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[142.162.112.119]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8971cddb9efsm45048286d6.51.2026.02.12.06.17.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Feb 2026 06:17:38 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1vqXVi-000000013HU-0xrD; Thu, 12 Feb 2026 10:17:38 -0400 Date: Thu, 12 Feb 2026 10:17:38 -0400 From: Jason Gunthorpe To: Julian Ruess Cc: schnelle@linux.ibm.com, wintera@linux.ibm.com, ts@linux.ibm.com, oberpar@linux.ibm.com, gbayer@linux.ibm.com, Alex Williamson , Yishai Hadas , Shameer Kolothum , Kevin Tian , mjrosato@linux.ibm.com, alifm@linux.ibm.com, raspl@linux.ibm.com, hca@linux.ibm.com, agordeev@linux.ibm.com, gor@linux.ibm.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, linux-pci@vger.kernel.org Subject: Re: [PATCH 1/3] vfio/pci: Set VFIO_PCI_OFFSET_SHIFT to 48 Message-ID: <20260212141738.GM750753@ziepe.ca> References: <20260212-vfio_pci_ism-v1-0-333262ade074@linux.ibm.com> <20260212-vfio_pci_ism-v1-1-333262ade074@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@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: <20260212-vfio_pci_ism-v1-1-333262ade074@linux.ibm.com> On Thu, Feb 12, 2026 at 03:02:15PM +0100, Julian Ruess wrote: > Extend VFIO_PCI_OFFSET_SHIFT to 48 to use the vfio-pci > VFIO_PCI_OFFSET_TO_INDEX() mechanism with the 256 TiB pseudo-BAR 0 of > the ISM device on s390. This bar is never mapped. Woah, this is dangerous, the size was selected to fit within a pgoff of a 32bit system.. Does this entirely break vfio on 32 bit? Jason