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GET /api/patches/2202625/?format=api
{ "id": 2202625, "url": "http://patchwork.ozlabs.org/api/patches/2202625/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260227221632.827046-8-vivek.kasireddy@intel.com/", "project": { "id": 14, "url": "http://patchwork.ozlabs.org/api/projects/14/?format=api", "name": "QEMU Development", "link_name": "qemu-devel", "list_id": "qemu-devel.nongnu.org", "list_email": "qemu-devel@nongnu.org", "web_url": "", "scm_url": "", "webscm_url": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260227221632.827046-8-vivek.kasireddy@intel.com>", "list_archive_url": null, "date": "2026-02-27T22:13:53", "name": "[v8,07/10] vfio/device: Add support for creating dmabuf from multiple ranges", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "41af175935f05b17efacb1bbd770a259f5dd8a82", "submitter": { "id": 81116, "url": "http://patchwork.ozlabs.org/api/people/81116/?format=api", "name": "Vivek Kasireddy", "email": "vivek.kasireddy@intel.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260227221632.827046-8-vivek.kasireddy@intel.com/mbox/", "series": [ { "id": 493824, "url": "http://patchwork.ozlabs.org/api/series/493824/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=493824", "date": "2026-02-27T22:13:46", "name": "vfio: Create dmabuf from multiple VFIO ranges and use it in virtio-gpu", "version": 8, "mbox": "http://patchwork.ozlabs.org/series/493824/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2202625/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2202625/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>", "X-Original-To": "incoming@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256\n header.s=Intel header.b=PMD4w9wh;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; helo=lists.gnu.org;\n envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n receiver=patchwork.ozlabs.org)" ], "Received": [ "from lists.gnu.org (lists.gnu.org [209.51.188.17])\n\t(using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fN2nm48n6z1xxx\n\tfor <incoming@patchwork.ozlabs.org>; Sat, 28 Feb 2026 09:20:12 +1100 (AEDT)", "from localhost ([::1] helo=lists1p.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.90_1)\n\t(envelope-from <qemu-devel-bounces@nongnu.org>)\n\tid 1vw6Bh-000671-IP; Fri, 27 Feb 2026 17:19:57 -0500", "from eggs.gnu.org ([2001:470:142:3::10])\n by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from <vivek.kasireddy@intel.com>)\n id 1vw6Bf-000665-FD\n for qemu-devel@nongnu.org; Fri, 27 Feb 2026 17:19:55 -0500", "from mgamail.intel.com ([198.175.65.16])\n by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from <vivek.kasireddy@intel.com>)\n id 1vw6Bd-0007ml-4m\n for qemu-devel@nongnu.org; Fri, 27 Feb 2026 17:19:55 -0500", "from fmviesa003.fm.intel.com ([10.60.135.143])\n by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384;\n 27 Feb 2026 14:19:40 -0800", "from vkasired-desk2.fm.intel.com ([10.105.128.132])\n by fmviesa003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384;\n 27 Feb 2026 14:19:40 -0800" ], "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/simple;\n