From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qv1-f49.google.com (mail-qv1-f49.google.com [209.85.219.49]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2919B14A8E for ; Tue, 4 Nov 2025 00:06:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.49 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762214784; cv=none; b=Dwo+cBwwZS3iwlmIy4jY6Ulmr2a/7vn1dTb01WNTENoRZYh+Em0GDwaA0TGxC3esHSFE8GZWXzSr/4kTPStuyT/X57BVnVVzUt6JXayPoH4JSCX5SG5ngsyVcJZFhYsS0YmzWTMQAUQl/M3PUxQLtCztzqiYMmb+ihV0sLo+WcM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762214784; c=relaxed/simple; bh=64FaqhTpKtgrI6Gs/Bdk6B1sd1M3Ri6MbXFvGYn46WM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=j+K6fcvgWIUFsSxbvopXSYavHej2xKaJoCrl3Jq72rXLvOIqToDkkvXoQB7VZipJZfA5FT0OQUGzq/McOFPh7Kkr3a1LwfnZPv3R6+EtULplVN1kJF2ggKddbGc5TWg0xo2bDPJsjmaSQAlTGHjFiJwRfY/2HhrchNkT9ZA3OS0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca; spf=pass smtp.mailfrom=ziepe.ca; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b=gCB62Kme; arc=none smtp.client-ip=209.85.219.49 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="gCB62Kme" Received: by mail-qv1-f49.google.com with SMTP id 6a1803df08f44-7ea50f94045so58856796d6.1 for ; Mon, 03 Nov 2025 16:06:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1762214781; x=1762819581; darn=lists.linux.dev; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=q7OiTJylN5oi1hTg8WqhFTipXs7uLO/TT2JZJ2yqlyQ=; b=gCB62Kme1lFlLIkkEo/d+qWKsK2aVVzElNFU1DtwTWxV7E6t1mvDhajNqZzjLWfjH3 zzpgukZ/x2wKke6qYtuwYp0wAmiwWnSu2c69kKho/4O+B6EEt9/f+7R4QQY5htG7BlFg xxaLPP5u6RKvTEPbQsu8Dt/dPUxgjkGdW9UUyh+HcE5TwaABMWDhz4ic9L+djA68Y/g4 GgsfmQjqZ0pYS2bCy48LlCyotNFM69/C7JR5P+XON3QPsYH5mvVdrjxOj95Wx3ZywTmB uzdv6RGsduTVx+FpZUnRO0gRqFnNrpDJtnMBaAoPqfq40zfMi/80aEN6PUSEhREQaemW BsPw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1762214781; x=1762819581; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=q7OiTJylN5oi1hTg8WqhFTipXs7uLO/TT2JZJ2yqlyQ=; b=H/WwDihCJ99tC7DorrJUCQ+qIUZ8NUB5bjEWfdyHsgs2f6oMiHkLY3QxKC3/mgbike 9dYqcqi40uwQaj6Kjzl6aZr/V2LYLtRFrDD4Npmkv2OUrJFIg+9vqlVRl9huXfeWJ3eu MAuythqDkQ7EiPwrIeyXt6kSeKWIxey0rh9ycXo3s7r7qD5o9L4B/IbZ2xp8ok2gpkKL vCIUZ5xuuqApxLwrZLGPnK66hc6EwwseT9nnl1YTygl5cuF+zOzc7i/AbUI9xA033xJT HTPUMGP2MVOA8cT4VhGKWq0K7lPm8qj6i/A512ll5E7/t8BKGcDhpypVNWBNZcrakFxA 4orw== X-Forwarded-Encrypted: i=1; AJvYcCWzIfhk8SpjsgPTuYXITlqvHqyMolQxB3C1kmzDhspOG/w5Yj29AdM770o4j6gqIKKzA77w6Q==@lists.linux.dev X-Gm-Message-State: AOJu0YyKv4q7ac2G7U+e4v4OxPMw03LKQl6jn7aSYDM2VDWucBxCnL3F Xx+bjNdLeArNK3tTGOY1eqSTyupM31Pnt8Z6flGAbmMYWD/5E7oiS1zvbs97R4KuzMw= X-Gm-Gg: ASbGncusfgPJZ2O1eg2o0rfVfmJVd6WEW/wVMUGMSsG9odFXX7Z0SIz4NRDkrJaepZu AhJch59qwF8K/sIa+cvfOqJJfO7yVqXY+CTQqUn6L6B+AZpDA6rm2azLX5GQ6syTNJ6g74o99bq