kernel.git/arch/loongarch/kernel/time.c, branch linux-6.15.y

LoongArch: Save and restore CSR.CNTC for hibernation

2025-05-14T14:17:52Z

Save and restore CSR.CNTC for hibernation which is similar to suspend. For host this is unnecessary because sched clock is ensured continuous, but for kvm guest sched clock isn't enough because rdtime.d should also be continuous. Host::rdtime.d = Host::CSR.CNTC + counter Guest::rdtime.d = Host::CSR.CNTC + Host::CSR.GCNTC + Guest::CSR.CNTC + counter so, Guest::rdtime.d = Host::rdtime.d + Host::CSR.GCNTC + Guest::CSR.CNTC To ensure Guest::rdtime.d continuous, Host::rdtime.d should be at first continuous, while Host::CSR.GCNTC / Guest::CSR.CNTC is maintained by KVM. Cc: stable@vger.kernel.org Signed-off-by: Xianglai Li Signed-off-by: Huacai Chen

LoongArch: Derive timer max_delta from PRCFG1's timer_bits

2025-01-25T10:51:33Z

As per arch spec, maximum timer bits is configurable and should not be hardcoded in any way. Probe timer bits from PRCFG1 and use that to determine the clockevent's max_delta to be conformance. Signed-off-by: Jiaxun Yang Signed-off-by: Huacai Chen

LoongArch: Reduce min_delta for the arch clockevent device

2024-11-26T10:06:03Z

Now the min_delta is 0x600 (1536) for LoongArch's constant clockevent device. For a 100MHz hardware timer this means ~15us. This is a little big, especially for PREEMPT_RT enabled kernels. So reduce it to 100 for PREEMPT_RT kernel, and 1000 for others (we don't want too small values to affect performance). Signed-off-by: Huacai Chen

LoongArch: KVM: Add PV steal time support in guest side

2024-07-09T08:25:51Z

Per-cpu struct kvm_steal_time is added here, its size is 64 bytes and also defined as 64 bytes, so that the whole structure is in one physical page. When a VCPU is online, function pv_enable_steal_time() is called. This function will pass guest physical address of struct kvm_steal_time and tells hypervisor to enable steal time. When a vcpu is offline, physical address is set as 0 and tells hypervisor to disable steal time. Here is an output of vmstat on guest when there is workload on both host and guest. It shows steal time stat information. procs -----------memory---------- -----io---- -system-- ------cpu----- r b swpd free inact active bi bo in cs us sy id wa st 15 1 0 7583616 184112 72208 20 0 162 52 31 6 43 0 20 17 0 0 7583616 184704 72192 0 0 6318 6885 5 60 8 5 22 16 0 0 7583616 185392 72144 0 0 1766 1081 0 49 0 1 50 16 0 0 7583616 184816 72304 0 0 6300 6166 4 62 12 2 20 18 0 0 7583632 184480 72240 0 0 2814 1754 2 58 4 1 35 Signed-off-by: Bibo Mao Signed-off-by: Huacai Chen

LoongArch/smp: Refine some ipi functions on LoongArch platform

2024-05-06T14:00:46Z

Refine the ipi handling on LoongArch platform, there are three modifications: 1. Add generic function get_percpu_irq(), replacing some percpu irq functions such as get_ipi_irq()/get_pmc_irq()/get_timer_irq() with get_percpu_irq(). 2. Change definition about parameter action called by function loongson_send_ipi_single() and loongson_send_ipi_mask(), and it is defined as decimal encoding format at ipi sender side. Normal decimal encoding is used rather than binary bitmap encoding for ipi action, ipi hw sender uses decimal encoding code, and ipi receiver will get binary bitmap encoding, the ipi hw will convert it into bitmap in ipi message buffer. 3. Add a structure smp_ops on LoongArch platform so that pv ipi can be used later. Signed-off-by: Bibo Mao Signed-off-by: Huacai Chen

LoongArch: Implement constant timer shutdown interface

2023-11-21T07:03:25Z

When a cpu is hot-unplugged, it is put in idle state and the function arch_cpu_idle_dead() is called. The timer interrupt for this processor should be disabled, otherwise there will be pending timer interrupt for the unplugged cpu, so that vcpu is prevented from giving up scheduling when system is running in vm mode. This patch implements the timer shutdown interface so that the constant timer will be properly disabled when a CPU is hot-unplugged. Reviewed-by: WANG Xuerui Signed-off-by: Bibo Mao Signed-off-by: Huacai Chen

