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Date: Sat, 21 Jul 2012 09:19:41 +0200
From: Jan Kiszka <jan.kiszka@....de>
To: Wen Congyang <wency@...fujitsu.com>
CC: kvm list <kvm@...r.kernel.org>, qemu-devel <qemu-devel@...gnu.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Avi Kivity <avi@...hat.com>,
"Daniel P. Berrange" <berrange@...hat.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
Gleb Natapov <gleb@...hat.com>
Subject: Re: [PATCH v7] kvm: notify host when the guest is panicked
On 2012-07-21 09:12, Wen Congyang wrote:
> 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 startint the kernel
>
> Signed-off-by: Wen Congyang <wency@...fujitsu.com>
> ---
> arch/ia64/include/asm/kvm_para.h | 5 +++++
> arch/powerpc/include/asm/kvm_para.h | 5 +++++
> arch/s390/include/asm/kvm_para.h | 5 +++++
> arch/x86/include/asm/kvm_para.h | 7 +++++++
> arch/x86/kernel/kvm.c | 14 ++++++++++++++
> include/linux/kvm_para.h | 13 +++++++++++++
> 6 files changed, 49 insertions(+), 0 deletions(-)
>
> diff --git a/arch/ia64/include/asm/kvm_para.h b/arch/ia64/include/asm/kvm_para.h
> index 2019cb9..187c0e2 100644
> --- a/arch/ia64/include/asm/kvm_para.h
> +++ b/arch/ia64/include/asm/kvm_para.h
> @@ -31,6 +31,11 @@ static inline bool kvm_check_and_clear_guest_paused(void)
> return false;
> }
>
> +static inline unsigned int kvm_arch_pv_features(void)
> +{
> + return 0;
> +}
> +
> #endif
>
> #endif
> diff --git a/arch/powerpc/include/asm/kvm_para.h b/arch/powerpc/include/asm/kvm_para.h
> index c18916b..be81aac 100644
> --- a/arch/powerpc/include/asm/kvm_para.h
> +++ b/arch/powerpc/include/asm/kvm_para.h
> @@ -211,6 +211,11 @@ static inline bool kvm_check_and_clear_guest_paused(void)
> return false;
> }
>
> +static inline unsigned int kvm_arch_pv_features(void)
> +{
> + return 0;
> +}
> +
> #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 a988329..3d993b7 100644
> --- a/arch/s390/include/asm/kvm_para.h
> +++ b/arch/s390/include/asm/kvm_para.h
> @@ -154,6 +154,11 @@ static inline bool kvm_check_and_clear_guest_paused(void)
> return false;
> }
>
> +static inline unsigned int kvm_arch_pv_features(void)
> +{
> + return 0;
> +}
> +
> #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 63ab166..c8ad86e 100644
> --- a/arch/x86/include/asm/kvm_para.h
> +++ b/arch/x86/include/asm/kvm_para.h
> @@ -89,6 +89,8 @@ struct kvm_vcpu_pv_apf_data {
> __u32 enabled;
> };
>
> +#define KVM_PV_PORT (0x505UL)
> +
> #ifdef __KERNEL__
> #include <asm/processor.h>
>
> @@ -221,6 +223,11 @@ static inline void kvm_disable_steal_time(void)
> }
> #endif
>
> +static inline unsigned int kvm_arch_pv_features(void)
> +{
> + return inl(KVM_PV_PORT);
> +}
> +
> #endif /* __KERNEL__ */
>
> #endif /* _ASM_X86_KVM_PARA_H */
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index e554e5a..9a97f7e 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -328,6 +328,17 @@ 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)
> +{
> + outl(KVM_PV_PANICKED, KVM_PV_PORT);
> + 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;
> @@ -414,6 +425,9 @@ void __init kvm_guest_init(void)
>
> paravirt_ops_setup();
> register_reboot_notifier(&kvm_pv_reboot_nb);
> + if (kvm_pv_has_feature(KVM_PV_FEATURE_PANICKED))
> + atomic_notifier_chain_register(&panic_notifier_list,
> + &kvm_pv_panic_nb);
> for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
> spin_lock_init(&async_pf_sleepers[i].lock);
> if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
> diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h
> index ff476dd..e73efcf 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 the value read from KVM_PV_PORT */
> +#define KVM_PV_FEATURE_PANICKED 0
> +
> +/* The value writen to KVM_PV_PORT */
> +#define KVM_PV_PANICKED 1
> +
> /*
> * hypercalls use architecture specific
> */
> @@ -33,5 +39,12 @@ static inline int kvm_para_has_feature(unsigned int feature)
> return 1;
> return 0;
> }
> +
> +static inline int kvm_pv_has_feature(unsigned int feature)
> +{
> + if (kvm_arch_pv_features() & (1UL << feature))
Reading from an invalid I/O port will return -1. So your test will
deliver a wrong result on a platform that doesn't support this PV channel.
Jan
> + return 1;
> + return 0;
> +}
> #endif /* __KERNEL__ */
> #endif /* __LINUX_KVM_PARA_H */
>
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