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GET /api/patches/2202628/?format=api
{ "id": 2202628, "url": "http://patchwork.ozlabs.org/api/patches/2202628/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260227221632.827046-9-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": "<20260227221632.827046-9-vivek.kasireddy@intel.com>", "list_archive_url": null, "date": "2026-02-27T22:13:54", "name": "[v8,08/10] vfio/device: Add a helper to mmap a dmabuf", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "c9b1c34a6c4235301120f1926bf62380a2407641", "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/20260227221632.827046-9-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/2202628/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2202628/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=iXYIjKG9;\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 4fN2pQ49NNz1xxx\n\tfor <incoming@patchwork.ozlabs.org>; Sat, 28 Feb 2026 09:20:46 +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 1vw6Bj-00067Q-Py; Fri, 27 Feb 2026 17:20:01 -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-00066C-OV\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 1vw6Be-0007n5-0w\n for qemu-devel@nongnu.org; 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a=\"73509365\"", "E=Sophos;i=\"6.21,314,1763452800\"; d=\"scan'208\";a=\"73509365\"" ], "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 08/10] vfio/device: Add a helper to mmap a dmabuf", "Date": "Fri, 27 Feb 2026 14:13:54 -0800", "Message-ID": "<20260227221632.827046-9-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 mmap a dmabuf, we first need to create a placeholder\nmapping that would fit the entire size of the dmabuf. This mapping\nwould then be replaced with smaller mappings of individual dmabuf\nsegments.\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 | 65 +++++++++++++++++++++++++++++++++++\n hw/vfio/dmabuf-stubs.c | 7 ++++\n include/hw/vfio/vfio-device.h | 17 +++++++++\n 3 files changed, 89 insertions(+)", "diff": "diff --git a/hw/vfio/device.c b/hw/vfio/device.c\nindex a25ecc3697..596fbceb68 100644\n--- a/hw/vfio/device.c\n+++ b/hw/vfio/device.c\n@@ -728,3 +728,68 @@ int vfio_device_create_dmabuf_fd(struct iovec *iov, unsigned int iov_cnt,\n }\n return ret;\n }\n+\n+bool vfio_device_mmap_dmabuf(struct iovec *iov, unsigned int iov_cnt,\n+ void **addr, size_t total_size, Error **errp)\n+{\n+ struct vfio_region_info *info = NULL;\n+ VFIODevice *vbasedev = NULL;\n+ ram_addr_t offset, len = 0;\n+ RAMBlock *first_rb, *rb;\n+ void *map, *submap;\n+ int i, index;\n+\n+ if (!vfio_device_lookup(iov, &vbasedev, errp)) {\n+ return false;\n+ }\n+\n+ /*\n+ * We first reserve a contiguous chunk of address space for the entire\n+ * dmabuf, then replace it with smaller mappings that correspond to the\n+ * individual segments of the dmabuf.\n+ */\n+ map = mmap(NULL, total_size, PROT_NONE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);\n+ if (map == MAP_FAILED) {\n+ error_setg_errno(errp, errno, \"Could not reserve placeholder mapping\");\n+ return false;\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 mmap dmabuf with different regions\\n\");\n+ goto err;\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+ goto err;\n+ }\n+\n+ if (vfio_device_get_region_info(vbasedev, index, &info)) {\n+ error_setg(errp, \"Cannot find region info for dmabuf segment\\n\");\n+ goto err;\n+ }\n+\n+ submap = mmap(map + len, iov[i].iov_len, PROT_READ,\n+ MAP_SHARED | MAP_FIXED, vbasedev->fd,\n+ info->offset + offset);\n+ if (submap == MAP_FAILED) {\n+ error_setg(errp, \"Could not mmap dmabuf segment\\n\");\n+ goto err;\n+ }\n+\n+ len += iov[i].iov_len;\n+ }\n+ *addr = map;\n+ return true;\n+err:\n+ munmap(map, total_size);\n+ error_prepend(errp, \"VFIO dmabuf mmap failed: \");\n+ return false;\n+}\n+\ndiff --git a/hw/vfio/dmabuf-stubs.c b/hw/vfio/dmabuf-stubs.c\nindex e71e2b68dd..c3aa37233d 100644\n--- a/hw/vfio/dmabuf-stubs.c\n+++ b/hw/vfio/dmabuf-stubs.c\n@@ -15,3 +15,10 @@ int vfio_device_create_dmabuf_fd(struct iovec *iov, unsigned int iov_cnt,\n error_setg(errp, \"VFIO dmabuf support is not enabled\");\n return VFIO_DMABUF_CREATE_HOST_ERROR;\n }\n+\n+bool vfio_device_mmap_dmabuf(struct iovec *iov, unsigned int iov_cnt,\n+ void **addr, size_t total_size, Error **errp)\n+{\n+ error_setg(errp, \"VFIO mmap dmabuf support is not enabled\");\n+ return false;\n+}\ndiff --git a/include/hw/vfio/vfio-device.h b/include/hw/vfio/vfio-device.h\nindex 9dcf3ea57d..a1381f5f30 100644\n--- a/include/hw/vfio/vfio-device.h\n+++ b/include/hw/vfio/vfio-device.h\n@@ -340,6 +340,23 @@ int vfio_get_region_index_from_mr(MemoryRegion *mr);\n */\n int vfio_device_create_dmabuf_fd(struct iovec *iov, unsigned int iov_cnt,\n Error **errp);\n+\n+/**\n+ * Mmap a dmabuf by first translating the addresses in the iovec\n+ * array into VFIO region offsets and then creating a placeholder\n+ * mapping that would be replaced later with mappings that\n+ * correspond to the dmabuf segments.\n+ *\n+ * @iov: array of iovec entries associated with the dmabuf\n+ * @iov_cnt: number of entries in the iovec array\n+ * @addr: pointer to store the resulting mmap address\n+ * @total_size: total size of the dmabuf\n+ * @errp: pointer to Error*, to store an error if it happens.\n+ *\n+ * Returns true on success and false in case of an error.\n+ */\n+bool vfio_device_mmap_dmabuf(struct iovec *iov, unsigned int iov_cnt,\n+ void **addr, size_t total_size, Error **errp);\n #endif\n \n /* Returns 0 on success, or a negative errno. */\n", "prefixes": [ "v8", "08/10" ] }