[PATCH v8] kvm: notify host when the guest is panicked

* [PATCH v8] kvm: notify host when the guest is panicked
@ 2012-08-08  2:43 Wen Congyang
  2012-08-08  2:44 ` [PATCH v8 1/6] start vm after reseting it Wen Congyang
                   ` (7 more replies)
  0 siblings, 8 replies; 34+ messages in thread
From: Wen Congyang @ 2012-08-08  2:43 UTC (permalink / raw)
  To: kvm list, qemu-devel, linux-kernel, Avi Kivity,
	Daniel P. Berrange, KAMEZAWA Hiroyuki, Jan Kiszka, Gleb Natapov

We can know the guest is panicked when the guest runs on xen.
But we do not have such feature on kvm.

Another purpose of this feature is: management app(for example:
libvirt) can do auto dump when the guest is panicked. If management
app does not do auto dump, the guest's user can do dump by hand if
he sees the guest is panicked.

We have three solutions to implement this feature:
1. use vmcall
2. use I/O port
3. use virtio-serial.

We have decided to avoid touching hypervisor. The reason why I choose
choose the I/O port is:
1. it is easier to implememt
2. it does not depend any virtual device
3. it can work when starting the kernel

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 Documentation/virtual/kvm/pv_event.txt |   32 ++++++++++++++++++++++++++++++++
 arch/ia64/include/asm/kvm_para.h       |   14 ++++++++++++++
 arch/powerpc/include/asm/kvm_para.h    |   14 ++++++++++++++
 arch/s390/include/asm/kvm_para.h       |   14 ++++++++++++++
 arch/x86/include/asm/kvm_para.h        |   27 +++++++++++++++++++++++++++
 arch/x86/kernel/kvm.c                  |   25 +++++++++++++++++++++++++
 include/linux/kvm_para.h               |   23 +++++++++++++++++++++++
 7 files changed, 149 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/virtual/kvm/pv_event.txt

diff --git a/Documentation/virtual/kvm/pv_event.txt b/Documentation/virtual/kvm/pv_event.txt
new file mode 100644
index 0000000..0ebc890
--- /dev/null
+++ b/Documentation/virtual/kvm/pv_event.txt
@@ -0,0 +1,32 @@
+The KVM paravirtual event interface
+=================================
+
+Initializing the paravirtual event interface
+======================
+kvm_pv_event_init()
+Argiments:
+	None
+
+Return Value:
+	0 : The guest kernel can't use paravirtual event interface.
+	-1: The guest kernel can use paravirtual event interface.
+
+Querying whether the event can be ejected
+======================
+kvm_pv_has_feature()
+Arguments:
+	feature: The bit value of this paravirtual event to query
+
+Return Value:
+	0: The guest kernel can't eject this paravirtual event.
+	1: The guest kernel can eject this paravirtual event.
+
+
+Ejecting paravirtual event
+======================
+kvm_pv_eject_event()
+Arguments:
+	event: The event to be ejected.
+
+Return Value:
+	None
diff --git a/arch/ia64/include/asm/kvm_para.h b/arch/ia64/include/asm/kvm_para.h
index 2019cb9..b5ec658 100644
--- a/arch/ia64/include/asm/kvm_para.h
+++ b/arch/ia64/include/asm/kvm_para.h
@@ -31,6 +31,20 @@ static inline bool kvm_check_and_clear_guest_paused(void)
 	return false;
 }
 
+static inline int kvm_arch_pv_event_init(void)
+{
+	return 0;
+}
+
+static inline unsigned int kvm_arch_pv_features(void)
+{
+	return 0;
+}
+
+static inline void kvm_arch_pv_eject_event(unsigned int event)
+{
+}
+
 #endif
 
 #endif
diff --git a/arch/powerpc/include/asm/kvm_para.h b/arch/powerpc/include/asm/kvm_para.h
index c18916b..01b98c7 100644
--- a/arch/powerpc/include/asm/kvm_para.h
+++ b/arch/powerpc/include/asm/kvm_para.h
@@ -211,6 +211,20 @@ static inline bool kvm_check_and_clear_guest_paused(void)
 	return false;
 }
 
+static inline int kvm_arch_pv_event_init(void)
+{
+	return 0;
+}
+
+static inline unsigned int kvm_arch_pv_features(void)
+{
+	return 0;
+}
+
+static inline void kvm_arch_pv_eject_event(unsigned int event)
+{
+}
+
 #endif /* __KERNEL__ */
 
