kernel.git/drivers/xen, branch linux-6.12.y

xen/acpi-processor: fix _CST detection using undersized evaluation buffer

2026-03-13T16:20:42Z

[ Upstream commit 8b57227d59a86fc06d4f09de08f98133680f2cae ] read_acpi_id() attempts to evaluate _CST using a stack buffer of sizeof(union acpi_object) (48 bytes), but _CST returns a nested Package of sub-Packages (one per C-state, each containing a register descriptor, type, latency, and power) requiring hundreds of bytes. The evaluation always fails with AE_BUFFER_OVERFLOW. On modern systems using FFH/MWAIT entry (where pblk is zero), this causes the function to return before setting the acpi_id_cst_present bit. In check_acpi_ids(), flags.power is then zero for all Phase 2 CPUs (physical CPUs beyond dom0's vCPU count), so push_cxx_to_hypervisor() is never called for them. On a system with dom0_max_vcpus=2 and 8 physical CPUs, only PCPUs 0-1 receive C-state data. PCPUs 2-7 are stuck in C0/C1 idle, unable to enter C2/C3. This costs measurable wall power (4W observed on an Intel Core Ultra 7 265K with Xen 4.20). The function never uses the _CST return value -- it only needs to know whether _CST exists. Replace the broken acpi_evaluate_object() call with acpi_has_method(), which correctly detects _CST presence using acpi_get_handle() without any buffer allocation. This brings C-state detection to parity with the P-state path, which already works correctly for Phase 2 CPUs. Fixes: 59a568029181 ("xen/acpi-processor: C and P-state driver that uploads said data to hypervisor.") Signed-off-by: David Thomson Reviewed-by: Jan Beulich Signed-off-by: Juergen Gross Message-ID: <20260224093707.19679-1-dt@linux-mail.net> Signed-off-by: Sasha Levin

xenbus: Use .freeze/.thaw to handle xenbus devices

2026-03-04T12:20:56Z

[ Upstream commit e08dd1ee49838750a514e83c0aa60cd12ba6ecbb ] The goal is to fix s2idle and S3 for Xen PV devices. A domain resuming from s3 or s2idle disconnects its PV devices during resume. The backends are not expecting this and do not reconnect. b3e96c0c7562 ("xen: use freeze/restore/thaw PM events for suspend/ resume/chkpt") changed xen_suspend()/do_suspend() from PMSG_SUSPEND/PMSG_RESUME to PMSG_FREEZE/PMSG_THAW/PMSG_RESTORE, but the suspend/resume callbacks remained. .freeze/restore are used with hiberation where Linux restarts in a new place in the future. .suspend/resume are useful for runtime power management for the duration of a boot. The current behavior of the callbacks works for an xl save/restore or live migration where the domain is restored/migrated to a new location and connecting to a not-already-connected backend. Change xenbus_pm_ops to use .freeze/thaw/restore and drop the .suspend/resume hook. This matches the use in drivers/xen/manage.c for save/restore and live migration. With .suspend/resume empty, PV devices are left connected during s2idle and s3, so PV devices are not changed and work after resume. Signed-off-by: Jason Andryuk Acked-by: Juergen Gross Signed-off-by: Juergen Gross Message-ID: <20251119224731.61497-2-jason.andryuk@amd.com> Signed-off-by: Sasha Levin

Partial revert "x86/xen: fix balloon target initialization for PVH dom0"

2026-03-04T12:19:30Z

[ Upstream commit 0949c646d64697428ff6257d52efa5093566868d ] This partially reverts commit 87af633689ce16ddb166c80f32b120e50b1295de so the current memory target for PV guests is still fetched from start_info->nr_pages, which matches exactly what the toolstack sets the initial memory target to. Using get_num_physpages() is possible on PV also, but needs adjusting to take into account the ISA hole and the PFN at 0 not considered usable memory despite being populated, and hence would need extra adjustments. Instead of carrying those extra adjustments switch back to the previous code. That leaves Linux with a difference in how current memory target is obtained for HVM vs PV, but that's better than adding extra logic just for PV. However if switching to start_info->nr_pages for PV domains we need to differentiate between released pages (freed back to the hypervisor) as opposed to pages in the physmap which are not populated to start with. Introduce a new xen_unpopulated_pages to account for papges that have never been populated, and hence in the PV case don't need subtracting. Fixes: 87af633689ce ("x86/xen: fix balloon target initialization for PVH dom0") Reported-by: James Dingwall Signed-off-by: Roger Pau Monné Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross Message-ID: <20260128110510.46425-2-roger.pau@citrix.com> Signed-off-by: Sasha Levin

xen/virtio: Don't use grant-dma-ops when running as Dom0

2026-03-04T12:19:27Z

[ Upstream commit dc8ea8714311e549ee93a2b0bdd5487d20bfadbf ] Dom0 inherit devices from the machine and is usually in PV mode. If we are running in a virtual that has virtio devices, these devices would be considered as using grants with Dom0 as backend, while being the said Dom0 itself, while we want to use these devices like regular PCI devices. Fix this by preventing grant-dma-ops from being used when running as Dom0 (initial domain). We still keep the device-tree logic as-is. Signed-off-by: Teddy Astie Fixes: 61367688f1fb0 ("xen/virtio: enable grant based virtio on x86") Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross Message-ID: <6698564dd2270a9f7377b78ebfb20cb425cabbe8.1767720955.git.teddy.astie@vates.tech> Signed-off-by: Sasha Levin

scsi: xen: scsiback: Fix potential memory leak in scsiback_remove()

