Re: Oops after resume from suspend

Jeremy Katz
2007-01-25T20:09:05Z

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Avi Kivity wrote:
> Jeremy Katz wrote:
>> When using kvm on my laptop, I get the following oops if I try using kvm
>> after a suspend (ACPI S3)/resume cycle. At first I thought it went away
>> if I unloaded the module before suspending and then reloading it
>> afterwards, but I can't reproduce that working now, so I might have just
>> been hallucinating. Thoughts of things to try?
>
> Module unload/reload should work. Can you try adding printks in
> hardware_disable() and hardware_enable()?

Okay, what was going wrong with reloading was the difference between -
and _ with module naming :-/ *sigh* Actually getting the module
unloaded then makes things work fine.

> For real suspend support, we need to flush any cached state on Intel
> cpus (vmcs_clear), and to do the hardware_disable()/hardware_enable()
> cycle. Should be easy.

The obvious approach (attached) fails to resume -- there may be console
output, but hard to tell on my laptop. I'll dig up a box with a serial
port to try there and see if I get something across serial console with it.

Jeremy

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Index: kvm_main.c
===================================================================
--- kvm_main.c (revision 4328)
+++ kvm_main.c (working copy)
@@ -26,6 +26,7 @@
#include <asm/msr.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
+#include <linux/sysdev.h>
#include <linux/vmalloc.h>
#include <asm/uaccess.h>
#include <linux/reboot.h>
@@ -2052,6 +2053,29 @@
.priority = 0,
};

+static int kvm_suspend(struct sys_device *dev, pm_message_t state)
+{
+ on_each_cpu(kvm_arch_ops->hardware_disable, 0, 0, 1);
+ return 0;
+}
+
+static int kvm_resume(struct sys_device *dev)
+{
+ on_each_cpu(kvm_arch_ops->hardware_enable, 0, 0, 1);
+ return 0;
+}
+
+static struct sysdev_class kvm_sysclass = {
+ .resume = kvm_resume,
+ .suspend = kvm_suspend,
+ set_kset_name("kvm"),
+};
+
+static struct sys_device kvm_sysdevice = {
+ .id = 0,
+ .cls = &kvm_sysclass,
+};
+
static __init void kvm_init_debug(void)
{
struct kvm_stats_debugfs_item *p;
@@ -2100,6 +2124,13 @@
on_each_cpu(kvm_arch_ops->hardware_enable, 0, 0, 1);
register_reboot_notifier(&kvm_reboot_notifier);

+ r = sysdev_class_register(&kvm_sysclass);
+ if (r)
+ return r;
+ r = sysdev_register(&kvm_sysdevice);
+ if (r)
+ return r;
+
kvm_chardev_ops.owner = module;

r = misc_register(&kvm_dev);
@@ -2121,6 +2152,9 @@
{
misc_deregister(&kvm_dev);

+ sysdev_unregister(&kvm_sysdevice);
+ sysdev_class_unregister(&kvm_sysclass);
+
unregister_reboot_notifier(&kvm_reboot_notifier);
on_each_cpu(kvm_arch_ops->hardware_disable, 0, 0, 1);
kvm_arch_ops->hardware_unsetup();

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