 #endif /* __POWERPC_KVM_PARA_H__ */
diff --git a/arch/s390/include/asm/kvm_para.h b/arch/s390/include/asm/kvm_para.h
index da44867..00ce058 100644
--- a/arch/s390/include/asm/kvm_para.h
+++ b/arch/s390/include/asm/kvm_para.h
@@ -154,6 +154,20 @@ static inline bool kvm_check_and_clear_guest_paused(void)
 	return false;
 }
 
+static inline int kvm_arch_pv_event_init(void)
+{
+	return 0;
+}
+
+static inline unsigned int kvm_arch_pv_features(void)
+{
+	return 0;
+}
+
+static inline void kvm_arch_pv_eject_event(unsigned int event)
+{
+}
+
 #endif
 
 #endif /* __S390_KVM_PARA_H */
diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 2f7712e..7d297f0 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -96,8 +96,11 @@ struct kvm_vcpu_pv_apf_data {
 #define KVM_PV_EOI_ENABLED KVM_PV_EOI_MASK
 #define KVM_PV_EOI_DISABLED 0x0
 
+#define KVM_PV_EVENT_PORT	(0x505UL)
+
 #ifdef __KERNEL__
 #include <asm/processor.h>
+#include <linux/ioport.h>
 
 extern void kvmclock_init(void);
 extern int kvm_register_clock(char *txt);
@@ -228,6 +231,30 @@ static inline void kvm_disable_steal_time(void)
 }
 #endif
 
+static inline int kvm_arch_pv_event_init(void)
+{
+	if (!request_region(KVM_PV_EVENT_PORT, 1, "KVM_PV_EVENT"))
+		return -1;
+
+	return 0;
+}
+
+static inline unsigned int kvm_arch_pv_features(void)
+{
+	unsigned int features = inl(KVM_PV_EVENT_PORT);
+
+	/* Reading from an invalid I/O port will return -1 */
+	if (features == ~0)
+		features = 0;
+
+	return features;
+}
+
+static inline void kvm_arch_pv_eject_event(unsigned int event)
+{
+	outl(event, KVM_PV_EVENT_PORT);
+}
+
 #endif /* __KERNEL__ */
 
 #endif /* _ASM_X86_KVM_PARA_H */
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index c1d61ee..6129459 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -368,6 +368,17 @@ static struct notifier_block kvm_pv_reboot_nb = {
 	.notifier_call = kvm_pv_reboot_notify,
 };
 
+static int
+kvm_pv_panic_notify(struct notifier_block *nb, unsigned long code, void *unused)
+{
+	kvm_pv_eject_event(KVM_PV_EVENT_PANICKED);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block kvm_pv_panic_nb = {
+	.notifier_call = kvm_pv_panic_notify,
+};
+
 static u64 kvm_steal_clock(int cpu)
 {
 	u64 steal;
@@ -447,6 +458,20 @@ static void __init kvm_apf_trap_init(void)
 	set_intr_gate(14, &async_page_fault);
 }
 
+static void __init kvm_pv_panicked_event_init(void)
+{
+	if (!kvm_para_available())
+		return;
+
+	if (kvm_pv_event_init())
+		return;
+
+	if (kvm_pv_has_feature(KVM_PV_FEATURE_PANICKED))
+		atomic_notifier_chain_register(&panic_notifier_list,
+			&kvm_pv_panic_nb);
+}
+arch_initcall(kvm_pv_panicked_event_init);
+
 void __init kvm_guest_init(void)
 {
 	int i;
diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h
index ff476dd..8e0fb81 100644
--- a/include/linux/kvm_para.h
+++ b/include/linux/kvm_para.h
@@ -20,6 +20,12 @@
 #define KVM_HC_FEATURES			3
 #define KVM_HC_PPC_MAP_MAGIC_PAGE	4
 
+/* The bit of supported pv event */
+#define KVM_PV_FEATURE_PANICKED	0
+
+/* The pv event value */
+#define KVM_PV_EVENT_PANICKED	1
+
 /*
  * hypercalls use architecture specific
  */
@@ -33,5 +39,22 @@ static inline int kvm_para_has_feature(unsigned int feature)
 		return 1;
 	return 0;
 }
+
+static inline int kvm_pv_event_init(void)
+{
+	return kvm_arch_pv_event_init();
+}
+
+static inline int kvm_pv_has_feature(unsigned int feature)
+{
+	if (kvm_arch_pv_features() & (1UL << feature))
+		return 1;
+	return 0;
+}
+
+static inline void kvm_pv_eject_event(unsigned int event)
+{
+	kvm_arch_pv_eject_event(event);
+}
 #endif /* __KERNEL__ */
 #endif /* __LINUX_KVM_PARA_H */
-- 
1.7.1


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