From: "Jan Beulich" <JBeulich@suse.com>
To: "xen-devel" <xen-devel@lists.xenproject.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
Wei Liu <wei.liu2@citrix.com>,
Roger Pau Monne <roger.pau@citrix.com>
Subject: [Xen-devel] [PATCH v2 1/3] x86/idle: re-arrange dead-idle handling
Date: Fri, 17 May 2019 04:11:54 -0600 [thread overview]
Message-ID: <5CDE88EA0200007800230031@prv1-mh.provo.novell.com> (raw)
Message-ID: <20190517101154.KC7yZDQNjd1azwPqGSLz4RvHuPY4fZYnHUaX_Hp3aDE@z> (raw)
In-Reply-To: <5CDE88900200007800230027@prv1-mh.provo.novell.com>
In order to be able to wake parked CPUs from default_dead_idle() (for
them to then enter a different dead-idle routine), the function should
not itself loop. Move the loop into play_dead(), and use play_dead() as
well on the AP boot error path.
Furthermore, not the least considering the comment in play_dead(),
make sure NMI raised (for now this would be a bug elsewhere, but that's
about to change) against a parked or fully offline CPU won't invoke the
actual, full-blown NMI handler.
Note however that this doesn't make #MC any safer for fully offline
CPUs.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v2: Add spec_ctrl_exit_idle() to default_dead_idle(). Add #MC related
remark to description.
---
Note: I had to drop the discussed acpi_dead_idle() adjustment again, as
it breaks booting with "smt=0" and "maxcpus=" on at least one of
my systems. I've not yet managed to understand why that would be.
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -100,14 +100,20 @@ void default_dead_idle(void)
*/
spec_ctrl_enter_idle(get_cpu_info());
wbinvd();
- for ( ; ; )
- halt();
+ halt();
+ spec_ctrl_exit_idle(get_cpu_info());
}
-static void play_dead(void)
+void play_dead(void)
{
+ unsigned int cpu = smp_processor_id();
+
local_irq_disable();
+ /* Change the NMI handler to a nop (see comment below). */
+ _set_gate_lower(&idt_tables[cpu][TRAP_nmi], SYS_DESC_irq_gate, 0,
+ &trap_nop);
+
/*
* NOTE: After cpu_exit_clear, per-cpu variables may no longer accessible,
* as they may be freed at any time if offline CPUs don't get parked. In
@@ -118,9 +124,10 @@ static void play_dead(void)
* Consider very carefully when adding code to *dead_idle. Most hypervisor
* subsystems are unsafe to call.
*/
- cpu_exit_clear(smp_processor_id());
+ cpu_exit_clear(cpu);
- (*dead_idle)();
+ for ( ; ; )
+ dead_idle();
}
static void idle_loop(void)
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -33,6 +33,7 @@
#include <xen/serial.h>
#include <xen/numa.h>
#include <xen/cpu.h>
+#include <asm/cpuidle.h>
#include <asm/current.h>
#include <asm/mc146818rtc.h>
#include <asm/desc.h>
@@ -209,8 +210,7 @@ static void smp_callin(void)
halt:
clear_local_APIC();
spin_debug_enable();
- cpu_exit_clear(cpu);
- (*dead_idle)();
+ play_dead();
}
/* Allow the master to continue. */
--- a/xen/include/asm-x86/cpuidle.h
+++ b/xen/include/asm-x86/cpuidle.h
@@ -20,6 +20,7 @@ int mwait_idle_init(struct notifier_bloc
int cpuidle_init_cpu(unsigned int cpu);
void default_dead_idle(void);
void acpi_dead_idle(void);
+void play_dead(void);
void trace_exit_reason(u32 *irq_traced);
void update_idle_stats(struct acpi_processor_power *,
struct acpi_processor_cx *, uint64_t, uint64_t);
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next prev parent reply other threads:[~2019-05-17 10:12 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-01 14:22 [PATCH 0/5] x86: more power-efficient CPU parking Jan Beulich
2018-08-01 14:31 ` [PATCH 1/5] x86/cpuidle: replace a pointless NULL check Jan Beulich
2018-08-01 14:33 ` Andrew Cooper
2018-08-01 15:12 ` Jan Beulich
2018-08-01 14:31 ` [PATCH 2/5] x86/idle: re-arrange dead-idle handling Jan Beulich
2018-09-07 17:08 ` Andrew Cooper
2018-09-10 10:13 ` Jan Beulich
2018-10-26 10:55 ` Ping: " Jan Beulich
2018-12-05 20:33 ` Andrew Cooper
2018-12-06 8:16 ` Jan Beulich
2018-08-01 14:32 ` [PATCH 3/5] x86/cpuidle: push parked CPUs into deeper sleep states when possible Jan Beulich
2018-10-26 10:56 ` Ping: " Jan Beulich
2018-08-01 14:33 ` [PATCH 4/5] x86/cpuidle: clean up Cx dumping Jan Beulich
2018-08-01 14:40 ` Andrew Cooper
2018-08-01 14:33 ` [PATCH 5/5] x86: place non-parked CPUs into wait-for-SIPI state after offlining Jan Beulich
2018-08-29 7:08 ` Ping: [PATCH 0/5] x86: more power-efficient CPU parking Jan Beulich
2018-08-29 17:01 ` Andrew Cooper
2018-08-30 7:29 ` Jan Beulich
[not found] ` <5B61C21202000000000FC1F1@prv1-mh.provo.novell.com>
[not found] ` <5B61C21202000078001F8805@prv1-mh.provo.novell.com>
[not found] ` <5B61C21202000000000FC6BD@prv1-mh.provo.novell.com>
[not found] ` <5B61C212020000780020B6D8@prv1-mh.provo.novell.com>
[not found] ` <5B61C21202000000000FF27E@prv1-mh.provo.novell.com>
[not found] ` <5B61C2120200007800224310@prv1-mh.provo.novell.com>
2019-04-03 10:12 ` Jan Beulich
2019-04-03 11:14 ` Andrew Cooper
2019-04-03 12:43 ` Jan Beulich
2019-04-03 14:44 ` Andrew Cooper
2019-04-03 15:20 ` Jan Beulich
[not found] ` <5B61C2120200000000101EDC@prv1-mh.provo.novell.com>
[not found] ` <5B61C212020000780022FF0D@prv1-mh.provo.novell.com>
2019-05-17 10:10 ` [PATCH v2 0/3] " Jan Beulich
2019-05-17 10:10 ` [Xen-devel] " Jan Beulich
2019-05-17 10:11 ` Jan Beulich [this message]
2019-05-17 10:11 ` [Xen-devel] [PATCH v2 1/3] x86/idle: re-arrange dead-idle handling Jan Beulich
2019-05-20 14:25 ` Andrew Cooper
2019-05-20 14:25 ` [Xen-devel] " Andrew Cooper
2019-05-17 10:12 ` [PATCH v2 2/3] x86/cpuidle: push parked CPUs into deeper sleep states when possible Jan Beulich
2019-05-17 10:12 ` [Xen-devel] " Jan Beulich
2019-05-17 10:12 ` [PATCH v2 3/3] x86/cpuidle: clean up Cx dumping Jan Beulich
2019-05-17 10:12 ` [Xen-devel] " Jan Beulich
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