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Fri, 24 Jul 2026 08:11:28 -0700 (PDT) Received: from jgg by NV-9X0Z6D3.localdomain with local (Exim 4.97) (envelope-from ) id 1wnHYe-000000002lY-0zFZ; Fri, 24 Jul 2026 12:11:28 -0300 Date: Fri, 24 Jul 2026 12:11:28 -0300 From: Jason Gunthorpe To: Bjorn Helgaas Cc: Mario Limonciello , Vasant Hegde , iommu@lists.linux.dev, joro@8bytes.org, linux-pci@vger.kernel.org, will@kernel.org, robin.murphy@arm.com, suravee.suthikulpanit@amd.com, bhelgaas@google.com, alexander.deucher@amd.com, Amandeep Kaur Longia , Gerd Bayer , Alex Williamson Subject: Re: [PATCH 2/2] iommu/amd: Force identity mode for selected GPUs only Message-ID: References: <70e6d40b-3e13-4efd-b1e7-62195ff66e91@amd.com> <20260723210246.GA856455@bhelgaas> 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: <20260723210246.GA856455@bhelgaas> On Thu, Jul 23, 2026 at 04:02:46PM -0500, Bjorn Helgaas wrote: > I don't think the Root Port is always passed into the guest. From > 1ae8c4ce1570 ("PCI: Enable AtomicOps only if Root Port supports > them"): If this device has broken support for iommu translation entirely then vfio is unsuably broken too. The right answer is to refuse to attach a paging domain to such a device, I think this patch series should be enhanced to include this. Like a qurik that says translation is broken and then def domain is changed and paging attach will fail Jason