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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 43A89CD13DA for ; Thu, 30 Apr 2026 20:11:32 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6D2DD10F44D; Thu, 30 Apr 2026 20:11:31 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=meta.com header.i=@meta.com header.b="ce6O/wDv"; dkim-atps=neutral Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by gabe.freedesktop.org (Postfix) with ESMTPS id 032BD10F44D for ; Thu, 30 Apr 2026 20:11:29 +0000 (UTC) Received: from pps.filterd (m0528005.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 63UDBBNv518622 for ; Thu, 30 Apr 2026 13:11:29 -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=XO4gDs/Vlu99NfyVjj4NXutxQm8yt30Ut2WY5+A6e1s=; b=ce6O/wDvLzBW 0tXIMu+id8OHvF0uHfUJEwOb97wJkuDhA4Jx5PCEzqDTQR2hqn4xpolTHrydAvny aA7QQDuMybLgvYqAhanYSC5TeaDxwBFN7bvU4dAqmpQLTld3yJppy4gUjUGw76pR xRIH9rTbGSSMNCR6ZrxV3X015hkYR6ZROFEQ3keoqFWxHvRIpD+rkyLk97B2aOLh RTqmG+hy9lFWNT6thNGodRXaXBhQnVzftJmJwJZawTEAV4Itwium/iSkXfsLyPKx SlJnMqsDYqnP+6c/7SBWortbHIRJt3ZYhKZAtS11FszZkICU68F7oXyn3+tGCeHP vP9heifzgA== Received: from maileast.thefacebook.com ([163.114.135.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 4dsf6p8rjn-4 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Thu, 30 Apr 2026 13:11:28 -0700 (PDT) Received: from twshared26632.02.snb2.facebook.com (2620:10d:c0a8:1b::2d) by mail.thefacebook.com (2620:10d:c0a9:6f::237c) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.2562.37; Thu, 30 Apr 2026 20:11:26 +0000 Received: by devbig259.ftw1.facebook.com (Postfix, from userid 664516) id 919901B9B4FCA; Thu, 30 Apr 2026 13:07:05 -0700 (PDT) From: Zhiping Zhang To: Alex Williamson , Jason Gunthorpe , Leon Romanovsky CC: Bjorn Helgaas , , , , , Keith Busch , Yochai Cohen , Yishai Hadas , Zhiping Zhang Subject: [PATCH v2 1/2] vfio: add dma-buf get_tph callback and DMA_BUF_TPH feature Date: Thu, 30 Apr 2026 13:06:56 -0700 Message-ID: <20260430200704.352228-2-zhipingz@meta.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260430200704.352228-1-zhipingz@meta.com> References: <20260430200704.352228-1-zhipingz@meta.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDMwMDIwOCBTYWx0ZWRfX+7/oASmFwJFt ezEDOIY+OQSuX2xlJ0aztBS87UzvbWzEuhUEfzJoibDLZX7V+1JfnwKJzcA76Fv+6aEU73/gTjP Pp6K138E1rHn0OPQNt0BFaIrOyyH77pQpd8kMEei01yKwXMivOS1INjv7oUEu7Cqv/sunQbsv74 WnTqyfFxMsKHgjnntC0MMfZ936JJLg5ddkFPTrA94a2Nfn2csp9ucAt/QmfJVavpUGcLrJ7kgXu rmFtcp8pSEOHPZ6M9LKATtS52ShMB4BzDdJlVqDpqGj7d4xZ49i942MCqYvhTBq3aYfVmnRkdp6 Sy/XwG8bJCx+ngtskzDT5L88plZ386ogKGxhDcMIY1QRGHqzsIe5nIyXekEO3Zk9OEc2HhukNhw u0pBkhzVzi1rFumPTVb2A1D5MrpuafOZul2acsE8NEOQG7yumCwNLtEgb/6yvLXNQaqvduUCLPi hxuEoRgGFUM+ESVlOiQ== X-Authority-Analysis: v=2.4 cv=Cfo4Irrl c=1 sm=1 tr=0 ts=69f3b771 cx=c_pps a=MfjaFnPeirRr97d5FC5oHw==:117 a=MfjaFnPeirRr97d5FC5oHw==:17 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=7x6HtfJdh03M6CCDgxCd:22 a=jCddH8ec0KUNCymVuxII:22 a=VabnemYjAAAA:8 a=I2VOSbTcSc4ADjQXWK4A:9 a=gKebqoRLp9LExxC7YDUY:22 X-Proofpoint-ORIG-GUID: J65JKkLu8e1LQAMLvML-aSmiYstQXL25 X-Proofpoint-GUID: J65JKkLu8e1LQAMLvML-aSmiYstQXL25 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=2026-04-30_05,2026-04-30_02,2025-10-01_01 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Add a dma-buf callback that returns raw TPH metadata