Re: Oops after resume from suspend

[Jeremy Katz <katzj-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

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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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