v2LrqbeFAEzCKEHIFhmB+5Zmi4QkhWAZ2wR6FwOQcqHTcgGdx5QtodvFYIq6Oumg9Dgw1a6c5Jw 0w91oYWhywHv9XWFppJumie3DiCpTm6Ph9NBnYUOBSHprAzfHb2JEx2OQkzgJaegmf4XdR3sYmn pWz7B/NevSNwhYm60ZDedf0Evy7oUEZj90xQK+X/mYLQEi4/SHfTeRdp1CpfSroQTWrjYUldlzI 5TMIomW77KIKacVyLiRxDUeFx6W1KBaZhJzDijV1VpWAAdpzKXQu67cRD5yQYs9bOyH6S4Q7Hzw e+UclbmsDieXe7UZ/NvCf2U/PqmgKObHOkJXbYAq7vWZa56VGpmjbUcZzn X-Google-Smtp-Source: AGHT+IHFK/K4+Si4Ey1hcSvTZvkQdBHi3cl9Mtxmbm7oCurYD+QrPfezppoNLd/K4DVB+Xp/dYAQ0Q== X-Received: by 2002:a05:6214:f22:b0:87c:270b:aadb with SMTP id 6a1803df08f44-880623a4a0emr16632746d6.16.1762214780972; Mon, 03 Nov 2025 16:06:20 -0800 (PST) Received: from ziepe.ca (hlfxns017vw-47-55-120-4.dhcp-dynamic.fibreop.ns.bellaliant.net. [47.55.120.4]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-88060de9b44sm10817116d6.20.2025.11.03.16.06.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Nov 2025 16:06:19 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1vG4Z1-00000006cRs-0csK; Mon, 03 Nov 2025 20:06:19 -0400 Date: Mon, 3 Nov 2025 20:06:19 -0400 From: Jason Gunthorpe To: Alex Mastro Cc: Leon Romanovsky , Bjorn Helgaas , Logan Gunthorpe , Jens Axboe , Robin Murphy , Joerg Roedel , Will Deacon , Marek Szyprowski , Andrew Morton , Jonathan Corbet , Sumit Semwal , Christian =?utf-8?B?S8O2bmln?= , Alex Williamson , Kees Cook , "Gustavo A. R. Silva" , Ankit Agrawal , Yishai Hadas , Shameer Kolothum , Kevin Tian , Krishnakant Jaju , Matt Ochs , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, iommu@lists.linux.dev, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, kvm@vger.kernel.org, linux-hardening@vger.kernel.org, Vivek Kasireddy Subject: Re: [PATCH v6 00/11] vfio/pci: Allow MMIO regions to be exported through dma-buf Message-ID: <20251104000619.GG1204670@ziepe.ca> References: <20251102-dmabuf-vfio-v6-0-d773cff0db9f@nvidia.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Nov 03, 2025 at 12:07:12PM -0800, Alex Mastro wrote: > On Sun, Nov 02, 2025 at 10:00:48AM +0200, Leon Romanovsky wrote: > > Changelog: > > v6: > > * Fixed wrong error check from pcim_p2pdma_init(). > > * Documented pcim_p2pdma_provider() function. > > * Improved commit messages. > > * Added VFIO DMA-BUF selftest. > > * Added __counted_by(nr_ranges) annotation to struct vfio_device_feature_dma_buf. > > * Fixed error unwind when dma_buf_fd() fails. > > * Document latest changes to p2pmem. > > * Removed EXPORT_SYMBOL_GPL from pci_p2pdma_map_type. > > * Moved DMA mapping logic to DMA-BUF. > > * Removed types patch to avoid dependencies between subsystems. > > * Moved vfio_pci_dma_buf_move() in err_undo block. > > * Added nvgrace patch. > > Thanks Leon. Attaching a toy program which sanity tests the dma-buf export UAPI > by feeding the allocated dma-buf into an dma-buf importer (libibverbs + CX-7). Oh! Here