From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [IPv6:2a01:7e0:0:424::9]) by lore.proxmox.com (Postfix) with ESMTPS id 712B21FF16F for ; Tue, 2 Sep 2025 13:27:13 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id C78BE1126E; Tue, 2 Sep 2025 13:27:25 +0200 (CEST) Mime-Version: 1.0 Date: Tue, 02 Sep 2025 13:26:52 +0200 Message-Id: Cc: "pve-devel" From: "Daniel Kral" To: "Proxmox VE development discussion" X-Mailer: aerc 0.20.0 References: <20250902112307.124706-1-d.kral@proxmox.com> <20250902112307.124706-5-d.kral@proxmox.com> In-Reply-To: <20250902112307.124706-5-d.kral@proxmox.com> X-Bm-Milter-Handled: 55990f41-d878-4baa-be0a-ee34c49e34d2 X-Bm-Transport-Timestamp: 1756812399351 X-SPAM-LEVEL: Spam detection results: 0 AWL 0.014 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% DMARC_MISSING 0.1 Missing DMARC policy KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Subject: Re: [pve-devel] [RFC qemu-server v2 3/4] fix #6378 (continued): warn intel-iommu users about iommu and host aw bits mismatch X-BeenThere: pve-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox VE development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Proxmox VE development discussion Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: pve-devel-bounces@lists.proxmox.com Sender: "pve-devel" On Tue Sep 2, 2025 at 1:22 PM CEST, Daniel Kral wrote: > For certain host CPUs, such as Intel consumer-grade CPUs, there is a > frequent mismatch between the CPU's physical address width and the > IOMMU's address width. > > If a virtual machine is setup with an intel-iommu device, qemu allocates > and maps the (virtual) I/O address space (IOAS) for a VFIO passthrough > device with iommufd. > > In case of a mismatch of the address width of the host CPU and IOMMU > CPU, the guest physical address space (GPAS) and memory-type range small error: it's just IOMMU, not "IOMMU CPU" > registers (MTRRs) are setup to the host CPU's address width, which > causes IOAS to be allocated and mapped outside of the IOMMU's maximum > guest address width (MGAW) and causes the following error from qemu (the > error message is copied from the user forum [0]): > > kvm: vfio_container_dma_map(0x5c9222494280, 0x380000000000, 0x10000, 0x78075ee70000) = -22 (Invalid argument) > > This error is rather confusing and unhelpful to users, so warn them > about a CPU physical address width that exceeds the IOMMU address width. > > [0] https://forum.proxmox.com/threads/vm-wont-start-with-pci-passthrough-after-upgrade-to-9-0.169586/page-3#post-795717 > > Signed-off-by: Daniel Kral _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel