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2025-09-03sched_ext: Use cgroup_lock/unlock() to synchronize against cgroup operationsTejun Heo3-56/+14
SCX hooks into CPU cgroup controller operations and read-locks scx_cgroup_rwsem to exclude them while enabling and disable schedulers. While this works, it's unnecessarily complicated given that cgroup_[un]lock() are available and thus the cgroup operations can be locked out that way. Drop scx_cgroup_rwsem locking from the tg on/offline and cgroup [can_]attach operations. Instead, grab cgroup_lock() from scx_cgroup_lock(). Drop scx_cgroup_finish_attach() which is no longer necessary. Drop the now unnecessary rcu locking and css ref bumping in scx_cgroup_init() and scx_cgroup_exit(). As scx_cgroup_set_weight/bandwidth() paths aren't protected by cgroup_lock(), rename scx_cgroup_rwsem to scx_cgroup_ops_rwsem and retain the locking there. This is overall simpler and will also allow enable/disable paths to synchronize against cgroup changes independent of the CPU controller. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Acked-by: Andrea Righi <arighi@nvidia.com>
2025-09-03sched_ext: Put event_stats_cpu in struct scx_sched_pcpuTejun Heo2-16/+19
scx_sched.event_stats_cpu is the percpu counters that are used to track stats. Introduce struct scx_sched_pcpu and move the counters inside. This will ease adding more per-cpu fields. No functional changes. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Andrea Righi <arighi@nvidia.com>
2025-09-03sched_ext: Move internal type and accessor definitions to ext_internal.hTejun Heo4-1057/+1062
There currently isn't a place to place SCX-internal types and accessors to be shared between ext.c and ext_idle.c. Create kernel/sched/ext_internal.h and move internal type and accessor definitions there. This trims ext.c a bit and makes future additions easier. Pure code reorganization. No functional changes. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Andrea Righi <arighi@nvidia.com>
2025-09-03sched_ext: Keep bypass on between enable failure and scx_disable_workfn()Tejun Heo1-1/+1
scx_enable() turns on the bypass mode while enable is in progress. If enabling fails, it turns off the bypass mode and then triggers scx_error(). scx_error() will trigger scx_disable_workfn() which will turn on the bypass mode again and unload the failed scheduler. This moves the system out of bypass mode between the enable error path and the disable path, which is unnecessary and can be brittle - e.g. the thread running scx_enable() may already be on the failed scheduler and can be switched out before it triggers scx_error() leading to a stall. The watchdog would eventually kick in, so the situation isn't critical but is still suboptimal. There is nothing to be gained by turning off the bypass mode between scx_enable() failure and scx_disable_workfn(). Keep bypass on. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Andrea Righi <arighi@nvidia.com>
2025-09-03sched_ext: Make explicit scx_task_iter_relock() calls unnecessaryTejun Heo1-20/+23
During tasks iteration, the locks can be dropped using scx_task_iter_unlock() to perform e.g. sleepable allocations. Afterwards, scx_task_iter_relock() has to be called prior to other iteration operations, which is error-prone. This can be easily automated by tracking whether scx_tasks_lock is held in scx_task_iter and re-acquiring when necessary. It already tracks whether the task's rq is locked after all. - Add scx_task_iter->list_locked which remembers whether scx_tasks_lock is held. - Rename scx_task_iter->locked to scx_task_iter->locked_task to better distinguish it from ->list_locked. - Replace scx_task_iter_relock() with __scx_task_iter_maybe_relock() which is automatically called by scx_task_iter_next() and scx_task_iter_stop(). - Drop explicit scx_task_iter_relock() calls. The resulting behavior should be equivalent. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Andrea Righi <arighi@nvidia.com>
2025-09-03sched: Fix sched_numa_find_nth_cpu() if mask offlineChristian Loehle1-0/+2
sched_numa_find_nth_cpu() uses a bsearch to look for the 'closest' CPU in sched_domains_numa_masks and given cpus mask. However they might not intersect if all CPUs in the cpus mask are offline. bsearch will return NULL in that case, bail out instead of dereferencing a bogus pointer. The previous behaviour lead to this bug when using maxcpus=4 on an rk3399 (LLLLbb) (i.e. booting with all big CPUs offline): [ 1.422922] Unable to handle kernel paging request at virtual address ffffff8000000000 [ 1.423635] Mem abort info: [ 1.423889] ESR = 0x0000000096000006 [ 1.424227] EC = 0x25: DABT (current EL), IL = 32 bits [ 1.424715] SET = 0, FnV = 0 [ 1.424995] EA = 0, S1PTW = 0 [ 1.425279] FSC = 0x06: level 2 translation fault [ 1.425735] Data abort info: [ 1.425998] ISV = 0, ISS = 0x00000006, ISS2 = 0x00000000 [ 1.426499] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 [ 1.426952] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [ 1.427428] swapper pgtable: 4k pages, 39-bit VAs, pgdp=0000000004a9f000 [ 1.428038] [ffffff8000000000] pgd=18000000f7fff403, p4d=18000000f7fff403, pud=18000000f7fff403, pmd=0000000000000000 [ 1.429014] Internal error: Oops: 0000000096000006 [#1] SMP [ 1.429525] Modules linked in: [ 1.429813] CPU: 3 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.17.0-rc4-dirty #343 PREEMPT [ 1.430559] Hardware name: Pine64 RockPro64 v2.1 (DT) [ 1.431012] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 1.431634] pc : sched_numa_find_nth_cpu+0x2a0/0x488 [ 1.432094] lr : sched_numa_find_nth_cpu+0x284/0x488 [ 1.432543] sp : ffffffc084e1b960 [ 1.432843] x29: ffffffc084e1b960 x28: ffffff80078a8800 x27: ffffffc0846eb1d0 [ 