from the exporter so peer devices can reuse the steering tag and processing hint associated with a VFIO-exported buffer. Add a new VFIO_DEVICE_FEATURE_DMA_BUF_TPH ioctl that takes the fd from VFIO_DEVICE_FEATURE_DMA_BUF along with a steering tag and processing hint, validates the fd is a vfio-exported dma-buf belonging to this device, and stores the TPH values under memory_lock. This keeps the existing VFIO_DEVICE_FEATURE_DMA_BUF uAPI completely unchanged. The user sequences setting TPH on the dma-buf before the importer consumes it. Add an st_width parameter to get_tph() so the exporter can reject steering tags that exceed the consumer's supported width (8 vs 16 bit). When no TPH metadata was supplied, get_tph() returns -EOPNOTSUPP. Signed-off-by: Zhiping Zhang diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci= _core.c --- a/drivers/vfio/pci/vfio_pci_core.c +++ b/drivers/vfio/pci/vfio_pci_core.c @@ -1534,6 +1534,9 @@ int vfio_pci_core_ioctl_feature(struct vfio_device = *device, u32 flags, return vfio_pci_core_feature_token(vdev, flags, arg, argsz); case VFIO_DEVICE_FEATURE_DMA_BUF: return vfio_pci_core_feature_dma_buf(vdev, flags, arg, argsz); + case VFIO_DEVICE_FEATURE_DMA_BUF_TPH: + return vfio_pci_core_feature_dma_buf_tph(vdev, flags, arg, + argsz); default: return -ENOTTY; } diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_p= ci_dmabuf.c --- a/drivers/vfio/pci/vfio_pci_dmabuf.c +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c @@ -19,6 +19,9 @@ struct vfio_pci_dma_buf { u32 nr_ranges; struct kref kref; struct completion comp; + u16 steering_tag; + u8 ph; + u8 tph_present : 1; u8 revoked : 1; }; =20 @@ -69,6 +72,22 @@ vfio_pci_dma_buf_map(struct dma_buf_attachment *attach= ment, return ret; } =20 +static int vfio_pci_dma_buf_get_tph(struct dma_buf *dmabuf, u16 *steerin= g_tag, + u8 *ph, u8 st_width) +{ + struct vfio_pci_dma_buf *priv =3D dmabuf->priv; + + if (!priv->tph_present) + return -EOPNOTSUPP; + + if (st_width < 16 && priv->steering_tag > ((1U << st_width) - 1)) + return -EINVAL; + + *steering_tag =3D priv->steering_tag; + *ph =3D priv->ph; + return 0; +} + static void vfio_pci_dma_buf_unmap(struct dma_buf_attachment *attachment= , struct sg_table *sgt, enum dma_data_direction dir) @@ -101,6 +120,7 @@ static void vfio_pci_dma_buf_release(struct dma_buf *= dmabuf) =20 static const struct dma_buf_ops vfio_pci_dmabuf_ops =3D { .attach =3D vfio_pci_dma_buf_attach, + .get_tph =3D vfio_pci_dma_buf_get_tph, .map_dma_buf =3D vfio_pci_dma_buf_map, .unmap_dma_buf =3D vfio_pci_dma_buf_unmap, .release =3D vfio_pci_dma_buf_release, @@ -331,6 +351,55 @@ int vfio_pci_core_feature_dma_buf(struct vfio_pci_co= re_device *vdev, u32 flags, return ret; } =20 +int vfio_pci_core_feature_dma_buf_tph(struct vfio_pci_core_device *vdev, + u32 flags, + struct vfio_device_feature_dma_buf_tph __user *arg, + size_t argsz) +{ + struct vfio_device_feature_dma_buf_tph set_tph; + struct vfio_pci_dma_buf *priv; + struct dma_buf *dmabuf; + int ret; + + ret =3D vfio_check_feature(flags, argsz, VFIO_DEVICE_FEATURE_SET, + sizeof(set_tph)); + if (ret !=3D 1) + return ret; + + if (copy_from_user(&set_tph, arg, sizeof(set_tph))) + return -EFAULT; + + if (set_tph.reserved) + return -EINVAL; + + dmabuf =3D dma_buf_get(set_tph.dmabuf_fd); + if (IS_ERR(dmabuf)) + return PTR_ERR(dmabuf); + + if (dmabuf->ops !