d=intel.com; i=@intel.com; q=dns/txt; s=Intel;\n t=1772230793; x=1803766793;\n h=from:to:cc:subject:date:message-id:in-reply-to:\n references:mime-version:content-transfer-encoding;\n bh=w3uTWrXd7VpeYAZj7l0t+FPlTl71pJf89qInb+jdvno=;\n b=PMD4w9whVnKdfhXufCfSIOO7+j9+UWaj7aw3QKiqTQOdpQ9hxQ4EQD25\n i+3M+YPKercSQjL4yWSTZefV8JdpdFwIVGgR9pS7bCLbGBGYatb5X+tHH\n ZCFCUvhZUYNEPIKdHwuaKZ+ytWGmRw8We64de7C3DtC8R/brw/Htv8Rzh\n MSliEoL08uZqWhzih8IjdLEkhSZQykpOQNDowXrWzaIT72jYvNrA7LBnd\n y3LtgM0ZQk22Sw0eNJsXxslke8PHehv3TkJ3i7IqdGXItxunBQbd2v28P\n e7h+m8iP4mW24sgNFAm42toRC1FZz47WvVPslDQHX4ub91GiaQKc9In6J w==;", "X-CSE-ConnectionGUID": [ "NtD6NHYJRHiCXxQh2fYHSw==", "UJmKq1egSZuBswMWk647Ag==" ], "X-CSE-MsgGUID": [ "u70RVhsjRKGezR+cQczWcg==", "1PhaXEl1SSK7ZQipksUNIA==" ], "X-IronPort-AV": [ "E=McAfee;i=\"6800,10657,11714\"; a=\"73509359\"", "E=Sophos;i=\"6.21,314,1763452800\"; d=\"scan'208\";a=\"73509359\"" ], "X-ExtLoop1": "1", "From": "Vivek Kasireddy <vivek.kasireddy@intel.com>", "To": "qemu-devel@nongnu.org", "Cc": "Vivek Kasireddy <vivek.kasireddy@intel.com>,\n Alex Williamson <alex@shazbot.org>,\n =?utf-8?q?C=C3=A9dric_Le_Goater?= <clg@redhat.com>", "Subject": "[PATCH v8 07/10] vfio/device: Add support for creating dmabuf from\n multiple ranges", "Date": "Fri, 27 Feb 2026 14:13:53 -0800", "Message-ID": "<20260227221632.827046-8-vivek.kasireddy@intel.com>", "X-Mailer": "git-send-email 2.53.0", "In-Reply-To": "<20260227221632.827046-1-vivek.kasireddy@intel.com>", "References": "<20260227221632.827046-1-vivek.kasireddy@intel.com>", "MIME-Version": "1.0", "Content-Type": "text/plain; charset=UTF-8", "Content-Transfer-Encoding": "8bit", "Received-SPF": "pass client-ip=198.175.65.16;\n envelope-from=vivek.kasireddy@intel.com; helo=mgamail.intel.com", "X-Spam_score_int": "-32", "X-Spam_score": "-3.3", "X-Spam_bar": "---", "X-Spam_report": "(-3.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001,\n DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.706,\n RCVD_IN_VALIDITY_RPBL_BLOCKED=0.401, SPF_HELO_NONE=0.001,\n SPF_PASS=-0.001 autolearn=ham autolearn_force=no", "X-Spam_action": "no action", "X-BeenThere": "qemu-devel@nongnu.org", "X-Mailman-Version": "2.1.29", "Precedence": "list", "List-Id": "qemu development <qemu-devel.nongnu.org>", "List-Unsubscribe": "<https://lists.nongnu.org/mailman/options/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>", "List-Archive": "<https://lists.nongnu.org/archive/html/qemu-devel>", "List-Post": "<mailto:qemu-devel@nongnu.org>", "List-Help": "<mailto:qemu-devel-request@nongnu.org?subject=help>", "List-Subscribe": "<https://lists.nongnu.org/mailman/listinfo/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=subscribe>", "Errors-To": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org", "Sender": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org" }, "content": "In order to create a dmabuf associated with a buffer that spans\nmultiple ranges, we first need to identify the VFIO region and\nindex the buffer (represented by iovec) belongs to and then\ntranslate its addresses to offsets within that region.