1.433495] x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000 [ 1.434144] x23: 0000000000000000 x22: fffffffffff7f093 x21: ffffffc081de6378 [ 1.434792] x20: 0000000000000000 x19: 0000000ffff7f093 x18: 00000000ffffffff [ 1.435441] x17: 3030303866666666 x16: 66663d736b73616d x15: ffffffc104e1b5b7 [ 1.436091] x14: 0000000000000000 x13: ffffffc084712860 x12: 0000000000000372 [ 1.436739] x11: 0000000000000126 x10: ffffffc08476a860 x9 : ffffffc084712860 [ 1.437389] x8 : 00000000ffffefff x7 : ffffffc08476a860 x6 : 0000000000000000 [ 1.438036] x5 : 000000000000bff4 x4 : 0000000000000000 x3 : 0000000000000000 [ 1.438683] x2 : 0000000000000000 x1 : ffffffc0846eb000 x0 : ffffff8000407b68 [ 1.439332] Call trace: [ 1.439559] sched_numa_find_nth_cpu+0x2a0/0x488 (P) [ 1.440016] smp_call_function_any+0xc8/0xd0 [ 1.440416] armv8_pmu_init+0x58/0x27c [ 1.440770] armv8_cortex_a72_pmu_init+0x20/0x2c [ 1.441199] arm_pmu_device_probe+0x1e4/0x5e8 [ 1.441603] armv8_pmu_device_probe+0x1c/0x28 [ 1.442007] platform_probe+0x5c/0xac [ 1.442347] really_probe+0xbc/0x298 [ 1.442683] __driver_probe_device+0x78/0x12c [ 1.443087] driver_probe_device+0xdc/0x160 [ 1.443475] __driver_attach+0x94/0x19c [ 1.443833] bus_for_each_dev+0x74/0xd4 [ 1.444190] driver_attach+0x24/0x30 [ 1.444525] bus_add_driver+0xe4/0x208 [ 1.444874] driver_register+0x60/0x128 [ 1.445233] __platform_driver_register+0x24/0x30 [ 1.445662] armv8_pmu_driver_init+0x28/0x4c [ 1.446059] do_one_initcall+0x44/0x25c [ 1.446416] kernel_init_freeable+0x1dc/0x3bc [ 1.446820] kernel_init+0x20/0x1d8 [ 1.447151] ret_from_fork+0x10/0x20 [ 1.447493] Code: 90022e21 f000e5f5 910de2b5 2a1703e2 (f8767803) [ 1.448040] ---[ end trace 0000000000000000 ]--- [ 1.448483] note: swapper/0[1] exited with preempt_count 1 [ 1.449047] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b [ 1.449741] SMP: stopping secondary CPUs [ 1.450105] Kernel Offset: disabled [ 1.450419] CPU features: 0x000000,00080000,20002001,0400421b [ 1.450935] Memory Limit: none [ 1.451217] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]--- Yury: with the fix, the function returns cpu == nr_cpu_ids, and later in smp_call_function_any -> smp_call_function_single -> generic_exec_single we test the cpu for '>= nr_cpu_ids' and return -ENXIO. So everything is handled correctly. Fixes: cd7f55359c90 ("sched: add sched_numa_find_nth_cpu()") Cc: stable@vger.kernel.org Signed-off-by: Christian Loehle <christian.loehle@arm.com> Signed-off-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>
2025-09-03sched/fair: Get rid of throttled_lb_pair()Aaron Lu1-31/+4
Now that throttled tasks are dequeued and can not stay on rq's cfs_tasks list, there is no need to take special care of these throttled tasks anymore in load balance. Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com> Signed-off-by: Aaron Lu <ziqianlu@bytedance.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Valentin Schneider <vschneid@redhat.com> Tested-by: Matteo Martelli <matteo.martelli@codethink.co.uk> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20250829081120.806-6-ziqianlu@bytedance.com
2025-09-03sched/fair: Task based throttle time accountingAaron Lu2-25/+32
With task based throttle model, the previous way to check cfs_rq's nr_queued to decide if throttled time should be accounted doesn't work as expected, e.g. when a cfs_rq which has a single task is throttled, that task could later block in kernel mode instead of being dequeued on limbo list and accounting this as throttled time is not accurate. Rework throttle time accounting for a cfs_rq as follows: - start accounting when the first task gets throttled in its hierarchy; - stop accounting on unthrottle. Note that there will be a time gap between when a cfs_rq is throttled and when a task in its hierarchy is actually throttled. This accounting mechanism only starts accounting in the latter case. Suggested-by: Chengming Zhou <chengming.zhou@linux.dev> # accounting mechanism Co-developed-by: K Prateek Nayak <kprateek.nayak@amd.com> # simplify implementation Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com> Signed-off-by: Aaron Lu <ziqianlu@bytedance.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Valentin Schneider <vschneid@redhat.com> Tested-by: Matteo Martelli <matteo.martelli@codethink.co.uk> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20250829081120.806-5-ziqianlu@bytedance.com
2025-09-03sched/fair: Switch to task based throttle modelValentin Schneider3-167/+181
In current throttle model, when a cfs_rq is throttled, its entity will be dequeued from cpu's rq, making tasks attached to it not able to run, thus achiveing the throttle target. This has a drawback though: assume a task is a reader of percpu_rwsem and is waiting. When it gets woken, it can not run till its task group's next period comes, which can be a relatively long time. Waiting writer will have to wait longer due to this and it also makes further reader build up and eventually trigger task hung. To improve this situation, change the throttle model to task based, i.e. when a cfs_rq is throttled, record its throttled status but do not remove it from cpu's rq. Instead, for tasks that belong to this cfs_rq, when they get picked, add a task work to them so that when they return to user, they can be dequeued there. In this way, tasks throttled will not hold any kernel resources. And on unthrottle, enqueue back those tasks so they can continue to run. Throttled cfs_rq's PELT clock is handled differently now: previously the cfs_rq's PELT clock is stopped once it entered throttled state but since now tasks(in kernel mode) can continue to run, change the behaviour to stop PELT clock when the throttled cfs_rq has no tasks left. Suggested-by: Chengming Zhou <chengming.zhou@linux.dev> # tag on pick Signed-off-by: Valentin Schneider <vschneid@redhat.com> Signed-off-by: Aaron Lu <ziqianlu@bytedance.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Valentin Schneider <vschneid@redhat.com> Tested-by: Chen Yu <yu.c.chen@intel.com> Tested-by: Matteo Martelli <matteo.martelli@codethink.co.uk> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20250829081120.806-4-ziqianlu@bytedance.com
