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 ADBBE2F3C12; Wed, 22 Oct 2025 07:08:53 +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=1761116936; cv=none; b=m1O7ktc+1gG2h8ASsaGSDMHWrX75XnErUtZJU6dos2NGnUs5R10VklwSg9QjYe5Awxp5IvoVElmFPwM/6MjRm15/rI9ca2gHaD6R2BXrracGIjDR0ZYgo8RjbW8TZt75+cmXPlP3QlzY9/WOFfHRlt34z5Nr4GNHsRV0PB5QYEM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761116936; c=relaxed/simple; bh=RZfNn8b8mW0sEmuXaQMaNf0XrCYG7zBzjmxoWD6SwPE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=MF26B+JEdLWP1fv0+5joatSGnv4hv12qOd57u54UfVLjslgRzCvTPLAEFcrDeKnvXDOOEq7y7YMnT5HjJyadx2fJw8xpfuHdTtl9aid9LYT7IOq1kNgwq4XqOde0AptGuPrq7ItwwCKd+N9wF8TxdOzpPKXRvTI+kbwFf5f4v9I= 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=SdNtRvN9; 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="SdNtRvN9" 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=v9tFlJ2fSBgWVG5dQp+BqV6oOUweYHcntX3sRf6YFKM=; b=SdNtRvN9ECbH+6Wq5VOUBng1tV rbcoTW7YrrfUGP/4J4whwouG1kDyvf3Lmdfi7LbnRPq89BMYv58xbUTBmXgSPXZVYRb6mJhJAPQU1 ZIA0/wC+S1RJMhiGYJjhCAdfm4FEwCrzY3g3l4cgwQjuPypeTpyBjpkFiGnJ3/MzMXNCCwCjSZrzm n6BBFOL61exQBTv/xlQB1DwMELcEAU2ArzUgD/NYvkI2kZUkmNNPseZu9Lnk8f+brxHeHjW+o2OQa 50dWmbeHSHNr0vGLwBLSjUlfEwJXoZAmppaRqh0WNeM+hhzaF/nXElPtxtD2OmafhI0Tejkvpb775 0PevGOYA==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vBSxk-00000001oCQ-0f7W; Wed, 22 Oct 2025 07:08:48 +0000 Date: Wed, 22 Oct 2025 00:08:48 -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> <20251020130855.GM316284@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: <20251020130855.GM316284@nvidia.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Mon, Oct 20, 2025 at 10:08:55AM -0300, Jason Gunthorpe wrote: > Sure, but this should be handled by the P2P subsystem and PCI quirks, > IMHO. It isn't VFIOs job.. If people complain about broken HW then it > is easy to add those things. I think it is. You now open up behavior generally that previously had specific drivers in charge. > IDK where Intel GPU lands on this, but VFIO has always supported P2P How?