LoongArch: Fix some build warnings with W=1

2023-09-20T06:26:28Z

There are some building warnings when building LoongArch kernel with W=1 as following, this patch fixes them. arch/loongarch/kernel/acpi.c:284:13: warning: no previous prototype for ‘acpi_numa_arch_fixup’ [-Wmissing-prototypes] 284 | void __init acpi_numa_arch_fixup(void) {} | ^~~~~~~~~~~~~~~~~~~~ arch/loongarch/kernel/time.c:32:13: warning: no previous prototype for ‘constant_timer_interrupt’ [-Wmissing-prototypes] 32 | irqreturn_t constant_timer_interrupt(int irq, void *data) | ^~~~~~~~~~~~~~~~~~~~~~~~ arch/loongarch/kernel/traps.c:496:25: warning: no previous prototype for 'do_fpe' [-Wmissing-prototypes] 496 | asmlinkage void noinstr do_fpe(struct pt_regs *regs | ^~~~~~ arch/loongarch/kernel/traps.c:813:22: warning: variable ‘opcode’ set but not used [-Wunused-but-set-variable] 813 | unsigned int opcode; | ^~~~~~ arch/loongarch/kernel/signal.c:895:14: warning: no previous prototype for ‘get_sigframe’ [-Wmissing-prototypes] 895 | void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, | ^~~~~~~~~~~~ arch/loongarch/kernel/syscall.c:21:40: warning: initialized field overwritten [-Woverride-init] 21 | #define __SYSCALL(nr, call) [nr] = (call), | ^ arch/loongarch/kernel/syscall.c:40:14: warning: no previous prototype for ‘do_syscall’ [-Wmissing-prototypes] 40 | void noinstr do_syscall(struct pt_regs *regs) | ^~~~~~~~~~ arch/loongarch/kernel/smp.c:502:17: warning: no previous prototype for ‘start_secondary’ [-Wmissing-prototypes] 502 | asmlinkage void start_secondary(void) | ^~~~~~~~~~~~~~~ arch/loongarch/kernel/process.c:309:15: warning: no previous prototype for ‘arch_align_stack’ [-Wmissing-prototypes] 309 | unsigned long arch_align_stack(unsigned long sp) | ^~~~~~~~~~~~~~~~ arch/loongarch/kernel/topology.c:13:5: warning: no previous prototype for ‘arch_register_cpu’ [-Wmissing-prototypes] 13 | int arch_register_cpu(int cpu) | ^~~~~~~~~~~~~~~~~ arch/loongarch/kernel/topology.c:27:6: warning: no previous prototype for ‘arch_unregister_cpu’ [-Wmissing-prototypes] 27 | void arch_unregister_cpu(int cpu) | ^~~~~~~~~~~~~~~~~~~ arch/loongarch/kernel/module-sections.c:103:5: warning: no previous prototype for ‘module_frob_arch_sections’ [-Wmissing-prototypes] 103 | int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, | ^~~~~~~~~~~~~~~~~~~~~~~~~ arch/loongarch/mm/hugetlbpage.c:56:5: warning: no previous prototype for ‘is_aligned_hugepage_range’ [-Wmissing-prototypes] 56 | int is_aligned_hugepage_range(unsigned long addr, unsigned long len) | ^~~~~~~~~~~~~~~~~~~~~~~~~ Signed-off-by: Bibo Mao Signed-off-by: Huacai Chen

loongarch: Provide noinstr sched_clock_read()

2023-06-05T19:11:05Z

With the intent to provide local_clock_noinstr(), a variant of local_clock() that's safe to be called from noinstr code (with the assumption that any such code will already be non-preemptible), prepare for things by providing a noinstr sched_clock_read() function. Specifically, preempt_enable_*() calls out to schedule(), which upsets noinstr validation efforts. Signed-off-by: Peter Zijlstra (Intel) Tested-by: Michael Kelley # Hyper-V Link: https://lore.kernel.org/r/20230519102715.502547082@infradead.org

