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authorKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2011-11-21 18:02:02 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2011-12-03 10:49:58 -0800
commite5fd47bfab2df0c2184cc0bf4245d8e1bb7724fb (patch)
tree7651116728e2d69a7a8362cf88c80761919b971b /arch/x86
parentaf968e29acd91ebeb4224e899202c46c93171ecd (diff)
xen/pm_idle: Make pm_idle be default_idle under Xen.
The idea behind commit d91ee5863b71 ("cpuidle: replace xen access to x86 pm_idle and default_idle") was to have one call - disable_cpuidle() which would make pm_idle not be molested by other code. It disallows cpuidle_idle_call to be set to pm_idle (which is excellent). But in the select_idle_routine() and idle_setup(), the pm_idle can still be set to either: amd_e400_idle, mwait_idle or default_idle. This depends on some CPU flags (MWAIT) and in AMD case on the type of CPU. In case of mwait_idle we can hit some instances where the hypervisor (Amazon EC2 specifically) sets the MWAIT and we get: Brought up 2 CPUs invalid opcode: 0000 [#1] SMP Pid: 0, comm: swapper Not tainted 3.1.0-0.rc6.git0.3.fc16.x86_64 #1 RIP: e030:[<ffffffff81015d1d>] [<ffffffff81015d1d>] mwait_idle+0x6f/0xb4 ... Call Trace: [<ffffffff8100e2ed>] cpu_idle+0xae/0xe8 [<ffffffff8149ee78>] cpu_bringup_and_idle+0xe/0x10 RIP [<ffffffff81015d1d>] mwait_idle+0x6f/0xb4 RSP <ffff8801d28ddf10> In the case of amd_e400_idle we don't get so spectacular crashes, but we do end up making an MSR which is trapped in the hypervisor, and then follow it up with a yield hypercall. Meaning we end up going to hypervisor twice instead of just once. The previous behavior before v3.0 was that pm_idle was set to default_idle regardless of select_idle_routine/idle_setup. We want to do that, but only for one specific case: Xen. This patch does that. Fixes RH BZ #739499 and Ubuntu #881076 Reported-by: Stefan Bader <stefan.bader@canonical.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/include/asm/system.h1
-rw-r--r--arch/x86/kernel/process.c8
-rw-r--r--arch/x86/xen/setup.c2
3 files changed, 10 insertions, 1 deletions
diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.h
index c2ff2a1d845..2d2f01ce6dc 100644
--- a/arch/x86/include/asm/system.h
+++ b/arch/x86/include/asm/system.h
@@ -401,6 +401,7 @@ extern unsigned long arch_align_stack(unsigned long sp);
extern void free_init_pages(char *what, unsigned long begin, unsigned long end);
void default_idle(void);
+bool set_pm_idle_to_default(void);
void stop_this_cpu(void *dummy);
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index b9b3b1a5164..ee5d4fbd53b 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -403,6 +403,14 @@ void default_idle(void)
EXPORT_SYMBOL(default_idle);
#endif
+bool set_pm_idle_to_default(void)
+{
+ bool ret = !!pm_idle;
+
+ pm_idle = default_idle;
+
+ return ret;
+}
void stop_this_cpu(void *dummy)
{
local_irq_disable();
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 38d0af4fefe..1093f80c162 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -410,6 +410,6 @@ void __init xen_arch_setup(void)
#endif
disable_cpuidle();
boot_option_idle_override = IDLE_HALT;
-
+ WARN_ON(set_pm_idle_to_default());
fiddle_vdso();
}