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Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/kernel/paravirt.c29
1 files changed, 21 insertions, 8 deletions
diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
index 75fed4460407..57c7c211f8c7 100644
--- a/arch/arm64/kernel/paravirt.c
+++ b/arch/arm64/kernel/paravirt.c
@@ -35,7 +35,7 @@ static u64 native_steal_clock(int cpu)
DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);
struct pv_time_stolen_time_region {
- struct pvclock_vcpu_stolen_time *kaddr;
+ struct pvclock_vcpu_stolen_time __rcu *kaddr;
};
static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region);
@@ -52,7 +52,9 @@ early_param("no-steal-acc", parse_no_stealacc);
/* return stolen time in ns by asking the hypervisor */
static u64 para_steal_clock(int cpu)
{
+ struct pvclock_vcpu_stolen_time *kaddr = NULL;
struct pv_time_stolen_time_region *reg;
+ u64 ret = 0;
reg = per_cpu_ptr(&stolen_time_region, cpu);
@@ -61,28 +63,37 @@ static u64 para_steal_clock(int cpu)
* online notification callback runs. Until the callback
* has run we just return zero.
*/
- if (!reg->kaddr)
+ rcu_read_lock();
+ kaddr = rcu_dereference(reg->kaddr);
+ if (!kaddr) {
+ rcu_read_unlock();
return 0;
+ }
- return le64_to_cpu(READ_ONCE(reg->kaddr->stolen_time));
+ ret = le64_to_cpu(READ_ONCE(kaddr->stolen_time));
+ rcu_read_unlock();
+ return ret;
}
static int stolen_time_cpu_down_prepare(unsigned int cpu)
{
+ struct pvclock_vcpu_stolen_time *kaddr = NULL;
struct pv_time_stolen_time_region *reg;
reg = this_cpu_ptr(&stolen_time_region);
if (!reg->kaddr)
return 0;
- memunmap(reg->kaddr);
- memset(reg, 0, sizeof(*reg));
+ kaddr = rcu_replace_pointer(reg->kaddr, NULL, true);
+ synchronize_rcu();
+ memunmap(kaddr);
return 0;
}
static int stolen_time_cpu_online(unsigned int cpu)
{
+ struct pvclock_vcpu_stolen_time *kaddr = NULL;
struct pv_time_stolen_time_region *reg;
struct arm_smccc_res res;
@@ -93,17 +104,19 @@ static int stolen_time_cpu_online(unsigned int cpu)
if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
return -EINVAL;
- reg->kaddr = memremap(res.a0,
+ kaddr = memremap(res.a0,
sizeof(struct pvclock_vcpu_stolen_time),
MEMREMAP_WB);
+ rcu_assign_pointer(reg->kaddr, kaddr);
+
if (!reg->kaddr) {
pr_warn("Failed to map stolen time data structure\n");
return -ENOMEM;
}
- if (le32_to_cpu(reg->kaddr->revision) != 0 ||
- le32_to_cpu(reg->kaddr->attributes) != 0) {
+ if (le32_to_cpu(kaddr->revision) != 0 ||
+ le32_to_cpu(kaddr->attributes) != 0) {
pr_warn_once("Unexpected revision or attributes in stolen time data\n");
return -ENXIO;
}