From cb3042d609e30e6144024801c89be3925106752b Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Mon, 24 Mar 2014 14:45:12 -0400 Subject: [PATCH] sparc64: Make sure %pil interrupts are enabled during hypervisor yield. In arch_cpu_idle() we must enable %pil based interrupts before potentially invoking the hypervisor cpu yield call. As per the Hypervisor API documentation for cpu_yield: Interrupts which are blocked by some mechanism other that pstate.ie (for example %pil) are not guaranteed to cause a return from this service. It seems that only first generation Niagara chips are hit by this bug. My best guess is that later chips implement this in hardware and wake up anyways from %pil events, whereas in first generation chips the yield is implemented completely in hypervisor code and requires %pil to be enabled in order to wake properly from this call. Fixes: 87fa05aeb3a5 ("sparc: Use generic idle loop") Reported-by: Fabio M. Di Nitto Reported-by: Jan Engelhardt Tested-by: Jan Engelhardt Signed-off-by: David S. Miller --- arch/sparc/kernel/process_64.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c index 32a280e..d7b4967 100644 --- a/arch/sparc/kernel/process_64.c +++ b/arch/sparc/kernel/process_64.c @@ -58,9 +58,12 @@ void arch_cpu_idle(void) { if (tlb_type != hypervisor) { touch_nmi_watchdog(); + local_irq_enable(); } else { unsigned long pstate; + local_irq_enable(); + /* The sun4v sleeping code requires that we have PSTATE.IE cleared over * the cpu sleep hypervisor call. */ @@ -82,7 +85,6 @@ void arch_cpu_idle(void) : "=&r" (pstate) : "i" (PSTATE_IE)); } - local_irq_enable(); } #ifdef CONFIG_HOTPLUG_CPU -- 2.7.4