summaryrefslogtreecommitdiff
path: root/arch
diff options
context:
space:
mode:
authorAndrew Jones <drjones@redhat.com>2020-09-16 17:45:30 +0200
committerCatalin Marinas <catalin.marinas@arm.com>2020-09-17 18:12:18 +0100
commit75df529bec9110dad43ab30e2d9490242529e8b8 (patch)
treed27d37d398bccf17dee37ef7d5b42069f0406bfa /arch
parent32f6865c7aa3c422f710903baa6eb81abc6f559b (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')
-rw-r--r--arch/arm64/kernel/paravirt.c26
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;