is my toy program to do the same with iommufd as the importer: #define _GNU_SOURCE #define __user #include #include #include #include #include #include "include/uapi/linux/vfio.h" #include "include/uapi/linux/iommufd.h" #include #include #include int main(int argc, const char *argv[]) { int vfio_dev_fd, iommufd_fd, ret; // Open the per-device VFIO file (e.g., /dev/vfio/devices/vfio3) vfio_dev_fd = open("/dev/vfio/devices/vfio0", O_RDWR); if (vfio_dev_fd < 0) { perror("Failed to open VFIO per-device file"); return 1; } // Open /dev/iommu for iommufd iommufd_fd = open("/dev/iommu", O_RDWR); if (iommufd_fd < 0) { perror("Failed to open /dev/iommu"); close(vfio_dev_fd); return 1; } // Bind device FD to iommufd struct vfio_device_bind_iommufd bind = { .argsz = sizeof(bind), .flags = 0, .iommufd = iommufd_fd, }; ret = ioctl(vfio_dev_fd, VFIO_DEVICE_BIND_IOMMUFD, &bind); if (ret < 0) { perror("VFIO_DEVICE_BIND_IOMMUFD failed"); close(vfio_dev_fd); close(iommufd_fd); return 1; } // Allocate an IOAS (I/O address space) struct iommu_ioas_alloc alloc_data = { .size = sizeof(alloc_data), .flags = 0, }; ret = ioctl(iommufd_fd, IOMMU_IOAS_ALLOC, &alloc_data); if (ret < 0) { perror("IOMMU_IOAS_ALLOC failed"); close(vfio_dev_fd); close(iommufd_fd); return 1; } // Attach the device to the IOAS struct vfio_device_attach_iommufd_pt attach_data = { .argsz = sizeof(attach_data), .flags = 0, .pt_id = alloc_data.out_ioas_id, }; ret = ioctl(vfio_dev_fd, VFIO_DEVICE_ATTACH_IOMMUFD_PT, &attach_data); if (ret < 0) { perror("VFIO_DEVICE_ATTACH_IOMMUFD_PT failed"); close(vfio_dev_fd); close(iommufd_fd); return 1; } #if 0 int mapfd = memfd_create("test", MFD_CLOEXEC); if (mapfd == -1) { perror("memfd_create failed"); return 1; } ftruncate(mapfd, 4096); #else struct dmabuf_arg { struct vfio_device_feature hdr; struct vfio_device_feature_dma_buf dma_buf; struct vfio_region_dma_range range; } dma_buf_feature = { .hdr = { .argsz = sizeof(dma_buf_feature), .flags = VFIO_DEVICE_FEATURE_GET | VFIO_DEVICE_FEATURE_DMA_BUF }, .dma_buf = { .region_index = VFIO_PCI_BAR0_REGION_INDEX, .open_flags = O_CLOEXEC, .nr_ranges = 1 }, .range = { .length = 4096 }, }; ret = ioctl(vfio_dev_fd, VFIO_DEVICE_FEATURE, &dma_buf_feature); if (ret < 0) { perror("VFIO_DEVICE_FEATURE_GET failed"); return 1; } int mapfd = ret; #endif struct iommu_ioas_map_file map_file = { .size = sizeof(map_file), .flags = IOMMU_IOAS_MAP_WRITEABLE | IOMMU_IOAS_MAP_READABLE, .ioas_id = alloc_data.out_ioas_id, .fd = mapfd, .start = 0, .length = 4096, }; ret = ioctl(iommufd_fd, IOMMU_IOAS_MAP_FILE, &map_file); if (ret < 0) { perror("IOMMU_IOAS_MAP_FILE failed"); return 1; } printf("Successfully attached device to IOAS ID: %u\n", alloc_data.out_ioas_id); close(vfio_dev_fd); close(iommufd_fd); return 0; }