From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) (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 15328471415 for ; Tue, 4 Aug 2026 18:51:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.200 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785869469; cv=none; b=RelVEXcSBioNKz+91nTqjqWkPY0AOadIKVl/eqfkQ0ZpALvSy5kocPj/qtYrZR58+LdeYLcUwDDz9HCu4WlY4bYuzHLtNwcox5QKIR3xh+wKMZvxgj1nWFhDJzxx/pAKG3WHKzjxNHnAmdiHkYe7KD3pjoUduI1NtL/yuiXVvrM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785869469; c=relaxed/simple; bh=XlkRowI/Bj2yqvZSSpDH2xbYCIlXFfReqBFODIvSLbU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=mjxhHclO7pG0sfB1hI19/Bkqup7BhhQUFsQGBhxcEMp75cYMcRIrRBXNH3rDw/je8I8YUntN1PL+AB6nGLNkAydCkk37Z7PFW7a5oA8lmQ1B5ksjDbU1UK2oOOZuamIzkC03Vn/Sc1xWtHRdn1vsf1eVPJLCuTdXf8nF6SHHs3I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--praan.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=MBB4roiW; arc=none smtp.client-ip=209.85.215.200 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--praan.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="MBB4roiW" Received: by mail-pg1-f200.google.com with SMTP id 41be03b00d2f7-cbb6433e9d4so109009a12.3 for ; Tue, 04 Aug 2026 11:51:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1785869467; x=1786474267; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=mN/ftuPXHTO6yPx2v45bEY7G4dZzvWxyQXkizaq1wVU=; b=MBB4roiWT6SNt7U1o9vGR9MgpQ8CYYNVUWs2n/mnVLwAcT3lrz5m2d84gRBHrner9I 2qmo7k+E4+aPEdqPG1cQbaTBcFi7tFBNq/YHnfrQdCHRTecNAPZll8J/uikWAw5e82NC TfX0IeNYYd7CwXN8zld7fpCF5GXya/6wiTc66CCEu062Kz5VExeXik1kh4u+ZFRI1Fcy tYMY69cyLbGKQKw7J+UK17te/WTkX0kVcPaN6Kr6WU7SknwPx77hsKNF5S4RBCBd/ovm aVnHu5x3yx/27N5kc4iGhvH7LAlq1du0cilZUrvDU8ekadkcn3zUovBtbHu3zSkd72Nv 5ldA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785869467; x=1786474267; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=mN/ftuPXHTO6yPx2v45bEY7G4dZzvWxyQXkizaq1wVU=; b=lM8H4CBifSoT+CdLRBiUnpI0xDJk/jm3fcFSQpF2Ru3vixzX4xyF0ElRJwdKK0DmrR hOrlZAvEkmumWidqvYS+ECyUIt9pLNiIxfZO6BaklvOEuK4Rb2XWKS/6T/wj2u6WCzHT wMS3R7Jihll8A0HuKgOXPLLeOXtM7mDjXbAtmM154g5HYzRQbp54+pm1QWAX+93OAvks 2IsXZFaYyo1VCeJXGjSMHDgFntSf4UQHh5p9xFDw5JSriy+WBRuFcmLtWDldQtZ95/VE 3wVSYXDiOwGsfUYu1L2U8sR7OiTNWlE6okLZis2OHjniOTQG8tJqhE+P7pKRH/+JDQ5S 0kKQ== X-Forwarded-Encrypted: i=1; AHgh+RqUNe/3evpvOA8/32f42fvJpfQq6O8ppZvrS2YTQ0MU77gvLptAqWsEsR75DK/XJGCxUs4rqtG+oqWiinE=@vger.kernel.org X-Gm-Message-State: AOJu0Yy2ARG8+70DzvgcbBaV07d280LxQNU23WczZbgjreFT+2g9DSnb i5D8FdTJFZXtuNbvQ2Jdufw5B5qZ5cvB5+gbhTmJPNxlUafu19NXBL0KUt2T07pbb9c6ie77B1o m/A== X-Received: from pgla35.prod.google.com ([2002:a63:b63:0:b0:c96:da8a:c09c]) (user=praan job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:428b:b0:3c3:64cc:311a with SMTP id adf61e73a8af0-3cb85ef9229mr901310637.22.1785869467266; Tue, 04 Aug 2026 11:51:07 -0700 (PDT) Date: Tue, 4 Aug 2026 18:50:46 +0000 In-Reply-To: <20260804185050.2053672-1-praan@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260804185050.2053672-1-praan@google.com> X-Mailer: git-send-email 2.55.0.571.g244d577d93-goog Message-ID: <20260804185050.2053672-2-praan@google.com> Subject: [RFC PATCH v2 1/5] vfio: Add UAPI flag for ZONE_DEVICE-backed DMABUF exports From: Pranjal Shrivastava To: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Bjorn Helgaas , Logan Gunthorpe , Alex Williamson , Jason Gunthorpe , Kevin Tian , Pranjal Shrivastava , Ankit Agrawal , Matt Evans , Vivek Kasireddy , Leon Romanovsky , Shivaji Kant , Samiullah Khawaja , Unnati Sachan Content-Type: text/plain; charset="UTF-8" Add an opt-in UAPI flag for exporting VFIO MMIO regions via dmabuf backed by struct page metadata (via ZONE_DEVICE registration). Signed-off-by: Pranjal Shrivastava --- include/uapi/linux/vfio.h | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index cbe03e5d1009..3ae025b33e7f 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -1505,7 +1505,13 @@ 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 supports: + * - VFIO_DMA_BUF_FLAG_ZONE_DEVICE_BACKED: Request the kernel to allocate + * valid struct pages for the exported dmabuf range (via ZONE_DEVICE + * registration). This allows the exported dmabuf fd to be used by + * subsystems that rely on page metadata. + * (NOTE: This consumes extra system RAM to store BAR_SIZE / PAGE_SIZE + * struct pages). * * Return: The fd number on success, -1 and errno is set on failure. */ @@ -1516,6 +1522,8 @@ struct vfio_region_dma_range { __u64 length; }; +#define VFIO_DMA_BUF_FLAG_ZONE_DEVICE_BACKED (1 << 0) + struct vfio_device_feature_dma_buf { __u32 region_index; __u32 open_flags; -- 2.55.0.571.g244d577d93-goog