linux-kernel - Re: [PATCH v5 8/9] vfio/pci: Enable peer-to-peer DMA transactions by default

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aPYq0jQZOrn-lUJW@infradead.org>
Date: Mon, 20 Oct 2025 05:28:02 -0700
From: Christoph Hellwig <hch@...radead.org>
To: Jason Gunthorpe <jgg@...dia.com>
Cc: Christoph Hellwig <hch@...radead.org>,
	Leon Romanovsky <leon@...nel.org>,
	Alex Williamson <alex.williamson@...hat.com>,
	Leon Romanovsky <leonro@...dia.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Christian König <christian.koenig@....com>,
	dri-devel@...ts.freedesktop.org, iommu@...ts.linux.dev,
	Jens Axboe <axboe@...nel.dk>, Joerg Roedel <joro@...tes.org>,
	kvm@...r.kernel.org, linaro-mm-sig@...ts.linaro.org,
	linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-media@...r.kernel.org, linux-mm@...ck.org,
	linux-pci@...r.kernel.org, Logan Gunthorpe <logang@...tatee.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Robin Murphy <robin.murphy@....com>,
	Sumit Semwal <sumit.semwal@...aro.org>,
	Vivek Kasireddy <vivek.kasireddy@...el.com>,
	Will Deacon <will@...nel.org>
Subject: Re: [PATCH v5 8/9] vfio/pci: Enable peer-to-peer DMA transactions by
 default

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 <leonro@...dia.com>
> > > 
> > > 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.