diff options
| author | Andrew Jones | 2020-09-16 17:45:30 +0200 |
|---|---|---|
| committer | Catalin Marinas | 2020-09-17 18:12:18 +0100 |
| commit | 75df529bec9110dad43ab30e2d9490242529e8b8 (patch) | |
| tree | d27d37d398bccf17dee37ef7d5b42069f0406bfa /arch/arm64 | |
| parent | 32f6865c7aa3c422f710903baa6eb81abc6f559b (diff) | |
arm64: paravirt: Initialize steal time when cpu is online
Steal time initialization requires mapping a memory region which
invokes a memory allocation. Doing this at CPU starting time results
in the following trace when CONFIG_DEBUG_ATOMIC_SLEEP is enabled:
BUG: sleeping function called from invalid context at mm/slab.h:498
in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.9.0-rc5+ #1
Call trace:
dump_backtrace+0x0/0x208
show_stack+0x1c/0x28
dump_stack+0xc4/0x11c
___might_sleep+0xf8/0x130
__might_sleep+0x58/0x90
slab_pre_alloc_hook.constprop.101+0xd0/0x118
kmem_cache_alloc_node_trace+0x84/0x270
__get_vm_area_node+0x88/0x210
get_vm_area_caller+0x38/0x40
__ioremap_caller+0x70/0xf8
ioremap_cache+0x78/0xb0
memremap+0x9c/0x1a8
init_stolen_time_cpu+0x54/0xf0
cpuhp_invoke_callback+0xa8/0x720
notify_cpu_starting+0xc8/0xd8
secondary_start_kernel+0x114/0x180
CPU1: Booted secondary processor 0x0000000001 [0x431f0a11]
However we don't need to initialize steal time at CPU starting time.
We can simply wait until CPU online time, just sacrificing a bit of
accuracy by returning zero for steal time until we know better.
While at it, add __init to the functions that are only called by
pv_time_init() which is __init.
Signed-off-by: Andrew Jones <drjones@redhat.com>
Fixes: e0685fa228fd ("arm64: Retrieve stolen time as paravirtualized guest")
Cc: stable@vger.kernel.org
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://lore.kernel.org/r/20200916154530.40809-1-drjones@redhat.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64')
| -rw-r--r-- | arch/arm64/kernel/paravirt.c | 26 |
1 files changed, 15 insertions, 11 deletions
diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c index 295d66490584..c07d7a034941 100644 --- a/arch/arm64/kernel/paravirt.c +++ b/arch/arm64/kernel/paravirt.c @@ -50,16 +50,19 @@ static u64 pv_steal_clock(int cpu) struct pv_time_stolen_time_region *reg; reg = per_cpu_ptr(&stolen_time_region, cpu); - if (!reg->kaddr) { - pr_warn_once("stolen time enabled but not configured for cpu %d\n", - cpu); + + /* + * paravirt_steal_clock() may be called before the CPU + * online notification callback runs. Until the callback + * has run we just return zero. + */ + if (!reg->kaddr) return 0; - } return le64_to_cpu(READ_ONCE(reg->kaddr->stolen_time)); } -static int stolen_time_dying_cpu(unsigned int cpu) +static int stolen_time_cpu_down_prepare(unsigned int cpu) { struct pv_time_stolen_time_region *reg; @@ -73,7 +76,7 @@ static int stolen_time_dying_cpu(unsigned int cpu) return 0; } -static int init_stolen_time_cpu(unsigned int cpu) +static int stolen_time_cpu_online(unsigned int cpu) { struct pv_time_stolen_time_region *reg; struct arm_smccc_res res; @@ -103,19 +106,20 @@ static int init_stolen_time_cpu(unsigned int cpu) return 0; } -static int pv_time_init_stolen_time(void) +static int __init pv_time_init_stolen_time(void) { int ret; - ret = cpuhp_setup_state(CPUHP_AP_ARM_KVMPV_STARTING, - "hypervisor/arm/pvtime:starting", - init_stolen_time_cpu, stolen_time_dying_cpu); + ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, + "hypervisor/arm/pvtime:online", + stolen_time_cpu_online, + stolen_time_cpu_down_prepare); if (ret < 0) return ret; return 0; } -static bool has_pv_steal_clock(void) +static bool __init has_pv_steal_clock(void) { struct arm_smccc_res res; |