=3D &vfio_pci_dmabuf_ops) { + ret =3D -EINVAL; + goto out_put; + } + + priv =3D dmabuf->priv; + down_write(&vdev->memory_lock); + if (priv->vdev !=3D vdev) { + ret =3D -EINVAL; + goto out_unlock; + } + + priv->steering_tag =3D set_tph.steering_tag; + priv->ph =3D set_tph.ph; + priv->tph_present =3D 1; + ret =3D 0; + +out_unlock: + up_write(&vdev->memory_lock); +out_put: + dma_buf_put(dmabuf); + return ret; +} + void vfio_pci_dma_buf_move(struct vfio_pci_core_device *vdev, bool revok= ed) { struct vfio_pci_dma_buf *priv; diff --git a/drivers/vfio/pci/vfio_pci_priv.h b/drivers/vfio/pci/vfio_pci= _priv.h --- a/drivers/vfio/pci/vfio_pci_priv.h +++ b/drivers/vfio/pci/vfio_pci_priv.h @@ -118,6 +118,10 @@ static inline bool vfio_pci_is_vga(struct pci_dev *p= dev) int vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32= flags, struct vfio_device_feature_dma_buf __user *arg, size_t argsz); +int vfio_pci_core_feature_dma_buf_tph(struct vfio_pci_core_device *vdev, + u32 flags, + struct vfio_device_feature_dma_buf_tph __user *arg, + size_t argsz); void vfio_pci_dma_buf_cleanup(struct vfio_pci_core_device *vdev); void vfio_pci_dma_buf_move(struct vfio_pci_core_device *vdev, bool revok= ed); #else @@ -128,6 +132,13 @@ vfio_pci_core_feature_dma_buf(struct vfio_pci_core_d= evice *vdev, u32 flags, { return -ENOTTY; } +static inline int +vfio_pci_core_feature_dma_buf_tph(struct vfio_pci_core_device *vdev, u32= flags, + struct vfio_device_feature_dma_buf_tph __user *arg, + size_t argsz) +{ + return -ENOTTY; +} static inline void vfio_pci_dma_buf_cleanup(struct vfio_pci_core_device = *vdev) { } diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -113,6 +113,23 @@ struct dma_buf_ops { */ void (*unpin)(struct dma_buf_attachment *attach); =20 + /** + * @get_tph: + * @dmabuf: DMA buffer for which to retrieve TPH metadata + * @steering_tag: Returns the raw TPH steering tag + * @ph: Returns the TPH processing hint + * @st_width: Consumer's supported steering tag width in bits (8 or 16) + * + * Return the TPH (TLP Processing Hints) metadata associated with this + * DMA buffer. Exporters that do not provide TPH metadata should return + * -EOPNOTSUPP. If the steering tag exceeds @st_width bits, return + * -EINVAL. + * + * This callback is optional. + */ + int (*get_tph)(struct dma_buf *dmabuf, u16 *steering_tag, u8 *ph, + u8 st_width); + /** * @map_dma_buf: * diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -1534,6 +1534,28 @@ struct vfio_device_feature_dma_buf { */ #define VFIO_DEVICE_FEATURE_MIG_PRECOPY_INFOv2 12 =20 +/** + * Upon VFIO_DEVICE_FEATURE_SET associate TPH (TLP Processing Hints) met= adata + * with a vfio-exported dma-buf. The dma-buf must have been created by + * VFIO_DEVICE_FEATURE_DMA_BUF on this device. + * + * dmabuf_fd is the file descriptor returned by VFIO_DEVICE_FEATURE_DMA_= BUF. + * steering_tag and ph are the raw TPH values that importing drivers sho= uld use + * when accessing the buffer. + * + * The user must set TPH on the dma-buf before the importer consumes it. + * + * Return: 0 on success, -errno on failure. + */ +#define VFIO_DEVICE_FEATURE_DMA_BUF_TPH 13 + +struct vfio_device_feature_dma_buf_tph { + __s32 dmabuf_fd; + __u16 steering_tag; + __u8 ph; + __u8 reserved; +}; + /* -------- API for Type1 VFIO IOMMU -------- */ =20 /**