2025-09-03sched/fair: Implement throttle task work and related helpersValentin Schneider1-0/+65
Implement throttle_cfs_rq_work() task work which gets executed on task's ret2user path where the task is dequeued and marked as throttled. Signed-off-by: Valentin Schneider <vschneid@redhat.com> Signed-off-by: Aaron Lu <ziqianlu@bytedance.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev> Tested-by: Valentin Schneider <vschneid@redhat.com> Tested-by: Matteo Martelli <matteo.martelli@codethink.co.uk> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20250829081120.806-3-ziqianlu@bytedance.com
2025-09-03sched/fair: Add related data structure for task based throttleValentin Schneider3-0/+19
Add related data structures for this new throttle functionality. Tesed-by: K Prateek Nayak <kprateek.nayak@amd.com> Signed-off-by: Valentin Schneider <vschneid@redhat.com> Signed-off-by: Aaron Lu <ziqianlu@bytedance.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev> Tested-by: Valentin Schneider <vschneid@redhat.com> Tested-by: Matteo Martelli <matteo.martelli@codethink.co.uk> Link: https://lore.kernel.org/r/20250829081120.806-2-ziqianlu@bytedance.com
2025-09-03sched: Move STDL_INIT() functions out-of-linePeter Zijlstra1-0/+45
Since all these functions are address-taken in SDTL_INIT() and called indirectly, it doesn't really make sense for them to be inline. Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2025-09-03sched/fair: Get rid of sched_domains_curr_level hack for tl->cpumask()Peter Zijlstra1-18/+10
Leon [1] and Vinicius [2] noted a topology_span_sane() warning during their testing starting from v6.16-rc1. Debug that followed pointed to the tl->mask() for the NODE domain being incorrectly resolved to that of the highest NUMA domain. tl->mask() for NODE is set to the sd_numa_mask() which depends on the global "sched_domains_curr_level" hack. "sched_domains_curr_level" is set to the "tl->numa_level" during tl traversal in build_sched_domains() calling sd_init() but was not reset before topology_span_sane(). Since "tl->numa_level" still reflected the old value from build_sched_domains(), topology_span_sane() for the NODE domain trips when the span of the last NUMA domain overlaps. Instead of replicating the "sched_domains_curr_level" hack, get rid of it entirely and instead, pass the entire "sched_domain_topology_level" object to tl->cpumask() function to prevent such mishap in the future. sd_numa_mask() now directly references "tl->numa_level" instead of relying on the global "sched_domains_curr_level" hack to index into sched_domains_numa_masks[]. The original warning was reproducible on the following NUMA topology reported by Leon: $ sudo numactl -H available: 5 nodes (0-4) node 0 cpus: 0 1 node 0 size: 2927 MB node 0 free: 1603 MB node 1 cpus: 2 3 node 1 size: 3023 MB node 1 free: 3008 MB node 2 cpus: 4 5 node 2 size: 3023 MB node 2 free: 3007 MB node 3 cpus: 6 7 node 3 size: 3023 MB node 3 free: 3002 MB node 4 cpus: 8 9 node 4 size: 3022 MB node 4 free: 2718 MB node distances: node 0 1 2 3 4 0: 10 39 38 37 36 1: 39 10 38 37 36 2: 38 38 10 37 36 3: 37 37 37 10 36 4: 36 36 36 36 10 The above topology can be mimicked using the following QEMU cmd that was used to reproduce the warning and test the fix: sudo qemu-system-x86_64 -enable-kvm -cpu host \ -m 20G -smp cpus=10,sockets=10 -machine q35 \ -object memory-backend-ram,size=4G,id=m0 \ -object memory-backend-ram,size=4G,id=m1 \ -object memory-backend-ram,size=4G,id=m2 \ -object memory-backend-ram,size=4G,id=m3 \ -object memory-backend-ram,size=4G,id=m4 \ -numa node,cpus=0-1,memdev=m0,nodeid=0 \ -numa node,cpus=2-3,memdev=m1,nodeid=1 \ -numa node,cpus=4-5,memdev=m2,nodeid=2 \ -numa node,cpus=6-7,memdev=m3,nodeid=3 \ -numa node,cpus=8-9,memdev=m4,nodeid=4 \ -numa dist,src=0,dst=1,val=39 \ -numa dist,src=0,dst=2,val=38 \ -numa dist,src=0,dst=3,val=37 \ -numa dist,src=0,dst=4,val=36 \ -numa dist,src=1,dst=0,val=39 \ -numa dist,src=1,dst=2,val=38 \ -numa dist,src=1,dst=3,val=37 \ -numa dist,src=1,dst=4,val=36 \ -numa dist,src=2,dst=0,val=38 \ -numa dist,src=2,dst=1,val=38 \ -numa dist,src=2,dst=3,val=37 \ -numa dist,src=2,dst=4,val=36 \ -numa dist,src=3,dst=0,val=37 \ -numa dist,src=3,dst=1,val=37 \ -numa dist,src=3,dst=2,val=37 \ -numa dist,src=3,dst=4,val=36 \ -numa dist,src=4,dst=0,val=36 \ -numa dist,src=4,dst=1,val=36 \ -numa dist,src=4,dst=2,val=36 \ -numa dist,src=4,dst=3,val=36 \ ... [ prateek: Moved common functions to include/linux/sched/topology.h, reuse the common bits for s390 and ppc, commit message ] Closes: https://lore.kernel.org/lkml/20250610110701.GA256154@unreal/ [1] Fixes: ccf74128d66c ("sched/topology: Assert non-NUMA topology masks don't (partially) overlap") # ce29a7da84cd, f55dac1dafb3 Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reported-by: Leon Romanovsky <leon@kernel.org> Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <vschneid@redhat.com> Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com> Tested-by: Valentin Schneider <vschneid@redhat.com> # x86 Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com> # powerpc Link: https://lore.kernel.org/lkml/a3de98387abad28592e6ab591f3ff6107fe01dc1.1755893468.git.tim.c.chen@linux.intel.com/ [2]
2025-09-03sched/deadline: Fix race in push_dl_task()Harshit Agarwal1-24/+49
