kernel/linux.git/drivers/xen, branch v6.12.80

xen/privcmd: unregister xenstore notifier on module exit

2026-04-02T11:09:54+00:00

[ Upstream commit cd7e1fef5a1ca1c4fcd232211962ac2395601636 ] Commit 453b8fb68f36 ("xen/privcmd: restrict usage in unprivileged domU") added a xenstore notifier to defer setting the restriction target until Xenstore is ready. XEN_PRIVCMD can be built as a module, but privcmd_exit() leaves that notifier behind. Balance the notifier lifecycle by unregistering it on module exit. This is harmless even if xenstore was already ready at registration time and the notifier was never queued on the chain. Fixes: 453b8fb68f3641fe ("xen/privcmd: restrict usage in unprivileged domU") Signed-off-by: GuoHan Zhao Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross Message-ID: <20260325120246.252899-1-zhaoguohan@kylinos.cn> Signed-off-by: Sasha Levin

xen/privcmd: add boot control for restricted usage in domU

2026-03-25T10:08:57+00:00

commit 1613462be621ad5103ec338a7b0ca0746ec4e5f1 upstream. When running in an unprivileged domU under Xen, the privcmd driver is restricted to allow only hypercalls against a target domain, for which the current domU is acting as a device model. Add a boot parameter "unrestricted" to allow all hypercalls (the hypervisor will still refuse destructive hypercalls affecting other guests). Make this new parameter effective only in case the domU wasn't started using secure boot, as otherwise hypercalls targeting the domU itself might result in violating the secure boot functionality. This is achieved by adding another lockdown reason, which can be tested to not being set when applying the "unrestricted" option. This is part of XSA-482 Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman

xen/privcmd: restrict usage in unprivileged domU

2026-03-25T10:08:57+00:00

commit 453b8fb68f3641fea970db88b7d9a153ed2a37e8 upstream. The Xen privcmd driver allows to issue arbitrary hypercalls from user space processes. This is normally no problem, as access is usually limited to root and the hypervisor will deny any hypercalls affecting other domains. In case the guest is booted using secure boot, however, the privcmd driver would be enabling a root user process to modify e.g. kernel memory contents, thus breaking the secure boot feature. The only known case where an unprivileged domU is really needing to use the privcmd driver is the case when it is acting as the device model for another guest. In this case all hypercalls issued via the privcmd driver will target that other guest. Fortunately the privcmd driver can already be locked down to allow only hypercalls targeting a specific domain, but this mode can be activated from user land only today. The target domain can be obtained from Xenstore, so when not running in dom0 restrict the privcmd driver to that target domain from the beginning, resolving the potential problem of breaking secure boot. This is XSA-482 Reported-by: Teddy Astie Fixes: 1c5de1939c20 ("xen: add privcmd driver") Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman

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

2026-03-13T16:20:42+00:00

[ 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

2026-03-04T12:20:56+00:00

[ 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"

2026-03-04T12:19:30+00:00

[ 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

2026-03-04T12:19:27+00:00

[ 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()

2026-01-30T09:28:40+00:00

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

2025-10-19T14:33:45+00:00

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

2025-10-19T14:33:45+00:00

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