPMyAC418PRnZqUDx+oll9uXnun/Z+BrsRoSzzs2WlaYS2W9dh gt2K/IopaUAFYYMziA/d9FPa/C9LQH5wdyC0sSi3ntjiA4/s8UbH9ERH7uM2Z9bWNkPZgFbQvI0 Kxb4/vjYaXCqT4Qjs0npsBl8qcX/6PFfOdd/xZYLSqfx/2Dmzs3VR2hTBgWd3WEF4oE6swai/Bi 8MsxvROtCG+xdthlcWrgCmCWhQZSdHVRyj+pv3d9KJyFJ/0U8N1DBSht0fL8TJc51Y4b29jrb8a F1thlt0Jz/aIP8oEaiHLYBfPcBJYCE7ov0bI6WZ8NQ5ImrzE3dwRhUjt0qpD2pjStgYI00w5Slv JSX088HrUF78v9dWd/U7btiZexNZHznyZF/KvPghTxYTWW2/3klJC9VdG34NbNq488M5weruVde mtD87JYknNYlzwyZOxw== X-Proofpoint-GUID: G5a8D1fswKo3D1yySENReTX4evzXtV9I X-Proofpoint-ORIG-GUID: G5a8D1fswKo3D1yySENReTX4evzXtV9I X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-16_03,2026-04-16_02,2025-10-01_01 A new field is reserved in vfio_device_feature_dma_buf.flags to request CPU-facing memory type attributes for mmap()s of the buffer. Add a flag VFIO_DEVICE_FEATURE_DMA_BUF_ATTR_WC, which results in WC PTEs for the DMABUF's BAR region. Signed-off-by: Matt Evans --- drivers/vfio/pci/vfio_pci_dmabuf.c | 15 +++++++++++++-- drivers/vfio/pci/vfio_pci_priv.h | 1 + include/uapi/linux/vfio.h | 12 +++++++++--- 3 files changed, 23 insertions(+), 5 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c index 48ec4da2db8b..00cedfe3a57d 100644 --- a/drivers/vfio/pci/vfio_pci_dmabuf.c +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c @@ -43,7 +43,10 @@ static int vfio_pci_dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct * if (req_start + req_len > priv->size) return -EINVAL; - vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); + if (priv->attrs == VFIO_DEVICE_FEATURE_DMA_BUF_ATTR_WC) + vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot); + else + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot); /* See comments in vfio_pci_core_mmap() re VM_ALLOW_ANY_UNCACHED. */ @@ -370,6 +373,12 @@ static int validate_dmabuf_input(struct vfio_device_feature_dma_buf *dma_buf, size_t length = 0; u32 i; + if ((dma_buf->flags != 0) && + ((dma_buf->flags & ~VFIO_DEVICE_FEATURE_DMA_BUF_ATTR_MASK) || + ((dma_buf->flags & VFIO_DEVICE_FEATURE_DMA_BUF_ATTR_MASK) != + VFIO_DEVICE_FEATURE_DMA_BUF_ATTR_WC))) + return -EINVAL; + for (i = 0; i < dma_buf->nr_ranges; i++) { u64 offset = dma_ranges[i].offset; u64 len = dma_ranges[i].length; @@ -413,7 +422,7 @@ int vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32 flags, if (copy_from_user(&get_dma_buf, arg, sizeof(get_dma_buf))) return -EFAULT; - if (!get_dma_buf.nr_ranges || get_dma_buf.flags) + if (!get_dma_buf.nr_ranges) return -EINVAL; /* @@ -457,6 +466,7 @@ int vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32 flags, priv->vdev = vdev; priv->nr_ranges = get_dma_buf.nr_ranges; priv->size = length; + priv->attrs = get_dma_buf.flags & VFIO_DEVICE_FEATURE_DMA_BUF_ATTR_MASK; ret = vdev->pci_ops->get_dmabuf_phys(vdev, &priv->provider, get_dma_buf.region_index, priv->phys_vec, dma_ranges, @@ -542,6 +552,7 @@ int vfio_pci_core_mmap_prep_dmabuf(struct vfio_pci_core_device *vdev, */ priv->vdev = vdev; priv->nr_ranges = nr_ranges; + priv->attrs = 0; priv->size = (vma->vm_pgoff << PAGE_SHIFT) + req_len; priv->provider = pcim_p2pdma_provider(vdev->pdev, res_index); if (!priv->provider) { diff --git a/drivers/vfio/pci/vfio_pci_priv.h b/drivers/vfio/pci/vfio_pci_priv.h index eac5606ca161..aeffd9f7f3b5 100644 --- a/drivers/vfio/pci/vfio_pci_priv.h +++ b/drivers/vfio/pci/vfio_pci_priv.h @@ -40,6 +40,7 @@ struct vfio_pci_dma_buf { u32 nr_ranges; struct kref kref; struct completion comp; + u32 attrs; enum vfio_pci_dma_buf_status status; }; diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index 77225ed8115f..93eef95dc7f3 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -1535,7 +1535,9 @@ struct vfio_device_feature_bus_master { * etc. offset/length specify a slice of the region to create the dmabuf from. * nr_ranges is the total number of (P2P DMA) ranges that comprise the dmabuf. * - * flags should be 0. + * flags contains: + * - A field for userspace mapping attribute: by default, suitable for regular + * MMIO. Alternate attributes (such as WC) can be selected. * * Return: The fd number on success, -1 and errno is set on failure. */ @@ -1549,8 +1551,12 @@ struct vfio_region_dma_range { struct vfio_device_feature_dma_buf { __u32 region_index; __u32 open_flags; - __u32 flags; - __u32 nr_ranges; + __u32 flags; + /* Flags sub-field reserved for attribute enum */ +#define VFIO_DEVICE_FEATURE_DMA_BUF_ATTR_MASK (0xfU << 28) +#define VFIO_DEVICE_FEATURE_DMA_BUF_ATTR_UC (0 << 28) +#define VFIO_DEVICE_FEATURE_DMA_BUF_ATTR_WC (1 << 28) + __u32 nr_ranges; struct vfio_region_dma_range dma_ranges[] __counted_by(nr_ranges); }; -- 2.47.3