When a CPU chooses to call push_dl_task and picks a task to push to another CPU's runqueue then it will call find_lock_later_rq method which would take a double lock on both CPUs' runqueues. If one of the locks aren't readily available, it may lead to dropping the current runqueue lock and reacquiring both the locks at once. During this window it is possible that the task is already migrated and is running on some other CPU. These cases are already handled. However, if the task is migrated and has already been executed and another CPU is now trying to wake it up (ttwu) such that it is queued again on the runqeue (on_rq is 1) and also if the task was run by the same CPU, then the current checks will pass even though the task was migrated out and is no longer in the pushable tasks list. Please go through the original rt change for more details on the issue. To fix this, after the lock is obtained inside the find_lock_later_rq, it ensures that the task is still at the head of pushable tasks list. Also removed some checks that are no longer needed with the addition of this new check. However, the new check of pushable tasks list only applies when find_lock_later_rq is called by push_dl_task. For the other caller i.e. dl_task_offline_migration, existing checks are used. Signed-off-by: Harshit Agarwal <harshit@nutanix.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Juri Lelli <juri.lelli@redhat.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250408045021.3283624-1-harshit@nutanix.com
2025-09-01copy_process: pass clone_flags as u64 across calltreeSimon Schuster3-5/+5
With the introduction of clone3 in commit 7f192e3cd316 ("fork: add clone3") the effective bit width of clone_flags on all architectures was increased from 32-bit to 64-bit, with a new type of u64 for the flags. However, for most consumers of clone_flags the interface was not changed from the previous type of unsigned long. While this works fine as long as none of the new 64-bit flag bits (CLONE_CLEAR_SIGHAND and CLONE_INTO_CGROUP) are evaluated, this is still undesirable in terms of the principle of least surprise. Thus, this commit fixes all relevant interfaces of callees to sys_clone3/copy_process (excluding the architecture-specific copy_thread) to consistently pass clone_flags as u64, so that no truncation to 32-bit integers occurs on 32-bit architectures. Signed-off-by: Simon Schuster <schuster.simon@siemens-energy.com> Link: https://lore.kernel.org/20250901-nios2-implement-clone3-v2-2-53fcf5577d57@siemens-energy.com Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-08-26sched/deadline: Don't count nr_running for dl_server proxy tasksYicong Yang1-2/+6
On CPU offline the kernel stalled with below call trace: INFO: task kworker/0:1:11 blocked for more than 120 seconds. cpuhp hold the cpu hotplug lock endless and stalled vmstat_shepherd. This is because we count nr_running twice on cpuhp enqueuing and failed the wait condition of cpuhp: enqueue_task_fair() // pick cpuhp from idle, rq->nr_running = 0 dl_server_start() [...] add_nr_running() // rq->nr_running = 1 add_nr_running() // rq->nr_running = 2 [switch to cpuhp, waiting on balance_hotplug_wait()] rcuwait_wait_event(rq->nr_running == 1 && ...) // failed, rq->nr_running=2 schedule() // wait again It doesn't make sense to count the dl_server towards runnable tasks, since it runs other tasks. Fixes: 63ba8422f876 ("sched/deadline: Introduce deadline servers") Signed-off-by: Yicong Yang <yangyicong@hisilicon.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20250627035420.37712-1-yangyicong@huawei.com
2025-08-26sched/deadline: Fix RT task potential starvation when expiry time passedkuyo chang1-3/+5
[Symptom] The fair server mechanism, which is intended to prevent fair starvation when higher-priority tasks monopolize the CPU. Specifically, RT tasks on the runqueue may not be scheduled as expected. [Analysis] The log "sched: DL replenish lagged too much" triggered. By memory dump of dl_server: curr = 0xFFFFFF80D6A0AC00 ( dl_server = 0xFFFFFF83CD5B1470( dl_runtime = 0x02FAF080, dl_deadline = 0x3B9ACA00, dl_period = 0x3B9ACA00, dl_bw = 0xCCCC, dl_density = 0xCCCC, runtime = 0x02FAF080, deadline = 0x0000082031EB0E80, flags = 0x0, dl_throttled = 0x0, dl_yielded = 0x0, dl_non_contending = 0x0, dl_overrun = 0x0, dl_server = 0x1, dl_server_active = 0x1, dl_defer = 0x1, dl_defer_armed = 0x0, dl_defer_running = 0x1, dl_timer = ( node = ( expires = 0x000008199756E700), _softexpires = 0x000008199756E700, function = 0xFFFFFFDB9AF44D30 = dl_task_timer, base = 0xFFFFFF83CD5A12C0, state = 0x0, is_rel = 0x0, is_soft = 0x0, clock_update_flags = 0x4, clock = 0x000008204A496900, - The timer expiration time (rq->curr->dl_server->dl_timer->expires) is already in the past, indicating the timer has expired. - The timer state (rq->curr->dl_server->dl_timer->state) is 0. [Suspected Root Cause] The relevant code flow in the throttle path of update_curr_dl_se() as follows: dequeue_dl_entity(dl_se, 0); // the DL entity is dequeued if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(dl_se))) { if (dl_server(dl_se)) // timer registration fails enqueue_dl_entity(dl_se, ENQUEUE_REPLENISH);//enqueue immediately ... } The failure of `start_dl_timer` is caused by attempting to register a timer with an expiration time that is already in the past. When this situation persists, the code repeatedly re-enqueues the DL entity without properly replenishing or restarting the timer, resulting in RT task may not be scheduled as expected. [Proposed Solution]: Instead of immediately re-enqueuing the DL entity on timer registration failure, this change ensures the DL entity is properly replenished and the timer is restarted, preventing RT potential starvation. Fixes: 63ba8422f876 ("sched/deadline: Introduce deadline servers") Signed-off-by: kuyo chang <kuyo.chang@mediatek.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Closes: https://lore.kernel.org/CAMuHMdXn4z1pioTtBGMfQM0jsLviqS2jwysaWXpoLxWYoGa82w@mail.gmail.com Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Jiri Slaby <jirislaby@kernel.org> Tested-by: Diederik de Haas <didi.debian@cknow.org> Link: https://lkml.kernel.org/r/20250615131129.954975-1-kuyo.chang@mediatek.com
