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ACRN: add monitor-less mwait support to default idle #128

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ACRN: add monitor-less mwait support to default idle #128

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15 changes: 12 additions & 3 deletions arch/x86/kernel/process.c
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Original file line number Diff line number Diff line change
Expand Up @@ -876,16 +876,25 @@ static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c)
*/
static __cpuidle void mwait_idle(void)
{
bool has_monitor_less_mwait;

if (!current_set_polling_and_test()) {
if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) {
mb(); /* quirk */
clflush((void *)&current_thread_info()->flags);
mb(); /* quirk */
}

has_monitor_less_mwait = ((cpuid_ecx(CPUID_MWAIT_LEAF) & CPUID5_ECX_MONITOR_LESS) != 0);
/* CPUID may cause vmexit, which we do not wish to see between monitor/mwait. */
mb();
__monitor((void *)&current_thread_info()->flags, 0, 0);
if (!need_resched())
__sti_mwait(0, 0);
if (!need_resched()) {
if (!hypervisor_is_type(X86_HYPER_NATIVE) && has_monitor_less_mwait) {
current_clr_polling();
__sti_mwait(0, 0x4);
} else
__sti_mwait(0, 0);
}
else
raw_local_irq_enable();
} else {
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