[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v2] xen/percpu: don't initialize percpu on resume
From: Mykola Kvach <mykola_kvach@xxxxxxxx> Invocation of the CPU_UP_PREPARE notification on ARM64 during resume causes a crash: (XEN) [ 315.807606] Error bringing CPU1 up: -16 (XEN) [ 315.811926] Xen BUG at common/cpu.c:258 [...] (XEN) [ 316.142765] Xen call trace: (XEN) [ 316.146048] [<00000a0000202264>] enable_nonboot_cpus+0x128/0x1ac (PC) (XEN) [ 316.153219] [<00000a000020225c>] enable_nonboot_cpus+0x120/0x1ac (LR) (XEN) [ 316.160391] [<00000a0000278180>] suspend.c#system_suspend+0x4c/0x1a0 (XEN) [ 316.167476] [<00000a0000206b70>] domain.c#continue_hypercall_tasklet_handler+0x54/0xd0 (XEN) [ 316.176117] [<00000a0000226538>] tasklet.c#do_tasklet_work+0xb8/0x100 (XEN) [ 316.183288] [<00000a0000226920>] do_tasklet+0x68/0xb0 (XEN) [ 316.189077] [<00000a000026e120>] domain.c#idle_loop+0x7c/0x194 (XEN) [ 316.195644] [<00000a0000277638>] shutdown.c#halt_this_cpu+0/0x14 (XEN) [ 316.202383] [<0000000000000008>] 0000000000000008 Freeing per-CPU areas and setting __per_cpu_offset to INVALID_PERCPU_AREA only occur when !park_offline_cpus and system_state is not SYS_STATE_suspend. On ARM64, park_offline_cpus is always false, so setting __per_cpu_offset to INVALID_PERCPU_AREA depends solely on the system state. If the system is suspended, this area is not freed, and during resume, an error occurs in init_percpu_area, causing a crash because INVALID_PERCPU_AREA is not set and park_offline_cpus remains 0: if ( __per_cpu_offset[cpu] != INVALID_PERCPU_AREA ) return park_offline_cpus ? 0 : -EBUSY; The same crash can occur on x86 if park_offline_cpus is set to 0 during Xen resume. Fixes: f75780d26b2f ("xen: move per-cpu area management into common code") Signed-off-by: Mykyta Poturai <mykyta_poturai@xxxxxxxx> Signed-off-by: Mykola Kvach <mykola_kvach@xxxxxxxx> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> --- Changes introduced in V2: - cosmetic fixes after review - chnages in a commit message: add "Fixes" --- xen/common/percpu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/xen/common/percpu.c b/xen/common/percpu.c index e4e8b7bcab..b20f0460fc 100644 --- a/xen/common/percpu.c +++ b/xen/common/percpu.c @@ -30,7 +30,9 @@ static int init_percpu_area(unsigned int cpu) char *p; if ( __per_cpu_offset[cpu] != INVALID_PERCPU_AREA ) - return park_offline_cpus ? 0 : -EBUSY; + return park_offline_cpus || system_state == SYS_STATE_resume + ? 0 + : -EBUSY; if ( (p = alloc_xenheap_pages(PERCPU_ORDER, 0)) == NULL ) return -ENOMEM; -- 2.43.0
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