From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f176.google.com (mail-pl1-f176.google.com [209.85.214.176]) (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 51ADD3E9598 for ; Wed, 21 Jan 2026 14:22:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.176 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769005365; cv=none; b=G5xdq6S1VIn2MJeA5ASiTkYv+3gS8qnco/AcXAWrGFOavkAAxXzUaqnfNCC5GRHfDc3lZKre3st1PQZAjn3fDEXiITZv8Zji1bdcbfUSDqMrEalv+JDb8T/5mF6hNTvtkdrsEQT0yVJzV2UaFHUIT1DKRx+Kobc5Svkx4LCsZ/k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769005365; c=relaxed/simple; bh=go5t4J2oCqftUfdoUso726J9QdhgF091WBBQZFq2rJc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JGgEK39y2IH8iBzUUhPFKVoYKvQbilvLzFt7hL5hC3df3JuWdioE7UrSgX4EgoGYtV9xPS0Hp9SKy7o5ckn8Ci5OYDCXgQLLJYKTN9fg6P1KLlwR3s+5kd0JHZK8IYJ2OMlhbmlbFAI+WOXBRaaQxAunYXoDQFkoqy+V2vr1wnA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=imMP9pgM; arc=none smtp.client-ip=209.85.214.176 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=google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="imMP9pgM" Received: by mail-pl1-f176.google.com with SMTP id d9443c01a7336-2a1462573caso88625ad.0 for ; Wed, 21 Jan 2026 06:22:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1769005361; x=1769610161; 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=Df9DnST7C0sPqC8cKGnMiT7cxfRi0XBTWHY9JjLQ7zk=; b=imMP9pgMw3An003kzIKUIZ2p5C1YpTti8hNMZYl735lUCQHEBp2hwvfPNJ5dDF9z11 LLpXyJOAiABW29XhO4DRJntWqxf8uWaDQ1l5ck98UCp6nV+MZWw9pgAaPcUkWv/VWc4g KmJLtEmK26sduHIgbdgEPjTGNVAD1wJdvQ07G8NcSCZqB0fqARHLQqxfXo06Z9KgWOg4 Mgwe9rDlLZPj8LDjjCwyNzeoWHqOIvorod2tWhqEm7qBxFFDlvb0OQa3FvXvASF9EQsb dXaV8JyLDoCyJ0ILTGjLGkpaw92pDPvJy0Vj4zbr2HrRPG8Be6w7leETcgaztiBoB1KQ xVyQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769005361; x=1769610161; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Df9DnST7C0sPqC8cKGnMiT7cxfRi0XBTWHY9JjLQ7zk=; b=jkmDWoHrK2hyJpSrkhvzs3119rYela+8J3BYx2vvat0w0EqKUTugFkFUd2ZYPqEekY H4mfSo1rCue2W/qcvPGFRN2uY5kOJ3/p3ALZH6hOogp+/2ndOfdO8DpZ01QZYAvd7ML6 sz8rmSFZc0JBnqkEFiHFkJHwhvZ8Hxibr8qfMZ1k7j4CVQ7e7KfavQIv51uGpSXi09H2 sAC39pk/ElzQ9yq56l9o4hvJaHdLnOOp2Y72z6Vw2CFtiluqzsFond5VVMe8seVrt3wE 6YBlJMZF2iD/WMxKzltMmDfzRAeX6eDVrlTeANNVhV6KxN+n3D19mX8UuKfjX5NwMcAU bVoQ== X-Forwarded-Encrypted: i=1; AJvYcCWJ1mE3AXAbM6bXE+BWGkVtboChvM9dTc4xv8vhxAQsA51xtZYy4vGmX7+glwPUOQSVqBB+Dg==@lists.linux.dev X-Gm-Message-State: AOJu0Yx8XU0XDTzMG1Mq7EPgVOKBG+3dnVKNqvzOmYNfu1FwWNpEWOPZ CUekqSRab6Ldm8TSNFnQ8WiDm1M+ZRGSzX4n7FZgcRgHWfkMghc6OVIxQd0sXOdglg== X-Gm-Gg: AZuq6aKlfJpjqyDei5LlsqAXmc5xARuwVbKXCEpHtYGtSX9QKg2ZD0e5BRcddvOx9yb XGC9yunWpppXIJHaeZEMx09Tre+PhwSOOFsYijAZvh/ZS4IF7WfdZT9K3lFUIpcIrR52d2Xn1Zy vLiMTdOafy9lKts7laso6xnlEEBEnMGIkDuEgWUYR7Tv7lKyMCYLb8OAplV8kfk09zVKlpZJ0wy lm7sv57C1Z6IkYnY901PVZAVXri/5M521luixuPJFG0LVbrBfctlZHLhtCxEEdeIFA7dQNe8LdP SWlsGPmJhnzqPq5X0n4Q58pBGaOIBbSh7e8EzFh7j8rydtfd6H97VRRDutvfHHxqoDzQZ5LUOc1 sSRHLZmBFKO20MA8n8Hmzv5cLMmaRMMu/jqoOQ8piNkFtUo07e4HtxtZnr5uCxl2rqz1JCExV0C h2tCUJ1EcP5BtBxexE37WtPJP0hhvtVIKQoSYjeW44SVt+aIIW X-Received: by 2002:a17:903:1c8:b0:295:5405:46be with SMTP id d9443c01a7336-2a7a23cc8f3mr2519245ad.1.1769005361111; Wed, 21 Jan 2026 06:22:41 -0800 (PST) Received: from google.com (222.245.187.35.bc.googleusercontent.com. [35.187.245.222]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a7190ce6a9sm159451235ad.34.2026.01.21.06.22.