On Tue, Nov 29, 2011 at 07:34:28PM +0100, Borislav Petkov wrote:
> On Tue, Nov 29, 2011 at 01:04:14PM -0500, Konrad Rzeszutek Wilk wrote:
> > This patch:
Borislav,
Thanks for your review comments. How does this patch look? I believe
I touched upon all of the things you mentioned.
>From eb6dbd80078312c428dde69e9313606b7513a2e6 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Mon, 21 Nov 2011 18:02:02 -0500
Subject: [PATCH] xen/pm_idle: Make pm_idle be default_idle under Xen.
This patch:
commit d91ee5863b71e8c90eaf6035bff3078a85e2e7b5
Author: Len Brown <len.brown@xxxxxxxxx>
Date: Fri Apr 1 18:28:35 2011 -0400
cpuidle: replace xen access to x86 pm_idle and default_idle
..scribble on pm_idle and access default_idle,
have it simply disable_cpuidle() so acpi_idle will not load and
architecture default HLT will be used.
idea 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
CPU 1
Modules linked in:
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
RSP: e02b:ffff8801d28ddf10 EFLAGS: 00010082
RAX: ffff8801d28dc010 RBX: ffff8801d28ddfd8 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: ffff8801d28ddf10 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000001 R11: ffff8801d28ddfd8 R12: ffffffff81b590d0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8801dff81000(0000) knlGS:0000000000000000
CS: e033 DS: 002b ES: 002b CR0: 000000008005003b
CR2: 0000000000000000 CR3: 0000000001a05000 CR4: 0000000000002660
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000000
Process swapper (pid: 0, threadinfo ffff8801d28dc000, task ffff8801d28cae60)
Stack:
ffff8801d28ddf40 ffffffff8100e2ed ffff8801dff8e390 c136dfe72feab515
0000000000000000 0000000000000000 ffff8801d28ddf50 ffffffff8149ee78
0000000000000000 0000000000000000 0000000000000000 0000000000000000
Call Trace:
[<ffffffff8100e2ed>] cpu_idle+0xae/0xe8
[<ffffffff8149ee78>] cpu_bringup_and_idle+0xe/0x10
RIP [<ffffffff81015d1d>] mwait_idle+0x6f/0xb4
RSP <ffff8801d28ddf10>
In 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 irregardless 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@xxxxxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
arch/x86/include/asm/system.h | 1 +
arch/x86/kernel/process.c | 8 ++++++++
arch/x86/xen/setup.c | 2 +-
3 files changed, 10 insertions(+), 1 deletions(-)
diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.h
index c2ff2a1..2d2f01c 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 1f7f8c8..31f47ba 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -404,6 +404,14 @@ 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 46d6d21..79dfb57 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -448,6 +448,6 @@ void __init xen_arch_setup(void)
#endif
disable_cpuidle();
boot_option_idle_override = IDLE_HALT;
-
+ WARN_ON(set_pm_idle_to_default());
fiddle_vdso();
}
--
1.7.7.3
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