\n\nThe qemu_ram_block_from_host() API gives us both the region and\nthe offset info we need to populate the dma ranges so that we can\ninvoke the VFIO_DEVICE_FEATURE_DMA_BUF feature to create the dmabuf.\n\nAlso, instead of iterating over all QOM devices to find the\nVFIODevice associated with a memory region, introduce a helper to\njust use the vfio_device_list to lookup the VFIODevice.\n\nLastly, introduce an enum to return the type of error encountered\nwhile creating the dmabuf fd.\n\nCc: Alex Williamson <alex@shazbot.org>\nCc: Cédric Le Goater <clg@redhat.com>\nSigned-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>\n---\n hw/vfio/device.c | 84 +++++++++++++++++++++++++++++++++++\n hw/vfio/dmabuf-stubs.c | 17 +++++++\n hw/vfio/meson.build | 1 +\n include/hw/vfio/vfio-device.h | 22 +++++++++\n 4 files changed, 124 insertions(+)\n create mode 100644 hw/vfio/dmabuf-stubs.c", "diff": "diff --git a/hw/vfio/device.c b/hw/vfio/device.c\nindex 973fc35b59..a25ecc3697 100644\n--- a/hw/vfio/device.c\n+++ b/hw/vfio/device.c\n@@ -21,6 +21,7 @@\n #include \"qemu/osdep.h\"\n #include <sys/ioctl.h>\n \n+#include \"system/ramblock.h\"\n #include \"hw/vfio/vfio-device.h\"\n #include \"hw/vfio/pci.h\"\n #include \"hw/core/iommu.h\"\n@@ -644,3 +645,86 @@ static VFIODeviceIOOps vfio_device_io_ops_ioctl = {\n .region_read = vfio_device_io_region_read,\n .region_write = vfio_device_io_region_write,\n };\n+\n+static bool vfio_device_lookup(struct iovec *iov, VFIODevice **vbasedevp,\n+ Error **errp)\n+{\n+ VFIODevice *vbasedev;\n+ RAMBlock *first_rb;\n+ ram_addr_t offset;\n+\n+ first_rb = qemu_ram_block_from_host(iov[0].iov_base, false, &offset);\n+ if (!first_rb) {\n+ error_setg(errp, \"Could not find first ramblock\\n\");\n+ return false;\n+ }\n+\n+ QLIST_FOREACH(vbasedev, &vfio_device_list, next) {\n+ if (vbasedev->dev == first_rb->mr->dev) {\n+ *vbasedevp = vbasedev;\n+ return true;\n+ }\n+ }\n+ error_setg(errp, \"No VFIO device found to create dmabuf from\\n\");\n+ return false;\n+}\n+\n+int vfio_device_create_dmabuf_fd(struct iovec *iov, unsigned int iov_cnt,\n+ Error **errp)\n+{\n+ g_autofree struct vfio_device_feature *feature = NULL;\n+ struct vfio_device_feature_dma_buf *dma_buf;\n+ RAMBlock *rb, *first_rb;\n+ VFIODevice *vbasedev;\n+ ram_addr_t offset;\n+ int i, index, ret;\n+ size_t argsz;\n+\n+ argsz = sizeof(*feature) + sizeof (*dma_buf) +\n+ sizeof(struct vfio_region_dma_range) * iov_cnt;\n+ feature = g_malloc0(argsz);\n+ *feature = (struct vfio_device_feature) {\n+ .argsz = argsz,\n+ .flags = VFIO_DEVICE_FEATURE_GET | VFIO_DEVICE_FEATURE_DMA_BUF,\n+ };\n+ dma_buf = (struct vfio_device_feature_dma_buf *)feature->data;\n+\n+ if (!vfio_device_lookup(iov, &vbasedev, errp)) {\n+ return VFIO_DMABUF_CREATE_GUEST_ERROR;\n+ }\n+\n+ for (i = 0; i < iov_cnt; i++) {\n+ rb = qemu_ram_block_from_host(iov[i].iov_base, false, &offset);\n+ if (i == 0) {\n+ first_rb = rb;\n+ }\n+ if (!rb || rb != first_rb) {\n+ error_setg(errp, \"Cannot create dmabuf with different regions\\n\");\n+ return VFIO_DMABUF_CREATE_GUEST_ERROR;\n+ }\n+\n+ index = vfio_get_region_index_from_mr(rb->mr);\n+ if (index < 0) {\n+ error_setg(errp, \"Cannot find region index for dmabuf segment\\n\");\n+ return VFIO_DMABUF_CREATE_GUEST_ERROR;\n+ }\n+\n+ dma_buf->region_index = index;\n+ dma_buf->dma_ranges[i].offset = offset;\n+ dma_buf->dma_ranges[i].length = iov[i].iov_len;\n+ }\n+\n+ dma_buf->nr_ranges = iov_cnt;\n+ dma_buf->open_flags = O_RDONLY | O_CLOEXEC;\n+\n+ ret = vfio_device_get_feature(vbasedev, feature);\n+ if (ret < 0) {\n+ error_setg_errno(errp, -ret,\n+ \"Could not create dmabuf fd via VFIO device\");\n+ if (ret == -ENODEV || ret == -EINVAL) {\n+ return VFIO_DMABUF_CREATE_GUEST_ERROR;\n+ }\n+ return VFIO_DMABUF_CREATE_HOST_ERROR;\n+ }\n+ return ret;\n+}\ndiff --git a/hw/vfio/dmabuf-stubs.c b/hw/vfio/dmabuf-stubs.c\nnew file mode 100644\nindex 0000000000..e71e2b68dd\n--- /dev/null\n+++ b/hw/vfio/dmabuf-stubs.c\n@@ -0,0 +1,17 @@\n+/*\n+ * Copyright (c) 2026 Intel and/or its affiliates.\n+ *\n+ * SPDX-License-Identifier: GPL-2.0-or-later\n+ */\n+\n+#include \"qemu/osdep.h\"\n+#include \"qemu/error-report.h\"\n+#include \"qemu/iov.h\"\n+#include \"hw/vfio/vfio-device.h\"\n+\n+int vfio_device_create_dmabuf_fd(struct iovec *iov, unsigned int iov_cnt,\n+ Error **errp)\n+{\n+ error_setg(errp, \"VFIO dmabuf support is not enabled\");\n+ return VFIO_DMABUF_CREATE_HOST_ERROR;\n+}\ndiff --git a/hw/vfio/meson.build b/hw/vfio/meson.build\nindex 82f68698fb..ac899d30a8 100644\n--- a/hw/vfio/meson.build\n+++ b/hw/vfio/meson.build\n@@ -34,3 +34,4 @@ system_ss.add(when: 'CONFIG_IOMMUFD', if_false: files('iommufd-stubs.c'))\n system_ss.add(when: 'CONFIG_VFIO_PCI', if_true: files(\n 'display.c',\n ))\n+system_ss.add(when: 'CONFIG_VFIO', if_false: files('dmabuf-stubs.c'))\ndiff --git a/include/hw/vfio/vfio-device.h b/include/hw/vfio/vfio-device.h\nindex 596c7f5a10..9dcf3ea57d 100644\n--- a/include/hw/vfio/vfio-device.h\n+++ b/include/hw/vfio/vfio-device.h\n@@ -41,6 +41,13 @@ enum {\n VFIO_DEVICE_TYPE_AP = 3,\n };\n \n+enum {\n+ /* Guest is responsible for this error */\n+ VFIO_DMABUF_CREATE_GUEST_ERROR = -1,\n+ /* Host is at fault for this error */\n+ VFIO_DMABUF_CREATE_HOST_ERROR = -2,\n+};\n+\n typedef struct VFIODeviceOps VFIODeviceOps;\n typedef struct VFIODeviceIOOps VFIODeviceIOOps;\n typedef struct VFIOMigration VFIOMigration;\n@@ -318,6 +325,21 @@ int vfio_device_get_irq_info(VFIODevice *vbasedev, int index,\n * Returns the region index or -1 on error.\n */\n int vfio_get_region_index_from_mr(MemoryRegion *mr);\n+\n+/**\n+ * Create a dmabuf fd by first translating the addresses in the\n+ * iovec array into VFIO region offsets and then invoking the\n+ * VFIO_DEVICE_FEATURE_DMA_BUF feature.\n+ *\n+ * @iov: array of iovec entries associated with a buffer\n+ * @iov_cnt: number of entries in the iovec array\n+ * @errp: pointer to Error*, to store an error if it happens.\n+ *\n+ * Returns the created dmabuf fd or either VFIO_DMABUF_CREATE_GUEST_ERROR\n+ * or VFIO_DMABUF_CREATE_HOST_ERROR on error.\n+ */\n+int vfio_device_create_dmabuf_fd(struct iovec *iov, unsigned int iov_cnt,\n+ Error **errp);\n #endif\n \n /* Returns 0 on success, or a negative errno. */\n", "prefixes": [ "v8", "07/10" ] }