2025-08-26sched/deadline: Always stop dl-server before changing parametersJuri Lelli1-4/+2
Commit cccb45d7c4295 ("sched/deadline: Less agressive dl_server handling") reduced dl-server overhead by delaying disabling servers only after there are no fair task around for a whole period, which means that deadline entities are not dequeued right away on a server stop event. However, the delay opens up a window in which a request for changing server parameters can break per-runqueue running_bw tracking, as reported by Yuri. Close the problematic window by unconditionally calling dl_server_stop() before applying the new parameters (ensuring deadline entities go through an actual dequeue). Fixes: cccb45d7c4295 ("sched/deadline: Less agressive dl_server handling") Reported-by: Yuri Andriaccio <yurand2000@gmail.com> Signed-off-by: Juri Lelli <juri.lelli@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <vschneid@redhat.com> Link: https://lore.kernel.org/r/20250721-upstream-fix-dlserver-lessaggressive-b4-v1-1-4ebc10c87e40@redhat.com
2025-08-26sched/deadline: Fix dl_server_stopped()Huacai Chen1-1/+1
Commit cccb45d7c429 ("sched/deadline: Less agressive dl_server handling") introduces dl_server_stopped(). But it is obvious that dl_server_stopped() should return true if dl_se->dl_server_active is 0. Fixes: cccb45d7c429 ("sched/deadline: Less agressive dl_server handling") Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20250809130419.1980742-1-chenhuacai@loongson.cn
2025-08-11sched/ext: Fix invalid task state transitions on class switchAndrea Righi1-0/+4
When enabling a sched_ext scheduler, we may trigger invalid task state transitions, resulting in warnings like the following (which can be easily reproduced by running the hotplug selftest in a loop): sched_ext: Invalid task state transition 0 -> 3 for fish[770] WARNING: CPU: 18 PID: 787 at kernel/sched/ext.c:3862 scx_set_task_state+0x7c/0xc0 ... RIP: 0010:scx_set_task_state+0x7c/0xc0 ... Call Trace: <TASK> scx_enable_task+0x11f/0x2e0 switching_to_scx+0x24/0x110 scx_enable.isra.0+0xd14/0x13d0 bpf_struct_ops_link_create+0x136/0x1a0 __sys_bpf+0x1edd/0x2c30 __x64_sys_bpf+0x21/0x30 do_syscall_64+0xbb/0x370 entry_SYSCALL_64_after_hwframe+0x77/0x7f This happens because we skip initialization for tasks that are already dead (with their usage counter set to zero), but we don't exclude them during the scheduling class transition phase. Fix this by also skipping dead tasks during class swiching, preventing invalid task state transitions. Fixes: a8532fac7b5d2 ("sched_ext: TASK_DEAD tasks must be switched into SCX on ops_enable") Cc: stable@vger.kernel.org # v6.12+ Signed-off-by: Andrea Righi <arighi@nvidia.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2025-08-04sched/psi: Fix psi_seq initializationPeter Zijlstra1-5/+1
With the seqcount moved out of the group into a global psi_seq, re-initializing the seqcount on group creation is causing seqcount corruption. Fixes: 570c8efd5eb7 ("sched/psi: Optimize psi_group_change() cpu_clock() usage") Reported-by: Chris Mason <clm@meta.com> Suggested-by: Beata Michalska <beata.michalska@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2025-07-31Merge tag 'sched_ext-for-6.17' of ↵Linus Torvalds6-190/+175
git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext Pull sched_ext updates from Tejun Heo: - Add support for cgroup "cpu.max" interface - Code organization cleanup so that ext_idle.c doesn't depend on the source-file-inclusion build method of sched/ - Drop UP paths in accordance with sched core changes - Documentation and other misc changes * tag 'sched_ext-for-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext: sched_ext: Fix scx_bpf_reenqueue_local() reference sched_ext: Drop kfuncs marked for removal in 6.15 sched_ext, rcu: Eject BPF scheduler on RCU CPU stall panic kernel/sched/ext.c: fix typo "occured" -> "occurred" in comments sched_ext: Add support for cgroup bandwidth control interface sched_ext, sched/core: Factor out struct scx_task_group sched_ext: Return NULL in llc_span sched_ext: Always use SMP versions in kernel/sched/ext_idle.h sched_ext: Always use SMP versions in kernel/sched/ext_idle.c sched_ext: Always use SMP versions in kernel/sched/ext.h sched_ext: Always use SMP versions in kernel/sched/ext.c sched_ext: Documentation: Clarify time slice handling in task lifecycle sched_ext: Make scx_locked_rq() inline sched_ext: Make scx_rq_bypassing() inline sched_ext: idle: Make local functions static in ext_idle.c sched_ext: idle: Remove unnecessary ifdef in scx_bpf_cpu_node()
2025-07-30Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds1-2/+20
