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-rw-r--r--arch/powerpc/include/asm/paravirt.h47
1 files changed, 44 insertions, 3 deletions
diff --git a/arch/powerpc/include/asm/paravirt.h b/arch/powerpc/include/asm/paravirt.h
index e08513d731..ac4279208d 100644
--- a/arch/powerpc/include/asm/paravirt.h
+++ b/arch/powerpc/include/asm/paravirt.h
@@ -71,6 +71,11 @@ static inline void yield_to_any(void)
{
plpar_hcall_norets_notrace(H_CONFER, -1, 0);
}
+
+static inline bool is_vcpu_idle(int vcpu)
+{
+ return lppaca_of(vcpu).idle;
+}
#else
static inline bool is_shared_processor(void)
{
@@ -100,6 +105,10 @@ static inline void prod_cpu(int cpu)
___bad_prod_cpu(); /* This would be a bug */
}
+static inline bool is_vcpu_idle(int vcpu)
+{
+ return false;
+}
#endif
#define vcpu_is_preempted vcpu_is_preempted
@@ -121,9 +130,23 @@ static inline bool vcpu_is_preempted(int cpu)
if (!is_shared_processor())
return false;
+ /*
+ * If the hypervisor has dispatched the target CPU on a physical
+ * processor, then the target CPU is definitely not preempted.
+ */
+ if (!(yield_count_of(cpu) & 1))
+ return false;
+
+ /*
+ * If the target CPU has yielded to Hypervisor but OS has not
+ * requested idle then the target CPU is definitely preempted.
+ */
+ if (!is_vcpu_idle(cpu))
+ return true;
+
#ifdef CONFIG_PPC_SPLPAR
if (!is_kvm_guest()) {
- int first_cpu;
+ int first_cpu, i;
/*
* The result of vcpu_is_preempted() is used in a
@@ -149,11 +172,29 @@ static inline bool vcpu_is_preempted(int cpu)
*/
if (cpu_first_thread_sibling(cpu) == first_cpu)
return false;
+
+ /*
+ * If any of the threads of the target CPU's core are not
+ * preempted or ceded, then consider target CPU to be
+ * non-preempted.
+ */
+ first_cpu = cpu_first_thread_sibling(cpu);
+ for (i = first_cpu; i < first_cpu + threads_per_core; i++) {
+ if (i == cpu)
+ continue;
+ if (!(yield_count_of(i) & 1))
+ return false;
+ if (!is_vcpu_idle(i))
+ return true;
+ }
}
#endif
- if (yield_count_of(cpu) & 1)
- return true;
+ /*
+ * None of the threads in target CPU's core are running but none of
+ * them were preempted too. Hence assume the target CPU to be
+ * non-preempted.
+ */
return false;
}