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envelope-from=pasic@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, 20 Apr 2026 09:47:34 -0500 Jaehoon Kim wrote: > On the s390 Linux kernel, IO_SPACE_LIMIT has been 0 since the initial > zPCI implementation (commit cd24834130ac "s390/pci: base support"), > making I/O BARs unusable. > > However, when virtio-pci devices operate in transitional mode, QEMU > unconditionally exposes the legacy interface via BAR0. This results in > firmware warnings during PCI enumeration, such as: > > pci 0005:00:00.0: [Firmware Bug]: BAR 0: invalid; can't size > > even though BAR0 is never usable on the s390 kernel. > > Close this gap by disabling legacy virtio-pci support starting from > machine version 11.1. This effectively makes virtio-pci devices > non-transitional and prevents the creation of the unusable legacy I/O > BAR. > > This introduces s390x-specific global compatibility properties that > set disable-legacy=on as the default for virtio-pci devices. Machine > versions v11.0 and earlier set disable-legacy=off to maintain their > original default behavior (legacy support enabled), ensuring VMs > created with those versions continue to work identically. > > Users can override the default on the command line if needed: > - On v11.1+: -global virtio-pci.disable-legacy=off (to enable legacy) > - On v11.0-: -global virtio-pci.disable-legacy=on (to disable legacy) > > Signed-off-by: Jaehoon Kim > Reviewed-by: Mohamed Mediouni Reviewed-by: Halil Pasic