Pull kvm updates from Paolo Bonzini: "ARM: - Host driver for GICv5, the next generation interrupt controller for arm64, including support for interrupt routing, MSIs, interrupt translation and wired interrupts - Use FEAT_GCIE_LEGACY on GICv5 systems to virtualize GICv3 VMs on GICv5 hardware, leveraging the legacy VGIC interface - Userspace control of the 'nASSGIcap' GICv3 feature, allowing userspace to disable support for SGIs w/o an active state on hardware that previously advertised it unconditionally - Map supporting endpoints with cacheable memory attributes on systems with FEAT_S2FWB and DIC where KVM no longer needs to perform cache maintenance on the address range - Nested support for FEAT_RAS and FEAT_DoubleFault2, allowing the guest hypervisor to inject external aborts into an L2 VM and take traps of masked external aborts to the hypervisor - Convert more system register sanitization to the config-driven implementation - Fixes to the visibility of EL2 registers, namely making VGICv3 system registers accessible through the VGIC device instead of the ONE_REG vCPU ioctls - Various cleanups and minor fixes LoongArch: - Add stat information for in-kernel irqchip - Add tracepoints for CPUCFG and CSR emulation exits - Enhance in-kernel irqchip emulation - Various cleanups RISC-V: - Enable ring-based dirty memory tracking - Improve perf kvm stat to report interrupt events - Delegate illegal instruction trap to VS-mode - MMU improvements related to upcoming nested virtualization s390x - Fixes x86: - Add CONFIG_KVM_IOAPIC for x86 to allow disabling support for I/O APIC, PIC, and PIT emulation at compile time - Share device posted IRQ code between SVM and VMX and harden it against bugs and runtime errors - Use vcpu_idx, not vcpu_id, for GA log tag/metadata, to make lookups O(1) instead of O(n) - For MMIO stale data mitigation, track whether or not a vCPU has access to (host) MMIO based on whether the page tables have MMIO pfns mapped; using VFIO is prone to false negatives - Rework the MSR interception code so that the SVM and VMX APIs are more or less identical - Recalculate all MSR intercepts from scratch on MSR filter changes, instead of maintaining shadow bitmaps - Advertise support for LKGS (Load Kernel GS base), a new instruction that's loosely related to FRED, but is supported and enumerated independently - Fix a user-triggerable WARN that syzkaller found by setting the vCPU in INIT_RECEIVED state (aka wait-for-SIPI), and then putting the vCPU into VMX Root Mode (post-VMXON). Trying to detect every possible path leading to architecturally forbidden states is hard and even risks breaking userspace (if it goes from valid to valid state but passes through invalid states), so just wait until KVM_RUN to detect that the vCPU state isn't allowed - Add KVM_X86_DISABLE_EXITS_APERFMPERF to allow disabling interception of APERF/MPERF reads, so that a "properly" configured VM can access APERF/MPERF. This has many caveats (APERF/MPERF cannot be zeroed on vCPU creation or saved/restored on suspend and resume, or preserved over thread migration let alone VM migration) but can be useful whenever you're interested in letting Linux guests see the effective physical CPU frequency in /proc/cpuinfo - Reject KVM_SET_TSC_KHZ for vm file descriptors if vCPUs have been created, as there's no known use case for changing the default frequency for other VM types and it goes counter to the very reason why the ioctl was added to the vm file descriptor. And also, there would be no way to make it work for confidential VMs with a "secure" TSC, so kill two birds with one stone - Dynamically allocation the shadow MMU's hashed page list, and defer allocating the hashed list until it's actually needed (the TDP MMU doesn't use the list) - Extract many of KVM's helpers for accessing architectural local APIC state to common x86 so that they can be shared by guest-side code for Secure AVIC - Various cleanups and fixes x86 (Intel): - Preserve the host's DEBUGCTL.FREEZE_IN_SMM when running the guest. Failure to honor FREEZE_IN_SMM can leak host state into guests - Explicitly check vmcs12.GUEST_DEBUGCTL on nested VM-Enter to prevent L1 from running L2 with features that KVM doesn't support, e.g. BTF x86 (AMD): - WARN and reject loading kvm-amd.ko instead of panicking the kernel if the nested SVM MSRPM offsets tracker can't handle an MSR (which is pretty much a static condition and therefore should never happen, but still) - Fix a variety of flaws and bugs in the AVIC device posted IRQ code - Inhibit AVIC if a vCPU's ID is too big (relative to what hardware supports) instead of rejecting vCPU creation - Extend enable_ipiv module param support to SVM, by simply leaving IsRunning clear in the vCPU's physical ID table entry - Disable IPI virtualization, via enable_ipiv, if the CPU is affected by erratum #1235, to allow (safely) enabling AVIC on such CPUs - Request GA Log interrupts if and only if the target vCPU is blocking, i.e. only if KVM needs a notification in order to wake the vCPU - Intercept SPEC_CTRL on AMD if the MSR shouldn't exist according to the vCPU's CPUID model - Accept any SNP policy that is accepted by the firmware with respect to SMT and single-socket restrictions. An incompatible policy doesn't put the kernel at risk in any way, so there's no reason for KVM to care - Drop a superfluous WBINVD (on all CPUs!) when destroying a VM and use WBNOINVD instead of WBINVD when possible for SEV cache maintenance - When reclaiming memory from an SEV guest, only do cache flushes on CPUs that have ever run a vCPU for the guest, i.e. don't flush the caches for CPUs that can't possibly have cache lines with dirty, encrypted data Generic: - Rework irqbypass to track/match producers and consumers via an xarray instead of a linked list. Using a linked list leads to O(n^2) insertion times, which is hugely problematic for use cases that create large numbers of VMs. Such use cases typically don't actually use irqbypass, but eliminating the pointless registration is a future problem to solve as it likely requires new uAPI - Track irqbypass's "token" as "struct eventfd_ctx *" instead of a "void *", to avoid making a simple concept unnecessarily difficult to understand - Decouple device posted IRQs from VFIO device assignment, as binding a VM to a VFIO group is not a requirement for enabling device posted IRQs - Clean up and document/comment the irqfd assignment code - Disallow binding multiple irqfds to an eventfd with a priority waiter, i.e. ensure