From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f174.google.com (mail-pl1-f174.google.com [209.85.214.174]) (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 B5C9B3ECBEB for ; Wed, 21 Jan 2026 14:22:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769005364; cv=none; b=NDYwapVcEu2YPXxygW1xxISlGttNBgNvY9lBYmkC3PlnSsra4lOzZZY0IyoWzugG4X4BkeZ0GXwZY/QUpEAVn3sHZCHZO2n131QdV5DtprFpYPxOE4ajC4oJHiw3EurK1Nww339+NczeVZ91ZfHbtYDytTDISIuIwrTnxHrlza8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769005364; c=relaxed/simple; bh=go5t4J2oCqftUfdoUso726J9QdhgF091WBBQZFq2rJc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=svEhNu29QP6W9xZQvXnLtDPCKhB9B+7vZx5I6lHm2vscWO4T1HIstrYuJlbfcRt1LycEo1tKWbb18ixGP/TWjgSuTkzSbPwtQUxRk8+tzgU1ut3UFLJ2Z82ZHsQp+13i5BavunrNhR3wzS3cA4pWg1El/y7qAullCWs2ZThmYGM= 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=F7ay76Bq; arc=none smtp.client-ip=209.85.214.174 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="F7ay76Bq" Received: by mail-pl1-f174.google.com with SMTP id d9443c01a7336-2a1462573caso88745ad.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=1769005362; x=1769610162; darn=vger.kernel.org; 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=F7ay76Bq9bpYj5UoSSVcnaszDZL7CbJH0DFrCbyDPp8dRVZH6PNrI9+TULlL2no0RQ rN5egE9vrruj2q2YIs43Ht05V54K5a5SDhYrWtnjQXjezqPrsgBP7kCTmhYfQ481LnE5 sPPfO28fOlwkpwFTnRfA6YCM5vQiyzhtL6yvTKg8XpCZt/vR0BCUbv0xkQTEYWlyekpt Xhwovl+wEm8fsUzgz/wG8ahQewuLf/CvrV6dXUvyFop2Th9vlgjP1aT8fDV5YVsSPuF/ YndPNLeOv3NUPch94X43fpnvZRIVpKe62RYRg7GelSsygDpUN6kM4HK7m45xoFWMVs2w xTug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769005362; x=1769610162; 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=DrZl/BoVp5DVt4ydfjISYaF/ExJeHT8Q268SXfXbR8m8oU1tY/jeUx4pK/Jj94anr1 T+72el05a+Nf+uuFFrHci/DuEK1XYJQrPBzhozCJF82KPzaAPu7FeOkQIg6FuJml7baq MLAq839JYBejoO6U9/nQCVRROQcydq17l9xKxY7dxuHMfeozP19s+jHtb1VmaJurSuDL VOn8qp1sj2KNDT2JIjViudrhc0fh5D2gicqSYCuAU0QmwC+rUL9+gMe1YlxC1FnPx/Kg wqtucSHwVZnYklWuK0BX2lhmGSV98KObhaJFTAGlZHAtdbGdiXPvuOxu8vIejR+slrQf teyw== X-Forwarded-Encrypted: i=1; AJvYcCVWpOsWTILzrcMcqKUeqtOfoG3OcnXu+ZjjNd0jhldL3sXrwsk/ZP4/5DuugvfMAw+h00pdP4vdwHLrcR0=@vger.kernel.org X-Gm-Message-State: AOJu0YxjPz+SK8mj0MhPpzFJ/W9k6BwOW9HuWS1lAMjgxWfRlySCh+zt Iw5ejiCL7uKFOygc007oehXgMBqnbf6UR1D0/j8SkoiCTw5RDpEah9oULj02w5fMVQ== X-Gm-Gg: AZuq6aKRsML+bnS5ZS+z7kbk81Y+N0TNbZnilNVJ2CIjwfCZmDoi4Nf1dJzju2t5bGe T80WOrgdJSUbW8L0jqPsLcVdOG7oSVZhXEILLEcDQxkGA4Way5mAme21NOQK6KP7YqTLM3ml3XL DLnjg/AbgOTEf6zR+BGb4qUe/DFraqW+Df1dDZzeJIxVWj2DhHTRjznIHLx7qztKPL9n2A+bL3d pw8eg0BpH/j/72DsE5roHqlCwAZAB1Jcf1lcnOGQ7TQs4m0WI5ZMcbWVbLc0ka8fdFfc8FxfkCq bJQgaDmSmqgrzMQZdj5TlDNb+Vme8M3e/43jjcg0Pkf2x5Qijv6rNCsxoOFJ9lsATRS/3ehWxZv 6lTzvxad7IbUwLgKEUlRDZcoC04QUVqHGny/LJgesH0RWDCtTQnhwH8gjzbPT8pf9mia+JeZIGe jI9OBLxxoKAAMAAO4up31WRwO/uiO5EE105O/p+LvTrs75JZWo 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: linux-kernel@vger.kernel.org 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