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Jan 2026 06:22:40 -0800 (PST) Date: Wed, 21 Jan 2026 14:22:31 +0000 From: Pranjal Shrivastava To: Jason Gunthorpe Cc: Leon Romanovsky , Sumit Semwal , Christian =?iso-8859-1?Q?K=F6nig?= , Alex Deucher , David Airlie , Simona Vetter , Gerd Hoffmann , Dmitry Osipenko , Gurchetan Singh , Chia-I Wu , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Lucas De Marchi , Thomas =?iso-8859-1?Q?Hellstr=F6m?= , Rodrigo Vivi , Kevin Tian , Joerg Roedel , Will Deacon , Robin Murphy , Felix Kuehling , Alex Williamson , Ankit Agrawal , Vivek Kasireddy , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, virtualization@lists.linux.dev, intel-xe@lists.freedesktop.org, linux-rdma@vger.kernel.org, iommu@lists.linux.dev, kvm@vger.kernel.org Subject: Re: [PATCH v4 8/8] vfio: Validate dma-buf revocation semantics Message-ID: References: <20260121-dmabuf-revoke-v4-0-d311cbc8633d@nvidia.com> <20260121-dmabuf-revoke-v4-8-d311cbc8633d@nvidia.com> <20260121134712.GZ961572@ziepe.ca> 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: <20260121134712.GZ961572@ziepe.ca> On Wed, Jan 21, 2026 at 09:47:12AM -0400, Jason Gunthorpe wrote: > On Wed, Jan 21, 2026 at 02:59:16PM +0200, Leon Romanovsky wrote: > > From: Leon Romanovsky > > > > Use the new dma_buf_attach_revocable() helper to restrict attachments to > > importers that support mapping invalidation. > > > > Signed-off-by: Leon Romanovsky > > --- > > drivers/vfio/pci/vfio_pci_dmabuf.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c > > index 5fceefc40e27..85056a5a3faf 100644 > > --- a/drivers/vfio/pci/vfio_pci_dmabuf.c > > +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c > > @@ -31,6 +31,9 @@ static int vfio_pci_dma_buf_attach(struct dma_buf *dmabuf, > > if (priv->revoked) > > return -ENODEV; > > > > + if (!dma_buf_attach_revocable(attachment)) > > + return -EOPNOTSUPP; > > + > > return 0; > > } > > We need to push an urgent -rc fix to implement a pin function here > that always fails. That was missed and it means things like rdma can > import vfio when the intention was to block that. It would be bad for > that uAPI mistake to reach a released kernel. > > It's tricky that NULL pin ops means "I support pin" :| > I've been wondering about this for a while now, I've been sitting on the following: diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index a4d8f2ff94e4..962bce959366 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -1133,6 +1133,8 @@ int dma_buf_pin(struct dma_buf_attachment *attach) if (dmabuf->ops->pin) ret = dmabuf->ops->pin(attach); + else + ret = -EOPNOTSUPP; return ret; } But didn't get a chance to dive in the history yet. I thought there's a good reason we didn't have it? Would it break exisitng dmabuf users? Praan