an eventfd is bound to at most one irqfd through the entire host, and add a selftest to verify eventfd:irqfd bindings are globally unique - Add a tracepoint for KVM_SET_MEMORY_ATTRIBUTES to help debug issues related to private <=> shared memory conversions - Drop guest_memfd's .getattr() implementation as the VFS layer will call generic_fillattr() if inode_operations.getattr is NULL - Fix issues with dirty ring harvesting where KVM doesn't bound the processing of entries in any way, which allows userspace to keep KVM in a tight loop indefinitely - Kill off kvm_arch_{start,end}_assignment() and x86's associated tracking, now that KVM no longer uses assigned_device_count as a heuristic for either irqbypass usage or MDS mitigation Selftests: - Fix a comment typo - Verify KVM is loaded when getting any KVM module param so that attempting to run a selftest without kvm.ko loaded results in a SKIP message about KVM not being loaded/enabled (versus some random parameter not existing) - Skip tests that hit EACCES when attempting to access a file, and print a "Root required?" help message. In most cases, the test just needs to be run with elevated permissions" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (340 commits) Documentation: KVM: Use unordered list for pre-init VGIC registers RISC-V: KVM: Avoid re-acquiring memslot in kvm_riscv_gstage_map() RISC-V: KVM: Use find_vma_intersection() to search for intersecting VMAs RISC-V: perf/kvm: Add reporting of interrupt events RISC-V: KVM: Enable ring-based dirty memory tracking RISC-V: KVM: Fix inclusion of Smnpm in the guest ISA bitmap RISC-V: KVM: Delegate illegal instruction fault to VS mode RISC-V: KVM: Pass VMID as parameter to kvm_riscv_hfence_xyz() APIs RISC-V: KVM: Factor-out g-stage page table management RISC-V: KVM: Add vmid field to struct kvm_riscv_hfence RISC-V: KVM: Introduce struct kvm_gstage_mapping RISC-V: KVM: Factor-out MMU related declarations into separate headers RISC-V: KVM: Use ncsr_xyz() in kvm_riscv_vcpu_trap_redirect() RISC-V: KVM: Implement kvm_arch_flush_remote_tlbs_range() RISC-V: KVM: Don't flush TLB when PTE is unchanged RISC-V: KVM: Replace KVM_REQ_HFENCE_GVMA_VMID_ALL with KVM_REQ_TLB_FLUSH RISC-V: KVM: Rename and move kvm_riscv_local_tlb_sanitize() RISC-V: KVM: Drop the return value of kvm_riscv_vcpu_aia_init() RISC-V: KVM: Check kvm_riscv_vcpu_alloc_vector_context() return value KVM: arm64: selftests: Add FEAT_RAS EL2 registers to get-reg-list ...
2025-07-30Merge tag 'trace-rv-6.17' of ↵Linus Torvalds1-3/+10
git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull runtime verification updates from Steven Rostedt: - Added Linear temporal logic monitors for RT application Real-time applications may have design flaws causing them to have unexpected latency. For example, the applications may raise page faults, or may be blocked trying to take a mutex without priority inheritance. However, while attempting to implement DA monitors for these real-time rules, deterministic automaton is found to be inappropriate as the specification language. The automaton is complicated, hard to understand, and error-prone. For these cases, linear temporal logic is found to be more suitable. The LTL is more concise and intuitive. - Make printk_deferred() public The new monitors needed access to printk_deferred(). Make them visible for the entire kernel. - Add a vpanic() to allow for va_list to be passed to panic. - Add rtapp container monitor. A collection of monitors that check for common problems with real-time applications that cause unexpected latency. - Add page fault tracepoints to risc-v These tracepoints are necessary to for the RV monitor to run on risc-v. - Fix the behaviour of the rv tool with -s and idle tasks. - Allow the rv tool to gracefully terminate with SIGTERM - Adjusts dot2c not to create lines over 100 columns - Properly order nested monitors in the RV Kconfig file - Return the registration error in all DA monitor instead of 0 - Update and add new sched collection monitors Replace tss and sncid monitors with more complete sts: Not only prove that switches occur in scheduling context and scheduling needs interrupt disabled but also that each call to the scheduler disables interrupts to (optionally) switch. New monitor: nrp Preemption requires need resched which is cleared by any switch (includes a non optimal workaround for /nested/ preemptions) New monitor: sssw suspension requires setting the task to sleepable and, after the switch occurs, the task requires a wakeup to come back to runnable New monitor: opid waking and need-resched operations occur with interrupts and preemption disabled or in IRQ without explicitly disabling preemption" * tag 'trace-rv-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (48 commits) rv: Add opid per-cpu monitor rv: Add nrp and sssw per-task monitors rv: Replace tss and sncid monitors with more complete sts sched: Adapt sched tracepoints for RV task model rv: Retry when da monitor detects race conditions rv: Adjust monitor dependencies rv: Use strings in da monitors tracepoints rv: Remove trailing whitespace from tracepoint string rv: Add da_handle_start_run_event_ to per-task monitors rv: Fix wrong type cast in reactors_show() and monitor_reactor_show() rv: Fix wrong type cast in monitors_show() rv: Remove struct rv_monitor::reacting rv: Remove rv_reactor's reference counter rv: Merge struct rv_reactor_def into struct rv_reactor rv: Merge struct rv_monitor_def into struct rv_monitor rv: Remove unused field in struct rv_monitor_def rv: Return init error when registering monitors verification/rvgen: Organise Kconfig entries for nested monitors tools/dot2c: Fix generated files going over 100 column limit tools/rv: Stop gracefully also on SIGTERM ...