2026-01-30T09:28:40Z

commit 901a5f309daba412e2a30364d7ec1492fa11c32c upstream. Memory allocated for struct vscsiblk_info in scsiback_probe() is not freed in scsiback_remove() leading to potential memory leaks on remove, as well as in the scsiback_probe() error paths. Fix that by freeing it in scsiback_remove(). Cc: stable@vger.kernel.org Fixes: d9d660f6e562 ("xen-scsiback: Add Xen PV SCSI backend driver") Signed-off-by: Abdun Nihaal Reviewed-by: Juergen Gross Link: https://patch.msgid.link/20251223063012.119035-1-nihaal@cse.iitm.ac.in Signed-off-by: Martin K. Petersen Signed-off-by: Greg Kroah-Hartman

xen/events: Update virq_to_irq on migration

2025-10-19T14:33:45Z

commit 3fcc8e146935415d69ffabb5df40ecf50e106131 upstream. VIRQs come in 3 flavors, per-VPU, per-domain, and global, and the VIRQs are tracked in per-cpu virq_to_irq arrays. Per-domain and global VIRQs must be bound on CPU 0, and bind_virq_to_irq() sets the per_cpu virq_to_irq at registration time Later, the interrupt can migrate, and info->cpu is updated. When calling __unbind_from_irq(), the per-cpu virq_to_irq is cleared for a different cpu. If bind_virq_to_irq() is called again with CPU 0, the stale irq is returned. There won't be any irq_info for the irq, so things break. Make xen_rebind_evtchn_to_cpu() update the per_cpu virq_to_irq mappings to keep them update to date with the current cpu. This ensures the correct virq_to_irq is cleared in __unbind_from_irq(). Fixes: e46cdb66c8fc ("xen: event channels") Cc: stable@vger.kernel.org Signed-off-by: Jason Andryuk Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross Message-ID: <20250828003604.8949-4-jason.andryuk@amd.com> Signed-off-by: Greg Kroah-Hartman

xen/events: Return -EEXIST for bound VIRQs

2025-10-19T14:33:45Z

commit 07ce121d93a5e5fb2440a24da3dbf408fcee978e upstream. Change find_virq() to return -EEXIST when a VIRQ is bound to a different CPU than the one passed in. With that, remove the BUG_ON() from bind_virq_to_irq() to propogate the error upwards. Some VIRQs are per-cpu, but others are per-domain or global. Those must be bound to CPU0 and can then migrate elsewhere. The lookup for per-domain and global will probably fail when migrated off CPU 0, especially when the current CPU is tracked. This now returns -EEXIST instead of BUG_ON(). A second call to bind a per-domain or global VIRQ is not expected, but make it non-fatal to avoid trying to look up the irq, since we don't know which per_cpu(virq_to_irq) it will be in. Cc: stable@vger.kernel.org Signed-off-by: Jason Andryuk Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross Message-ID: <20250828003604.8949-3-jason.andryuk@amd.com> Signed-off-by: Greg Kroah-Hartman

xen/manage: Fix suspend error path

2025-10-19T14:33:45Z

commit f770c3d858687252f1270265ba152d5c622e793f upstream. The device power management API has the following asymmetry: * dpm_suspend_start() does not clean up on failure (it requires a call to dpm_resume_end()) * dpm_suspend_end() does clean up on failure (it does not require a call to dpm_resume_start()) The asymmetry was introduced by commit d8f3de0d2412 ("Suspend-related patches for 2.6.27") in June 2008: It removed a call to device_resume() from device_suspend() (which was later renamed to dpm_suspend_start()). When Xen began using the device power management API in May 2008 with commit 0e91398f2a5d ("xen: implement save/restore"), the asymmetry did not yet exist. But since it was introduced, a call to dpm_resume_end() is missing in the error path of dpm_suspend_start(). Fix it. Fixes: d8f3de0d2412 ("Suspend-related patches for 2.6.27") Signed-off-by: Lukas Wunner Cc: stable@vger.kernel.org # v2.6.27 Reviewed-by: "Rafael J. Wysocki (Intel)" Signed-off-by: Juergen Gross Message-ID: <22453676d1ddcebbe81641bb68ddf587fee7e21e.1756990799.git.lukas@wunner.de> Signed-off-by: Greg Kroah-Hartman

xen/events: Cleanup find_virq() return codes

2025-10-19T14:33:45Z

commit 08df2d7dd4ab2db8a172d824cda7872d5eca460a upstream. rc is overwritten by the evtchn_status hypercall in each iteration, so the return value will be whatever the last iteration is. This could incorrectly return success even if the event channel was not found. Change to an explicit -ENOENT for an un-found virq and return 0 on a successful match. Fixes: 62cc5fc7b2e0 ("xen/pv-on-hvm kexec: rebind virqs to existing eventchannel ports") Cc: stable@vger.kernel.org Signed-off-by: Jason Andryuk Reviewed-by: Jan Beulich Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross Message-ID: <20250828003604.8949-2-jason.andryuk@amd.com> Signed-off-by: Greg Kroah-Hartman

xen/gntdev: remove struct gntdev_copy_batch from stack

2025-08-15T10:13:43Z

[ Upstream commit 70045cf6593cbf0740956ea9b7b4269142c6ee38 ] When compiling the kernel with LLVM, the following warning was issued: drivers/xen/gntdev.c:991: warning: stack frame size (1160) exceeds limit (1024) in function 'gntdev_ioctl' The main reason is struct gntdev_copy_batch which is located on the stack and has a size of nearly 1kb. For performance reasons it shouldn't by just dynamically allocated instead, so allocate a new instance when needed and instead of freeing it put it into a list of free structs anchored in struct gntdev_priv. Fixes: a4cdb556cae0 ("xen/gntdev: add ioctl for grant copy") Reported-by: Abinash Singh Reviewed-by: Stefano Stabellini Signed-off-by: Juergen Gross Message-ID: <20250703073259.17356-1-jgross@suse.com> Signed-off-by: Sasha Levin