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Message-ID: <4F4C6596.8020903@cn.fujitsu.com>
Date: Tue, 28 Feb 2012 13:26:46 +0800
From: Wen Congyang <wency@...fujitsu.com>
To: Jan Kiszka <jan.kiszka@...mens.com>
CC: kvm list <kvm@...r.kernel.org>, Avi Kivity <avi@...hat.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
"Daniel P. Berrange" <berrange@...hat.com>,
linux-kernel@...r.kernel.org, qemu-devel <qemu-devel@...gnu.org>
Subject: Re: [PATCH] kvm: notify host when guest paniced
At 02/27/2012 11:08 PM, Jan Kiszka Wrote:
> On 2012-02-27 04:01, Wen Congyang wrote:
>> We can know the guest is paniced when the guest runs on xen.
>> But we do not have such feature on kvm. This patch implemnts
>> this feature, and the implementation is the same as xen:
>> register panic notifier, and call hypercall when the guest
>> is paniced.
>>
>> Signed-off-by: Wen Congyang <wency@...fujitsu.com>
>> ---
>> arch/x86/kernel/kvm.c | 12 ++++++++++++
>> arch/x86/kvm/svm.c | 8 ++++++--
>> arch/x86/kvm/vmx.c | 8 ++++++--
>> arch/x86/kvm/x86.c | 13 +++++++++++--
>> include/linux/kvm.h | 1 +
>> include/linux/kvm_para.h | 1 +
>> 6 files changed, 37 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
>> index f0c6fd6..b928d1d 100644
>> --- a/arch/x86/kernel/kvm.c
>> +++ b/arch/x86/kernel/kvm.c
>> @@ -331,6 +331,17 @@ 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_hypercall0(KVM_HC_GUEST_PANIC);
>> + return NOTIFY_DONE;
>> +}
>> +
>> +static struct notifier_block kvm_pv_panic_nb = {
>> + .notifier_call = kvm_pv_panic_notify,
>> +};
>> +
>
> You should split up host and guest-side changes.
OK
>
>> static u64 kvm_steal_clock(int cpu)
>> {
>> u64 steal;
>> @@ -417,6 +428,7 @@ void __init kvm_guest_init(void)
>>
>> paravirt_ops_setup();
>> register_reboot_notifier(&kvm_pv_reboot_nb);
>> + 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/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
>> index 0b7690e..38b4705 100644
>> --- a/arch/x86/kvm/svm.c
>> +++ b/arch/x86/kvm/svm.c
>> @@ -1900,10 +1900,14 @@ static int halt_interception(struct vcpu_svm *svm)
>>
>> static int vmmcall_interception(struct vcpu_svm *svm)
>> {
>> + int ret;
>> +
>> svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
>> skip_emulated_instruction(&svm->vcpu);
>> - kvm_emulate_hypercall(&svm->vcpu);
>> - return 1;
>> + ret = kvm_emulate_hypercall(&svm->vcpu);
>> +
>> + /* Ignore the error? */
>> + return ret == 0 ? 0 : 1;
>
> Why can't kvm_emulate_hypercall return the right value?
Because before this patch, kvm always ignores the error.
After rereading the code, kvm_emulate_hypercall() will return -KVM_EPERM
when vcpu's CPL is not 0. I think we should deal with this exception
in kvm_emulate_hypercall(), and return 1. But I donot know
how to do it. kvm_queue_exception(vcpu, UD_VECTOR)?
>
>> }
>>
>> static unsigned long nested_svm_get_tdp_cr3(struct kvm_vcpu *vcpu)
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index 66147ca..1b57ebb 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -4582,9 +4582,13 @@ static int handle_halt(struct kvm_vcpu *vcpu)
>>
>> static int handle_vmcall(struct kvm_vcpu *vcpu)
>> {
>> + int ret;
>> +
>> skip_emulated_instruction(vcpu);
>> - kvm_emulate_hypercall(vcpu);
>> - return 1;
>> + ret = kvm_emulate_hypercall(vcpu);
>> +
>> + /* Ignore the error? */
>> + return ret == 0 ? 0 : 1;
>> }
>>
>> static int handle_invd(struct kvm_vcpu *vcpu)
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index c9d99e5..3fc2853 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -4923,7 +4923,7 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
>> u64 param, ingpa, outgpa, ret;
>> uint16_t code, rep_idx, rep_cnt, res = HV_STATUS_SUCCESS, rep_done = 0;
>> bool fast, longmode;
>> - int cs_db, cs_l;
>> + int cs_db, cs_l, r = 1;
>>
>> /*
>> * hypercall generates UD from non zero cpl and real mode
>> @@ -4964,6 +4964,10 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
>> case HV_X64_HV_NOTIFY_LONG_SPIN_WAIT:
>> kvm_vcpu_on_spin(vcpu);
>> break;
>> + case KVM_HC_GUEST_PANIC:
>> + vcpu->run->exit_reason = KVM_EXIT_GUEST_PANIC;
>> + r = 0;
>> + break;
>
> That's the wrong place. This is a KVM hypercall, not a HyperV one.
OK, I will remove it.
Thanks
Wen Congyang
>
>> default:
>> res = HV_STATUS_INVALID_HYPERCALL_CODE;
>> break;
>> @@ -4977,7 +4981,7 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
>> kvm_register_write(vcpu, VCPU_REGS_RAX, ret & 0xffffffff);
>> }
>>
>> - return 1;
>> + return r;
>> }
>>
>> int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
>> @@ -5013,6 +5017,11 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
>> case KVM_HC_VAPIC_POLL_IRQ:
>> ret = 0;
>> break;
>> + case KVM_HC_GUEST_PANIC:
>> + ret = 0;
>> + vcpu->run->exit_reason = KVM_EXIT_GUEST_PANIC;
>> + r = 0;
>> + break;
>> default:
>> ret = -KVM_ENOSYS;
>> break;
>> diff --git a/include/linux/kvm.h b/include/linux/kvm.h
>> index acbe429..8f0e31b 100644
>> --- a/include/linux/kvm.h
>> +++ b/include/linux/kvm.h
>> @@ -163,6 +163,7 @@ struct kvm_pit_config {
>> #define KVM_EXIT_OSI 18
>> #define KVM_EXIT_PAPR_HCALL 19
>> #define KVM_EXIT_S390_UCONTROL 20
>> +#define KVM_EXIT_GUEST_PANIC 21
>>
>> /* For KVM_EXIT_INTERNAL_ERROR */
>> #define KVM_INTERNAL_ERROR_EMULATION 1
>> diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h
>> index ff476dd..cf94023 100644
>> --- a/include/linux/kvm_para.h
>> +++ b/include/linux/kvm_para.h
>> @@ -19,6 +19,7 @@
>> #define KVM_HC_MMU_OP 2
>> #define KVM_HC_FEATURES 3
>> #define KVM_HC_PPC_MAP_MAGIC_PAGE 4
>> +#define KVM_HC_GUEST_PANIC 5
>>
>> /*
>> * hypercalls use architecture specific
>
> Jan
>
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