From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DBBAF2E1C6B; Mon, 20 Oct 2025 12:28:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760963287; cv=none; b=ZLRKX99Mvt2rBGt/uFkd6zIOcXiPUix/2xuo4G4aI7rq8NON2vojAgLHm2hmm3buVwGUQuQyTt1wB/razErAIjbxUkbA1YXE6eCfTBDJd4Jc7c0h5GRsq7MbECoCzdC7jFFRTK42WrES5HrbCf5xZcGAJPAYUkqDSNUE52aRG9g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760963287; c=relaxed/simple; bh=1lO772fc4p3qDgbZy7pAy3hVsBDNuQC1cZ8gI4aaH8k=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=YwZP1GoW+eXhM5Hv26HqulbGSgI+03ew61Mxf1yvpDX0olTIda6MZmRPtvS54ol5/Xr249hGhLBQU1f5ElH53VlXYpdKd5WJfpzaP3g5DuwVYJWf1zixwG/6ItIfQtTOZPDwbxck4mgGPzcWuKWTn3qKDfXrNZY41f1SYs+Xlg8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=bBc3P6XH; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="bBc3P6XH" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=7ETt/cIS7y36wzPdSWatPH0bjRaT9Kgy267Fn9GummA=; b=bBc3P6XH7OO6YaM6cL+h/RmHiB pDsB9AwmEla0WgHxgeNIiwwubVzoGXiigjeTvvej2RHeBXuzYAo99jNSU/Y44MSsDSW2oaom1jTJS yiWdm/IfNyvT3pB0m5irfyIriyKYefci4PDagpdEftDl1FFqk7mB/Y92Cb+ziu1dqwrNVNnTYbHE9 BemCDU97SZrbmKGLwQHL7UIMD1F7tJWpFBNqWqCpc+wmV4bhsvaJiPHQ5CvZ1lcFlJVQfSSyFfMLS AkcS83i+dBFyjGqtFgcCKRA/A/MjU/IhUJR4CHIoZ2HclrlrsHruKWu6PFSUYnL8P2+TyEfe+KXQU DQeNiswQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vAoza-0000000DPeN-2I74; Mon, 20 Oct 2025 12:28:02 +0000 Date: Mon, 20 Oct 2025 05:28:02 -0700 From: Christoph Hellwig To: Jason Gunthorpe Cc: Christoph Hellwig , Leon Romanovsky , Alex Williamson , Leon Romanovsky , Andrew Morton , Bjorn Helgaas , Christian =?iso-8859-1?Q?K=F6nig?= , dri-devel@lists.freedesktop.org, iommu@lists.linux.dev, Jens Axboe , Joerg Roedel , kvm@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Logan Gunthorpe , Marek Szyprowski , Robin Murphy , Sumit Semwal , Vivek Kasireddy , Will Deacon Subject: Re: [PATCH v5 8/9] vfio/pci: Enable peer-to-peer DMA transactions by default Message-ID: References: <20251017115524.GG3901471@nvidia.com> Precedence: bulk X-Mailing-List: linux-block@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: <20251017115524.GG3901471@nvidia.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Fri, Oct 17, 2025 at 08:55:24AM -0300, Jason Gunthorpe wrote: > On Thu, Oct 16, 2025 at 11:32:59PM -0700, Christoph Hellwig wrote: > > On Mon, Oct 13, 2025 at 06:26:10PM +0300, Leon Romanovsky wrote: > > > From: Leon Romanovsky > > > > > > Make sure that all VFIO PCI devices have peer-to-peer capabilities > > > enables, so we would be able to export their MMIO memory through DMABUF, > > > > How do you know that they are safe to use with P2P? > > All PCI devices are "safe" for P2P by spec. I've never heard of a > non-complaint device causing problems in this area. Real PCIe device, yes. But we have a lot of stuff mascquerading as such with is just emulated or special integrated. I.e. a lot of integrated Intel GPUs claim had issue there.