2025-07-29Merge tag 'sched-core-2025-07-28' of ↵Linus Torvalds38-1245/+1054
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: "Core scheduler changes: - Better tracking of maximum lag of tasks in presence of different slices duration, for better handling of lag in the fair scheduler (Vincent Guittot) - Clean up and standardize #if/#else/#endif markers throughout the entire scheduler code base (Ingo Molnar) - Make SMP unconditional: build the SMP scheduler's data structures and logic on UP kernel too, even though they are not used, to simplify the scheduler and remove around 200 #ifdef/[#else]/#endif blocks from the scheduler (Ingo Molnar) - Reorganize cgroup bandwidth control interface handling for better interfacing with sched_ext (Tejun Heo) Balancing: - Bump sd->max_newidle_lb_cost when newidle balance fails (Chris Mason) - Remove sched_domain_topology_level::flags to simplify the code (Prateek Nayak) - Simplify and clean up build_sched_topology() (Li Chen) - Optimize build_sched_topology() on large machines (Li Chen) Real-time scheduling: - Add initial version of proxy execution: a mechanism for mutex-owning tasks to inherit the scheduling context of higher priority waiters. Currently limited to a single runqueue and conditional on CONFIG_EXPERT, and other limitations (John Stultz, Peter Zijlstra, Valentin Schneider) - Deadline scheduler (Juri Lelli): - Fix dl_servers initialization order (Juri Lelli) - Fix DL scheduler's root domain reinitialization logic (Juri Lelli) - Fix accounting bugs after global limits change (Juri Lelli) - Fix scalability regression by implementing less agressive dl_server handling (Peter Zijlstra) PSI: - Improve scalability by optimizing psi_group_change() cpu_clock() usage (Peter Zijlstra) Rust changes: - Make Task, CondVar and PollCondVar methods inline to avoid unnecessary function calls (Kunwu Chan, Panagiotis Foliadis) - Add might_sleep() support for Rust code: Rust's "#[track_caller]" mechanism is used so that Rust's might_sleep() doesn't need to be defined as a macro (Fujita Tomonori) - Introduce file_from_location() (Boqun Feng) Debugging & instrumentation: - Make clangd usable with scheduler source code files again (Peter Zijlstra) - tools: Add root_domains_dump.py which dumps root domains info (Juri Lelli) - tools: Add dl_bw_dump.py for printing bandwidth accounting info (Juri Lelli) Misc cleanups & fixes: - Remove play_idle() (Feng Lee) - Fix check_preemption_disabled() (Sebastian Andrzej Siewior) - Do not call __put_task_struct() on RT if pi_blocked_on is set (Luis Claudio R. Goncalves) - Correct the comment in place_entity() (wang wei)" * tag 'sched-core-2025-07-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (84 commits) sched/idle: Remove play_idle() sched: Do not call __put_task_struct() on rt if pi_blocked_on is set sched: Start blocked_on chain processing in find_proxy_task() sched: Fix proxy/current (push,pull)ability sched: Add an initial sketch of the find_proxy_task() function sched: Fix runtime accounting w/ split exec & sched contexts sched: Move update_curr_task logic into update_curr_se locking/mutex: Add p->blocked_on wrappers for correctness checks locking/mutex: Rework task_struct::blocked_on sched: Add CONFIG_SCHED_PROXY_EXEC & boot argument to enable/disable sched/topology: Remove sched_domain_topology_level::flags x86/smpboot: avoid SMT domain attach/destroy if SMT is not enabled x86/smpboot: moves x86_topology to static initialize and truncate x86/smpboot: remove redundant CONFIG_SCHED_SMT smpboot: introduce SDTL_INIT() helper to tidy sched topology setup tools/sched: Add dl_bw_dump.py for printing bandwidth accounting info tools/sched: Add root_domains_dump.py which dumps root domains info sched/deadline: Fix accounting after global limits change sched/deadline: Reset extra_bw to max_bw when clearing root domains sched/deadline: Initialize dl_servers after SMP ...
2025-07-29Merge tag 'core-entry-2025-07-29' of ↵Linus Torvalds1-4/+4
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull generic entry code updates from Thomas Gleixner: - Split the code into syscall and exception/interrupt parts to ease the conversion of ARM[64] to the generic entry infrastructure - Extend syscall user dispatching to support a single intercepted range instead of the default single non-intercepted range. That allows monitoring/analysis of a specific executable range, e.g. a library, and also provides flexibility for sandboxing scenarios - Cleanup and extend the user dispatch selftest * tag 'core-entry-2025-07-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: entry: Split generic entry into generic exception and syscall entry selftests: Add tests for PR_SYS_DISPATCH_INCLUSIVE_ON syscall_user_dispatch: Add PR_SYS_DISPATCH_INCLUSIVE_ON selftests: Fix errno checking in syscall_user_dispatch test
2025-07-29Merge tag 'kvm-x86-irqs-6.17' of https://github.com/kvm-x86/linux into HEADPaolo Bonzini1-2/+20
KVM IRQ changes for 6.17 - Rework irqbypass to track/match producers and consumers via an xarray instead of a linked list. Using a linked list leads to O(n^2) insertion times, which is hugely problematic for use cases that create large numbers of VMs. Such use cases typically don't actually use irqbypass, but eliminating the pointless registration is a future problem to solve as it likely requires new uAPI. - Track irqbypass's "token" as "struct eventfd_ctx *" instead of a "void *", to avoid making a simple concept unnecessarily difficult to understand. - Add CONFIG_KVM_IOAPIC for x86 to allow disabling support for I/O APIC, PIC, and PIT emulation at compile time. - Drop x86's irq_comm.c, and move a pile of IRQ related code into irq.c. - Fix a variety of flaws and bugs in the AVIC device posted IRQ code. - Inhibited AVIC if a vCPU's ID is too big (relative to what hardware supports) instead of rejecting vCPU creation. - Extend enable_ipiv module param support to SVM, by simply leaving IsRunning clear in the vCPU's physical ID table entry. - Disable IPI virtualization, via enable_ipiv, if the CPU is affected by erratum #1235, to allow (safely) enabling AVIC on such CPUs. - Dedup x86's device posted IRQ code, as the vast majority of functionality can be shared verbatime between SVM and VMX. - Harden the device posted IRQ code against bugs and runtime errors. - Use vcpu_idx, not vcpu_id, for GA log tag/metadata, to make lookups O(1) instead of O(n). - Generate GA Log interrupts if and only if the target vCPU is blocking, i.e. only if KVM needs a notification in order to wake the vCPU. - Decouple device posted IRQs from VFIO device assignment, as binding a VM to a VFIO group is not a requirement for enabling device posted IRQs. - Clean up and document/comment the irqfd assignment code. - Disallow binding multiple irqfds to an eventfd with a priority waiter, i.e. ensure an eventfd is bound to at most one irqfd through the entire host, and add a selftest to verify eventfd:irqfd bindings are globally unique.