LoongArch: Clean up the architectural interrupt definitions

2023-05-01T09:19:10Z

While interrupts are assigned ECodes `64 + interrupt number`, all existing use sites of interrupt numbers want the 64 subtracted. Re-arrange the definitions so that the actual interrupt number is used everywhere, and make EXCCODE_INT_END inclusive as it is more intuitive that way. While at it, according to the asm/loongarch.h definitions, the total number of architectural interrupts should be 14, but various other places indicate otherwise (13 or 15). Those places have been adjusted to 14 as well for consistency. Signed-off-by: WANG Xuerui Signed-off-by: Huacai Chen

LoongArch: Only call get_timer_irq() once in constant_clockevent_init()

2023-02-25T14:12:16Z

Under CONFIG_DEBUG_ATOMIC_SLEEP=y and CONFIG_DEBUG_PREEMPT=y, we can see the following messages on LoongArch, this is because using might_sleep() in preemption disable context. [ 0.001127] smp: Bringing up secondary CPUs ... [ 0.001222] Booting CPU#1... [ 0.001244] 64-bit Loongson Processor probed (LA464 Core) [ 0.001247] CPU1 revision is: 0014c012 (Loongson-64bit) [ 0.001250] FPU1 revision is: 00000000 [ 0.001252] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:283 [ 0.001255] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/1 [ 0.001257] preempt_count: 1, expected: 0 [ 0.001258] RCU nest depth: 0, expected: 0 [ 0.001259] Preemption disabled at: [ 0.001261] [<9000000000223800>] arch_dup_task_struct+0x20/0x110 [ 0.001272] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.2.0-rc7+ #43 [ 0.001275] Hardware name: Loongson Loongson-3A5000-7A1000-1w-A2101/Loongson-LS3A5000-7A1000-1w-A2101, BIOS vUDK2018-LoongArch-V4.0.05132-beta10 12/13/202 [ 0.001277] Stack : 0072617764726148 0000000000000000 9000000000222f1c 90000001001e0000 [ 0.001286] 90000001001e3be0 90000001001e3be8 0000000000000000 0000000000000000 [ 0.001292] 90000001001e3be8 0000000000000040 90000001001e3cb8 90000001001e3a50 [ 0.001297] 9000000001642000 90000001001e3be8 be694d10ce4139dd 9000000100174500 [ 0.001303] 0000000000000001 0000000000000001 00000000ffffe0a2 0000000000000020 [ 0.001309] 000000000000002f 9000000001354116 00000000056b0000 ffffffffffffffff [ 0.001314] 0000000000000000 0000000000000000 90000000014f6e90 9000000001642000 [ 0.001320] 900000000022b69c 0000000000000001 0000000000000000 9000000001736a90 [ 0.001325] 9000000100038000 0000000000000000 9000000000222f34 0000000000000000 [ 0.001331] 00000000000000b0 0000000000000004 0000000000000000 0000000000070000 [ 0.001337] ... [ 0.001339] Call Trace: [ 0.001342] [<9000000000222f34>] show_stack+0x5c/0x180 [ 0.001346] [<90000000010bdd80>] dump_stack_lvl+0x60/0x88 [ 0.001352] [<9000000000266418>] __might_resched+0x180/0x1cc [ 0.001356] [<90000000010c742c>] mutex_lock+0x20/0x64 [ 0.001359] [<90000000002a8ccc>] irq_find_matching_fwspec+0x48/0x124 [ 0.001364] [<90000000002259c4>] constant_clockevent_init+0x68/0x204 [ 0.001368] [<900000000022acf4>] start_secondary+0x40/0xa8 [ 0.001371] [<90000000010c0124>] smpboot_entry+0x60/0x64 Here are the complete call chains: smpboot_entry() start_secondary() constant_clockevent_init() get_timer_irq() irq_find_matching_fwnode() irq_find_matching_fwspec() mutex_lock() might_sleep() __might_sleep() __might_resched() In order to avoid the above issue, we should break the call chains, using timer_irq_installed variable as check condition to only call get_timer_irq() once in constant_clockevent_init() is a simple and proper way. Signed-off-by: Tiezhu Yang Signed-off-by: Huacai Chen